Sample records for retention mechanisms viscosity

  1. Mobile phase viscosity and velocity dependence on protein retention using nonequilibrium chromatographic techniques. (United States)

    Guillaume, Y C; Thomassin, M; Guinchard, C


    Nonequilibrium chromatography (NEC) is an alternative chromatographic procedure for the separation of macromolecules. The retardation of a protein series is studied using a phosphate buffer as a mobile phase with various concentrations of glycerol fraction (used as a viscosity modifier) at different mobile phase velocities and a C1 column with a very low packing particle diameter as a stationary phase. It is shown that the two factors (viscosity and velocity) of the mobile phase constituted important parameters in the retention mechanism of the proteins in NEC. The retardation velocity domain is divided into two regions. For low velocity regions, the protein retention decreased with a mobile phase velocity increase. This retention is enhanced above a critical value of the mobile phase velocity. The transition between the two well-known NEC methods, slalom chromatography and hydrodynamic chromatography, is clearly visualized for the first time for the protein retention of particular values of the mobile phase velocity.

  2. Oral glucose retention, saliva viscosity and flow rate in 5-year-old children. (United States)

    Negoro, M; Nakagaki, H; Tsuboi, S; Adachi, K; Hanaki, M; Tanaka, D; Takami, Y; Nakano, T; Kuwahara, M; Thuy, T T


    There are significant differences of glucose retention in site-specificity and individuals. Sixty-two 5-year-old nursery schoolchildren participated in this study on the relation between the viscosity of saliva and flow rate and glucose retention. Each child was instructed to rinse his/her mouth with a glucose solution (0.5 M, 5 ml) and then to spit out. Three minutes after rinsing, glucose retention was determined. Resting saliva was collected by a natural outflow method, then the flow rate was determined. A rotational viscometer was used to determine the viscosity. Glucose retention and flow rate were correlated at the left maxillary primary molars, and glucose retention and viscosity were correlated at the maxillary central primary incisors. It was concluded that glucose retention after glucose mouth rinsing was site-specific, and that glucose retention and the index of decayed, missing and filled primary teeth (dmft) were slightly correlated with the salivary viscosity and flow rate.

  3. Correlation between retention force of experimental plates and viscosity of experimental fluids

    Directory of Open Access Journals (Sweden)

    Mladenović Dragan


    Full Text Available Introduction. Saliva viscosity plays a significant role in the biophysical segment of the total retention potential of total dentures. Objective. The aim of the paper was to establish the dependence of dynamic retention force of experimental plates on experimental fluid viscosity and especially time dependence of these parameters, following at the same time relative changes of the distance between the experimental plate and dentures support established by the dislocation of the experimental plate in both directions. Methods. For experimental verification we used an original device with the aim to enable in vivo simulation on the phantom made of the upper total denture prosthesis support and experimental plate. The experiment consisted of two parts. In the first part we determined the value of the dynamic retention force with plates without and with achieved ventilation effect. In the second part we determined time dependence of the dynamic retention force of experimental plates on the viscosity of experimental fluids that had been priorly determined on identical samples (8 ml of experimental fluid samples using a rotational viscometer (Haake RV-12 with a sensor (MV, Germany. Results Under the conditions of variable viscosity rates of seven experimental fluids (from 0.02 to 1309.04 mPa•s, we registered the time dependence of dynamic retention force of the experimental plate related to fluid viscosity during the action of the continual dislocating force of the separating directions. In addition, the maximal height of the dislocation of the experimental plate was registered. The dynamic retention force, manifested by the separating direction of the experimental plate dislocation, was increased concurrently with increased viscosity. Conclusion. The increase of dynamic retention force depends directly on medium viscosity. Close border values of fluid viscosity above the investigated ones, the impossibility of experimental layer thinning and the

  4. Mechanism of viscosity modification in multigrade oils

    Energy Technology Data Exchange (ETDEWEB)

    Song, W.R.


    Multigrade motor oil viscosity modifiers such as acrylates, polyisobutylene, and olefin copolymers were examined to compare the basic physical properties of these polymers. Results of viscosity measurements and hydrodynamic volume changes are tabulated and discussed. Discussions are also included on temporary viscosity losses in polymer solutions. (JRD)

  5. Basic Retention Mechanisms

    DEFF Research Database (Denmark)

    Jensen, Bror Skytte; Jensen, H.


    . The data for kaolinite were similarly interpreted as adsorption of hydroxylated complexes of the polyvalent cations, a mechanism which has previously been suggested for the adsorption of heavy metals onto muds, sludges and organic debris. In the case of kaolinite, indications of additional reactions like......The effect of multiple cation competition on the adsorption of Sr onto two synthetic ion-exchange resins, i. e. DOWEX 50W and DOWEX CCR-2, as well as onto the clay mineral, kaolinite has been studied. The results for DOWEX 50W, and under certain experimental conditions also for DOWEX CCR-2 were...... in good agreement with theoretical predictions for multielement ion-exchange taking the limiting effect of ion-exchange capacity into account. In the case of very low cation adsorption, DOWEX CCR-2 showed an unexpected behavior which is interpreted as ion-pair or ion-cluster adsorption of polyvalent ions...


    Directory of Open Access Journals (Sweden)

    GROSU Marian-Cătălin


    Full Text Available In the context of the rapid growth in the number of electrical and electronic devices and accessories that emit electromagnetic energy in different frequency bands we present and characterize here several magnetic functionalized viscose twisted yarns. A 100% viscose twisted staple yarn was covered through an in-house developed process with a polymeric solution containing micrometric sized barium hexaferrite magnetic powder. The in-house developed process allows deposition of micrometric thickness polymeric paste layer on the yarn surface. Barium hexaferrite is a hard magnetic material exhibiting high chemical stability and corrosion resistivity, relatively large saturation and residual magnetization and microwave absorbing properties. Five different percentages of the magnetic powder in the polymer solution were used, i.e. ranging from 15 wt% to 45 wt%. Physical characterization shows a very good adherence between the highly hygroscopic viscose staple fibers and the polymeric solution that contains polyvinyl acetate and polyurethane as binders. SEM images evidenced the fact that the polymeric solution penetrated more than 1/3 of the yarn diameter. The concentration of magnetic powder in the polymeric solution has a direct influence on the coating amount, diameter and density. The mechanical characterization of the coated yarns revealed that the breaking force is increasing with increasing magnetic powder content up to o certain value and then decreased because the magnetic layer became stiffer. At the same time, the elongation at brake is decreasing.

  7. Mechanism of viscosity effect on magnetic island rotation

    Energy Technology Data Exchange (ETDEWEB)

    Mikhailovskii, A.B.; Konovalov, S.V. [Institute of Nuclear Fusion, Russian Research Centre ' Kurchatov Institute' , Kurchatov Sq., 1, Moscow (Russian Federation); Pustovitov, V.D. [National Inst. for Fusion Science, Toki, Gifu (Japan); Tsypin, V.S. [Institute of Physics, University of Sao Paulo, Rua do Matao, Travessa R, SP (Brazil)


    It is shown that plasma viscosity does not influence the magnetic island rotation directly. Nevertheless, it leads to nonstationarity of the plasma velocity. This nonstationarity is the reason of the viscosity effect on island rotation. (author)

  8. A viscosity-enhanced mechanism for biogenic ocean mixing. (United States)

    Katija, Kakani; Dabiri, John O


    Recent observations of biologically generated turbulence in the ocean have led to conflicting conclusions regarding the significance of the contribution of animal swimming to ocean mixing. Measurements indicate elevated turbulent dissipation--comparable with levels caused by winds and tides--in the vicinity of large populations of planktonic animals swimming together. However, it has also been noted that elevated turbulent dissipation is by itself insufficient proof of substantial biogenic mixing, because much of the turbulent kinetic energy of small animals is injected below the Ozmidov buoyancy length scale, where it is primarily dissipated as heat by the fluid viscosity before it can affect ocean mixing. Ongoing debate regarding biogenic mixing has focused on comparisons between animal wake turbulence and ocean turbulence. Here, we show that a second, previously neglected mechanism of fluid mixing--first described over 50 years ago by Charles Darwin--is the dominant mechanism of mixing by swimming animals. The efficiency of mixing by Darwin's mechanism is dependent on animal shape rather than fluid length scale and, unlike turbulent wake mixing, is enhanced by fluid viscosity. Therefore, it provides a means of biogenic mixing that can be equally effective in small zooplankton and large mammals. A theoretical model for the relative contributions of Darwinian mixing and turbulent wake mixing is created and validated by in situ field measurements of swimming jellyfish using a newly developed scuba-based laser velocimetry device. Extrapolation of these results to other animals is straightforward given knowledge of the animal shape and orientation during vertical migration. On the basis of calculations of a broad range of aquatic animal species, we conclude that biogenic mixing via Darwin's mechanism can be a significant contributor to ocean mixing and nutrient transport.

  9. Flow mechanism and viscosity in basaltic magma chambers (United States)

    Nicolas, A.; Ildefonse, B.

    Magmatic flow in the dense suspension of crystallizing gabbros below the free surface of basaltic magma chambers is considered from the point of view of flow mechanisms and rheology. Hyperdense suspensions (˜20% melt fraction) may arise if flat plagioclase crystals develop a strong preferred orientation induced by magmatic flow. With the help of Nomarski differential interference contrast and back scattered electron figures, we show that suspension flow is possible even for smaller melt fractions if impingements between moving crystals are reduced by chemical dissolution at their contact points. This dissolution process is rate controlling. With strain rates near 10-9 s-1 and viscosities near 1014-16 Pa.s, such crystalline mushes should be closer to plastically deforming solids than to the overlying basaltic suspension. If we characterize magma chambers by suspension flow, no matter how small the melt fraction, magma chambers below oceanic fast spreading centers should not be restricted to a perched melt lens, but should extend to the Moho and comprise the entire volume of observed strong seismic attenuation.

  10. Mechanism for cavitation in the mechanical heart valve with an artificial heart: nuclei and viscosity dependence. (United States)

    Lee, Hwansung; Taenaka, Yoshiyuki; Kitamura, Soichiro


    Until now, we have estimated cavitation for mechanical heart valves (MHV) mounted in an electrohydraulic total artificial heart (EHTAH) with tap water. However, tap water at room temperature is not a proper substitute for blood at 37 degrees C. We therefore investigated fluid characterization in studies of MHV cavitation associated with the viscosity and nuclei content of a testing fluid. We used the Medtronic Hall valve mounted in the mitral position of the EHTAH. As testing fluids, tap water, distilled water, and glycerin solution were used. The valve-closing velocity, pressure-drop measurements, and a high-speed video camera were employed to determine the cavitation intensity in MHV. Most of the cavitation bubbles were observed at the edge of the valve stop. Our analysis of the results indicates that squeeze flow is the major cause of cavitation in the Medtronic Hall valve. The cavitation intensity increased with increases in the fluid viscosity and the valve-closing velocity. Even if cavitation intensity in glycerin solution was greater, the cavitation occurrence probability was less in glycerin solution than in tap water. Our results suggest that tap water contains particles that cause an increase in the cavitation occurrence probability. We conclude that cavitation intensity is greatly affected by the nuclei concentration in the fluid and the fluid viscosity.

  11. Effect of chyme viscosity and nutrient feedback mechanism on gastric emptying. (United States)

    Moxon, Thomas E; Nimmegeers, Philippe; Telen, Dries; Fryer, Peter J; Van Impe, Jan; Bakalis, Serafim


    A comprehensive mathematical model of the digestive processes in humans could allow for better design of functional foods which may play a role in stemming the prevalence of food related diseases around the world. This work presents a mathematical model for a nutrient based feedback mechanism controlling gastric emptying, which has been identified in vivo by numerous researchers. The model also takes into account the viscosity of nutrient meals upon gastric secretions and emptying. The results show that modelling the nutrient feedback mechanism as an on/off system, with an initial emptying rate dependent upon the secretion rate (which is a function of the gastric chyme viscosity) provides a good fit to the trends of emptying rate for liquid meals of low and high nutrient content with varying viscosity.

  12. Mechanisms of renal NaCl retention in proteinuric disease

    DEFF Research Database (Denmark)

    Svenningsen, Per; Friis, Ulla G; Versland, Jostein B


    In diseases with proteinuria, for example nephrotic syndrome and pre-eclampsia, there often are suppression of plasma renin-angiotensin-aldosterone system components, expansion of extracellular volume and avid renal sodium retention. Mechanisms of sodium retention in proteinuria are reviewed...... pressure. Aberrant filtration of plasminogen and conversion within the urinary space to plasmin may activate gamma ENaC proteolytically and contribute to inappropriate NaCl retention and oedema in acute proteinuric conditions and to hypertension in diseases with chronic microalbuminuria/proteinuria....

  13. Application and mechanism of ultrasonic static mixer in heavy oil viscosity reduction. (United States)

    Shi, Chunwei; Yang, Wei; Chen, Jianbin; Sun, Xiaoping; Chen, Wenyi; An, Huiyong; Duo, Yili; Pei, Mingyuan


    In the present study, heavy oil viscosity reduction in Daqing oil field was investigated by using an ultrasonic static mixer. The influence of the ultrasonic power on the viscosity reduction rate was investigated and the optimal technological conditions were determined for the ultrasonic treatment. The mechanism for ultrasonic viscosity reduction was analyzed. The flow characteristics of heavy oil in the mixer under the effect of cavitation were investigated using numerical modeling, and energy consumptions were calculated during the ultrasonic treatment and vis-breaking processes. The experimental results indicated that the ultrasonic power made the largest impact on the viscosity reduction rate, followed by the reaction time and temperature. The highest viscosity reduction rate was 57.34%. Vacuole was migrated from the axis to the wall along the fluid, accelerating the two-phase transmission and enhancing the radial flow of the fluid, which significantly improved the ultrasonic viscosity reduction. Compared to the vis-breaking process, the energy consumption of ultrasonic treatment process was 43.03% lower when dealing with the same quality heavy oil. The optimal process conditions were found to be as follows: ultrasonic power of 1.8kW, reaction time of 45min and reaction temperature of 360°C. The dissociation of the molecules of heavy oil after ultrasonication has been checked. After being kept at room temperature 12days, some light components were produced by the cavitation cracking, so the viscosity of the residual oil could not return to that of the original residual oil, which meant that the "cage effect" was not reformed. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Electrical Transmission Line Diametrical Retention Mechanism (United States)

    Hall, David R.; Hall, Jr., H. Tracy; Pixton, David; Dahlgren, Scott; Sneddon, Cameron; Briscoe, Michael; Fox, Joe


    The invention is a mechanism for retaining an electrical transmission line. In one embodiment of the invention it is a system for retaining an electrical transmission line within downhole components. The invention allows a transmission line to be attached to the internal diameter of drilling components that have a substantially uniform drilling diameter. In accordance with one aspect of the invention, the system includes a plurality of downhole components, such as sections of pipe in a drill string, drill collars, heavy weight drill pipe, and jars. The system also includes a coaxial cable running between the first and second end of a drill pipe, the coaxial cable having a conductive tube and a conductive core within it. The invention allows the electrical transmission line to withstand the tension and compression of drill pipe during routine drilling cycles.

  15. Protein Nanosheet Mechanics Controls Cell Adhesion and Expansion on Low-Viscosity Liquids. (United States)

    Kong, Dexu; Megone, William; Nguyen, Khai D Q; Di Cio, Stefania; Ramstedt, Madeleine; Gautrot, Julien E


    Adherent cell culture typically requires cell spreading at the surface of solid substrates to sustain the formation of stable focal adhesions and assembly of a contractile cytoskeleton. However, a few reports have demonstrated that cell culture is possible on liquid substrates such as silicone and fluorinated oils, even displaying very low viscosities (0.77 cSt). Such behavior is surprising as low viscosity liquids are thought to relax much too fast (viscosity liquids are enabled by the self-assembly of mechanically strong protein nanosheets at these interfaces. We propose that this phenomenon results from the denaturation of globular proteins, such as albumin, in combination with the coupling of surfactant molecules to the resulting protein nanosheets. We use interfacial rheology and atomic force microscopy indentation to characterize the mechanical properties of protein nanosheets and associated liquid-liquid interfaces. We identify a direct relationship between interfacial mechanics and the association of surfactant molecules with proteins and polymers assembled at liquid-liquid interfaces. In addition, our data indicate that cells primarily sense in-plane mechanical properties of interfaces, rather than relying on surface tension to sustain spreading, as in the spreading of water striders. These findings demonstrate that bulk and nanoscale mechanical properties may be designed independently, to provide structure and regulate cell phenotype, therefore calling for a paradigm shift for the design of biomaterials in regenerative medicine.

  16. Digestibility and energy value of cereal-based diets in relation to digesta viscosity and retention time in turkeys and chickens at different ages estimated with different markers. (United States)

    Palander, Samu; Näsi, Matti; Palander, Pälvi


    Digesta viscosity, ileal transit time of digesta, apparent ileal protein digestibility and apparent metabolisable energy (AME(N)) of diets based on wheat and dehulled barley (WB), oats (O) or a mixture of these (WBO) fed as such or with enzyme supplementation in three- and six-week old turkeys and broilers were investigated. In addition, differences between ileal digestibility and AME(N) calculated by using titanium dioxide (TiO2), chromic oxide (Cr2O3) or acid insoluble ash (AIA) as indigestible markers were compared. Digesta viscosities were generally moderate reaching from 2.5 mPa x s to 7.3 mPa x s. The highest viscosities were observed in WBO diets. Viscosities were reduced with age in broilers, and were generally higher in turkeys than in broilers, especially at six weeks of age. Digesta retention time in ileum was elongated with age of the birds, pronouncedly in broilers. Oat inclusion to the diets decreased retention time especially in broilers at six weeks of age. Apparent ileal digestibility of protein ranged from 0.64-0.83, was lower at six weeks of age than at three weeks of age and generally lowest in O diets, especially in turkeys. AME(N) of the diets ranged from 11.2-13.4 MJ/kg being higher at six weeks of age than at three weeks of age. AME(N) of Diets O was the lowest but AME(N) of WBO diets was higher than that of WB diets indicating a synergistic interaction of cereals, this trend being more pronounced in broilers. Enzyme supplementation decreased viscosity and improved AME(N) in most diets, but did not affect ileal protein digestibility. Differences between ileal digestibility estimates obtained with TiO2 or Cr2O3 were small and mainly not significantly different from 0. AME(N) estimates were generally higher when calculated with Cr2O3 than with TiO2. AIA gave remarkably lower AME(N) values than TiO2 (the significant differences ranging from 0.24-0.94 MJ/kg). In addition, effects of markers on AME(N) estimates interacted with age of the birds

  17. Live-streaming: Time-lapse video evidence of novel streamer formation mechanism and varying viscosity. (United States)

    Parvinzadeh Gashti, Mazeyar; Bellavance, Julien; Kroukamp, Otini; Wolfaardt, Gideon; Taghavi, Seyed Mohammad; Greener, Jesse


    Time-lapse videos of growing biofilms were analyzed using a background subtraction method, which removed camouflaging effects from the heterogeneous field of view to reveal evidence of streamer formation from optically dense biofilm segments. In addition, quantitative measurements of biofilm velocity and optical density, combined with mathematical modeling, demonstrated that streamer formation occurred from mature, high-viscosity biofilms. We propose a streamer formation mechanism by sudden partial detachment, as opposed to continuous elongation as observed in other microfluidic studies. Additionally, streamer formation occurred in straight microchannels, as opposed to serpentine or pseudo-porous channels, as previously reported.

  18. Predicting the Mechanical Properties of Viscose/Lycra Knitted Fabrics Using Fuzzy Technique

    Directory of Open Access Journals (Sweden)

    Ismail Hossain


    Full Text Available The main objective of this research is to predict the mechanical properties of viscose/lycra plain knitted fabrics by using fuzzy expert system. In this study, a fuzzy prediction model has been built based on knitting stitch length, yarn count, and yarn tenacity as input variables and fabric mechanical properties specially bursting strength as an output variable. The factors affecting the bursting strength of viscose knitted fabrics are very nonlinear. Hence, it is very challenging for scientists and engineers to create an exact model efficiently by mathematical or statistical model. Alternatively, developing a prediction model via ANN and ANFIS techniques is also difficult and time consuming process due to a large volume of trial data. In this context, fuzzy expert system (FES is the promising modeling tool in a quality modeling as FES can map effectively in nonlinear domain with minimum experimental data. The model derived in the present study has been validated by experimental data. The mean absolute error and coefficient of determination between the actual bursting strength and that predicted by the fuzzy model were found to be 2.60% and 0.961, respectively. The results showed that the developed fuzzy model can be applied effectively for the prediction of fabric mechanical properties.

  19. Localisation and mechanism of renal retention of radiolabelled somatostatin analogues

    Energy Technology Data Exchange (ETDEWEB)

    Melis, Marleen; Krenning, Eric P.; Bernard, Bert F.; Jong, Marion de [Erasmus MC, Department of Nuclear Medicine, Rotterdam (Netherlands); Barone, Raffaella [UCL, Centre of Nuclear Medicine and Laboratory of PET, Brussels (Belgium); Visser, Theo J. [Erasmus MC, Department of Internal Medicine, Rotterdam (Netherlands)


    Radiolabelled somatostatin analogues, such as octreotide and octreotate, are used for tumour scintigraphy and radionuclide therapy. The kidney is the most important critical organ during such therapy owing to the reabsorption and retention of radiolabelled peptides. The aim of this study was to investigate in a rat model both the localisation and the mechanism of renal uptake after intravenous injection of radiolabelled somatostatin analogues. The multi-ligand megalin/cubilin receptor complex, responsible for reabsorption of many peptides and proteins in the kidney, is an interesting candidate for renal endocytosis of these peptide analogues. For localisation studies, ex vivo autoradiography and micro-autoradiography of rat kidneys were performed 1-24 h after injection of radiolabelled somatostatin analogues and compared with the renal anti-megalin immunohistochemical staining pattern. To confirm a role of megalin in the mechanism of renal retention of [{sup 111}In-DTPA]octreotide, the effects of three inhibitory substances were explored in rats. Renal ex vivo autoradiography showed high cortical radioactivity and lower radioactivity in the outer medulla. The distribution of cortical radioactivity was inhomogeneous. Micro-autoradiography indicated that radioactivity was only retained in the proximal tubules. The anti-megalin immunohistochemical staining pattern showed a strong similarity with the renal [{sup 111}In-DTPA]octreotide ex vivo autoradiograms. Biodistribution studies showed that co-injection of positively charged d-lysine reduced renal uptake to 60% of control. Sodium maleate reduced renal [{sup 111}In-DTPA]octreotide uptake to 15% of control. Finally, cisplatin pre-treatment of rats reduced kidney uptake to 70% of control. Renal retention of [{sup 111}In-DTPA]octreotide is confined to proximal tubules in the rat kidney, in which megalin-mediated endocytosis may play an important part. (orig.)

  20. Experimental study on viscosity reduction for residual oil by ultrasonic. (United States)

    Huang, Xintong; Zhou, Cuihong; Suo, Quanyu; Zhang, Lanting; Wang, Shihan


    Because of characteristics of large density, high viscosity and poor mobility, the processing and transportation of residual oil are difficult and challenging, viscosity reduction of residual oil is of great significance. In this paper, the effects of different placement forms of ultrasonic transducers on the sound pressure distribution of ultrasonic inside a cubic container have been simulated, the characteristics of oil bath heating and ultrasonic viscosity reduction were compared, viscosity reduction rule of residual oil was experimentally analyzed by utilizing Response Surface Method under conditions of changing ultrasonic exposure time, power and action mode, the mechanism of viscosity reduction was studied by applying Fourier transform infrared spectrometer, the viscosity retentivity experiment was carried out at last. Experiments were conducted using two kinds of residual oil, and results show that ultrasonic effect on the viscosity reduction of residual oil is significant, the higher viscosity of residual oil, the better effect of ultrasonic, ultrasonic power and exposure time are the significant factors affecting the viscosity reduction rate of residual oil. The maximum viscosity reduction rate is obtained under condition of ultrasonic power is 900W, exposure time is 14min and action mode of exposure time is 2s and interrupting time is 2s, viscosity reduction rate reaching up to 63.95%. The infrared spectroscopy results show that light component in residual oil increased. The viscosity retentivity experiment results show that the viscosity reduction effect remains very well. This paper can provide data reference for the application of ultrasonic in the field of viscosity reduction for residual oil. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. The Effect of the Melt Viscosity and Impregnation of a Film on the Mechanical Properties of Thermoplastic Composites

    Directory of Open Access Journals (Sweden)

    Jong Won Kim


    Full Text Available Generally, to produce film-type thermoplastic composites with good mechanical properties, high-performance reinforcement films are used. In this case, films used as a matrix are difficult to impregnate into tow due to their high melt viscosity and high molecular weight. To solve the problem, in this paper, three polypropylene (PP films with different melt viscosities were used separately to produce film-type thermoplastic composites. A film with a low melt viscosity was stacked so that tow was impregnated first and a film with a higher melt viscosity was then stacked to produce the composite. Four different composites were produced by regulating the pressure rising time. The thickness, density, fiber volume fraction (Vf, and void content (Vc were analyzed to identify the physical properties and compare them in terms of film stacking types. The thermal properties were identified by using differential scanning calorimetry (DSC and dynamical mechanical thermal analysis (DMTA. The tensile property, flexural property, interlaminar shear strength (ILSS, and scanning electron microscopy (SEM were performed to identify the mechanical properties. For the films with low molecular weight, impregnation could be completed fast but showed low strength. Additionally, the films with high molecular weight completed impregnation slowly but showed high strength. Therefore, appropriate films should be used considering the forming process time and their mechanical properties to produce film-type composites.

  2. Mechanisms of deterioration of nutrients. [retention of flavor during freeze drying (United States)

    Karel, M.; Flink, J. M.


    The retention of flavor during freeze drying was studied with model systems. Mechanisms by which flavor retention phenomena is explained were developed and process conditions specified so that flavor retention is optimized. The literature is reviewed and results of studies of the flavor retention behavior of a number of real food products, including both liquid and solid foods are evaluated. Process parameters predicted by the mechanisms to be of greatest significance are freezing rate, initial solids content, and conditions which result in maintenance of sample structure. Flavor quality for the real food showed the same behavior relative to process conditions as predicted by the mechanisms based on model system studies.

  3. Mechanical Properties of High-Viscosity Glass Ionomer Cement and Nanoparticle Glass Carbomer

    Directory of Open Access Journals (Sweden)

    Isabel Cristina Olegário


    Full Text Available Introduction. The lack of evidence regarding the best available material for restoring occlusal-proximal cavities in primary teeth leads to the development of new restorative material, with nanoparticles, in order to enhance mechanical properties, resulting in increased restoration longevity. Aim. To evaluate the Knoop hardness and bond strength of nanoparticles material glass carbomer cement (CAR and high-viscosity glass ionomer cement (GIC in sound and caries-affected dentin. Methods. Forty bovine incisors were selected and assigned into four groups (n=10: SGIC, sound dentin and GIC; SCAR, sound dentin and CAR; CGIC, caries-affected dentin and GIC; and CCAR, caries-affected dentin and CAR. All groups were submitted to microshear bond strength (MPa. Knoop hardness was also performed. Bond strength values were subjected to two-way ANOVA and Tukey test. Knoop hardness data were subjected to one-way ANOVA. Results. GIC presented higher Knoop hardness (P<0.001 and bond strength (P=0.027 than CAR. Also, both materials showed better performance in sound than in caries-affected substrates (P=0.001. The interaction between factors was not statistically different (P=0.494. Conclusion. Despite nanoparticles, CAR shows inferior performance as compared to GIC for the two properties tested in vitro. Moreover, sound dentin results in better bonding performance of both restorative materials evaluated.

  4. Polymerization Behavior and Mechanical Properties of High-Viscosity Bulk Fill and Low Shrinkage Resin Composites. (United States)

    Shibasaki, S; Takamizawa, T; Nojiri, K; Imai, A; Tsujimoto, A; Endo, H; Suzuki, S; Suda, S; Barkmeier, W W; Latta, M A; Miyazaki, M

    The present study determined the mechanical properties and volumetric polymerization shrinkage of different categories of resin composite. Three high viscosity bulk fill resin composites were tested: Tetric EvoCeram Bulk Fill (TB, Ivoclar Vivadent), Filtek Bulk Fill posterior restorative (FB, 3M ESPE), and Sonic Fill (SF, Kerr Corp). Two low-shrinkage resin composites, Kalore (KL, GC Corp) and Filtek LS Posterior (LS, 3M ESPE), were used. Three conventional resin composites, Herculite Ultra (HU, Kerr Corp), Estelite ∑ Quick (EQ, Tokuyama Dental), and Filtek Supreme Ultra (SU, 3M ESPE), were used as comparison materials. Following ISO Specification 4049, six specimens for each resin composite were used to determine flexural strength, elastic modulus, and resilience. Volumetric polymerization shrinkage was determined using a water-filled dilatometer. Data were evaluated using analysis of variance followed by Tukey's honestly significant difference test (α=0.05). The flexural strength of the resin composites ranged from 115.4 to 148.1 MPa, the elastic modulus ranged from 5.6 to 13.4 GPa, and the resilience ranged from 0.70 to 1.0 MJ/m 3 . There were significant differences in flexural properties between the materials but no clear outliers. Volumetric changes as a function of time over a duration of 180 seconds depended on the type of resin composite. However, for all the resin composites, apart from LS, volumetric shrinkage began soon after the start of light irradiation, and a rapid decrease in volume during light irradiation followed by a slower decrease was observed. The low shrinkage resin composites KL and LS showed significantly lower volumetric shrinkage than the other tested materials at the measuring point of 180 seconds. In contrast, the three bulk fill resin composites showed higher volumetric change than the other resin composites. The findings from this study provide clinicians with valuable information regarding the mechanical properties and

  5. Dislocation mechanism of deuterium retention in tungsten under plasma implantation. (United States)

    Dubinko, V I; Grigorev, P; Bakaev, A; Terentyev, D; van Oost, G; Gao, F; Van Neck, D; Zhurkin, E E


    We have developed a new theoretical model for deuterium (D) retention in tungsten-based alloys on the basis of its being trapped at dislocations and transported to the surface via the dislocation network with parameters determined by ab initio calculations. The model is used to explain experimentally observed trends of D retention under sub-threshold implantation, which does not produce stable lattice defects to act as traps for D in conventional models. Saturation of D retention with implantation dose and effects due to alloying of tungsten with, e.g. tantalum, are evaluated, and comparison of the model predictions with experimental observations under high-flux plasma implantation conditions is presented.

  6. Odd Viscosity


    Avron, J. E.


    When time reversal is broken the viscosity tensor can have a non vanishing odd part. In two dimensions, and only then, such odd viscosity is compatible with isotropy. Elementary and basic features of odd viscosity are examined by considering solutions of the wave and Navier-Stokes equations for hypothetical fluids where the stress is dominated by odd viscosity.

  7. Rolling-Tooth Core Breakoff and Retention Mechanism (United States)

    Badescu, Mircea; Bickler, Donald B.; Sherrit, Stewart; Bar-Cohen, Yoseph; Bao, Xiaoqi; Hudson, Nicolas H.


    Sampling cores requires the controlled breakoff of the core at a known location with respect to the drill end. An additional problem is designing a mechanism that can be implemented at a small scale that is robust and versatile enough to be used for a variety of core samples. This design consists of a set of tubes (a drill tube and an inner tube) and a rolling element (rolling tooth). An additional tube can be used as a sample tube. The drill tube and the inner tube have longitudinal holes with the axes offset from the axis of each tube. The two eccentricities are equal. The inner tube fits inside the drill tube, and the sample tube fits inside the inner tube. While drilling, the two tubes are positioned relative to each other such that the sample tube is aligned with the drill tube axis and core. The drill tube includes teeth and flutes for cuttings removal. The inner tube includes, at the base, the rolling element implemented as a wheel on a shaft in an eccentric slot. An additional slot in the inner tube and a pin in the drill tube limit the relative motion of the two tubes. While drilling, the drill assembly rotates relative to the core and forces the rolling tooth to stay hidden in the slot along the inner tube wall. When the drilling depth has been reached, the drill bit assembly is rotated in the opposite direction, and the rolling tooth is engaged and penetrates into the core. Depending on the strength of the created core, the rolling tooth can score, lock the inner tube relative to the core, start the eccentric motion of the inner tube, and break the core. The tooth and the relative position of the two tubes can act as a core catcher or core-retention mechanism as well. The design was made to fit the core and hole parameters produced by an existing bit; the parts were fabricated and a series of demonstration tests were performed. This invention is potentially applicable to sample return and in situ missions to planets such as Mars and Venus, to moons such

  8. Viscosity and not biological mechanisms often controls the effects of temperature on ciliary activity and swimming velocity of small aquatic organisms

    DEFF Research Database (Denmark)

    Larsen, Poul Scheel; Riisgård, H. U.


    A number of studies have shown that temperature-dependent viscosity of the ambient water controls or strongly affects bio-mechanical activity such as beat frequency of water-pumping cilia in mussels and ascidians, swimming velocity of sperm cells, ciliates and small (micro- and meso-scale) aquatic...... organisms using cilia or small appendages for propulsion. Here we summarize results from the literature and from own studies on bio-mechanical activities in response to changing temperature or manipulated viscosity at constant temperature, both having the same change in kinematic viscosity. The survey...... is used to assess to what extent the response is purely physical/mechanical or biological. We argue that a power-law dependence of bio-mechanical activity (a) on kinematic viscosity (ν), i.e. a ~ ν^−m, should be applied to available data. Based on a general close matching of the response data to power...

  9. Mechanisms of nutrient retention and its relation to flow connectivity in river-floodplain corridors (United States)

    Larsen, Laurel; Harvey, Judson; Maglio, Morgan M.


    Understanding heterogeneity or patchiness in the distribution of vegetation and retention of C and nutrients in river corridors is critical for setting priorities for river management and restoration. Several mechanisms of spatial differentiation in nutrient retention in river and floodplain corridors have been recognized, but few studies have distinguished their relative importance or established their role in long-term geomorphic change, nutrient retention, and connectivity with downstream systems. We evaluated the ability of 3 mechanisms (evapotranspiration focusing [EF], differential hydrologic exchange [DHE], and particulate nutrient redistribution [PNR]) to explain spatial patterns of P retention and function in the Everglades (Florida, USA). We used field measurements in sloughs and on slightly higher, more densely vegetated ridges to quantify P fluxes attributable to the 3 mechanisms. EF does not explain Everglades nutrient retention or P concentrations on ridges and in sloughs. However, DHE resulting from different periods of groundwater–surface-water connectivity across topographic elements is the primary cause of elevated P concentrations on ridges and completely explains interpatch differences in long-term P accumulation rates. With historical flow velocities, which were an order of magnitude higher than at present, PNR would have further increased the interpatch difference in long-term P retention rates nearly 2-fold. In conclusion, DHE and PNR are the dominant drivers of nutrient patchiness in the Everglades and are hypothesized to be important in P-limited river and floodplain corridors globally.

  10. Mechanical basis for bone retention around dental implants. (United States)

    Alexander, Harold; Ricci, John L; Hrico, George J


    This study, analytically, through finite element analysis, predicts the minimization of crestal bone stress resulting from implant collar surface treatment. A tapered dental implant design with (LL) and without (control, C) laser microgrooving surface treatment are evaluated. The LL implant has the same tapered body design and thread surface treatment as the C implant, but has a 2-mm wide collar that has been laser micromachined with 8 and 12 microm grooves in the lower 1.5 mm to enhance tissue attachment. In vivo animal and human studies previously demonstrated decreased crestal bone loss with the LL implant. Axial and side loading with two different collar/bone interfaces (nonbonded and bonded, to simulate the C and LL surfaces, respectively) are considered. For 80 N side load, the maximum crestal bone distortional stress around C is 91.9 MPa, while the maximum crestal bone stress around LL, 22.6 MPa, is significantly lower. Finite element analysis suggests that stress overload may be responsible for the loss of crestal bone. Attaching bone to the collar with LL is predicted to diminish this effect, benefiting crestal bone retention. Copyright 2007 Wiley Periodicals, Inc.

  11. Colloidal suspensions hydrodynamic retention mechanisms in model porous media; Mecanismes de retention hydrodynamique de suspensions colloidales en milieux poreux modeles

    Energy Technology Data Exchange (ETDEWEB)

    Salehi, N.


    This study deals with the retention mechanisms of colloidal particles in porous media flows, and the subsequent reduction in permeability in the case of stable and non adsorbing colloids. It combines experimental results and modelling. This study has been realised with stable dispersion of monodispersed carboxylate polystyrene latexes negatively charged injected through negatively charged polycarbonate membranes having mono-sized cylindrical pores. The mean particle diameter is smaller than the mean pore diameter. Both batch and flow experiments in Nuclepore membranes have been done. The results of batch experiments have proved no adsorption of the colloidal latex particles on the surface of the Nuclepore membranes without flow at low salinity. In flow experiments at low particle concentration, only deposition on the upstream side of the membrane have been induced by hydrodynamic forces even for non adsorbing particles without creating any permeability reduction. The retention levels are zero at low and high Peclet numbers with a maximum at intermediate values. Partial plugging was observed at higher colloid concentration even at low salinity without any upstream surface deposition. The modelling of plugging processes is achieved by considering the particle concentration, fluid rate and ratio between the mean pore diameter and the mean particle diameter. This study can be particularly useful in the fields of water treatment and of restoration of lands following radioactive contamination. (author). 96 refs., 99 figs., 29 tabs.

  12. Multiple particle retention mechanisms during filtration in porous media. (United States)

    Santos, A; Barros, P H L


    A statistical model for filtration in porous media is proposed and analytical solutions for particle concentrations are derived. The proposed model takes multiple particle capture mechanisms into account and allows a fundamental physical interpretation of the filtration coefficients. Considering two distinct particle capture mechanisms, the inverse problem solution was discussed and applied to determine the filtration coefficients by fitting experimental data from the literature. Finally, a comparison between the classic and proposed model predictions led to the conclusion that the proposed model showed better agreement with experimental data.

  13. Nickel release from orthodontic retention wires: the action of mechanical loading and pH

    NARCIS (Netherlands)

    Milheiro, A.; Kleverlaan, C.; Muris, J.; Feilzer, A.; Pallav, P.


    Nickel (Ni) is a potent sensitizer and may induce innate and adaptive immune responses. Ni is an important component of orthodontic appliances (8-50 wt%). Due to chemical and mechanical factors in the oral environment, Ni is released from these appliances. Retention wires are in situ for a long

  14. Investigating the Retention Mechanisms of Liquid Chromatography Using Solid-Phase Extraction Cartridges (United States)

    O'Donnell, Mary E.; Musial, Beata A.; Bretz, Stacey Lowery; Danielson, Neil D.; Ca, Diep


    Liquid chromatography (LC) experiments for the undergraduate analytical laboratory course often illustrate the application of reversed-phase LC to solve a separation problem, but rarely compare LC retention mechanisms. In addition, a high-performance liquid chromatography instrument may be beyond what some small colleges can purchase. Solid-phase…

  15. Nonmonotonic Aging and Memory Retention in Disordered Mechanical Systems (United States)

    Lahini, Yoav; Gottesman, Omer; Amir, Ariel; Rubinstein, Shmuel M.


    We observe nonmonotonic aging and memory effects, two hallmarks of glassy dynamics, in two disordered mechanical systems: crumpled thin sheets and elastic foams. Under fixed compression, both systems exhibit monotonic nonexponential relaxation. However, when after a certain waiting time the compression is partially reduced, both systems exhibit a nonmonotonic response: the normal force first increases over many minutes or even hours until reaching a peak value, and only then is relaxation resumed. The peak time scales linearly with the waiting time, indicating that these systems retain long-lasting memory of previous conditions. Our results and the measured scaling relations are in good agreement with a theoretical model recently used to describe observations of monotonic aging in several glassy systems, suggesting that the nonmonotonic behavior may be generic and that athermal systems can show genuine glassy behavior.

  16. Viscosity Solution


    Camilli, Fabio; Prados, Emmanuel


    International audience; Viscosity solution is a notion of weak solution for a class of partial differential equations of Hamilton-Jacobi type. The range of applications of the notions of viscosity solution and Hamilton-Jacobi equations is enormous, including common class of partial differential equations such as evolutive problems and problems with boundary conditions, equations arising in optimal control theory, differential games, second-order equations arising in stochastic optimal control...

  17. Transport of Sulfide-Reduced Graphene Oxide in Saturated Quartz Sand: Cation-Dependent Retention Mechanisms. (United States)

    Xia, Tianjiao; Fortner, John D; Zhu, Dongqiang; Qi, Zhichong; Chen, Wei


    We describe how the reduction of graphene oxide (GO) via environmentally relevant pathways affects its transport behavior in porous media. A pair of sulfide-reduced GOs (RGOs), prepared by reducing 10 mg/L GO with 0.1 mM Na2S for 3 and 5 days, respectively, exhibited lower mobility than did parent GO in saturated quartz sand. Interestingly, decreased mobility cannot simply be attributed to the increased hydrophobicity and aggregation upon GO reduction because the retention mechanisms of RGOs were highly cation-dependent. In the presence of Na(+) (a representative monovalent cation), the main retention mechanism was deposition in the secondary energy minimum. However, in the presence of Ca(2+) (a model divalent cation), cation bridging between RGO and sand grains became the most predominant retention mechanism; this was because sulfide reduction markedly increased the amount of hydroxyl groups (a strong metal-complexing moiety) on GO. When Na(+) was the background cation, increasing pH (which increased the accumulation of large hydrated Na(+) ions on grain surface) and the presence of Suwannee River humic acid (SRHA) significantly enhanced the transport of RGO, mainly due to steric hindrance. However, pH and SRHA had little effect when Ca(2+) was the background cation because neither affected the extent of cation bridging that controlled particle retention. These findings highlight the significance of abiotic transformations on the fate and transport of GO in aqueous systems.

  18. Determining Parameters and Mechanisms of Colloid Retention and Release in Porous Media. (United States)

    Bradford, Scott A; Torkzaban, Saeed


    A modeling framework is presented to determine fundamental parameters and controlling mechanisms of colloid (microbes, clays, and nanoparticles) retention and release on surfaces of porous media that exhibit wide distributions of nanoscale chemical heterogeneity, nano- to microscale roughness, and pore water velocity. Primary and/or secondary minimum interactions in the zone of electrostatic influence were determined over the heterogeneous solid surface. The Maxwellian kinetic energy model was subsequently employed to determine the probability of immobilization and diffusive release of colloids from each of these minima. In addition, a balance of applied hydrodynamic and resisting adhesive torques was conducted to determine locations of immobilization and hydrodynamic release in the presence of spatially variable water flow and microscopic roughness. Locations for retention had to satisfy both energy and torque balance conditions for immobilization, whereas release could occur either due to diffusion or hydrodynamics. Summation of energy and torque balance results over the elementary surface area of the porous medium provided estimates for colloid retention and release parameters that are critical to predicting environmental fate, including the sticking and release efficiencies and the maximum concentration of retained colloids on the solid phase. Nanoscale roughness and chemical heterogeneity produced localized primary minimum interactions that controlled long-term retention, even when mean chemical conditions were unfavorable. Microscopic roughness played a dominant role in colloid retention under low ionic strength and high hydrodynamic conditions, especially for larger colloids.

  19. Fast Simulation of Membrane Filtration by Combining Particle Retention Mechanisms and Network Models (United States)

    Krupp, Armin; Griffiths, Ian; Please, Colin


    Porous membranes are used for their particle retention capabilities in a wide range of industrial filtration processes. The underlying mechanisms for particle retention are complex and often change during the filtration process, making it hard to predict the change in permeability of the membrane during the process. Recently, stochastic network models have been shown to predict the change in permeability based on retention mechanisms, but remain computationally intensive. We show that the averaged behaviour of such a stochastic network model can efficiently be computed using a simple partial differential equation. Moreover, we also show that the geometric structure of the underlying membrane and particle-size distribution can be represented in our model, making it suitable for modelling particle retention in interconnected membranes as well. We conclude by demonstrating the particular application to microfluidic filtration, where the model can be used to efficiently compute a probability density for flux measurements based on the geometry of the pores and particles. A. U. K. is grateful for funding from Pall Corporation and the Mathematical Institute, University of Oxford. I.M.G. gratefully acknowledges support from the Royal Society through a University Research Fellowship.

  20. [Preparation and retention mechanism of a mixed-mode reversed-phase/strong-cationic-exchange chromatographic packing]. (United States)

    Peng, Xitian; Wang, Jue; Feng, Yuqi


    A simple and efficient method has been proposed for the preparation of octyl-sulfonic co-bonded silica (OSS) packing by the method of "mixed ligand". The resulting OSS packing was characterized by elemental analysis and ion-exchange capacity to prove the successful immobilization of octyl and sulfonic groups on the surface of silica gel. Then the retention mechanism of several basic analytes on the developed OSS phases was evaluated under the conditions of reversed-phase liquid chromatography (RPLC) mobile phase. The results indicated that the OSS stationary phases demonstrated a mixed-mode reversed-phase/strong-cationic-exchange (RP/SCX) retention mechanism and ion-exchange interaction maybe dominate the retention of the basic analytes. By changing the salt concentration of mobile phase, the one-site and two-site mixed-mode retention models of the several basic analytes on the OSS phases were obtained by investigating the logarithm and reciprocal relationships of retention factor and salt concentration. On the basis of the linear fitting of the two mathematical equations of the retention models, the experimental results demonstrated that the two-site model was more suitable for the description of the retention mechanism of the basic analytes on the OSS phases. Furthermore, the individual RP or SCX contribution to total retention was obtained according to the mathematical equations of the two-site retention mechanism, which can provide some valuable guidance for the separation of complex samples.

  1. A Discussion of SY-101 Crust Gas Retention and Release Mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    SD Rassat; PA Gauglitz; SM Caley; LA Mahoney; DP Mendoza


    The flammable gas hazard in Hanford waste tanks was made an issue by the behavior of double-shell Tank (DST) 241-SY-101 (SY-101). Shortly after SY-101 was filled in 1980, the waste level began rising periodically, due to the generation and retention of gases within the slurry, and then suddenly dropping as the gases were released. An intensive study of the tank's behavior revealed that these episodic releases posed a safety hazard because the released gas was flammable, and, in some cases, the volume of gas released was sufficient to exceed the lower flammability limit (LFL) in the tank headspace (Allemann et al. 1993). A mixer pump was installed in SY-101 in late 1993 to prevent gases from building up in the settled solids layer, and the large episodic gas releases have since ceased (Allemann et al. 1994; Stewart et al. 1994; Brewster et al. 1995). However, the surface level of SY-101 has been increasing since at least 1995, and in recent months the level growth has shown significant and unexpected acceleration. Based on a number of observations and measurements, including data from the void fraction instrument (VFI), we have concluded that the level growth is caused largely by increased gas retention in the floating crust. In September 1998, the crust contained between about 21 and 43% void based on VFI measurements (Stewart et al. 1998). Accordingly, it is important to understand the dominant mechanisms of gas retention, why the gas retention is increasing, and whether the accelerating level increase will continue, diminish or even reverse. It is expected that the retained gas in the crust is flammable, with hydrogen as a major constituent. This gas inventory would pose a flammable gas hazard if it were to release suddenly. In May 1997, the mechanisms of bubble retention and release from crust material were the subject of a workshop. The evaluation of the crust and potential hazards assumed a more typical void of roughly 15% gas. It could be similar to

  2. [Renal and extra-renal mechanisms of sodium and water retention in cirrhosis with ascites]. (United States)

    Peña, J C


    In this work we analyze the renal and systemic factors involved in the sodium retention in two conditions: in extracellular volume depletion and in edema forming states, particularly liver cirrhosis with ascitis. In this paper we accept that the volume loss of body fluids stimulates the "effective arterial blood volume" (VAE). This term results from a decrease in the arterial blood volume secondary to a fall in cardiac output or a peripheral arterial vasodilatation. The reduction in the VAE stimulates: the high pressure baroreceptors (carotid sinus and aortic arch); the intrarrenal mechanisms, such as the yuxtaglomerular apparatus and the renin angiotensin aldosterone system; the sympathetic adrenergic system; the non osmotic release of antidiuretic hormone; prostaglandins (PGE1, Tromboxane) and endothelin; and inhibits the atrial natriuretic peptide. We also describe the sodium transport mechanisms along the nephron during physiological conditions and after volume depletion, and in edema formation states, specially hepatic cirrhosis with ascitis. We speculate that the intrarenal mechanisms are more important and persistent than the systemic mechanisms. It is possible that the sodium retention of these states might be the result of direct stimuli of the tubular sodium transport mechanisms in the different segments of the nephron, mediated by the co and counter transports, ATPase activity or by the second messengers cyclic AMP and cyclic GMP. The clonation and structural characterization of the different sodium transports may help us to establish, more precisely, the intracellular tubular mechanisms responsible for the tendency of the body to retain sodium. The amount of information generated in the future may help us to demonstrate, with more precision, the mechanisms responsible for the sodium retention and excretion in normal and pathological conditions, particularly the edema forming states such as cardiac failure, nephrotic syndrome and hepatic cirrhosis with

  3. Strong-Sludge Gas Retention and Release Mechanisms in Clay Simulants

    Energy Technology Data Exchange (ETDEWEB)

    Gauglitz, Phillip A.; Buchmiller, William C.; Probert, Samuel G.; Owen, Antionette T.; Brockman, Fred J.


    The Hanford Site has 28 double-shell tanks (DSTs) and 149 single-shell tanks (SSTs) containing radioactive wastes that are complex mixes of radioactive and chemical products. The mission of the Department of Energy's River Protection Project is to retrieve and treat the Hanford tank waste for disposal and close the tank farms. A key aspect of the mission is to retrieve and transfer waste from the SSTs, which are at greater risk for leaking, into DSTs for interim storage until the waste is transferred to and treated in the Waste Treatment and Immobilization Plant. There is, however, limited space in the existing DSTs to accept waste transfers from the SSTs, and approaches to overcoming the limited DST space will benefit the overall mission. The purpose of this study is to summarize and analyze the key previous experiment that forms the basis for the relaxed controls and to summarize progress and results on new experiments focused on understanding the conditions that result in low gas retention. The previous large-scale test used about 50 m3 of sediment, which would be unwieldy for doing multiple parametric experiments. Accordingly, experiments began with smaller-scale tests to determine whether the desired mechanisms can be studied without the difficulty of conducting very large experiments. The most significant results from the current experiments are that progressively lower gas retention occurs in tests with progressively deeper sediment layers and that the method of gas generation also affects the maximum retention. Based on the results of this study, it is plausible that relatively low gas retention could occur in sufficiently deep tank waste in DSTs. The current studies and previous work, however, have not explored how gas retention and release will behave when two or more layers with different properties are present.

  4. Transcription factor retention on mitotic chromosomes: regulatory mechanisms and impact on cell fate decisions. (United States)

    Raccaud, Mahé; Suter, David M


    During mitosis, gene transcription stops, and the bulk of DNA-binding proteins are excluded from condensed chromosomes. While most gene-specific transcription factors are largely evicted from mitotic chromosomes, a subset remains bound to specific and non-specific DNA sites. Here, we review the current knowledge on the mechanisms leading to the retention of a subset of transcription factors on mitotic chromosomes and discuss the implications in gene expression regulation and their potential as an epigenetic mechanism controlling stem cell self-renewal and differentiation. © 2017 Federation of European Biochemical Societies.

  5. Evaluations of Mechanisms for Pu Uptake and Retention within Spherical Resorcinol-Formaldehyde Resin Columns

    Energy Technology Data Exchange (ETDEWEB)

    Delegard, Calvin H. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Levitskaia, Tatiana G. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Fiskum, Sandra K. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)


    The unexpected uptake and retention of plutonium (Pu) onto columns containing spherical resorcinol-formaldehyde (sRF) resin during ion exchange testing of Cs (Cs) removal from alkaline tank waste was observed in experiments at both the Pacific Northwest National Laboratory (PNNL) and the Savannah River National Laboratory (SRNL). These observations have raised concern regarding the criticality safety of the Cs removal unit operation within the low-activity waste pretreatment system (LAWPS). Accordingly, studies have been initiated at Washington River Protection Solutions (WRPS), who manages the operations of the Hanford Site tank farms, including the LAWPS, PNNL, and elsewhere to investigate these findings. As part of these efforts, PNNL has prepared the present report to summarize the laboratory testing observations, evaluate these phenomena in light of published and unpublished technical information, and outline future laboratory testing, as deemed appropriate based on the literature studies, with the goal to elucidate the mechanisms for the observed Pu uptake and retention.

  6. Viscosity of colloidal suspensions

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, E.G.D. [Rockefeller Univ., New York, NY (United States); Schepper, I.M. de [Delft Univ. of Technology (Netherlands)


    Simple expressions are given for the effective Newtonian viscosity as a function of concentration as well as for the effective visco-elastic response as a function of concentration and imposed frequency, of monodisperse neutral colloidal suspensions over the entire fluid range. The basic physical mechanisms underlying these formulae are discussed. The agreement with existing experiments is very good.

  7. Retention mechanism of proteins in hydroxyapatite chromatography - multimodal interaction based protein separations: A model study. (United States)

    Itoh, Daisuke; Yoshimoto, Noriko; Yamamoto, Shuichi


    Retention mechanism of proteins in hydroxyapatite chromatography (HAC) was investigated by linear gradient elution experiments. Several mobile phase (buffer) solution strategies and solutes were evaluated in order to probe the relative contributions of two adsorption sites of hydroxyapatite (HA) particles, C-site due to Ca (metal affinity) and P-site due to PO4 (cation-exchange). When P-site was blocked, two basic proteins, lysozyme (Lys) and ribonuclease A(RNase), were not retained whereas cytochrome C(Cyt C) and lactoferrin (LF) were retained and also retention of acidic proteins became stronger as the repulsion due to P-site was eliminated. The number of the binding site B values determined from LGE also increased, which also showed reduction of repulsion forces. The selectivity (retention) of four basic proteins (RNase, Lys, Cyt C, LF) in HAC was different from that in ion-exchange chromatography. Moreover, it was possible to tune the selectivity by using NaCl gradient. Copyright© Bentham Science Publishers; For any queries, please email at

  8. Retention and Mechanical Behavior of Attachment Systems for Implant-Retained Auricular Prostheses. (United States)

    Sigua-Rodriguez, Eder Alberto; Goulart, Douglas Rangel; Santos, Zarina Tatia; Alvarez-Pinzon, Natalia; Olate, Sergio; de Albergaria-Barbosa, José Ricardo


    Auricular prostheses are artificial substitutes for facial defects. The retention of these has often been a problem. This study aimed to evaluate the mechanical behavior of 3 retained auricular prosthetic connections when submitted to a mechanical cycling test. Twelve samples with installed implants were obtained and divided into 3 groups according to their retention system with 4 samples in each group. I: bar-clip system; II: magnet system; and III: ball/o-ring system. Each of samples was submitted to the pull-out test during 3240 cycles (f = 0.5 Hz) to determine its tensile strength. The mechanical cycling test was performed using the servo-hydraulic machine MTS 810-Flex Test 40 (Eden Prairie, MN) that had a 2.5 mm shift at a 10 mm/s velocity. The retaining strength for each of the samples was obtained at 7 intervals. The tensile strength for the group retained by the bar-clip system (29.60 N) was higher with statistically significant difference (P < 0.05) when compared with the group retained by the ball/o-ring system (9.41 N) and magnets system (8.61 N) for all periods assessed. The ball/o-ring system showed loss of retention during the fatigue test (Kruskal-Wallis, chi-squared = 17.28; P < 0.01). The evaluated systems showed a tensile strength compatible with the clinical use and no fractures of the components were observed.

  9. Thorough investigation of the retention mechanisms and retention behavior of amides and sulfonamides on amino column in hydrophilic interaction liquid chromatography. (United States)

    Jovanović, Marko; Stojanović, Biljana Jančić


    In this paper detailed analysis of a mixture of four amides (tropicamide, nicotinamide, tiracetam, and piracetam) and six sulfonamides (sulfanilamide, sulfacetamide, sulfamethoxazole, sulfafurazole, furosemide, and bumetanide) on aminopropyl column in hydrophilic interaction chromatography (HILIC) was carried out. Since, there are no papers on the topic of the assessment of the contribution of ion-exchange retention mechanism involved in the separation of the acidic compounds on aminopropyl column in HILIC mode, the authors utilized the retention data of the acidic sulfonamides for this purpose. Next, broad range of the aqueous buffer concentrations in the mobile phase was examined providing the separation under either HILIC or RP conditions. Turning points between these two mechanisms were determined and then the fitting of the experimental data in the localized and non-localized adsorption models in both RP and HILIC regions was assessed. Since not many papers in the literature were dealing with the estimation of factor influence on the retention behavior of neutral and acidic compounds on aminopropyl column in HILIC, Box-Behnken design and Response Surface Methodology were applied. On the basis of the obtained data, ten quadratic models were proposed and their adequacy was confirmed using ANOVA test. Furthermore, retention data was graphically evaluated by the construction of 3D response surface plots. Finally, good predictive ability of the suggested models was proved with five additional verification experiments. Copyright © 2013 Elsevier B.V. All rights reserved.

  10. Thiazolidinedione-Induced Fluid Retention: Recent Insights into the Molecular Mechanisms

    Directory of Open Access Journals (Sweden)

    Jerzy Bełtowski


    Full Text Available Peroxisome proliferator-activated receptor-γ (PPARγ agonists such as rosiglitazone and pioglitazone are used to improve insulin sensitivity in patients with diabetes mellitus. However, thiazolidinediones induce fluid retention, edema, and sometimes precipitate or exacerbate heart failure in a subset of patients. The mechanism through which thiazolidinediones induce fluid retention is controversial. Most studies suggest that this effect results from the increase in tubular sodium and water reabsorption in the kidney, but the role of specific nephron segments and sodium carriers involved is less clear. Some studies suggested that PPARγ agonist stimulates Na+ reabsorption in the collecting duct by activating epithelial Na+ channel (ENaC, either directly or through serum and glucocorticoid-regulated kinase-1 (SGK-1. However, other studies did not confirm this mechanism and even report the suppression of ENaC. Alternative mechanisms in the collecting duct include stimulation of non-ENaC sodium channel or inhibition of chloride secretion to the tubular lumen. In addition, thiazolidinediones may augment sodium reabsorption in the proximal tubule by stimulating the expression and activity of apical Na+/H+ exchanger-3 and basolateral Na+- cotransporter as well as of Na+,K+-ATPase. These effects are mediated by PPARγ-induced nongenomic transactivation of the epidermal growth factor receptor and downstream extracellular signal-regulated kinases (ERK.

  11. Radionuclide Retention Mechanisms in Secondary Waste-Form Testing: Phase II

    Energy Technology Data Exchange (ETDEWEB)

    Um, Wooyong; Valenta, Michelle M.; Chung, Chul-Woo; Yang, Jungseok; Engelhard, Mark H.; Serne, R. Jeffrey; Parker, Kent E.; Wang, Guohui; Cantrell, Kirk J.; Westsik, Joseph H.


    This report describes the results from laboratory tests performed at Pacific Northwest National Laboratory (PNNL) for Washington River Protection Solutions (WRPS) to evaluate candidate stabilization technologies that have the potential to successfully treat liquid secondary waste stream effluents produced by the Hanford Tank Waste Treatment and Immobilization Plant (WTP). WRPS is considering the design and construction of a Solidification Treatment Unit (STU) for the Effluent Treatment Facility (ETF) at Hanford. The ETF, a multi-waste, treatment-and-storage unit that has been permitted under the Resource Conservation and Recovery Act (RCRA), can accept dangerous, low-level, and mixed wastewaters for treatment. The STU needs to be operational by 2018 to receive secondary liquid waste generated during operation of the WTP. The STU will provide the additional capacity needed for ETF to process the increased volume of secondary waste expected to be produced by WTP. This report on radionuclide retention mechanisms describes the testing and characterization results that improve understanding of radionuclide retention mechanisms, especially for pertechnetate, {sup 99}TcO{sub 4}{sup -} in four different waste forms: Cast Stone, DuraLith alkali aluminosilicate geopolymer, encapsulated fluidized bed steam reforming (FBSR) product, and Ceramicrete phosphate bonded ceramic. These data and results will be used to fill existing data gaps on the candidate technologies to support a decision-making process that will identify a subset of the candidate waste forms that are most promising and should undergo further performance testing.

  12. Exploring particulate retention mechanisms through visualization of E. coli transport through a single, saturated fracture (United States)

    Burke, M. G.; Dickson, S. E.; Schutten, M.


    Groundwater is an extremely valuable resource; a large body of work has been conducted towards remediating, tracking and reducing its contamination. Even so, there are large gaps within the current understanding of groundwater flow and contaminant transport, particularly within fractured media. Fractured media has the ability transport contaminants over longer distances in less time relative to porous media. Furthermore, colloids display unique transport characteristics in comparison to dissolved constituents, including the fact that they typically exhibit earlier initial arrival times. Of particular concern to human health are pathogenic microorganisms, which often originate from fecal contamination. Escherichia coli is a common indicator for fecal contamination; some strains are pathogenic, causing acute illness and sometimes death, in humans. A comprehensive understanding of the transport and retention of E. coli in fractured media will improve our ability to accurately assess whether a site is at risk of becoming contaminated by pathogenic microorganisms. Therefore, the goal of this work is to expand our mechanistic understanding particulate retention, specifically E. coli, in fractures, and the influence of flow rate on these mechanisms. In order to achieve this goal, clear epoxy casts were fabricated of two dolomitic limestone fractures retrieved from a quarry in Guelph, Ontario. Each aperture field was characterized through hydraulic and tracer tests, and measured directly using the light transmission technique. E. coli RS2-GFP, which is a non-pathogenic strain of E. coli that has been tagged with a green fluorescent protein, was injected into the cast under three separate specific discharges ranging from 5 - 30 m/d. These experiments were conducted on an ultraviolet light source, and a high resolution charged-couple device (CCD) camera was employed to take photos at regular intervals in order to capture the dominant flow paths and the areas of retention

  13. Retention mechanisms for basic drugs in the submicellar and micellar reversed-phase liquid chromatographic modes. (United States)

    Ruiz-Angel, M J; Torres-Lapasió, J R; García-Alvarez-Coque, M C; Carda-Broch, S


    The reversed-phase liquid chromatographic (RPLC) behavior (retention, elution strength, selectivity, efficiency, and peak asymmetry) for a group of basic drugs (beta-blockers), with mobile phases containing the anionic surfactant sodium dodecyl sulfate (SDS) and acetonitrile, revealed different separation environments, depending on the concentrations of both modifiers: hydro-organic, submicellar at low surfactant concentration and high concentration of organic solvent, micellar, and submicellar at high concentration of both surfactant and organic solvent. In the surfactant-mediated modes, the anionic surfactant layer adsorbed on the stationary phase interacts strongly with the positively charged basic drugs increasing the retention and masks the silanol groups that are the origin of the poor efficiencies and tailing peaks in hydro-organic RPLC with conventional columns. Also, the strong attraction between the cationic solutes and anionic SDS micelles or monomers in the mobile phase enhances the solubility and allows a direct transfer mechanism of the cationic solutes from micelles to the modified stationary phase, which has been extensively described for highly hydrophobic solutes.

  14. Tritium well depth, tritium well time and sponge mechanism for reducing tritium retention (United States)

    Deng, B. Q.; Li, Z. X.; Li, C. Y.; Feng, K. M.


    and theoretical studies, some new mechanisms are proposed for reducing the tritium retention in PFC and structure materials of tritium-breeding blanket. In this paper, a qualitative analysis of the 'sponge effect' is carried out. The 'sponge effect' may help us to reduce tritium retention by ~20% in the PFC.

  15. About a mechanism of the influence of shear stress for viscosity of the blood in vessels of small diameter

    Directory of Open Access Journals (Sweden)

    Лев Николаевич Катюхин


    Full Text Available It is proposed a physiological and experimentally confirmed explanation of Fåhraeus-Lindqvist-effect in capillaries using the profile analyses of osmotic deformability of red blood cells. It was shown the dose-dependent change of the erythrocytes deformability in the stage of isotropic spheres after forming artificial water pores (nystatin and occlusion (PbCl2 of available pores. The Sigma-effect reducing of hematocrit and viscosity in a shear flow of blood through the vessels of a small diameter was conditioned by the interchange of liquid phase between the erythrocyte and the plasma.

  16. On the Effects of Viscosity on the Shock Waves for a Hydrodynamical Case—Part I: Basic Mechanism

    Directory of Open Access Journals (Sweden)

    Huseyin Cavus


    Full Text Available The interaction of shock waves with viscosity is one of the central problems in the supersonic regime of compressible fluid flow. In this work, numerical solutions of unmagnetised fluid equations, with the viscous stress tensor, are investigated for a one-dimensional shock wave. In the algorithm developed the viscous stress terms are expressed in terms of the relevant Reynolds number. The algorithm concentrated on the compression rate, the entropy change, pressures, and Mach number ratios across the shock wave. The behaviour of solutions is obtained for the Reynolds and Mach numbers defining the medium and shock wave in the supersonic limits.

  17. Hydro-mechanical paths within unsaturated compacted soil framed through water retention surfaces

    Directory of Open Access Journals (Sweden)

    Pelizzari Benjamin


    Full Text Available Compaction is a key issue of modern earthworks... From sustainable development, a need arise of using materials for compaction under given conditions that would normally be avoid due to unpredictable pathologies. The application of compaction on fine grained soils, without a change of gravimetric water content, lead to very important modifications of the void ratio and hence suction. Therefore the hydro-mechanical behaviour of fine grained soil need to be rendered around three variables: suction, void ratio, saturation degree or water content. The barring capacity of the soil is assessed through Penetrometers (In-situ manual penetrometer, CBR in order to assess gains through compaction. The three states variables are then assessed for in situ and frame through water retention surfaces, realized from Proctor tests, in which compaction effect and path could be described.

  18. Mechanisms for the retention of inorganic N in acidic forest soils of southern China (United States)

    Zhang, Jin-bo; Cai, Zu-cong; Zhu, Tong-bin; Yang, Wen-yan; Müller, Christoph


    The mechanisms underlying the retention of inorganic N in acidic forest soils in southern China are not well understood. Here, we simultaneously quantified the gross N transformation rates of various subtropical acidic forest soils located in southern China (southern soil) and those of temperate forest soils located in northern China (northern soil). We found that acidic southern soils had significantly higher gross rates of N mineralization and significantly higher turnover rates but a much greater capacity for retaining inorganic N than northern soils. The rates of autotrophic nitrification and NH3 volatilization in acidic southern soils were significantly lower due to low soil pH. Meanwhile, the relatively higher rates of NO3− immobilization into organic N in southern soils can counteract the effects of leaching, runoff, and denitrification. Taken together, these processes are responsible for the N enrichment of the humid subtropical forest soils in southern China. PMID:23907561

  19. Volatiles Which Increase Magma Viscosity (United States)

    Webb, S.


    The standard model of an erupting volcano is one in which the viscosity of a decompressing magma increases as the volatiles leave the melt structure to form bubbles. It has now been observed that the addition of the "volatiles" P, Cl and F result in an increase in silicate melt viscosity. This observation would mean that the viscosity of selected degassing magmas would decrease rather than increase. Here we look at P, Cl and F as three volatiles which increase viscosity through different structural mechanisms. In all three cases the volatiles increase the viscosity of peralkaline composition melts, but appear to always decrease the viscosity of peraluminous melts. Phosphorus causes the melt to unmix into a Na-P rich phase and a Na-poor silicate phase. Thus as the network modifying Na (or Ca) are removed to the phosphorus-rich melt, the matrix melt viscosity increases. With increasing amounts of added phosphorus (at network modifying Na ~ P) the addition of further phosphorus causes a decrease in viscosity. The addition of chlorine to Fe-free aluminosilicate melts results in an increase in viscosity. NMR data on these glass indicates that the chlorine sits in salt-like structures surrounded by Na and/or Ca. Such structures would remove network-modifying atoms from the melt structure and thus result in an increase in viscosity. The NMR spectra of fluorine-bearing glasses shows that F takes up at least 5 different structural positions in peralkaline composition melts. Three of these positions should result in a decrease in viscosity due to the removal of bridging oxygens. Two of the structural positons of F, however, should result in an increase in viscosity as they require the removal of network-modifying atoms from the melt structure (with one of the structures being that observed for Cl). This would imply that increasing amounts of F might result in an increase in viscosity. This proposed increase in viscosity with increasing F has now been experimentally confirmed.

  20. Retention models and interaction mechanisms of benzene and other aromatic molecules with an amylose-based sorbent. (United States)

    Hsieh, Han-Yu; Wu, Shyuan-Guey; Tsui, Hung-Wei


    Stoichiometric displacement models have been widely used for understanding the adsorption mechanisms of solutes in chromatography systems. Such models are used for interpreting plots of solute retention factor versus concentrations of polar modifier in an inert solvent. However, these models often assume that dispersion forces are negligible and they are unable to account for solutes with significant aromatic interactions. In this study, a systematic investigation of the relationship between retention behavior and aromatic groups was performed using five simple aromatic molecules-benzene, naphthalene, mesitylene, durene, and toluene-with a commercially available amylose tris(3,5-dimethylphenylcarbamate)-based sorbent. The enthalpy changes of adsorption, determined from van't Hoff plots, were obtained separately in pure n-hexane and in pure isopropanol (IPA). In pure n-hexane, the solute adsorptions were driven by electrostatic interactions, favoring a T-shaped binding configuration (edge-to-face π-π interaction). The order of enthalpy change indicated the amount of effective T-shaped π-interactions. In pure IPA, solute adsorption was dominated by dispersion forces, favoring a sandwich binding configuration (face-to-face π-π interaction). The adsorption isotherms of toluene revealed that in pure IPA and in pure n-hexane, the isotherms were linear. The results suggested that the high solvent strength of IPA weakened the interactions between aromatic molecules. The retention behavior of the benzene, naphthalene, mesitylene, and durene as a function of IPA concentration was investigated. U-shaped retention curves were found for all aromatic solutes. A new retention model for monovalent aromatic solutes was developed for describing the U-shaped curves. Three key dimensionless groups were revealed to control the retention behavior. The models suggested that solvophobic interactions should be accounted for in the retention models used to investigate the retention

  1. Cytocompatibility, degradation, mechanical property retention and ion release profiles for phosphate glass fibre reinforced composite rods. (United States)

    Felfel, R M; Ahmed, I; Parsons, A J; Palmer, G; Sottile, V; Rudd, C D


    Fibre reinforced composites have recently received much attention as potential bone fracture fixation applications. Bioresorbable composites based on poly lactic acid (PLA) and phosphate based glass fibre were investigated according to ion release, degradation, biocompatibility and mechanical retention profiles. The phosphate based glass fibres used in this study had the composition of 40P2O5-24MgO-16CaO-16Na2O-4Fe2O3 in mol% (P40). The degradation and ion release profiles for the composites showed similar trends with the amount of sodium and orthophosphate ions released being greater than the other cations and anions investigated. This was attributed to low Dietzal's field strength for the Na(+) in comparison with Mg(2+) and Ca(2+) and breakdown of longer chain polyphosphates into orthophosphate ions. P40 composites exhibited good biocompatibility to human mesenchymal stem cells (MSCs), which was suggested to be due to the low degradation rate of P40 fibres. After 63 days immersion in PBS at 37 °C, the P40 composite rods lost ~1.1% of mass. The wet flexural, shear and compressive strengths for P40 UD rods were ~70%, ~80% and ~50% of their initial dry values after 3 days of degradation, whereas the flexural modulus, shear and compressive strengths were ~70%, ~80%, and ~65% respectively. Subsequently, the mechanical properties remained stable for the duration of the study at 63 days. The initial decrease in mechanical properties was attributed to a combination of the plasticisation effect of water and degradation of the fibre-matrix interface, with the subsequent linear behaviour being attributed to the chemical durability of P40 fibres. P40 composite rods showed low degradation and ion release rates, good biocompatibility and maintained mechanical properties similar to cortical bone for the duration of the study. Therefore, P40 composite rods have huge potential as resorbable intramedullary nails or rods. Copyright © 2013 Elsevier B.V. All rights reserved.

  2. Motor Learning in Childhood Reveals Distinct Mechanisms for Memory Retention and Re-Learning (United States)

    Musselman, Kristin E.; Roemmich, Ryan T.; Garrett, Ben; Bastian, Amy J.


    Adults can easily learn and access multiple versions of the same motor skill adapted for different conditions (e.g., walking in water, sand, snow). Following even a single session of adaptation, adults exhibit clear day-to-day retention and faster re-learning of the adapted pattern. Here, we studied the retention and re-learning of an adapted…

  3. Mechanisms of abdominal distension in severe intestinal dysmotility: abdomino-thoracic response to gut retention. (United States)

    Barba, E; Quiroga, S; Accarino, A; Lahoya, E M; Malagelada, C; Burri, E; Navazo, I; Malagelada, J-R; Azpiroz, F


    We previously showed that abdominal distension in patients with functional gut disorders is due to a paradoxical diaphragmatic contraction without major increment in intraabdominal volume. Our aim was to characterize the pattern of gas retention and the abdomino-thoracic mechanics associated with abdominal distension in patients with intestinal dysmotility. In 15 patients with manometrically proven intestinal dysmotility, two abdominal CT scans were performed: one during basal conditions and other during an episode of severe abdominal distension. In 15 gender- and age-matched healthy controls, a basal scan was performed. In basal conditions, patients exhibited more abdominal gas than healthy subjects, particularly in the small bowel, and the volume significantly increased during an episode of distension. During episodes of abdominal distension, the increase in abdominal content was associated with increased girth and antero-posterior abdominal diameter, as well as a cephalic displacement of the diaphragm, which reduced the height of the lung. The consequent reduction in the air volume of the lung was attenuated by an increase in the antero-posterior diameter of the chest. Abdominal distension in patients with severe intestinal dysfunction is related to marked pooling of gut contents, particularly in the small bowel. This increase in content is accommodated within the abdominal cavity by a global and coordinated abdomino-phreno-thoracic response, involving an accommodative ascent of the diaphragm and a compensatory expansion of the chest wall. © 2013 John Wiley & Sons Ltd.

  4. Mechanism underlying the inner membrane retention of Escherichia coli lipoproteins caused by Lol avoidance signals. (United States)

    Hara, Takashi; Matsuyama, Shin-ichi; Tokuda, Hajime


    Escherichia coli lipoproteins are localized to either the inner or outer membrane depending on the residue at position 2. The inner membrane retention signal, Asp at position 2 in combination with certain residues at position 3, functions as a Lol avoidance signal, i.e. the signal inhibits the recognition of lipoproteins by LolCDE that releases lipoproteins from the inner membrane. To understand the role of the residue at position 2, outer membrane-specific lipoproteins with Cys at position 2 were subjected to chemical modification followed by the release reaction in reconstituted proteoliposomes. Sulfhydryl-specific introduction of nonprotein molecules or a negative charge to Cys did not inhibit the LolCDE-dependent release. In contrast, oxidation of Cys to cysteic acid resulted in generation of the Lol avoidance signal, indicating that the Lol avoidance signal requires a critical length of negative charge at the second residue. Furthermore, not only modification of the carboxylic acid of Asp at position 2 but also that of the amine of phosphatidylethanolamine abolished the Lol avoidance function. Based on these results, the Lol avoidance mechanism is discussed.

  5. Baroclinic instability of a symmetric, rotating, stratified flow: a study of the nonlinear stabilisation mechanisms in the presence of viscosity

    Directory of Open Access Journals (Sweden)

    R. Mantovani


    Full Text Available This paper presents the analysis of symmetric circulations of a rotating baroclinic flow, forced by a steady thermal wind and dissipated by Laplacian friction. The analysis is performed with numerical time-integration. Symmetric flows, vertically bound by horizontal walls and subject to either periodic or vertical wall lateral boundary conditions, are investigated in the region of parameter-space where unstable small amplitude modes evolve into stable stationary nonlinear solutions. The distribution of solutions in parameter-space is analysed up to the threshold of chaotic behaviour and the physical nature of the nonlinear interaction operating on the finite amplitude unstable modes is investigated. In particular, analysis of time-dependent energy-conversions allows understanding of the physical mechanisms operating from the initial phase of linear instability to the finite amplitude stable state. Vertical shear of the basic flow is shown to play a direct role in injecting energy into symmetric flow since the stage of linear growth. Dissipation proves essential not only in limiting the energy of linearly unstable modes, but also in selecting their dominant space-scales in the finite amplitude stage.

  6. Mixed-mode retention mechanism for (-)-epigallocatechin gallate on a 12% cross-linked agarose gel media. (United States)

    Xu, Jun; Tan, Tianwei; Janson, Jan-Christer


    The adsorption behaviour of (-)-epigallocatechin gallate (EGCG), the major polyphenolic substance in green tea extracts, on the cross-linked agarose gel Superose 12 HR 10/30, has been studied using a variety of solvent systems and shown to be based on a mixture of hydrogen bonding and hydrophobic interaction. The hydrogen bonding was studied in acetonitrile in the presence of different co-solvents possessing varying hydrogen bond donor (HBD) and/or hydrogen bond acceptor (HBA) characteristics. The HBA-value of the co-solvent had the highest effect whereas the HBD-value played a subordinate role. Retention due to hydrophobic interaction could be demonstrated when mobile phases containing high water content were applied. The retention of EGCG, and its analogues (-)-epigallocatechin (EGC) and (-)-catechin (C) were thus shown to be dependent on the polarity of the organic modifiers added. However, the elution order of EGC and C, was inversed to that observed in reversed phase chromatography, indicating that some hydrogen bonding was still in effect. The retardation of EGCG in the presence of a wide concentration range of acetonitrile in water confirmed the interpretation that the retention mechanism is of mixed-mode character based on both hydrogen bonding and hydrophobic interaction.

  7. Chemical adhesion rather than mechanical retention enhances resin bond durability of a dental glass-ceramic with leucite crystallites

    Energy Technology Data Exchange (ETDEWEB)

    Meng, X F [Department of Prosthodontics, The Stomatological Hospital Affiliated Medical School, Nanjing University, Nanjing 210008 (China); Yoshida, K [Division of Applied Prosthodontics, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki 852-8588 (Japan); Gu, N, E-mail: [Jiangsu Key Laboratory for Biomaterials and Devices, School of Biological Science and Medical Engineering, Southeast University, Nanjing 210096 (China)


    This study aims to evaluate the effect of chemical adhesion by a silane coupler and mechanical retention by hydrofluoric acid (HFA) etching on the bond durability of resin to a dental glass ceramic with leucite crystallites. Half of the ceramic plates were etched with 4.8% HFA (HFA group) for 60 s, and the other half were not treated (NoHFA group). The scale of their surface roughness and rough area was measured by a 3D laser scanning microscope. These plates then received one of the following two bond procedures to form four bond test groups: HFA/cement, NoHFA/cement, HFA/silane/cement and NoHFA/silane/cement. The associated micro-shear bond strength and bond failure modes were tested after 0 and 30 000 thermal water bath cycles. Four different silane/cement systems (Monobond S/Variolink II, GC Ceramic Primer/Linkmax HV, Clearfil Ceramic Primer/Clearfil Esthetic Cement and Porcelain Liner M/SuperBond C and B) were used. The data for each silane/cement system were analyzed by three-way ANOVA. HFA treatment significantly increased the surface R{sub a} and R{sub y} values and the rough area of the ceramic plates compared with NoHFA treatment. After 30 000 thermal water bath cycles, the bond strength of all the test groups except the HFA/Linkmax HV group was significantly reduced, while the HFA/Linkmax HV group showed only adhesive interface failure. The other HFA/cement groups and all NoHFA/cement groups lost bond strength completely, and all NoHFA/silane/cement groups with chemical adhesion had significantly higher bond strength and more ceramic cohesive failures than the respective HFA/cement groups with mechanical retention. The result of the HFA/silane/cement groups with both chemical adhesion and mechanical retention revealed that HFA treatment could enhance the bond durability of resin/silanized glass ceramics, which might result from the increase of the chemical adhesion area on the ceramic rough surface and subsequently reduced degradation speed of the silane

  8. Retention Mechanism of Localized Silicon-Oxide-Nitride-Oxide-Silicon Embedded NOR Device (United States)

    Hyun, JaeWoong; Jeong, YounSeok; Chae, HeeSoon; Seo, Sunae; Kim, JinHee; Um, MyungYoon; Lee, ByoungJin; Kim, KiChul; Cho, InWook; Bae, GeumJong; Lee, NaeIn; Kim, ChungWoo


    Reliability studies of localized oxide-nitride-oxide memory (LONOM) devices are presented. The observed reduction in channel threshold voltage as a result of the retention charge loss of a programmed cell is demonstrated in terms of vertical leakage paths. Despite the apparent controversy of charge transport with nitride read-only memory (NROM) devices, the vertical paths are evidently observed via the channel and junction threshold voltage changes, which were monitored using Ids-Vds curves and gate-induced drain leakage (GIDL) measurements, visualizing the internal status of interface charges and stored charges in a nitride layer.

  9. Enhanced retention of polymer physical characteristics and mechanical strength of 70:30 poly(L-lactide-co-D,L-lactide) after ethylene oxide sterilization. (United States)

    McManus, Anastasia J; Moser, Rodney C; Dabkowski, Rhiannon B; Thomas, Kevin A


    This study examined the effect of ethylene oxide (EtO) and electron beam (e-beam) irradiation on the properties of 70:30 poly(L-lactide-co-D,L-lactide). The effects of sterilization upon the polymer physical characteristics and strength retention of the material were examined, both initially and after being subjected to real time ageing. Commercially available 70:30 poly(L-lactide-co-D,L-lactide) material was fabricated into rectangular, cylindrical, screw, and sheet designs, and tested in compression, shear, or tension. Sterilization of 70:30 poly(L-lactide-co-D,L-lactide) by ethylene oxide had a nearly negligible effect on the physical properties of the polymer, regardless of specimen size or manufacturing technique. The molecular weight and inherent viscosity of the specimens decreased by approximately 3% after sterilization by EtO. However, sterilization of 70:30 poly(L-lactide-co-D,L-lactide) by e-beam irradiation resulted in immediate changes to some of the physical properties of the polymer. Specimens sterilized by e-beam irradiation displayed an immediate decrease in inherent viscosity of approximately 67% as compared to the respective nonsterile samples. The immediate decrease in inherent viscosity and molecular weight with e-beam irradiation required approximately 39 weeks of real time ageing of the EtO sterilized parts. At all time points investigated in the present study, the strength retention of the EtO sterilized devices equaled or exceeded that of the e-beam irradiated samples.

  10. Viscosity and Solvation (United States)

    Robertson, C. T.


    Discusses theories underlying the phenomena of solution viscosities, involving the Jones and Dole equation, B-coefficient determination, and flickering cluster model. Indicates that viscosity measurements provide a basis for the study of the structural effects of ions in aqueous solutions and are applicable in teaching high school chemistry. (CC)

  11. Viscosity measuring using microcantilevers (United States)

    Oden, Patrick Ian


    A method for the measurement of the viscosity of a fluid uses a micromachined cantilever mounted on a moveable base. As the base is rastered while in contact with the fluid, the deflection of the cantilever is measured and the viscosity determined by comparison with standards.

  12. Surface heterogeneity on hemispheres-in-cell model yields all experimentally-observed non-straining colloid retention mechanisms in porous media in the presence of energy barriers. (United States)

    Ma, Huilian; Pazmino, Eddy; Johnson, William P


    Many mechanisms of colloid retention in porous media under unfavorable conditions have been identified from experiments or theory, such as attachment at surface heterogeneities, wedging at grain to grain contacts, retention via secondary energy minimum association in zones of low flow drag, and straining in pore throats too small to pass. However, no previously published model is capable of representing all of these mechanisms of colloid retention. In this work, we demonstrate that incorporation of surface heterogeneity into our hemispheres-in-cell model yields all experimentally observed non-straining retention mechanisms in porous media under unfavorable conditions. We also demonstrate that the predominance of any given retention mechanism depends on the coupled colloid-collector-flow interactions that are governed by parameters such as the size and spatial frequency of heterogeneous attractive domains, colloid size, and solution ionic strength. The force/torque balance-simulated retention is shown to decrease gradually with decreasing solution ionic strength, in agreement with experimental observations. This gradual decrease stands in sharp contrast to predictions from mean field theory that does not account for discrete surface heterogeneity. © 2011 American Chemical Society

  13. Mobile phase effects on the retention on polar columns with special attention to the dual hydrophilic interaction - reversed-phase liquid chromatography mechanism: A review. (United States)

    Jandera, Pavel; Hájek, Tomáš


    Hydrophilic interaction liquid chromatography on polar columns in aqueous-organic mobile phases has become increasingly popular for the separation of many biologically important compounds in chemical, environmental, food, toxicological and other samples. In spite of many new applications appearing in literature, the retention mechanism is still controversial. This review addresses recent progress in understanding of the retention models in hydrophilic interaction liquid chromatography. The main attention is focused on the role of water, both adsorbed by the column and contained in the bulk mobile phase. Further, the theoretical retention models in the isocratic and gradient elution modes are discussed. The dual hydrophilic interaction liquid chromatography reversed-phase retention mechanism on polar columns is treated in detail, especially with respect to the practical use in one- and two-dimensional liquid chromatography separations. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  14. Modelling retention and dispersion mechanisms of bluefin tuna eggs and larvae in the Northwest Mediterranean Sea

    DEFF Research Database (Denmark)

    Mariani, Patrizio; MacKenzie, Brian; Iudicone, D.


    Knowledge of early life history of most fish species in the Mediterranean Sea is sparse and processes affecting their recruitment are poorly understood. This is particularly true for bluefin tuna, Thunnus thynnus, even though this species is one of the world's most valued fish species. Here we...... Sea. The model reproduced the drift and growth of anchovy larvae as they drifted along the Catalan coast and yielded similar patterns as those observed in the field. We then applied the model to investigate transport and retention processes affecting the spatial distribution of bluefin tuna eggs...... locations of spawning bluefin tuna using hydrographic backtracking procedures; these locations were situated in a major salinity frontal zone and coincided with distributions of an electronically tagged bluefin tuna and commercial bluefin tuna fishing vessels. Moreover, we hypothesized that mesoscale...

  15. Tidal viscosity of Enceladus (United States)

    Efroimsky, Michael


    In the preceding paper (Efroimsky, 2017), we derived an expression for the tidal dissipation rate in a homogeneous near-spherical Maxwell body librating in longitude. Now, by equating this expression to the outgoing energy flux due to the vapour plumes, we estimate the mean tidal viscosity of Enceladus, under the assumption that the Enceladean mantle behaviour is Maxwell. This method yields a value of 0.24 × 1014 Pa s for the mean tidal viscosity, which is very close to the viscosity of ice near the melting point.

  16. Retention Mechanisms of Citric Acid in Ternary Kaolinite-Fe(III)-Citrate Acid Systems Using Fe K-edge EXAFS and L3,2-edge XANES Spectroscopy (United States)

    Yang, Jianjun; Wang, Jian; Pan, Weinan; Regier, Tom; Hu, Yongfeng; Rumpel, Cornelia; Bolan, Nanthi; Sparks, Donald


    Organic carbon (OC) stability in tropical soils is strongly interlinked with multivalent cation interaction and mineral association. Low molecular weight organic acids (LMWOAs) represent the readily biodegradable OC. Therefore, investigating retention mechanisms of LMWOAs in mineral-cation-LMWOAs systems is critical to understanding soil C cycling. Given the general acidic conditions and dominance of kaolinite in tropical soils, we investigated the retention mechanisms of citric acid (CA) in kaolinite-Fe(III)-CA systems with various Fe/CA molar ratios at pH ~3.5 using Fe K-edge EXAFS and L3,2-edge XANES techniques. With Fe/CA molar ratios >2, the formed ferrihydrite mainly contributed to CA retention through adsorption and/or coprecipitation. With Fe/CA molar ratios from 2 to 0.5, ternary complexation of CA to kaolinite via a five-coordinated Fe(III) bridge retained higher CA than ferrihydrite-induced adsorption and/or coprecipitation. With Fe/CA molar ratios ≤0.5, kaolinite-Fe(III)-citrate complexation preferentially occurred, but less CA was retained than via outer-sphere kaolinite-CA complexation. This study highlighted the significant impact of varied Fe/CA molar ratios on CA retention mechanisms in kaolinite-Fe(III)-CA systems under acidic conditions, and clearly showed the important contribution of Fe-bridged ternary complexation on CA retention. These findings will enhance our understanding of the dynamics of CA and other LMWOAs in tropical soils. PMID:27212680

  17. An upwelling-induced retention area off Senegal: A mechanism to ...

    African Journals Online (AJOL)

    However, in areas such as Peru, Senegal and Côte d'Ivoire-Ghana, spawning and upwelling occur simultaneously. What are the mechanisms that allow such reproductive strategies to be successful? To attempt to answer this question, some environmental characteristics of the spawning ground of Sardinella aurita in the ...

  18. Imaging aerosol viscosity (United States)

    Pope, Francis; Athanasiadis, Thanos; Botchway, Stan; Davdison, Nicholas; Fitzgerald, Clare; Gallimore, Peter; Hosny, Neveen; Kalberer, Markus; Kuimova, Marina; Vysniauskas, Aurimas; Ward, Andy


    Organic aerosol particles play major roles in atmospheric chemistry, climate, and public health. Aerosol particle viscosity is important since it can determine the ability of chemical species such as oxidants, organics or water to diffuse into the particle bulk. Recent measurements indicate that OA may be present in highly viscous states; however, diffusion rates of small molecules such as water appear not to be limited by these high viscosities. We have developed a technique for measuring viscosity that allows for the imaging of aerosol viscosity in micron sized aerosols through use of fluorescence lifetime imaging of viscosity sensitive dyes which are also known as 'molecular rotors'. These rotors can be introduced into laboratory generated aerosol by adding minute quantities of the rotor to aerosol precursor prior to aerosolization. Real world aerosols can also be studied by doping them in situ with the rotors. The doping is achieved through generation of ultrafine aerosol particles that contain the rotors; the ultrafine aerosol particles deliver the rotors to the aerosol of interest via impaction and coagulation. This work has been conducted both on aerosols deposited on microscope coverslips and on particles that are levitated in their true aerosol phase through the use of a bespoke optical trap developed at the Central Laser Facility. The technique allows for the direct observation of kinetic barriers caused by high viscosity and low diffusivity in aerosol particles. The technique is non-destructive thereby allowing for multiple experiments to be carried out on the same sample. It can dynamically quantify and track viscosity changes during atmospherically relevant processes such oxidation and hygroscopic growth (1). This presentation will focus on the oxidation of aerosol particles composed of unsaturated and saturated organic species. It will discuss how the type of oxidant, oxidation rate and the composition of the oxidized products affect the time

  19. Studies on the Mechanisms of Methyl Iodide Adsorption and Iodine Retention on Silver-Mordenite

    Energy Technology Data Exchange (ETDEWEB)

    Nenoff, Tina Maria [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Soelberg, Nick [Idaho National Lab. (INL), Idaho Falls, ID (United States)


    Silver-containing mordenite (MOR) is a longstanding benchmark for radioiodine capture, reacting with molecular iodine (I2) to form AgI. However the mechanisms for organoiodine capture are not well understood. Here we investigate the capture of methyl iodide from complex mixed gas streams by combining chemical analysis of the effluent gas stream with in depth characterization of the recovered sorbent.

  20. Short-term retention of visual information: Evidence in support of feature-based attention as an underlying mechanism. (United States)

    Sneve, Markus H; Sreenivasan, Kartik K; Alnæs, Dag; Endestad, Tor; Magnussen, Svein


    Retention of features in visual short-term memory (VSTM) involves maintenance of sensory traces in early visual cortex. However, the mechanism through which this is accomplished is not known. Here, we formulate specific hypotheses derived from studies on feature-based attention to test the prediction that visual cortex is recruited by attentional mechanisms during VSTM of low-level features. Functional magnetic resonance imaging (fMRI) of human visual areas revealed that neural populations coding for task-irrelevant feature information are suppressed during maintenance of detailed spatial frequency memory representations. The narrow spectral extent of this suppression agrees well with known effects of feature-based attention. Additionally, analyses of effective connectivity during maintenance between retinotopic areas in visual cortex show that the observed highlighting of task-relevant parts of the feature spectrum originates in V4, a visual area strongly connected with higher-level control regions and known to convey top-down influence to earlier visual areas during attentional tasks. In line with this property of V4 during attentional operations, we demonstrate that modulations of earlier visual areas during memory maintenance have behavioral consequences, and that these modulations are a result of influences from V4. Copyright © 2014 Elsevier Ltd. All rights reserved.

  1. Kinetics and Mechanism of Metal Retention/Release in Geochemical Processes in Soil - Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, Robert W.


    Effective, remediation of soils contaminated with heavy metals requires a better understanding of the mechanisms by which the metals are retained/released in soils over a long period of time. Studies on reaction of Cr(VI) with iron-rich clays indicated that structural iron (II) in these surfaces is capable of reducing chromate to chromium (III). We found that iron (II) either found naturally or produced by treatment of clay with sodium dithionite, effectively reduced Cr (VI) to Cr (III). Thus, in situ remediation of chromium combines reduction of Cr (VI) to Cr (III) and immobilization of chromium on mineral surfaces. During this study, lead sorption on a kaolin surface was found to be a rapid and a pH dependant process in which lead sorption significantly increased with the amount of phosphate on the clay surface. This study verifies that methylmercury cation remains intact when it binds to humic acids, forming a monodentate complex with some sub-population of humic thiol ligands .

  2. "Understanding" cosmological bulk viscosity


    Zimdahl, Winfried


    A universe consisting of two interacting perfect fluids with the same 4-velocity is considered. A heuristic mean free time argument is used to show that the system as a whole cannot be perfect as well but neccessarily implies a nonvanishing bulk viscosity. A new formula for the latter is derived and compared with corresponding results of radiative hydrodynamics.

  3. Mechanism of altruism approach to blood donor recruitment and retention: a review and future directions. (United States)

    Ferguson, E


    Why do people donate blood? Altruism is the common answer. However, altruism is a complex construct and to answer this question requires a systematic analysis of the insights from the biology, economics and psychology of altruism. I term this the mechanism of altruism (MOA) approach and apply it here for understanding blood donor motivation. The answer also has enormous implications for the type of interventions we choose to adopt as a society. A MOA approach so far shows that blood donors are a mixture of (i) warm-glow givers (donation is emotionally rewarding) and (ii) reluctant altruists (cooperate rather than defect when free-riding is high). Donors also show 'saintly sinning' with the extra 'moral currency' form blood donation allowing them to be less generous in other contexts. The MOA approach suggests why financial incentives, in terms of gifts/lottery tickets, are effective and suggests a number of novel interventions for donor recruitment: 'voluntary reciprocal altruism' and 'charitable incentivisation'. The MOA approach also highlights the need for an intervention developed specifically for recipients to allow them to show their gratitude to donors and for society to celebrate blood donation. It is suggests a 'Monument to Blood Donors' will achieve this. The approach suggests a number of novel research questions into (i) donor self-selection effects, (ii) conditional cooperation and (iii) construct overlap with Theory of Planned Behaviour (e.g. affective attitudes and warm-glow). The MOA offers a powerful way to understand blood donor motivations around altruism and develop theoretically driven interventions. © 2015 British Blood Transfusion Society.

  4. Skyrmions and Hall viscosity


    Kim, Bom Soo


    We discuss the contribution of magnetic Skyrmions to the Hall viscosity and propose a simple way to identify it in experiments. The topological Skyrmion charge density has a distinct signature in the electric Hall conductivity that is identified in existing experimental data. In an electrically neutral system, the Skyrmion charge density is directly related to the thermal Hall conductivity. These results are direct consequences of the field theory Ward identities, which relate various physica...

  5. Early dissipation and viscosity


    Bozek, Piotr


    We consider dissipative phenomena due to the relaxation of an initial anisotropic local pressure in the fireball created in relativistic heavy-ion collisions, both for the Bjorken boost-invariant case and for the azimuthally symmetric radial expansion with boost-invariance. The resulting increase of the entropy can be counterbalanced by a suitable retuning of the initial temperature. An increase of the transverse collective flow is observed. The influence of the shear viscosity on the longitu...

  6. Mechanism of removal and retention of heavy metals from the acid mine drainage to coastal wetland in the Patagonian marsh. (United States)

    Idaszkin, Yanina L; Carol, Eleonora; María Del Pilar, Alvarez


    The attenuation of the acid mine drainage is one of the most important environmental challenges facing the mining industry worldwide. Mining waste deposits from an ancient metallurgical extraction of heavy metals were found near to the San Antonio marsh in Patagonia. The aim of this work was to determinate which mechanisms regulate the mobilization and retention of metals by acid drainage. A geological and geomorphological survey was carried out and samples from the mining waste deposits and the marsh were collected to determine soil texture, Eh pH, organic matter, Cu, Pb, Zn and Fe content, and soil mineralogical composition. Metals in marsh plants were determined in above- and below-ground structures. In the mining waste deposits polymetallic sulphides were recognized where the oxidation and formation of oxy-hydroxides and sulphates of Fe, Cu, Pb and Zn occurs. Then, by the alteration of those minerals, the metals enter in solution and are mobilized with the surface drainage towards the marsh where adsorption in the soils fine fraction and organic matter and/or by plants occurs. Locally, in the mining waste deposits, the precipitation/dissolution of Cu, Pb, and Zn sulphates take place in small centripetal drainage basins. In topographically lower portions of the marsh desorption and removal of metals by tidal flow could also be happen. The results allow to concluding that the marsh adjacent to the mining waste deposits is a geochemically active environment that naturally mitigates the contamination caused by acid drainage. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Novel expandable gastro retentive system by unfolding mechanism of levetiracetam using simple lattice design – Formulation optimization and in vitro evaluation

    Directory of Open Access Journals (Sweden)

    S. Sivaneswari


    Full Text Available The aim of the present study was to develop and characterize a novel expandable gastro-retentive dosage form (GRDF, based on unfolding mechanism. The dosage form consists of a drug loaded the polymeric patch, folded into a hard gelatin capsule. Gastro retention obtained from unfolding and swelling of the patch and its adhesion to the gastric mucosa. Therefore in this work, a gastro retentive patch of levetiracetam was developed using simple lattice design considering concentration of Hydroxy Propyl Methyl Cellulose, Carbopol 934P and Xanthan gum as independent variables. A response surface plot and multiple regression equations were used to evaluate the effect of independent variables on dependent variables such as mucoadhesive strength (g/cm2 and t90 (h. The prepared patches were evaluated for weight and thickness variation, mechanical properties, in vitro drug release and unfolding behavior. The absence of drug-polymer interaction and uniform drug dispersion in the polymeric patches was revealed by FT-IR, DSC, XRD and SEM. The results indicates, the novel GRDF based on unfolding mechanism can be alternative for other mucoadhesive dosage forms which will provide sustained release for 12 h.

  8. Critical Viscosity of Xenon (United States)


    The Critical Viscosity of Xenon Experiment (CVX-2) on the STS-107 Research 1 mission in 2001 will measure the viscous behavior of xenon, a heavy inert gas used in flash lamps and ion rocket engines, at its critical point. The thermostat for CVX sits inside the white cylinder on a support structure that is placed inside a pressure canister. A similar canister holds the electronics and control systems. The CVX-2 arrangement is identical. The principal investigator is Dr. Robert F. Berg (not shown) of the National Institutes of Standards and Technology, Gaithersburg, MD. This is a detail view of MSFC 0100143.

  9. Quantitatively mapping cellular viscosity with detailed organelle information via a designed PET fluorescent probe. (United States)

    Liu, Tianyu; Liu, Xiaogang; Spring, David R; Qian, Xuhong; Cui, Jingnan; Xu, Zhaochao


    Viscosity is a fundamental physical parameter that influences diffusion in biological processes. The distribution of intracellular viscosity is highly heterogeneous, and it is challenging to obtain a full map of cellular viscosity with detailed organelle information. In this work, we report 1 as the first fluorescent viscosity probe which is able to quantitatively map cellular viscosity with detailed organelle information based on the PET mechanism. This probe exhibited a significant ratiometric fluorescence intensity enhancement as solvent viscosity increases. The emission intensity increase was attributed to combined effects of the inhibition of PET due to restricted conformational access (favorable for FRET, but not for PET), and the decreased PET efficiency caused by viscosity-dependent twisted intramolecular charge transfer (TICT). A full map of subcellular viscosity was successfully constructed via fluorescent ratiometric detection and fluorescence lifetime imaging; it was found that lysosomal regions in a cell possess the highest viscosity, followed by mitochondrial regions.

  10. Quantitatively Mapping Cellular Viscosity with Detailed Organelle Information via a Designed PET Fluorescent Probe (United States)

    Liu, Tianyu; Liu, Xiaogang; Spring, David R.; Qian, Xuhong; Cui, Jingnan; Xu, Zhaochao


    Viscosity is a fundamental physical parameter that influences diffusion in biological processes. The distribution of intracellular viscosity is highly heterogeneous, and it is challenging to obtain a full map of cellular viscosity with detailed organelle information. In this work, we report 1 as the first fluorescent viscosity probe which is able to quantitatively map cellular viscosity with detailed organelle information based on the PET mechanism. This probe exhibited a significant ratiometric fluorescence intensity enhancement as solvent viscosity increases. The emission intensity increase was attributed to combined effects of the inhibition of PET due to restricted conformational access (favorable for FRET, but not for PET), and the decreased PET efficiency caused by viscosity-dependent twisted intramolecular charge transfer (TICT). A full map of subcellular viscosity was successfully constructed via fluorescent ratiometric detection and fluorescence lifetime imaging; it was found that lysosomal regions in a cell possess the highest viscosity, followed by mitochondrial regions. PMID:24957323

  11. Retention of alkali ions by hydrated low-pH cements: Mechanism and Na{sup +}/K{sup +} selectivity

    Energy Technology Data Exchange (ETDEWEB)

    Bach, T.T.H.; Chabas, E. [Commissariat à l' Énergie Atomique et aux Énergies Alternatives, DEN/MAR/DTCD/SPDE, BP 17171, 30207 Bagnols-sur-Cèze Cedex (France); Pochard, I., E-mail: [ICB, UMR 6303 CNRS Université de Bourgogne, 21078 Dijon (France); Cau Dit Coumes, C. [Commissariat à l' Énergie Atomique et aux Énergies Alternatives, DEN/MAR/DTCD/SPDE, BP 17171, 30207 Bagnols-sur-Cèze Cedex (France); Haas, J. [ICB, UMR 6303 CNRS Université de Bourgogne, 21078 Dijon (France); Frizon, F. [Commissariat à l' Énergie Atomique et aux Énergies Alternatives, DEN/MAR/DTCD/SPDE, BP 17171, 30207 Bagnols-sur-Cèze Cedex (France); Nonat, A. [ICB, UMR 6303 CNRS Université de Bourgogne, 21078 Dijon (France)


    Low-pH cements, also referred to as low-alkalinity cements, can be designed by replacing significant amounts of Portland cement by pozzolanic materials. Their pore solution is characterized by a pH near 11, and an alkali concentration much lower than that of Portland cement. This work investigates the retention of sodium and potassium by a hydrated low-pH cement comprising 60% Portland cement and 40% silica fume. It is shown that sorption of potassium is higher than that of sodium and mainly results from counterion charge balancing of the C-S-H negative surface charge. To explain the greater retention of potassium compared to sodium, it is postulated that potassium, unlike sodium, may enter the interlayer of C-S-H to compensate the negative charges in the interlayer, in addition to the external surfaces. This assumption is supported by structural characterization of C-S-H using X-ray diffraction.

  12. Grade Retention

    Directory of Open Access Journals (Sweden)

    Gia A. Renaud


    Full Text Available Academic accountability is of great concern, therefore grade retention is being considered for both students with and without disabilities who are not meeting end-of-the-year achievement benchmarks. The purpose of this study was to investigate teacher attitudes toward grade retention and whether practices differ when recommending retention of students with or without disabilities. This mixed-methods study utilized a paper-and-pencil questionnaire using a Likert-type scale, as well as two open-ended questions and a checklist. Teacher interviews were also conducted. The findings of this study indicate that teachers are considering a multitude of factors when considering grade retention for their struggling students. Academic performance was the factor that teachers (77% indicated the most frequently. Although teachers felt pressure and accountability from high stakes testing, they felt test results should be one of many factors considered in the retention decision.

  13. Heat flux viscosity in collisional magnetized plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Liu, C., E-mail: [Princeton University, Princeton, New Jersey 08544 (United States); Fox, W. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States); Bhattacharjee, A. [Princeton University, Princeton, New Jersey 08544 (United States); Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)


    Momentum transport in collisional magnetized plasmas due to gradients in the heat flux, a “heat flux viscosity,” is demonstrated. Even though no net particle flux is associated with a heat flux, in a plasma there can still be momentum transport owing to the velocity dependence of the Coulomb collision frequency, analogous to the thermal force. This heat-flux viscosity may play an important role in numerous plasma environments, in particular, in strongly driven high-energy-density plasma, where strong heat flux can dominate over ordinary plasma flows. The heat flux viscosity can influence the dynamics of the magnetic field in plasmas through the generalized Ohm's law and may therefore play an important role as a dissipation mechanism allowing magnetic field line reconnection. The heat flux viscosity is calculated directly using the finite-difference method of Epperlein and Haines [Phys. Fluids 29, 1029 (1986)], which is shown to be more accurate than Braginskii's method [S. I. Braginskii, Rev. Plasma Phys. 1, 205 (1965)], and confirmed with one-dimensional collisional particle-in-cell simulations. The resulting transport coefficients are tabulated for ease of application.

  14. Sensor for Viscosity and Shear Strength Measurement

    Energy Technology Data Exchange (ETDEWEB)

    Dillon, J.; Moore, J.E. Jr.; Ebadian, M.A.; Jones, W.K.


    Measurement of the physical properties (viscosity and density) of waste slurries is critical in evaluating transport parameters to ensure turbulent flow through transport pipes. The environment for measurement and sensor exposure is extremely harsh; therefore, reliability and ruggedness are critical in the sensor design. The work for this project will be performed in three phases. The first phase, carried out in FY96, involved (1) an evaluation of acoustic and other methods for viscosity measurement; (2) measurement of the parameters of slurries over the range of percent solids found in tanks and transport systems; (3) a comparison of physical properties (e.g., viscosity and density) to percent solids found composition; and (4) the design of a prototype sensor. The second phase (FY97) will involve the fabrication of a prototype hybrid sensor to measure the viscosity and mechanical properties of slurries in remote, high-radiation environments. Two different viscometer designs are being investigated in this study: a magnetostrictive pulse wave guide viscometer; an oscillating cylinder viscometer. In FY97, the Hemispheric Center for Environmental Technology (HCET) at Florida International University (FIU), which has printed circuit, thick film, thin film, and co-fired ceramic fabrication capability, will fabricate five probes for demonstration after technology selection and evaluation.

  15. Spiders Tune Glue Viscosity to Maximize Adhesion. (United States)

    Amarpuri, Gaurav; Zhang, Ci; Diaz, Candido; Opell, Brent D; Blackledge, Todd A; Dhinojwala, Ali


    Adhesion in humid conditions is a fundamental challenge to both natural and synthetic adhesives. Yet, glue from most spider species becomes stickier as humidity increases. We find the adhesion of spider glue, from five diverse spider species, maximizes at very different humidities that matches their foraging habitats. By using high-speed imaging and spreading power law, we find that the glue viscosity varies over 5 orders of magnitude with humidity for each species, yet the viscosity at maximal adhesion for each species is nearly identical, 10(5)-10(6) cP. Many natural systems take advantage of viscosity to improve functional response, but spider glue's humidity responsiveness is a novel adaptation that makes the glue stickiest in each species' preferred habitat. This tuning is achieved by a combination of proteins and hygroscopic organic salts that determines water uptake in the glue. We therefore anticipate that manipulation of polymer-salts interaction to control viscosity can provide a simple mechanism to design humidity responsive smart adhesives.

  16. Pressure Effect on Extensional Viscosity

    DEFF Research Database (Denmark)

    Christensen, Jens Horslund; Kjær, Erik Michael


    The primary object of these experiments was to investigate the influence of hydrostatic pressure on entrance flow. The effect of pressure on shear and extensional viscosity was evaluated using an axis symmetric capillary and a slit die where the hydrostatic pressure was raised with valves....... The experiments show a significant increase in extensional viscosity with increasing pressure....

  17. The viscosity of dimethyl ether

    DEFF Research Database (Denmark)

    Sivebæk, Ion Marius; Jakobsen, Jørgen


    and NOx traps are installed. The most significant problem encountered when engines are fuelled with DME is that the injection equipment breaks down prematurely due to extensive wear. This tribology issue can be explained by the very low lubricity and viscosity of DME. Recently, laboratory methods have...... appeared capable of measuring these properties of DME. The development of this is rendered difficult because DME has to be pressurised to remain in the liquid state and it dissolves most of the commercially available elastomers. This paper deals fundamentally with the measurement of the viscosity of DME...... and extends the discussion to the difficulty of viscosity establishing of very thin fluids. The main issue here is that it is not easy to calibrate the viscometers in the very low viscosity range corresponding to about one-fifth of that of water. The result is that the low viscosity is measured at high...

  18. Capillary waves with surface viscosity (United States)

    Shen, Li; Denner, Fabian; Morgan, Neal; van Wachem, Berend; Dini, Daniele


    Experiments over the last 50 years have suggested a correlation between the surface (shear) viscosity and the stability of a foam or emulsion. With recent techniques allowing more accurate measurements of the elusive surface viscosity, we examine this link theoretically using small-amplitude capillary waves in the presence of the Marangoni effect and surface viscosity modelled via the Boussinesq-Scriven model. The surface viscosity effect is found to contribute a damping effect on the amplitude of the capillary wave with subtle differences to the effect of the convective-diffusive Marangoni transport. The general wave dispersion is augmented to take into account the Marangoni and surface viscosity effects, and a first-order correction to the critical damping wavelength is derived. The authors acknowledge the financial support of the Shell University Technology Centre for fuels and lubricants.

  19. Urinary retention in children. (United States)

    Nevo, Amihay; Mano, Roy; Livne, Pinhas M; Sivan, Bezalel; Ben-Meir, David


    To describe the causes and outcome of urinary retention in children and assess its prevalence by gender and age. The medical records of all children (aged <18 years) who presented to the emergency room with acute urinary retention from 2000 to 2012 were reviewed. Patients with postoperative urinary retention, a known neurologic disorder, and neonates were excluded. Data were collected on patient demographics and cause, treatment, and outcome of the urinary retention. Findings were evaluated and compared by age and gender. The study group comprised 42 boys (75%) and 14 girls (25%). Median follow-up time was 25 months. Causes of urinary retention were mechanical obstruction in 14 patients (25%), infection or inflammation in 10 (18%), fecal impaction in 7 (13%), neurologic disorders in 6 (11%), gynecologic disorders in 4 (7%), and behavioral processes in 3 patients (5%); 12 patients (21%) were idiopathic. All patients with mechanical obstruction were boys, of whom 5 had a pelvic tumor. Age distribution was bimodal: 29% of the events occurred between ages 3 and 5 years, and 32%, between ages 10 and 13 years. Fifteen children underwent surgery. Three children required continuous catheterization during follow-up. Urinary retention in children is characterized by a variable etiology and bimodal age distribution. The high rate of severe underlying disease is noteworthy and should alert physicians to the importance of a prompt, comprehensive, primary evaluation of this patient population in a hospital setting to initiate appropriate treatment and avoid complications. Copyright © 2014 Elsevier Inc. All rights reserved.

  20. Influence of Febrile Neutropenia Period on Plasma Viscosity at Malignancy

    Directory of Open Access Journals (Sweden)

    Ibrahim Tek


    Full Text Available Cancer, chemotherapy, and infections all together make changes in blood rheology and may affect the defense mechanisms by changing the thrombocyte function and endothelial cell. We have examined changes of blood rheology on plasma viscosity to put on probable following criteria for starting the treatment of febrile neutropenia immediately. A total of 27 postchemotherapy patients (16 males and 11 females with febrile neutropenia diagnosed according to international guidelines have been included into the study. The plasma viscosity of the patients whose febrile neutropenia has been successfully treated was also measured to assess the impact of the duration of neutropenia on viscosity. The plasma viscosities of the patients were significantly higher during neutropenic episode than in nonneutropenic state ( except for alkaline phosphatase. All study parameters, particularly acute phase reactants, were statistically similar during both states. In the correlation of analysis with study parameters and stages, significant correlation was not observed between plasma viscosity alteration and leukocyte-neutrophil alteration, also other study parameters. We have demonstrated significantly elevated plasma viscosity in our patients during febrile neutropenic episode. Despite normal values of various parameters known to trigger plasma viscosity, particularly fibrinogen, it can be easily argued that the main mechanism may be the endothelial injury during infectious process and immune response mediated microcirculatory blood flow alterations.

  1. Viscosity Measurement for Tellurium Melt (United States)

    Lin, Bochuan; Li, Chao; Ban, Heng; Scripa, Rosalia N.; Su, Ching-Hua; Lehoczky, Sandor L.


    The viscosity of high temperature Te melt was measured using a new technique in which a rotating magnetic field was applied to the melt sealed in a suspended ampoule, and the torque exerted by rotating melt flow on the ampoule wall was measured. Governing equations for the coupled melt flow and ampoule torsional oscillation were solved, and the viscosity was extracted from the experimental data by numerical fitting. The computational result showed good agreement with experimental data. The melt velocity transient initiated by the rotating magnetic field reached a stable condition quickly, allowing the viscosity and electrical conductivity of the melt to be determined in a short period.

  2. Ciliary-propelling mechanism, effect of temperature and viscosity on swimming speed, and adaptive significance of ‘jumping’ in the ciliate Mesodinium rubrum

    DEFF Research Database (Denmark)

    Riisgård, Hans Ulrik; Larsen, Poul Scheel


    law Vs ~ µ^-n, n~1.93. For small M. rubrum, swimming velocity decreased from 6.1 +/- 1.3 mm/s at 21.1C to 3.8 +/- 0.3 mm/s at 9.5C, while the power-law exponent was n ~ 1.4 and 3 for changing temperature and temperature equivalent, respectively, but with n ~ 1.96 for all data taken together....... The results, supplemented with an analysis of a hydrodynamic model for self-propagation of an idealized micro-organism, support the hypothesis that the response is mainly physical/mechanical rather than biological. Since the jump-speed of M. rubrum is nearly the same for all tracks of varying jumplengths...

  3. Viscosity of particle laden films (United States)

    Timounay, Yousra; Rouyer, Florence


    We perform retraction experiments on soap films where large particles bridge the two interfaces. Local velocities are measured by PIV during the unstationnary regime. The velocity variation in time and space can be described by a continuous fluid model from which effective viscosity (shear and dilatational) of particulate films is measured. The 2D effective viscosity of particulate films η2D increases with particle surface fraction ϕ: at low ϕ, it tends to the interfacial dilatational viscosity of the liquid/air interfaces and it diverges at the critical particle surface fraction ϕc ≃ 0.84. Experimental data agree with classical viscosity laws of hard spheres suspensions adapted to the 2D geometry, assuming viscous dissipation resulting from the squeeze of the liquid/air interfaces between the particles. Finally, we show that the observed viscous dissipation in particulate films has to be considered to describe the edge velocity during a retraction experiment at large particle coverage.

  4. Effect of Fluid Dynamic Viscosity on the Strength of Chalk

    DEFF Research Database (Denmark)

    Hedegaard, K.; Fabricius, Ida Lykke

    The mechanical strength of high porosity and weakly cemented chalk is affected by the fluid in the pores. In this study, the effect of the dynamic viscosity of non-polar fluids has been measured on outcrop chalk from Sigerslev Quarry, Stevns, Denmark. The outcome is that the measured strength...... of the chalk decreases with increasing dynamic viscosity. The proposed qualitative explanation is that pressure difference supports and enhances the generation of microscopic shear and tensile failures....

  5. Concentration and retention of Toxoplasma gondii oocysts by marine snails demonstrate a novel mechanism for transmission of terrestrial zoonotic pathogens in coastal ecosystems. (United States)

    Krusor, Colin; Smith, Woutrina A; Tinker, M Tim; Silver, Mary; Conrad, Patricia A; Shapiro, Karen


    The parasite Toxoplasma gondii is an environmentally persistent pathogen that can cause fatal disease in humans, terrestrial warm-blooded animals and aquatic mammals. Although an association between T. gondii exposure and prey specialization on marine snails was identified in threatened California sea otters, the ability of kelp-dwelling snails to transmit terrestrially derived pathogens has not been previously investigated. The objective of this study was to measure concentration and retention of T. gondii by marine snails in laboratory aquaria, and to test for natural T. gondii contamination in field-collected snails. Following exposure to T. gondii-containing seawater, oocysts were detected by microscopy in snail faeces and tissues for 10 and 3 days respectively. Nested polymerase chain reaction was also applied as a method for confirming putative T. gondii oocysts detected in snail faeces and tissues by microscopy. Toxoplasma gondii was not detected in field-collected snails. Results suggest that turban snails are competent transport hosts for T. gondii. By concentrating oocysts in faecal pellets, snails may facilitate entry of T. gondii into the nearshore marine food web. This novel mechanism also represents a general pathway by which marine transmission of terrestrially derived microorganisms can be mediated via pathogen concentration and retention by benthic invertebrates. © 2015 Society for Applied Microbiology and John Wiley & Sons Ltd.

  6. Concentration and retention of Toxoplasma gondii oocysts by marine snails demonstrate a novel mechanism for transmission of terrestrial zoonotic pathogens in coastal ecosystems (United States)

    Krusor, Colin; Smith, Woutrina A.; Tinker, M. Tim; Silver, Mary; Conrad, Patricia A.; Shapiro, Karen


    The parasite Toxoplasma gondii is an environmentally persistent pathogen that can cause fatal disease in humans, terrestrial warm-blooded animals and aquatic mammals. Although an association between T. gondii exposure and prey specialization on marine snails was identified in threatened California sea otters, the ability of kelp-dwelling snails to transmit terrestrially derived pathogens has not been previously investigated. The objective of this study was to measure concentration and retention of T. gondii by marine snails in laboratory aquaria, and to test for natural T. gondii contamination in field-collected snails. Following exposure to T. gondii-containing seawater, oocysts were detected by microscopy in snail faeces and tissues for 10 and 3 days respectively. Nested polymerase chain reaction was also applied as a method for confirming putative T. gondii oocysts detected in snail faeces and tissues by microscopy. Toxoplasma gondiiwas not detected in field-collected snails. Results suggest that turban snails are competent transport hosts for T. gondii. By concentrating oocysts in faecal pellets, snails may facilitate entry of T. gondii into the nearshore marine food web. This novel mechanism also represents a general pathway by which marine transmission of terrestrially derived microorganisms can be mediated via pathogen concentration and retention by benthic invertebrates.

  7. Effect of alcohol aggregation on the retention factors of chiral solutes with an amylose-based sorbent: modeling and implications for the adsorption mechanism. (United States)

    Tsui, Hung-Wei; Franses, Elias I; Wang, Nien-Hwa Linda


    Various displacement models in the literature have been widely used for understanding the adsorption mechanisms of solutes in various chromatography systems. The models were used for describing the often-observed linear plots of the logarithms of the retention factor versus the logarithms of the polar modifier concentration CI(0). The slopes of such a plot was inferred to be equal to the number of the displaced modifier molecules upon adsorption of one solute molecule, and were generally found to be greater than 1. In this study, the retention factors of four structurally related chiral solutes, ethyl lactate (EL), methyl mandelate (MM), benzoin (B), and pantolactone (PL), were measured for the amylose tris[(S)-α-methylbenzylcarbamate] sorbent, or AS, as a function of the concentration of isopropanol (IPA) in n-hexane. With increasing IPA concentration CI(0), the slopes increase from less than 1, at a concentration range from 0.13 to 1.3M, to slightly more than 1 at higher concentrations. Such slopes cannot be explained by the conventional retention models. It was found previously for monovalent solutes that such slopes can only be explained when the aggregation of the mobile phase modifier, isopropyl alcohol, was accounted for. A new retention model is presented here, accounting for alcohol aggregation, multivalent solute adsorption, multivalent solute-alcohol complexation, alcohol adsorption, and solute intra hydrogen-bonding, which occur in these four solutes. The slope is found to be controlled by three key dimensionless groups, the fraction of the sorbent binding sites covered by IPA, the fraction of the solute molecules in complex form, and the fraction of the IPA molecules in aggregate form. The limiting slope at a very high IPA concentration is equal to the value of (x+y)/n, where x is the number of the solute-sorbent binding sites and y is the number of the alcohol molecules in the solute-alcohol complex, and n is the alcohol aggregation number. The model

  8. Hydrodynamic simulations of accretion flows with time-varying viscosity (United States)

    Roy, Abhishek; Chakrabarti, Sandip K.


    X-ray outbursts of stellar-mass black hole candidates are believed to be due to a sudden rise in viscosity, which transports angular momentum efficiently and increases the accretion rates, causing higher X-ray flux. After the viscosity is reduced, the outburst subsides and the object returns back to the pre-outburst quiescence stage. In the absence of a satisfactory understanding of the physical mechanism leading to such a sharp time dependence of viscous processes, we perform numerical simulations where we include the rise and fall of a viscosity parameter at an outer injection grid, assumed to be located at the accumulation radius where matter from the companion is piled up before being released by enhanced viscosity. We use a power-law radial dependence of the viscosity parameter (α ˜ rɛ), but the exponent (ɛ) is allowed to vary with time to mimic a fast rise and decay of the viscosity parameter. Since X-ray spectra of a black hole candidate can be explained by a Keplerian disc component in the presence of a post-shock region of an advective flow, our goal here is also to understand whether the flow configurations required to explain the spectral states of an outbursting source could be obtained by a time-varying viscosity. We present the results of our simulations to prove that low-angular-momentum (sub-Keplerian) advective flows do form a Keplerian disc in the pre-shock region when the viscosity is enhanced, which disappears on a much longer time-scale after the viscosity is withdrawn. From the variation of the Keplerian disc inside an advective halo, we believe that our result, for the first time, is able to simulate the two-component advective flow dynamics during an entire X-ray outburst and explain the observed hysteresis effects in the hardness-intensity diagram.

  9. A novel mechanism of immune regulation: interferon-γ regulates retention of CD4+ T cells during delayed type hypersensitivity (United States)

    Seabrook, Tim J; Borron, Paul J; Dudler, Lisbeth; Hay, John B; Young, Alan J


    The local immune response is characterized by an increase in the rate of entry of lymphocytes from the blood into regional lymph nodes and changes in the output of cells in lymph. While significant data are available regarding the role of inflammation-induced vascular adhesion processes in regulating lymphocyte entry into inflamed tissues and lymph nodes, relatively little is known about the molecular processes governing lymphocyte exit into efferent lymph. We have defined a novel role for lymphatic endothelial cells in the regulation of lymphocyte exit during a delayed type hypersensitivity (DTH) response to mycobacterial purified protein derivative (PPD). Soluble, pro-adhesive factors were identified in efferent lymph concomitant with reduced lymphocyte output in lymph, which significantly increased lymphocyte binding to lymphatic endothelial cells. While all lymphocyte subsets were retained, CD4+ T cells appeared less susceptible than others. Among a panel of cytokines in inflammatory lymph plasma, interferon (IFN)-γ alone appeared responsible for this retention. In vitro adhesion assays using physiological levels of IFN-γ confirmed the interaction between recirculating lymphocytes and lymphatic endothelium. These data demonstrate a new level of immune regulation, whereby the exit of recirculating lymphocytes from lymph nodes is selectively and sequentially regulated by cytokines in a manner equally as complex as lymphocyte recruitment. PMID:16162267

  10. Comparison of Parallel Viscosity with Neoclassical Theory


    K., Ida; N., Nakajima


    Toroidal rotation profiles are measured with charge exchange spectroscopy for the plasma heated with tangential NBI in CHS heliotron/torsatron device to estimate parallel viscosity. The parallel viscosity derived from the toroidal rotation velocity shows good agreement with the neoclassical parallel viscosity plus the perpendicular viscosity. (mu_perp =2m^2 /s).

  11. Effect of viscosity on harmonic signals from magnetic fluid

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, Takashi, E-mail:; Bai, Shi; Hirokawa, Aiki; Tanabe, Kazuhiro; Enpuku, Keiji


    We explored the effect of viscosity on harmonic signals from a magnetic fluid. Using a numerical simulation that accounts for both the Brownian and Néel processes, we clarified how the magnetization mechanism is affected by viscosity. When the excitation field varies much slower than the Brownian relaxation time, magnetization can be described by the Langevin function. On the other hand, for the case when the excitation field varies much faster than the Brownian relaxation time, but much slower than the Néel relaxation time, the easy axes of the magnetic nanoparticles (MNPs) turn to some extent toward the direction of the excitation field in an equilibrium state. This alignment of the easy axes of MNPs caused by the AC field becomes more significant with the increase of the AC field strength. Consequently, the magnetization is different from the Langevin function even though Néel relaxation time is faster than time period of the external frequency. It is necessary to consider these results when we use harmonic signals from a magnetic fluid in a high-viscosity medium. - Highlights: • We explore the effect of viscosity on harmonic signals from a magnetic fluid. • We clarify how the magnetization mechanism is affected by the viscosity of the fluid. • The magnetization in a high-viscosity medium is different from a Langevin function. • We empirically express the alignment of easy axes of the MNPs caused by an AC field.

  12. Addition of water-soluble soy extract and probiotic culture, viscosity, water retention capacity and syneresis characteristics of goat milk yogurt Adição de extrato hidrossolúvel de soja e cultura probiótica e características de viscosidade, capacidade de retenção de água e de sinerese de iogurte produzido com leite de cabra

    Directory of Open Access Journals (Sweden)

    Danielle Cristina Guimarães da Silva


    Full Text Available Yogurts from goat milk were elaborated and water-soluble soybean extract (WSSE and Bifidobacterium lactis probiotic culture added during processing. The characteristics of apparent viscosity, water retention capacity and syneresis were analyzed during 29 days of storage and it was verified the influence of WSSE and the probiotic on these rheological properties. The suplementation of WSSE provoked an increase in the viscosity and water retention capacity of the yogurts while reducing the syneresis. The inoculation of the probiotic culture during elaboration of the yogurts did not significantly alter the rheological characteristics of the products. Therefore, the water-soluble soybean extract and the probiotic culture can contribute to the rheological characteristics of yogurts, besides the nutritional and functional improvement advantages already known with the use of these products.Iogurtes a base de leite de cabra foram elaborados e a eles adicionados extrato hidrossolúvel de soja (EHS e de cultura probiótica Bifidobacterium lactis durante o processamento. As características de viscosidade aparente, capacidade de retenção de água e sinerese foram analisadas durante 29 dias de armazenamento e verificadas a influência do EHS e do probiótico nestas propriedades reológicas. A suplementação de EHS provocou aumento na viscosidade e capacidade de retenção de água dos iogurtes e, ao mesmo tempo, a sinerese foi reduzida. A inoculação da cultura probiótica durante elaboração dos iogurtes não alterou de forma significativa as características reológicas dos produtos. Portanto, a adição de extrato hidrossolúvel de soja e a cultura probiótica, pode contribuir para melhora nas características reológicas de iogurtes, além das vantagens na melhoria nutricional e funcional já conhecidas com a utilização destes produtos.

  13. Optimization of the silk scaffold sericin removal process for retention of silk fibroin protein structure and mechanical properties

    Energy Technology Data Exchange (ETDEWEB)

    Teh, Thomas K H; Toh, Siew-Lok; Goh, James C H, E-mail:, E-mail:, E-mail: [Division of Bioengineering, National University of Singapore (Singapore)


    In the process of removing sericin (degumming) from a raw silk scaffold, the fibroin structural integrity is often challenged, leading to mechanical depreciation. This study aims to identify the factors and conditions contributing to fibroin degradation during alkaline degumming and to perform an optimization study of the parameters involved to achieve preservation of fibroin structure and properties. The methodology involves degumming knitted silk scaffolds for various durations (5-90 min) and temperatures (60-100 {sup 0}C). Mechanical agitation and use of the refreshed solution during degumming are included to investigate how these factors contribute to degumming efficiency and fibroin preservation. Characterizations of silk fibroin morphology, mechanical properties and protein components are determined by scanning electron microscopy (SEM), single fiber tensile tests and gel electrophoresis (SDS-PAGE), respectively. Sericin removal is ascertained via SEM imaging and a protein fractionation method involving SDS-PAGE. The results show that fibroin fibrillation, leading to reduced mechanical integrity, is mainly caused by prolonged degumming duration. Through a series of optimization, knitted scaffolds are observed to be optimally degummed and experience negligible mechanical and structural degradation when subjected to alkaline degumming with mechanical agitation for 30 min at 100 {sup 0}C.

  14. Viscosity kernel of molecular fluids

    DEFF Research Database (Denmark)

    Puscasu, Ruslan; Todd, Billy; Daivis, Peter


    The wave-vector dependent shear viscosities for butane and freely jointed chains have been determined. The transverse momentum density and stress autocorrelation functions have been determined by equilibrium molecular dynamics in both atomic and molecular hydrodynamic formalisms. The density......, temperature, and chain length dependencies of the reciprocal and real-space viscosity kernels are presented. We find that the density has a major effect on the shape of the kernel. The temperature range and chain lengths considered here have by contrast less impact on the overall normalized shape. Functional...... forms that fit the wave-vector-dependent kernel data over a large density and wave-vector range have also been tested. Finally, a structural normalization of the kernels in physical space is considered. Overall, the real-space viscosity kernel has a width of roughly 3–6 atomic diameters, which means...

  15. Viscosity Control Experiment Feasibility Study

    Energy Technology Data Exchange (ETDEWEB)

    Morris, Heidi E. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Bradley, Paul Andrew [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)


    Turbulent mix has been invoked to explain many results in Inertial Confinement Fusion (ICF) and High Energy Density (HED) physics, such as reduced yield in capsule implosions. Many ICF capsule implosions exhibit interfacial instabilities seeded by the drive shock, but it is not clear that fully developed turbulence results from this. Many simulations use turbulent mix models to help match simulation results to data, but this is not appropriate if turbulence is not present. It would be useful to have an experiment where turbulent mixing could be turned on or off by design. The use of high-Z dopants to modify viscosity and the resulting influence on turbulence is considered here. A complicating factor is that the plasma in some implosions can become strongly coupled, which makes the Spitzer expression for viscosity invalid. We first consider equations that cover a broad parameter space in temperature and density to address regimes for various experimental applications. Next, a previous shock-tube and other ICF experiments that investigate viscosity or use doping to examine the effects on yield are reviewed. How viscosity and dopants play a role in capsule yield depends on the region and process under consideration. Experiments and simulations have been performed to study the effects of viscosity on both the hot spot and the fuel/ablator mix. Increases in yield have been seen for some designs, but not all. We then discuss the effect of adding krypton dopant to the gas region of a typical OMEGA and a 2-shock NIF implosion to determine approximately the effect of adding dopant on the computed Reynolds number. Recommendations for a path forward for possible experiments using high-Z dopants to affect viscosity and turbulence are made.

  16. Titin Based Viscosity in Ventricular Physiology: An Integrative Investigation of PEVK-Actin Interactions (United States)

    Chung, Charles S; Methawasin, Methajit; Nelson, O Lynne; Radke, Michael H; Hidalgo, Carlos G; Gotthardt, Michael; Granzier, Henk L


    Viscosity is proposed to modulate diastolic function, but only limited understanding of the source(s) of viscosity exists. In-vitro experiments have shown that the proline-glutamic acid-valine-lysine (PEVK) rich element of titin interacts with actin, causing a viscous force in the sarcomere. It is unknown whether this mechanism contributes to viscosity in-vivo. We tested the hypothesis that PEVK-actin interaction causes cardiac viscosity and is important in-vivo via an integrative physiological study on a unique PEVK-knockout (KO) model. Both skinned cardiomyocytes and papillary muscle fibers were isolated from wildtype (WT) and PEVK KO mice and passive viscosity was examined using stretch-hold-release and sinusoidal analysis. Viscosity was reduced by ~60% in KO myocytes and ~50% in muscle fibers at room temperature. The PEVK-actin interaction was not modulated by temperature or diastolic calcium, but was increased by lattice compression. Stretch-hold and sinusoidal frequency protocols on intact isolated mouse hearts showed a smaller, 30–40% reduction in viscosity, possibly due to actomyosin interactions, and showed that microtubules did not contribute to viscosity. Transmitral Doppler echocardiography similarly revealed a 40% decrease in LV chamber viscosity in the PEVK KO in-vivo. This integrative study is the first to quantify the influence of a specific molecular (PEVK-actin) viscosity in-vivo and shows that PEVK-actin interactions are an important physiological source of viscosity. PMID:21708170

  17. Molecular clutch drives cell response to surface viscosity. (United States)

    Bennett, Mark; Cantini, Marco; Reboud, Julien; Cooper, Jonathan M; Roca-Cusachs, Pere; Salmeron-Sanchez, Manuel


    Cell response to matrix rigidity has been explained by the mechanical properties of the actin-talin-integrin-fibronectin clutch. Here the molecular clutch model is extended to account for cell interactions with purely viscous surfaces (i.e., without an elastic component). Supported lipid bilayers present an idealized and controllable system through which to study this concept. Using lipids of different diffusion coefficients, the mobility (i.e., surface viscosity) of the presented ligands (in this case RGD) was altered by an order of magnitude. Cell size and cytoskeletal organization were proportional to viscosity. Furthermore, there was a higher number of focal adhesions and a higher phosphorylation of FAK on less-mobile (more-viscous) surfaces. Actin retrograde flow, an indicator of the force exerted on surfaces, was also seen to be faster on more mobile surfaces. This has consequential effects on downstream molecules; the mechanosensitive YAP protein localized to the nucleus more on less-mobile (more-viscous) surfaces and differentiation of myoblast cells was enhanced on higher viscosity. This behavior was explained within the framework of the molecular clutch model, with lower viscosity leading to a low force loading rate, preventing the exposure of mechanosensitive proteins, and with a higher viscosity causing a higher force loading rate exposing these sites, activating downstream pathways. Consequently, the understanding of how viscosity (regardless of matrix stiffness) influences cell response adds a further tool to engineer materials that control cell behavior. Copyright © 2018 the Author(s). Published by PNAS.

  18. Human capability in the perception of extensional and shear viscosity. (United States)

    Lv, Zhihong; Chen, Jianshe; Holmes, Melvin


    Shear and extensional deformation are two basic rheological phenomena which occur commonly in our daily life. Because of the very different nature of the two deformations, fluid materials may exhibit significant differences in their responses to shear and extensional forces. This work investigated the human perception of shear and extensional viscosity and tested the hypothesis that human have different discriminatory sensation mechanisms including scaling to the two deformations. A series of fluid samples were prepared using two common food thickeners, guar gum and sodium carboxylmethylcellulose (CMC-Na). The shear and extensional flow behavior of these fluids were assessed using shear and extensional rheometers and in addition two separate sensory analysis sessions were organized to assess human sensitivity in perceiving the two viscosities. Magnitude estimation was used in the first session to assess human sensitivity in the perception of the shear and extensional viscosities and just-noticeable-difference (JND) assessment was used for the second session to identify the typical threshold of viscosity discrimination. For the participants considered, it was found that the perception of both shear and extensional viscosity follow a power law relationship i.e. Steven's law. It was also observed that the human has a greater discriminatory capacity in perceiving extensional viscosity. JND analysis showed that the human threshold in detecting shear viscosity difference was 9.33%, but only 6.20% for extensional viscosity. Shear and extensional deformation are two basic rheological properties which occur during food manipulation, mastication, deglutition executed during oral consumption and also in the processing and packaging of foods. Fluid resistance against shear and extensional deformation differ widely and whilst this has been confirmed theoretically and experimentally, a clear understanding of human perception of these properties will have beneficial returns to

  19. Viscosity in hot mix construction. (United States)


    Viscosity, one of the oldest known and tested properties of Asphalt, yet one of the least studied is recently being given the attention it so rightfully deserves. Numerous engineers did recognize the importance of this property to the extent that sev...

  20. Effective viscosity of confined hydrocarbons

    DEFF Research Database (Denmark)

    Sivebæk, Ion Marius; Samoilov, V.N.; Persson, B.N.J.


    We present molecular dynamics friction calculations for confined hydrocarbon films with molecular lengths from 20 to 1400 carbon atoms. We find that the logarithm of the effective viscosity ηeff for nanometer-thin films depends linearly on the logarithm of the shear rate: log ηeff=C-nlog γ̇, where...

  1. Fission hindrance and nuclear viscosity

    Indian Academy of Sciences (India)


    Jul 29, 2015 ... We discuss the role of nuclear viscosity in hindering the fission of heavy nuclei as observed in the experimental measurements of GDR -ray spectra from the fissioning nuclei. We review a set of experiments carried out and reported by us previously [see Dioszegi et al, Phys. Rev. C 61, 024613 (2000); ...

  2. Fission hindrance and nuclear viscosity

    Indian Academy of Sciences (India)

    is in exact conformity with all the previous measurements [7,10–13]. The CASCADE calculations (solid lines in figure 1) used in this first level of analysis do not include any viscosity or temperature-dependent nuclear level density parameter a. The γ and particle decay are calculated using the standard prescriptions as ...

  3. Comparative analysis of the mechanical properties of fiber and stainless steel multistranded wires used for lingual fixed retention. (United States)

    Annousaki, O; Zinelis, S; Eliades, G; Eliades, T


    To evaluate the effect of different resins used for the co-polymerization of EverStick fiber-reinforced fixed orthodontic retainer on its mechanical properties and to compare the mechanical properties of these configurations to commonly used multistrand wires. Ten 0.0175-in. WildCat (WC175), ten 0.0215-in. WildCat (WC215) three-strand twisted wires and thirty EverStick fibers were tested in this study. The EverStcik fibers were equally shared in three groups (n=10). The samples of first group (ESRE) were polymerized employing Stickresin (Light cure enamel adhesives), the second one (ESFT) employing Flow Tain (Light cured composite), whilst the specimens for the third group (ES) were not combined with resin. All samples were loaded in tensile up to fracture in a universal tensile testing machine and the modulus of elasticity, tensile strength and strain after fracture were recorded. The same groups were also tested employing Instrumented Indentation Testing (IIT) and Martens Hardness (HM), Indentation Modulus (EIT) and elastic index (ηIT) were determined. The results of tensile testing and IIT were statistically analyzed employing one way Anova and the Student Newman Keuls test (SNK) at a=0.05 level of significance. WC175 and WC215 showed higher modulus of elasticity and tensile strength but lower strain after fracture compared to Everstic groups. IIT illustrated significantly higher values for HM, EIT, and ηIT for WC groups compared to ESRE, ESFT and ES. ESFT showed higher HM and elastic index compared to ESRE and ES, a finding which is attributed to the fact the FlowTain is a filler-reinforce composite with higher hardness compared to unfilled resins. Multistrand wires demonstrated higher values in mechanical properties compared to EverStick ones. The co-polymerization with difference resins does not affect the tensile properties of Everstic, however the use of a light cured composite has a beneficial effect on hardness. Copyright © 2017 The Academy of Dental

  4. Shear viscosity of the quark matter


    Iwasaki, Masaharu; Ohnishi, Hiromasa; Fukutome, Takahiko


    We discuss shear viscosity of the quark matter by using Kubo formula. The shear viscosity is calculated in the framework of the quasi-particle RPA for the Nambu-Jona-Lasinio model. We obtain a formula that the shear viscosity is expressed by the quadratic form of the quark spectral function in the chiral symmetric phase. The magnitude of the shear viscosity is discussed assuming the Breit-Wigner type for the spectral function.

  5. Density and viscosity of lipids under pressure (United States)

    There is a lack of data for the viscosity of lipids under pressure. The current report is a part of the effort to fill this gap. The viscosity, density, and elastohydrodynamic film thicknesses of vegetable oil (HOSuO) were investigated. Pressure–viscosity coefficients (PVC) of HOSuO at different tem...

  6. Effect of viscosity on learned satiation

    NARCIS (Netherlands)

    Mars, M.; Hogenkamp, P.S.; Gosses, A.M.; Stafleu, A.; Graaf,


    A higher viscosity of a food leads to a longer orosensory stimulation. This may facilitate the learned association between sensory signals and metabolic consequences. In the current study we investigated the effect of viscosity on learned satiation. In two intervention groups a low viscosity (LV)

  7. Shear viscosity of nuclear matter (United States)

    Magner, A. G.; Gorenstein, M. I.; Grygoriev, U. V.; Plujko, V. A.


    Shear viscosity η is calculated for the nuclear matter described as a system of interacting nucleons with the van der Waals (VDW) equation of state. The Boltzmann-Vlasov kinetic equation is solved in terms of the plane waves of the collective overdamped motion. In the frequent-collision regime, the shear viscosity depends on the particle-number density n through the mean-field parameter a , which describes attractive forces in the VDW equation. In the temperature region T =15 -40 MeV, a ratio of the shear viscosity to the entropy density s is smaller than 1 at the nucleon number density n =(0.5 -1.5 ) n0 , where n0=0.16 fm-3 is the particle density of equilibrium nuclear matter at zero temperature. A minimum of the η /s ratio takes place somewhere in a vicinity of the critical point of the VDW system. Large values of η /s ≫1 are, however, found in both the low-density, n ≪n0 , and high-density, n >2 n0 , regions. This makes the ideal hydrodynamic approach inapplicable for these densities.

  8. Nonlocal viscosity kernel of mixtures (United States)

    Smith, Ben; Hansen, J. S.; Todd, B. D.


    In this Brief Report we investigate the multiscale hydrodynamical response of a liquid as a function of mixture composition. This is done via a series of molecular dynamics simulations in which the wave-vector-dependent viscosity kernel is computed for three mixtures, each with 7-15 different compositions. We observe that the viscosity kernel is dependent on composition for simple atomic mixtures for all the wave vectors studied here; however, for a molecular mixture the kernel is independent of composition for large wave vectors. The deviation from ideal mixing is also studied. Here it is shown that the Lorentz-Berthelot interaction rule follows ideal mixing surprisingly well for a large range of wave vectors, whereas for both the Kob-Andersen and molecular mixtures large deviations are found. Furthermore, for the molecular system the deviation is wave-vector dependent such that there exists a characteristic correlation length scale at which the ideal mixing goes from underestimating to overestimating the viscosity.

  9. Viscosity of Earth's Outer Core

    CERN Document Server

    Smylie, D E


    A viscosity profile across the entire fluid outer core is found by interpolating between measured boundary values, using a differential form of the Arrhenius law governing pressure and temperature dependence. The discovery that both the retrograde and prograde free core nutations are in free decay (Palmer and Smylie, 2005) allows direct measures of viscosity at the top of the outer core, while the reduction in the rotational splitting of the two equatorial translational modes of the inner core allows it to be measured at the bottom. We find 2,371 plus/minus 1,530 Pa.s at the top and 1.247 plus/minus 0.035 x 10^11 Pa.s at the bottom. Following Brazhkin (1998) and Brazhkin and Lyapin (2000) who get 10^2 Pa.s at the top, 10^11 Pa.s at the bottom, by an Arrhenius extrapolation of laboratory experiments, we use a differential form of the Arrhenius law to interpolate along the melting temperature curve to find a viscosity profile across the outer core. We find the variation to be closely log-linear between the meas...

  10. Viscosity Relaxation in Molten HgZnTe (United States)

    Baird, James K.


    Because of its narrow electronic band-gap, HgZnTe solid solutions have been proposed as effective detectors for infrared radiation. To produce the best single crystals of these materials for this application, knowledge of the phase diagram that governs the freezing of the liquid is essential. Besides the phase diagram, however, some information concerning the thermophysical properties of the melt, such as viscosity, density, specific heat, and enthalpy of mixing, can also be useful. Of these thermophysical properties, the viscosity is perhaps of the most interest scientifically. Measurements using the oscillating cup method have shown that the isothermal melt requires tens of hours of equilibration time before a steady value of the viscosity can be achieved. Over this equilibration time, which depends upon temperature, the viscosity can increase by as much as a factor of two before reaching a steady state. We suggest that this relaxation phenomenon may be due to a slight polymerization of Te atoms in the melt. To account for the time dependence of the viscosity in the HgZnTe melt, we propose that the liquid acts as a solvent that favors the formation of Te atom chains. We suggest that as the melt is cooled from a high temperature to the temperature for measurement of the viscosity, a free radical polymerization of Te atoms begins. To estimate this average molecular weight, we use a simple free radical polymerization mechanism, including a depolymerization step, to calculate the time dependence to the concentration of each Te polymer molecular weight fraction. From these molecular weight fractions, we compute the weight average molecular weight of the distribution. Using the semi-empirical relation between average molecular weight and viscosity, we obtain a formula for the time dependence of the viscosity of the melt. Upon examining this formula, we find that the viscosity achieves a steady value when a balance is achieved between the rate of formation of the chains

  11. The relationship between plate velocity and trench viscosity in Newtonian and power-law subduction calculations (United States)

    King, Scott D.; Hager, Bradford H.


    The relationship between oceanic trench viscosity and oceanic plate velocity is studied using a Newtonian rheology by varying the viscosity at the trench. The plate velocity is a function of the trench viscosity for fixed Rayleigh number and plate/slab viscosity. Slab velocities for non-Newtonian rheology calculations are significantly different from slab velocities from Newtonian rheology calculations at the same effective Rayleigh number. Both models give reasonable strain rates for the slab when compared with estimates of seismic strain rate. Non-Newtonian rheology eliminates the need for imposed weak zones and provides a self-consistent fluid dynamical mechanism for subduction in numerical convection models.

  12. Solvent viscosity dependence for enzymatic reactions

    CERN Document Server

    Sitnitsky, A E


    A mechanism for relationship of solvent viscosity with reaction rate constant at enzyme action is suggested. It is based on fluctuations of electric field in enzyme active site produced by thermally equilibrium rocking (cranckshaft motion) of the rigid plane (in which the dipole moment $\\approx 3.6 D$ lies) of a favourably located and oriented peptide group (or may be a few of them). Thus the rocking of the plane leads to fluctuations of the electric field of the dipole moment. These fluctuations can interact with the reaction coordinate because the latter in its turn has transition dipole moment due to separation of charges at movement of the reacting system along it. The rocking of the plane of the peptide group is sensitive to the microviscosity of its environment in protein interior and the latter is a function of the solvent viscosity. Thus we obtain an additional factor of interrelationship for these characteristics with the reaction rate constant. We argue that due to the properties of the cranckshaft ...

  13. The viscosity of Earth's lower mantle inferred from sinking speed of subducted lithosphere

    NARCIS (Netherlands)

    Čížková, H.; van den Berg, A.P.; Spakman, W.; Matyska, C.


    The viscosity of the mantle is indispensable for predicting Earth's mechanical behavior at scales ranging from deep mantle material flow to local stress accumulation in earthquakes zones. But, mantle viscosity is not well determined. For the lower mantle, particularly, only few constraints result

  14. Effective viscosity of actively swimming algae suspensions (United States)

    Ewoldt, Randy; Caretta, Lucas; Chengala, Anwar; Sheng, Jian


    Suspensions of actively swimming microorganisms exhibit an effective viscosity which may depend on volume fraction, cell shape, and the nature of locomotion (e.g. "pushers" vs. "pullers"). Here we report experimental measurements of shear viscosity for suspensions of unicellular green algae (Dunaliella primolecta, a biflagellated "puller"). We use a cone-and-plate rheometer to measure the dynamic shear viscosity for both motile and non-motile suspensions of D. primolecta. Viscosity increases with concentration for both cases, but the active suspensions of "pullers" have a comparatively lower effective viscosity than passive suspensions. This observation contrasts recently proposed theories which predict that "pullers" should instead have a higher viscosity than non-motile suspensions. Additionally, we observe shear-induced migration of active suspensions and consider its impact on the resulting effective shear viscosity.

  15. Biopolymer solution viscosity stabilization-polymer degradation and antioxidant use

    Energy Technology Data Exchange (ETDEWEB)

    Wellington, S.L.


    Dilute solutions of polymers used to provide mobility control for EOR often lose viscosity, especially at higher temperatures. This loss of viscosity with time brings into question the feasibility of using polymers as mobility control agents. A literature study of the many possible reaction mechanisms indicated that oxidation/reduction (redox) reactions involving free radicals probably caused polymer degradation and concomitant viscosity loss. A preliminary search for antioxidants known to retard free-radical reactions located several types and positive synergistic formulations that significantly retarded biopolymer solution viscosity loss during accelerated tests at high temperature. The most effective type formulation found contained (1) a radical transfer agent; (2) a sacrificial, easily oxidizable alcohol; (3) a compatible oxygen scavenger; and (4) sufficient brine concentration. Samples prepared with this technology have not lost viscosity after 1-year storage at 207/sup 0/F (97/sup 0/C). A high-surface-area effect (so-called ''wall effect''), known to retard radical propagation, was also found to operate in the presence of sandpacks; this should be beneficial in porous media. The variables and beneficial antioxidant formulations identified in this study allow tentative conclusions and recommendations regarding biopolymer mixing and handling procedures prior to injection.

  16. In situ viscosity measurements of albite melt under high pressure

    CERN Document Server

    Funakoshi, K I; Terasaki, H


    The viscosities of albite (NaAlSi sub 3 O sub 8) melt under high pressures have been measured using an x-ray radiography falling sphere method with synchrotron radiation. This method has enabled us to determine the precise sinking velocity directly. Recent experiments of albite melt showed the presence of a viscosity minimum around 5 GPa (Poe et al 1997 Science 276 1245, Mori et al 2000 Earth Planet. Sci. Lett. 175 87). We present the results for albite melt up to 5.2 GPa at 1600 and 1700 deg. C. The viscosity minimum is clearly observed to be around 4.5 GPa, and it might be explained not by the change of the compression mechanism in albite melt but by change of the phase itself.

  17. Viscosity of ring polymer melts

    KAUST Repository

    Pasquino, Rossana


    We have measured the linear rheology of critically purified ring polyisoprenes, polystyrenes, and polyethyleneoxides of different molar masses. The ratio of the zero-shear viscosities of linear polymer melts η0,linear to their ring counterparts η0,ring at isofrictional conditions is discussed as a function of the number of entanglements Z. In the unentangled regime η0,linear/η 0,ring is virtually constant, consistent with the earlier data, atomistic simulations, and the theoretical expectation η0,linear/ η0,ring = 2. In the entanglement regime, the Z-dependence of ring viscosity is much weaker than that of linear polymers, in qualitative agreement with predictions from scaling theory and simulations. The power-law extracted from the available experimental data in the rather limited range 1 < Z < 20, η0,linear/η0,ring ∼ Z 1.2±0.3, is weaker than the scaling prediction (η0,linear/η0,ring ∼ Z 1.6±0.3) and the simulations (η0,linear/ η0,ring ∼ Z2.0±0.3). Nevertheless, the present collection of state-of-the-art experimental data unambiguously demonstrates that rings exhibit a universal trend clearly departing from that of their linear counterparts, and hence it represents a major step toward resolving a 30-year-old problem. © 2013 American Chemical Society.

  18. Drop Spreading with Random Viscosity (United States)

    Xu, Feng; Jensen, Oliver


    Airway mucus acts as a barrier to protect the lung. However as a biological material, its physical properties are known imperfectly and can be spatially heterogeneous. In this study we assess the impact of these uncertainties on the rate of spreading of a drop (representing an inhaled aerosol) over a mucus film. We model the film as Newtonian, having a viscosity that depends linearly on the concentration of a passive solute (a crude proxy for mucin proteins). Given an initial random solute (and hence viscosity) distribution, described as a Gaussian random field with a given correlation structure, we seek to quantify the uncertainties in outcomes as the drop spreads. Using lubrication theory, we describe the spreading of the drop in terms of a system of coupled nonlinear PDEs governing the evolution of film height and the vertically-averaged solute concentration. We perform Monte Carlo simulations to predict the variability in the drop centre location and width (1D) or area (2D). We show how simulation results are well described (at much lower computational cost) by a low-order model using a weak disorder expansion. Our results show for example how variability in the drop location is a non-monotonic function of the solute correlation length increases. Engineering and Physical Sciences Research Council.

  19. Transport Signatures of the Hall Viscosity. (United States)

    Delacrétaz, Luca V; Gromov, Andrey


    Hall viscosity is a nondissipative response function describing momentum transport in two-dimensional systems with broken parity. It is quantized in the quantum Hall regime, and contains information about the topological order of the quantum Hall state. Hall viscosity can distinguish different quantum Hall states with identical Hall conductances, but different topological order. To date, an experimentally accessible signature of Hall viscosity is lacking. We exploit the fact that Hall viscosity contributes to charge transport at finite wavelengths, and can therefore be extracted from nonlocal resistance measurements in inhomogeneous charge flows. We explain how to determine the Hall viscosity from such a transport experiment. In particular, we show that the profile of the electrochemical potential close to contacts where current is injected is sensitive to the value of the Hall viscosity.

  20. Viscosity dictates metabolic activity of Vibrio ruber (United States)

    Borić, Maja; Danevčič, Tjaša; Stopar, David


    Little is known about metabolic activity of bacteria, when viscosity of their environment changes. In this work, bacterial metabolic activity in media with viscosity ranging from 0.8 to 29.4 mPas was studied. Viscosities up to 2.4 mPas did not affect metabolic activity of Vibrio ruber. On the other hand, at 29.4 mPas respiration rate and total dehydrogenase activity increased 8 and 4-fold, respectively. The activity of glucose-6-phosphate dehydrogenase (GPD) increased up to 13-fold at higher viscosities. However, intensified metabolic activity did not result in faster growth rate. Increased viscosity delayed the onset as well as the duration of biosynthesis of prodigiosin. As an adaptation to viscous environment V. ruber increased metabolic flux through the pentose phosphate pathway and reduced synthesis of a secondary metabolite. In addition, V. ruber was able to modify the viscosity of its environment. PMID:22826705

  1. Tension Independence of Lipid Diffusion and Membrane Viscosity. (United States)

    Thoms, Vincent L; Hormel, Tristan T; Reyer, Matthew A; Parthasarathy, Raghuveer


    The diffusion of biomolecules at lipid membranes is governed by the viscosity of the underlying two-dimensionally fluid lipid bilayer. For common three-dimensional fluids, viscosity can be modulated by hydrostatic pressure, and pressure-viscosity data have been measured for decades. Remarkably, the two-dimensional analogue of this relationship, the dependence of molecular mobility on tension, has to the best of our knowledge never been measured for lipid bilayers, limiting our understanding of cellular mechanotransduction as well as the fundamental fluid mechanics of membranes. Here we report both molecular-scale and mesoscopic measures of fluidity in giant lipid vesicles as a function of mechanical tension applied using micropipette aspiration. Both molecular-scale data, from fluorescence recovery after photobleaching, and micron-scale data, from tracking the diffusion of phase-separated domains, show a surprisingly weak dependence of viscosity on tension, in contrast to predictions of recent molecular dynamics simulations, highlighting fundamental gaps in our understanding of membrane fluidity.

  2. Viscosity in Modified Gravity 

    Directory of Open Access Journals (Sweden)

    Iver Brevik


    Full Text Available A bulk viscosity is introduced in the formalism of modified gravity. It is shownthat, based on a natural scaling law for the viscosity, a simple solution can be found forquantities such as the Hubble parameter and the energy density. These solutions mayincorporate a viscosity-induced Big Rip singularity. By introducing a phase transition inthe cosmic fluid, the future singularity can nevertheless in principle be avoided. 

  3. Uniaxial Elongational viscosity of bidisperse polystyrene melts

    DEFF Research Database (Denmark)

    Nielsen, Jens Kromann; Rasmussen, Henrik K.; Hassager, Ole


    The startup and steady uniaxial elongational viscosity have been measured for three bidisperse polystyrene (PS) melts, consisting of blends of monodisperse PS with molecular weights of 52 kg/mole or 103 kg/mole and 390 kg/mole. The bidisperse melts have a maximum in the steady elongational...... viscosity, of up to a factor of 7 times the Trouton limit of 3 times the zero-shear viscosity....

  4. Drop spreading with random viscosity

    CERN Document Server

    Xu, Feng


    We examine theoretically the spreading of a viscous liquid drop over a thin film of uniform thickness, assuming the liquid's viscosity is regulated by the concentration of a solute that is carried passively by the spreading flow. The solute is assumed to be initially heterogeneous, having a spatial distribution with prescribed statistical features. To examine how this variability influences the drop's motion, we investigate spreading in a planar geometry using lubrication theory, combining numerical simulations with asymptotic analysis. We assume diffusion is sufficient to suppress solute concentration gradients across but not along the film. The solute field beneath the bulk of the drop is stretched by the spreading flow, such that the initial solute concentration immediately behind the drop's effective contact lines has a long-lived influence on the spreading rate. Over long periods, solute swept up from the precursor film accumulates in a short region behind the contact line, allowing patches of elevated v...

  5. Shear Viscosity from Lattice QCD

    CERN Document Server

    Mages, Simon W; Fodor, Zoltán; Schäfer, Andreas; Szabó, Kálmán


    Understanding of the transport properties of the the quark-gluon plasma is becoming increasingly important to describe current measurements at heavy ion collisions. This work reports on recent efforts to determine the shear viscosity h in the deconfined phase from lattice QCD. The main focus is on the integration of the Wilson flow in the analysis to get a better handle on the infrared behaviour of the spectral function which is relevant for transport. It is carried out at finite Wilson flow time, which eliminates the dependence on the lattice spacing. Eventually, a new continuum limit has to be carried out which sends the new regulator introduced by finite flow time to zero. Also the non-perturbative renormalization strategy applied for the energy momentum tensor is discussed. At the end some quenched results for temperatures up to 4 : 5 T c are presented


    Directory of Open Access Journals (Sweden)

    Rita Prasetyowati


    Full Text Available This study aims to determine the value of the kinematic viscosity lubricants motorcycle that has been used at various temperatures and the use of distance. This study also aims to remedy mengtahui how the value of the kinematic viscosity of the lubricant car that has been used in a wide range of temperature variation and distance usage. Viscosity liquid, in this case is the lubricants, can be determined using the Redwood viscometer By using Redwood viscometer, can be measured flow time required by 50 ml of the sample at a constant temperature. Time measurement result is known as the Redwood's sec or conventional viscosity. Conventional viscosity can be determined from the kinematic viscosity values. For motorcycle lubricant viscosity measured at a temperature of 30ͦ C, 50ͦ C, 65ͦ C and 100ͦ C, with the use of distance variation 0 Km, 5 Km, 10 Km, 15 Km and 20 Km. For car lubricant viscosity measured at a temperature of 30ͦ C, 50ͦ C, 65ͦ C and 100ͦ C, with variations in the use of distance 0 km, 1000 km, 5000 km, and 10000 Km. Motorcycle lubricant viscosity values at a temperature of 100ͦ C is 9.54 m2 / s (new lubricant, 1.15 m2 / s (use 5 Km, 5.86 m2 / s (use of 10 Km, 8.02 m2 / s (use of 15 Km, and 9.11 m2 / s (use of 20 Km. Lubricant viscosity values at a temperature of 1000C car is 6.73 m 2 / s (new lubricant, 7.89 m2 / s (use 1,000 km, 6.0 m2 / s (use 5000 Km, and 7.55 m2 / s (use 10000 Km.   Keywords: viscosity, oil, temperature

  7. Is mechanical retention for adhesive core build-up needed to restore a vital tooth with a monolithic zirconium crown? - An in vitro study. (United States)

    Walczak, Katarzyna; Rues, Stefan; Wieckiewicz, Mieszko; Range, Ursula; Schmitter, Marc


    To show the influence of retentive cavity, cavity wall preparation and different luting techniques on the fracture resistance of severely damaged teeth restored with adhesive core build-ups and monolithic zirconium crowns. Extracted molars were prepared with 2 mm ferrule height and divided into eleven groups (n = 8/group). In nine groups a retentive occlusal cavity with a width and depth of 1 or 2 mm was prepared. Two control groups without a retentive cavity were made. Zirconium crowns were manufactured. 48 copings were cemented with glass-ionomer cement (Ketac Cem), the others (n = 40) with adhesive resin cement (Panavia F 2.0). Artificial ageing was carried out in the following way: n = 88, thermocycling (10,000 cycles, 6° C/60° C), n = 80 chewing simulation (1,200,000 cycles, 64 N). The samples were tested for load at first damage and fracture load with non-axial force. For statistical analysis ANCOVA with post hoc, Bonferroni-adjusted t-test were used ( p ≤ 0.05). No differences between the tested cements were detected. Influence of the cavity wall thickness was significant ( p = 0.001). Mostly, the samples with wall thickness of 2 mm showed better results. Both control groups (no cavity) showed results comparable to study groups with cavity. Retentive cavity is most likely not mandatory. However, if prepared, the cavity wall thickness is of higher importance than cavity depth. Glass-ionomer and adhesive resin cement are comparable for use with zirconia crowns.

  8. Measuring membrane rigidity and viscosity: New methods, and new insights (United States)

    Parthasarathy, Raghuveer


    Lipid membranes are remarkable materials: flexible, two-dimensional fluids whose physical properties guide cellular function. Bending rigidity and viscosity are two of the key mechanical parameters that characterize membranes. Both, however, are challenging to measure. I describe improvements in experimental techniques to quantify the bending modulus and the two-dimensional viscosity of lipid membranes. First, I show that using selective plane illumination microscopy (SPIM, also known as light sheet fluorescence microscopy) to image the thermal fluctuations of freely suspended giant lipid vesicles enables straightforward measurements of membrane rigidity, and also provides insights into changes in rigidity induced by cargo trafficking proteins. Second, I show that tracking both the rotational and translational diffusion of membrane-anchored tracer particles allows quantification of membrane viscosity, measurement of the effective radii of the tracers, and assessment of theoretical models of membrane hydrodynamics. Surprisingly, we find a wide distribution of effective tracer sizes, due presumably to a wide variety of couplings to the membrane. I also provide an example of protein-mediated changes in lipid viscosity.


    NARCIS (Netherlands)



    A new viscosity equation for the description of the viscosity of concentrated aqueous starch pastes is proposed: eta(app) = Ke([Bmstarch+(C/T)-DW+(n-1)ln gamma]) with: m(starch) = mass fraction starch in paste, T = temperature, W = amount of work performed on the starch, n = power-law index, K =

  10. Haptic Discrimination and Matching of Viscosity

    NARCIS (Netherlands)

    Bergmann Tiest, W.M.; Vrijling, A.C.L.; Kappers, A.M.L.


    In three experiments, viscosity perception of liquids using the sense of touch was studied. The first two were discrimination experiments in which Weber fractions were determined for a number of viscosities spanning the range of what is encountered in daily life, and for two ways of perceiving

  11. Viscosity: From air to hot nuclei

    Indian Academy of Sciences (India)


    Oct 9, 2014 ... After a brief review of the history of viscosity from classical to quantal fluids, a discussion of how the shear viscosity of a finite hot nucleus is calculated directly from the width and energy of the giant dipole resonance (GDR) of the nucleus is given in this paper. The ratio / with s being the entropy volume ...

  12. Viscosity evolution of anaerobic granular sludge

    NARCIS (Netherlands)

    Pevere, A.; Guibaud, G.; Hullebusch, van E.D.; Lens, P.N.L.; Baudu, M.


    The evolution of the apparent viscosity at steady shear rate of sieved anaerobic granular sludge (20¿315 ¿m diameter) sampled from different full-scale anaerobic reactors was recorded using rotation tests. The ¿limit viscosity¿ of sieved anaerobic granular sludge was determined from the apparent

  13. Reducing blood viscosity with magnetic fields. (United States)

    Tao, R; Huang, K


    Blood viscosity is a major factor in heart disease. When blood viscosity increases, it damages blood vessels and increases the risk of heart attacks. Currently, the only method of treatment is to take drugs such as aspirin, which has, however, several unwanted side effects. Here we report our finding that blood viscosity can be reduced with magnetic fields of 1 T or above in the blood flow direction. One magnetic field pulse of 1.3 T lasting ~1 min can reduce the blood viscosity by 20%-30%. After the exposure, in the absence of magnetic field, the blood viscosity slowly moves up, but takes a couple of hours to return to the original value. The process is repeatable. Reapplying the magnetic field reduces the blood viscosity again. By selecting the magnetic field strength and duration, we can keep the blood viscosity within the normal range. In addition, such viscosity reduction does not affect the red blood cells' normal function. This technology has much potential for physical therapy.

  14. Employee voice and employee retention. (United States)

    Spencer, D G


    This study investigates the relationship between the extent to which employees have opportunities to voice dissatisfaction and voluntary turnover in 111 short-term, general care hospitals. Results show that, whether or not a union is present, high numbers of mechanisms for employee voice are associated with high retention rates. Implications for theory and research as well as management practice are discussed.

  15. Viscosity of Common Seed and Vegetable Oils (United States)

    Wes Fountain, C.; Jennings, Jeanne; McKie, Cheryl K.; Oakman, Patrice; Fetterolf, Monty L.


    Viscosity experiments using Ostwald-type gravity flow viscometers are not new to the physical chemistry laboratory. Several physical chemistry laboratory texts (1 - 3) contain at least one experiment studying polymer solutions or other well-defined systems. Several recently published articles (4 - 8) indicated the continued interest in using viscosity measurements in the teaching lab to illustrate molecular interpretation of bulk phenomena. Most of these discussions and teaching experiments are designed around an extensive theory of viscous flow and models of molecular shape that allow a full data interpretation to be attempted. This approach to viscosity experiments may not be appropriate for all teaching situations (e.g., high schools, general chemistry labs, and nonmajor physical chemistry labs). A viscosity experiment is presented here that is designed around common seed and vegetable oils. With the importance of viscosity to foodstuffs (9) and the importance of fatty acids to nutrition (10), an experiment using these common, recognizable oils has broad appeal.

  16. Odd viscosity in chiral active fluids. (United States)

    Banerjee, Debarghya; Souslov, Anton; Abanov, Alexander G; Vitelli, Vincenzo


    We study the hydrodynamics of fluids composed of self-spinning objects such as chiral grains or colloidal particles subject to torques. These chiral active fluids break both parity and time-reversal symmetries in their non-equilibrium steady states. As a result, the constitutive relations of chiral active media display a dissipationless linear-response coefficient called odd (or equivalently, Hall) viscosity. This odd viscosity does not lead to energy dissipation, but gives rise to a flow perpendicular to applied pressure. We show how odd viscosity arises from non-linear equations of hydrodynamics with rotational degrees of freedom, once linearized around a non-equilibrium steady state characterized by large spinning speeds. Next, we explore odd viscosity in compressible fluids and suggest how our findings can be tested in the context of shock propagation experiments. Finally, we show how odd viscosity in weakly compressible chiral active fluids can lead to density and pressure excess within vortex cores.

  17. The Friction Theory for Viscosity Modeling

    DEFF Research Database (Denmark)

    Cisneros, Sergio; Zeberg-Mikkelsen, Claus Kjær; Stenby, Erling Halfdan


    In this work the one-parameter friction theory (f-theory) general models have been extended to the viscosity prediction and modeling of characterized oils. It is demonstrated that these simple models, which take advantage of the repulsive and attractive pressure terms of cubic equations of state...... such as the SRK, PR and PRSV, can provide accurate viscosity prediction and modeling of characterized oils. In the case of light reservoir oils, whose properties are close to those of normal alkanes, the one-parameter f-theory general models can predict the viscosity of these fluids with good accuracy. Yet......, in the case when experimental information is available a more accurate modeling can be obtained by means of a simple tuning procedure. A tuned f-theory general model can deliver highly accurate viscosity modeling above the saturation pressure and good prediction of the liquid-phase viscosity at pressures...

  18. Plasma viscosity elevations with simulated weightlessness (United States)

    Martin, D. G.; Convertino, V. A.; Goldwater, D.; Ferguson, E. W.; Schoomaker, E. B.


    A hypothesis correlating an increase in blood viscosity during bed rest to a decrease in aerobic capacity during simulated weightlessness is tested. Eight human subjects were studied on the sixth day of bed rest during two consecutive 10-d bed rest periods separated by a 14-d recovery interval designed to simulate the flight-layover schedule of Shuttle astronauts. Plasma viscosity and volume were measured, together with maximal aerobic capacity (VO2max). An increase in hematocrit, plasma protein, and fibrinogen concentrations was found, contributing to an elevation in plasma viscosity. VO2max decreased significantly in the first, but not the second bed rest cycle, and though many individuals exhibited a decrease in plasma volume and aerobic capacity coupled with elevated plasma viscosity, correlations between these variables were lacking. It is concluded that the decrease in VO2max observed following simulated weightlessness cannot be attributed to alterations in muscle blood flow resulting from increased blood viscosity.

  19. Viscosity of Water Interfaces with Hydrophobic Nanopores: Application to Water Flow in Carbon Nanotubes. (United States)

    Shaat, M


    The nanoconfinement of water results in changes in water properties and nontraditional water flow behaviors. The determination of the interfacial interactions between water and hydrophobic surfaces helps in understanding many of the nontraditional behaviors of nanoconfined water. In this study, an approach for the identification of the viscosity of water interfaces with hydrophobic nanopores as a function of the nanopore diameter and water-solid (nanopore) interactions is proposed. In this approach, water in a hydrophobic nanopore is represented as a double-phase water with two distinct viscosities: water interface and water core. First, the slip velocity to pressure gradient ratio of water flow in hydrophobic nanopores is obtained via molecular dynamics (MD) simulations. Then the water interface viscosity is determined via a pressure gradient-based bilayer water flow model. Moreover, the core viscosity and the effective viscosity of water flow in hydrophobic nanopores are derived as functions of the nanopore diameter and water-solid interactions. This approach is utilized to report the interface viscosity, core viscosity, and effective viscosity of water flow in carbon nanotubes (CNTs) as functions of the CNT diameter. Moreover, using the proposed approach, the transition from MD to continuum mechanics is revealed where the bulk water properties are recovered for large CNTs.

  20. Influence of Oil Viscosity on Alkaline Flooding for Enhanced Heavy Oil Recovery

    Directory of Open Access Journals (Sweden)

    Yong Du


    Full Text Available Oil viscosity was studied as an important factor for alkaline flooding based on the mechanism of “water drops” flow. Alkaline flooding for two oil samples with different viscosities but similar acid numbers was compared. Besides, series flooding tests for the same oil sample were conducted at different temperatures and permeabilities. The results of flooding tests indicated that a high tertiary oil recovery could be achieved only in the low-permeability (approximately 500 mD sandpacks for the low-viscosity heavy oil (Zhuangxi, 390 mPa·s; however, the high-viscosity heavy oil (Chenzhuang, 3450 mPa·s performed well in both the low- and medium-permeability (approximately 1000 mD sandpacks. In addition, the results of flooding tests for the same oil at different temperatures also indicated that the oil viscosity put a similar effect on alkaline flooding. Therefore, oil with a high-viscosity is favorable for alkaline flooding. The microscopic flooding test indicated that the water drops produced during alkaline flooding for oils with different viscosities differed significantly in their sizes, which might influence the flow behaviors and therefore the sweep efficiencies of alkaline fluids. This study provides an evidence for the feasibility of the development of high-viscosity heavy oil using alkaline flooding.

  1. Cellular Viscosity in Prokaryotes and Thermal Stability of Low Molecular Weight Biomolecules. (United States)

    Cuecas, Alba; Cruces, Jorge; Galisteo-López, Juan F; Peng, Xiaojun; Gonzalez, Juan M


    Some low molecular weight biomolecules, i.e., NAD(P)H, are unstable at high temperatures. The use of these biomolecules by thermophilic microorganisms has been scarcely analyzed. Herein, NADH stability has been studied at different temperatures and viscosities. NADH decay increased at increasing temperatures. At increasing viscosities, NADH decay rates decreased. Thus, maintaining relatively high cellular viscosity in cells could result in increased stability of low molecular weight biomolecules (i.e., NADH) at high temperatures, unlike what was previously deduced from studies in diluted water solutions. Cellular viscosity was determined using a fluorescent molecular rotor in various prokaryotes covering the range from 10 to 100°C. Some mesophiles showed the capability of changing cellular viscosity depending on growth temperature. Thermophiles and extreme thermophiles presented a relatively high cellular viscosity, suggesting this strategy as a reasonable mechanism to thrive under these high temperatures. Results substantiate the capability of thermophiles and extreme thermophiles (growth range 50-80°C) to stabilize and use generally considered unstable, universal low molecular weight biomolecules. In addition, this study represents a first report, to our knowledge, on cellular viscosity measurements in prokaryotes and it shows the dependency of prokaryotic cellular viscosity on species and growth temperature. Copyright © 2016 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  2. The viscosity measurement of molten rocks

    Directory of Open Access Journals (Sweden)

    Rybár Pavol


    Full Text Available This paper deals with the viscosity measurtement of molten rocks. The reason of such investigation was due to the solving of SC No. 95/135/059 LITHO-JET. Technology of thermic rock melting for trenching of tenous vertical works. One task in the scope of above investigation was to experimentally verify the properties of melts of various types of works. An important moment in the trenching of tenuous vertical works by rock melting is the ability of melt to penetrate into the rock cracks. From this point of view an important physical property of molten rock is its viscosity. There are various methods how to measure viscosity but for the continuous measurements just some of them are suitable. The most suitable is rotary viscosimeter because it is simple in its construction, it allows to measure the viscosity as a function of temperature, concentration of wide class of sub stances with different rheologic properties. Hence, it allows to measure structural viscosity of the chemical reaction systems. The viscosity of molten nefelitic basanite as the function of temperature is studied in this paper. Viscosity of the nefelinitic basanite taken at locality Konrádovce was measured using rotary viscosimeter HAAKE ROTOVISKO. Eperimental conditions shown, that rising of the temperature vs. viscosity is in reverse order. Measurement is realised in scale 1370-1550°C. Under 1370°C was sample very viscous and measurement was impossible. Viscosity is the function of the temperature, pressure and gas components of rock.Though the viscosity measurements was carried out at atmospheric pressure, what does not fully conform real condition during trenching, it is still possible to express the effect of pressure. Other conditions, which take effect of viscosityof molten rocks in nature conditions will be subject of future investigation.

  3. Selenide retention by mackinawite. (United States)

    Finck, N; Dardenne, K; Bosbach, D; Geckeis, H


    The isotope (79)Se may be of great concern with regard to the safe disposal of nuclear wastes in deep geological repositories due to its long half-life and potential mobility in the geosphere. The Se mobility is controlled by the oxidation state: the oxidized species (Se(IV)) and (Se(VI)) are highly mobile, whereas the reduced species (Se(0) and Se(-II)) form low soluble solids. The mobility of this trace pollutant can be greatly reduced by interacting with the various barriers of the repository. Numerous studies report on the oxidized species retention by mineral phases, but only very scarce studies report on the selenide (Se(-II)) retention. In the present study, the selenide retention by coprecipitation with and by adsorption on mackinawite (FeS) was investigated. XRD and SEM analyses of the samples reveal no significant influence of Se on the mackinawite precipitate morphology and structure. Samples from coprecipitation and from adsorption are characterized at the molecular scale by a multi-edge X-ray absorption spectroscopy (XAS) investigation. In the coprecipitation experiment, all elements (S, Fe, and Se) are in a low ionic oxidation state and the EXAFS data strongly point to selenium located in a mackinawite-like sulfide environment. By contacting selenide ions with FeS in suspension, part of Se is located in an environment similar to that found in the coprecipitation experiment. The explanation is a dynamical dissolution-recrystallization mechanism of the highly reactive mackinawite. This is the first experimental study to report on selenide incorporation in iron monosulfide by a multi-edge XAS approach.

  4. Einstein viscosity with fluid elasticity (United States)

    Einarsson, Jonas; Yang, Mengfei; Shaqfeh, Eric S. G.


    We give the first correction to the suspension viscosity due to fluid elasticity for a dilute suspension of spheres in a viscoelastic medium. Our perturbation theory is valid to O (ϕ Wi2) in the particle volume fraction ϕ and the Weissenberg number Wi =γ ˙λ , where γ ˙ is the typical magnitude of the suspension velocity gradient, and λ is the relaxation time of the viscoelastic fluid. For shear flow we find that the suspension shear-thickens due to elastic stretching in strain "hot spots" near the particle, despite the fact that the stress inside the particles decreases relative to the Newtonian case. We thus argue that it is crucial to correctly model the extensional rheology of the suspending medium to predict the shear rheology of the suspension. For uniaxial extensional flow we correct existing results at O (ϕ Wi ) , and find dramatic strain-rate thickening at O (ϕ Wi2) . We validate our theory with fully resolved numerical simulations.

  5. Viscosity of beta-glucan in oat products

    Directory of Open Access Journals (Sweden)



    Full Text Available Oats contain 3-5% of mixed linked beta-glucan, or (1-3, (1-4 â-D-glucan, referred to hereafter as beta-glucan. Oat beta-glucan is a viscous, and soluble dietary fibre component. Soluble and viscous dietary fibres, including the beta-glucan present in oats are associated with two major health promoting effects, i.e. the attenuation of postprandial plasma glucose and insulin levels and the control of cholesterol. Increased viscosity in the intestine delays absorption of glucose and suppresses absorption of cholesterol and reabsorption of bile acids. In spite of its apparent key role physiologically the viscosity of beta-glucan has been discussed relatively little in terms of analytical procedures. In clinical studies performed with oats, the viscosity of beta-glucan has been properly documented in only a few cases. Viscosity of beta-glucan in foods and in the food digest depends on solubility, concentration and molecular weight. A food manufacturer aiming at health-promoting products must pay attention not only to sufficient concentration of beta-glucan (dose in the raw material, but also to the processing methods that will ensure sufficient solubility of beta-glucan and minimize enzymatic or mechanical breakdown of the beta-glucan molecule. We have been working both with different food processes utilising oat fractions high in beta-glucan and with the development of a method for viscosity determination of the soluble beta-glucan fibre. This review discusses some of the aspects related to the development with a method that could predict the behaviour of beta-glucan in oat processing with respect to its anticipated physiological functions.;

  6. Studies of the retention mechanism of the brain perfusion imaging agent {sup 99m}{Tc}-bicisate ({sup 99m}{Tc}-ECD)

    Energy Technology Data Exchange (ETDEWEB)

    Walovitch, R.C.; Cheesman, E.H.; Maheu, L.J.; Hall, K.M. [DuPont Merck Pharmaceutical Co., North Billerica, MA (United States)


    The structure-activity relationship in a series of analogues of {sup 99m}{Tc}-bicisate ({sup 99m}{Tc}-N,N{prime}-1,2-ethylene-diylbis-L-cysteine diethyl ester dihydrochloride, RP-217) is described using in vivo studies in rodent and primate brain tissue. All analogues investigated were {sup 99m}{Tc}-diamine dithiol diesters, which were neutral and lipophilic and had modified brain uptake indexes ({ge}40) suggesting adequate first-pass extraction. All analogues were poorly retained by the rodent brain. In contrast, the stereochemistry and structure of the {sup 99m}{Tc}-complexes affected their brain retention in primates. All compounds that demonstrated selective primate brain retention were L-diesters that were metabolized in primate brain tissue to nonlypophilic complexes resulted from ester hydrolysis. Unretained complexes were not metabolized in primate brain tissue. More extensive studies were performed with {sup 99m}{Tc}-bicisate, which demonstrated poor brain retention in several nonprimate species (i.e., dogs, ferrets, pigs, and rodents). In rodent and nonhuman primate tissue, {sup 99m}{Tc}-bicisate was rapidly metabolized to a monoacid ester ({sup 99m}{Tc}-N,N{prime}-1,2-ethylenediylbis-L-cysteine monoethyl ester). Therefore, brain metabolism of {sup 99m}{Tc}-bicisate results in the formation of an acid product(s) that is selectively trapped in primate brain. 20 refs., 2 figs., 4 tabs.

  7. Comparative evaluation of aqueous humor viscosity. (United States)

    Davis, Kyshia; Carter, Renee; Tully, Thomas; Negulescu, Ioan; Storey, Eric


    To evaluate aqueous humor viscosity in the raptor, dog, cat, and horse, with a primary focus on the barred owl (Strix varia). Twenty-six raptors, ten dogs, three cats, and one horse. Animals were euthanized for reasons unrelated to this study. Immediately, after horizontal and vertical corneal dimensions were measured, and anterior chamber paracentesis was performed to quantify anterior chamber volume and obtain aqueous humor samples for viscosity analysis. Dynamic aqueous humor viscosity was measured using a dynamic shear rheometer (AR 1000 TA Instruments, New Castle, DE, USA) at 20 °C. Statistical analysis included descriptive statistics, unpaired t-tests, and Tukey's test to evaluate the mean ± standard deviation for corneal diameter, anterior chamber volume, and aqueous humor viscosity amongst groups and calculation of Spearman's coefficient for correlation analyses. The mean aqueous humor viscosity in the barred owl was 14.1 centipoise (cP) ± 9, cat 4.4 cP ± 0.2, and dog 2.9 cP ± 1.3. The aqueous humor viscosity for the horse was 1 cP. Of the animals evaluated in this study, the raptor aqueous humor was the most viscous. The aqueous humor of the barred owl is significantly more viscous than the dog (P humor viscosity of the raptor, dog, cat, and horse can be successfully determined using a dynamic shear rheometer. © 2014 American College of Veterinary Ophthalmologists.

  8. The extension of radiative viscosity to superfluid matter


    Pi, Chun-Mei; Yang, Shu-Hua; Zheng, Xiao-Ping


    The radiative viscosity of superfluid $npe$ matter is studied, and it is found that to the lowest order of $\\delta \\mu/T$ the ratio of radiative viscosity to bulk viscosity is the same as that of the normal matter.

  9. Shear viscosity of liquid mixtures Mass dependence

    CERN Document Server

    Kaushal, R


    Expressions for zeroth, second, and fourth sum rules of transverse stress autocorrelation function of two component fluid have been derived. These sum rules and Mori's memory function formalism have been used to study shear viscosity of Ar-Kr and isotopic mixtures. It has been found that theoretical result is in good agreement with the computer simulation result for the Ar-Kr mixture. The mass dependence of shear viscosity for different mole fraction shows that deviation from ideal linear model comes even from mass difference in two species of fluid mixture. At higher mass ratio shear viscosity of mixture is not explained by any of the emperical model.

  10. Intrinsic viscosity of a suspension of cubes

    KAUST Repository

    Mallavajula, Rajesh K.


    We report on the viscosity of a dilute suspension of cube-shaped particles. Irrespective of the particle size, size distribution, and surface chemistry, we find empirically that cubes manifest an intrinsic viscosity [η]=3.1±0.2, which is substantially higher than the well-known value for spheres, [η]=2.5. The orientation-dependent intrinsic viscosity of cubic particles is determined theoretically using a finite-element solution of the Stokes equations. For isotropically oriented cubes, these calculations show [η]=3.1, in excellent agreement with our experimental observations. © 2013 American Physical Society.

  11. Viscosity studies of water based magnetite nanofluids

    Energy Technology Data Exchange (ETDEWEB)

    Anu, K.; Hemalatha, J. [Advanced Materials Lab, Department of Physics, National Institute of Technology, Tiruchirappalli, Tamilnadu, India – 620015 (India)


    Magnetite nanofluids of various concentrations have been synthesized through co-precipitation method. The structural and topographical studies made with the X-Ray Diffractometer and Atomic Force Microscope are presented in this paper. The density and viscosity studies for the ferrofluids of various concentrations have been made at room temperature. The experimental viscosities are compared with theoretical values obtained from Einstein, Batchelor and Wang models. An attempt to modify the Rosensweig model is made and the modified Rosensweig equation is reported. In addition, new empirical correlation is also proposed for predicting viscosity of ferrofluid at various concentrations.

  12. Laboratory Tests for Dispersive Soil Viscosity Determining (United States)

    Ter-Martirosyan, Z. G.; Ter-Martirosyan, A. Z.; Sobolev, E. S.


    There are several widespread methods for soil viscosity determining now. The standard shear test device and torsion test apparatus are the most commonly used installations to do that. However, the application of them has a number of disadvantages. Therefore, the specialists of Moscow State University of Civil Engineering proposed a new device to determine the disperse soil viscosity on the basis of a stabilometer with the B-type camera (viscosimeter). The paper considers the construction of a viscosimeter and the technique for determining soil viscosity inside this tool as well as some experimental verification results of its work.

  13. Fall 1982 Retention Study. (United States)

    Peralta Community Coll. District, Oakland, CA. Office of Research, Planning and Development.

    In fall 1982, a study was conducted in the Peralta Community College District (PCCD) using withdrawal and grade distribution data to analyze student retention patterns. Successful retention rates were based on the percentage of students who received a passing grade, while total retention rates were based on the percentage of students who received…

  14. Fall 1984 Retention Study. (United States)

    Peralta Community Coll. District, Oakland, CA. Office of Research, Planning and Development.

    A study was conducted of the retention patterns of students enrolled in the Peralta Community College District (PCCD) in fall 1984 using college reports on withdrawals and grade distributions. The study focused on successful retention (i.e., all students who received a passing grade) and on total retention (i.e., all students who received any…

  15. Viscosity of aqueous and cyanate ester suspensions containing alumina nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Lawler, Katherine [Iowa State Univ., Ames, IA (United States)


    The viscosities of both aqueous and cyanate ester monomer (BECy) based suspensions of alumina nanoparticle were studied. The applications for these suspensions are different: aqueous suspensions of alumina nanoparticles are used in the production of technical ceramics made by slip casting or tape casting, and the BECy based suspensions are being developed for use in an injection-type composite repair resin. In the case of aqueous suspensions, it is advantageous to achieve a high solids content with low viscosity in order to produce a high quality product. The addition of a dispersant is useful so that higher solids content suspensions can be used with lower viscosities. For BECy suspensions, the addition of nanoparticles to the BECy resin is expected to enhance the mechanical properties of the cured composite. The addition of saccharides to aqueous suspensions leads to viscosity reduction. Through DSC measurements it was found that the saccharide molecules formed a solution with water and this resulted in lowering the melting temperature of the free water according to classic freezing point depression. Saccharides also lowered the melting temperature of the bound water, but this followed a different rule. The shear thinning and melting behaviors of the suspensions were used to develop a model based on fractal-type agglomeration. It is believed that the structure of the particle flocs in these suspensions changes with the addition of saccharides which leads to the resultant viscosity decrease. The viscosity of the BECy suspensions increased with solids content, and the viscosity increase was greater than predicted by the classical Einstein equation for dilute suspensions. Instead, the Mooney equation fits the viscosity behavior well from 0-20 vol% solids. The viscosity reduction achieved at high particle loadings by the addition of benzoic acid was also investigated by NMR. It appears that the benzoic acid interacts with the surface of the alumina particle which may

  16. Low Viscosity Imides Based on Asymmetric Oxydiphthalic Anhydride (United States)

    Chuang, Kathy C.; Criss, Jim M., Jr.; Mintz, Eric A.; Scheiman, Daniel A.; Nguyen, Baochau N.; McCorkle, Linda S.


    A series of low-melt viscosity imide resins were prepared from asymmetric oxydiphthalic dianhydride (a-ODPA) and 4-phenylethynylphthalic anhydride as the endcap, along with 3,4' - oxydianiline (3,4' -ODA), 3,4' -methylenedianiline (3,4' -MDA), 3,3' -methylenedianiline (3,3' - MDA) and 3,3'-diaminobenzophenone (3,3'-DABP), using a solvent-free melt process. These imide oligomers displays low-melt viscosities (2-15 poise) at 260-280 C, which made them amenable to low-cost resin transfer molding (RTM) process. The a-ODPA based RTM resins exhibits glass transition temperatures (Tg's) in the range of 265-330 C after postcure at 343 C. The mechanical properties of these polyimide/carbon fiber composites fabricated by RTM will be discussed.

  17. Imparting permanent antimicrobial activity onto viscose and acrylic fabrics. (United States)

    Mekewi, M; El-Sayed, A Atef; Amin, M S; Said, Hala I


    Viscose and acrylic fabrics were aminated to enhance metal chelation of Cu, Zn and Ni for the purpose of imparting fabrics antimicrobial activity against Escherichia coli and Staphylococcus aureus. Fabrics were firstly epoxidized using epichlorohydrin prior amination. Optimization of the reaction conditions, e.g., temperature, medium pH, amine type and metal type and their concentrations, are reported. Aminated fabrics of viscose and acrylic were shown to be viable for chelation with divalent metal cations. The overall results revealed that antibacterial resistance of metalized aminated fabrics that the activity trend of metals is in the order Cu-complex>Zn-complex>Ni-complex with regard to fighting of microorganisms and permanent even after 10 washing. Reaction mechanism of epoxidation, amination and metal chelation of fabrics are offered supported by FT-IR structural study, nitrogen content and atomic absorption spectroscopy. Copyright © 2012 Elsevier B.V. All rights reserved.

  18. Quartz resonator fluid density and viscosity monitor (United States)

    Martin, Stephen J.; Wiczer, James J.; Cernosek, Richard W.; Frye, Gregory C.; Gebert, Charles T.; Casaus, Leonard; Mitchell, Mary A.


    A pair of thickness-shear mode resonators, one smooth and one with a textured surface, allows fluid density and viscosity to be independently resolved. A textured surface, either randomly rough or regularly patterned, leads to trapping of liquid at the device surface. The synchronous motion of this trapped liquid with the oscillating device surface allows the device to weigh the liquid; this leads to an additional response that depends on liquid density. This additional response enables a pair of devices, one smooth and one textured, to independently resolve liquid density and viscosity; the difference in responses determines the density while the smooth device determines the density-viscosity product, and thus, the pair determines both density and viscosity.

  19. A study on high-viscosity oil-water two-phase flow in horizontal pipes


    Shi, Jing


    A study on high-viscosity oil-water flow in horizontal pipes has been conducted applying experimental, mechanism analysis and empirical modelling, and CFD simulation approaches. A horizontal 1 inch flow loop was modified by adding a designed sampling section to achieve water holdup measurement. Experiments on high-viscosity oil-water flow were conducted. Apart from the data obtained in the present experiments, raw data from previous experiments conducted in the same resea...

  20. A Simple BODIPY-Based Viscosity Probe for Imaging of Cellular Viscosity in Live Cells

    Directory of Open Access Journals (Sweden)

    Dongdong Su


    Full Text Available Intracellular viscosity is a fundamental physical parameter that indicates the functioning of cells. In this work, we developed a simple boron-dipyrromethene (BODIPY-based probe, BTV, for cellular mitochondria viscosity imaging by coupling a simple BODIPY rotor with a mitochondria-targeting unit. The BTV exhibited a significant fluorescence intensity enhancement of more than 100-fold as the solvent viscosity increased. Also, the probe showed a direct linear relationship between the fluorescence lifetime and the media viscosity, which makes it possible to trace the change of the medium viscosity. Furthermore, it was demonstrated that BTV could achieve practical applicability in the monitoring of mitochondrial viscosity changes in live cells through fluorescence lifetime imaging microscopy (FLIM.

  1. A Simple BODIPY-Based Viscosity Probe for Imaging of Cellular Viscosity in Live Cells (United States)

    Su, Dongdong; Teoh, Chai Lean; Gao, Nengyue; Xu, Qing-Hua; Chang, Young-Tae


    Intracellular viscosity is a fundamental physical parameter that indicates the functioning of cells. In this work, we developed a simple boron-dipyrromethene (BODIPY)-based probe, BTV, for cellular mitochondria viscosity imaging by coupling a simple BODIPY rotor with a mitochondria-targeting unit. The BTV exhibited a significant fluorescence intensity enhancement of more than 100-fold as the solvent viscosity increased. Also, the probe showed a direct linear relationship between the fluorescence lifetime and the media viscosity, which makes it possible to trace the change of the medium viscosity. Furthermore, it was demonstrated that BTV could achieve practical applicability in the monitoring of mitochondrial viscosity changes in live cells through fluorescence lifetime imaging microscopy (FLIM). PMID:27589762

  2. Intrinsic viscosity of actively swimming microalgae suspensions (United States)

    Ewoldt, Randy; Caretta, Lucas; Chengala, Anwar; Sheng, Jian


    Suspensions of actively swimming microorganisms exhibit an effective viscosity which may depend on volume fraction, cell shape, and the nature of locomotion (e.g. ``pushers'' vs. ``pullers''). Although several dilute-regime theories have been offered for active suspensions, no experimental study to our knowledge has been able to resolve the dilute-regime intrinsic viscosity of actively swimming microorganism suspensions. Here we use a cone-and-plate rheometer to experimentally measure the dynamic shear viscosity for motile and non-motile suspensions of unicellular green algae (Dunaliella primolecta, a biflagellated ``puller''). The low viscosity biological samples require careful experimental protocols to avoid settling and flow-induced migration, and to minimize precision error. With these protocols in place we can distinguish the intrinsic viscosity which we show is higher for the motile ``puller'' swimmers compared to the immobilized counterparts. This observation is consistent with recently proposed dilute-regime theories which predict that ``pullers'' should have a higher viscosity than non-motile suspensions.

  3. The Role of Viscosity in Causing the Plasma Poloidal Motion in Magnetic Clouds

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Ake; Wang, Yuming; Liu, Jiajia; Zhou, Zhenjun; Shen, Chenglong; Liu, Rui; Zhuang, Bin; Zhang, Quanhao, E-mail: [CAS Key Laboratory of Geospace Environment, Department of Geophysics and Planetary Sciences, University of Science and Technology of China, Hefei, Anhui 230026 (China)


    An interesting phenomenon, plasma poloidal motion, has been found in many magnetic clouds (MCs), and viscosity has been proposed as a possible mechanism. However, it is not clear how significant the role of viscosity is in generating such motion. In this paper, we conduct a statistical study of the MCs detected by the Wind spacecraft during 1995–2012. It is found that, for 19% of all the studied MCs (186), the poloidal velocities of the MC plasma near the MC boundaries are well correlated with those of the corresponding ambient solar wind plasma. A non-monotonic increase from inner to outer MCs suggests that the viscosity does play a role, albeit weak, on the poloidal motion in the MC statistically. The possible dependence on the solar wind parameters is then studied in detail for the nine selected crossings, which represent the viscosity characteristic. There is an evident negative correlation between the viscosity and the density, a weak negative correlation between the viscosity and the turbulence strength, and no clear correlation between the viscosity and the temperature.

  4. Viscosity of Xenon Examined in Microgravity (United States)

    Zimmerli, Gregory A.; Berg, Robert F.; Moldover, Michael R.


    Why does water flow faster than honey? The short answer, that honey has a greater viscosity, merely rephrases the question. The fundamental answer is that viscosity originates in the interactions between a fluid s molecules. These interactions are so complicated that, except for low-density gases, the viscosity of a fluid cannot be accurately predicted. Progress in understanding viscosity has been made by studying moderately dense gases and, more recently, fluids near the critical point. Modern theories predict a universal behavior for all pure fluids near the liquid-vapor critical point, and they relate the increase in viscosity to spontaneous fluctuations in density near this point. The Critical Viscosity of Xenon (CVX) experiment tested these theories with unprecedented precision when it flew aboard the Space Shuttle Discovery (STS-85) in August 1997. Near the critical point, xenon is a billion times more compressible than water, yet it has about the same density. Because the fluid is so "soft," it collapses under its own weight when exposed to the force of Earth s gravity - much like a very soft spring. Because the CVX experiment is conducted in microgravity, it achieves a very uniform fluid density even very close to the critical point. At the heart of the CVX experiment is a novel viscometer built around a small nickel screen. An oscillating electric field forces the screen to oscillate between pairs of electrodes. Viscosity, which dampens the oscillations, can be calculated by measuring the screen motion and the force applied to the screen. So that the fluid s delicate state near the critical point will not be disrupted, the screen oscillations are set to be both slow and small.

  5. Measuring Lipid Membrane Viscosity Using Rotational and Translational Probe Diffusion (United States)

    Hormel, Tristan T.; Kurihara, Sarah Q.; Brennan, M. Kathleen; Wozniak, Matthew C.; Parthasarathy, Raghuveer


    The two-dimensional fluidity of lipid bilayers enables the motion of membrane-bound macromolecules and is therefore crucial to biological function. Microrheological methods that measure fluid viscosity via the translational diffusion of tracer particles are challenging to apply and interpret for membranes, due to uncertainty about the local environment of the tracers. Here, we demonstrate a new technique in which determination of both the rotational and translational diffusion coefficients of membrane-linked particles enables quantification of viscosity, measurement of the effective radii of the tracers, and assessment of theoretical models of membrane hydrodynamics. Surprisingly, we find a wide distribution of effective tracer radii, presumably due to a variable number of lipids linked to each tracer particle. Furthermore, we show for the first time that a protein involved in generating membrane curvature, the vesicle trafficking protein Sar1p, dramatically increases membrane viscosity. Using the rheological method presented here, therefore, we are able to reveal a class of previously unknown couplings between protein activity and membrane mechanics.

  6. Surface Shear Viscosity and Phase Transitions of Monolayers at the Air-Water Interface (United States)

    Relini, A.; Ciuchi, F.; Rolandi, R.


    The canal method has been employed to measure the in-plane steady shear viscosity of monolayers of bolaform lipids extracted from the membrane of the thermophilic microorganism Sulfolobus solfataricus. Monolayers were formed with the polar lipid extract (PLE), which is a mixture of several bolaform lipids, each one endowed with two nonequivalent polar headgroups. Viscosities were obtained from the measured flows by using the equation introduced by Joly; this equation contains a semiempirical parameter A, which takes into account the monolayer-subphase mechanical coupling. Measuring the flows for two different substances (PLE and oleic acid) and channel widths, the monolayer viscosities and the parameter A were determined at the same time. The analysis of the viscosity data according to the free area model shows evidences of the molecular conformational changes matching monolayer phase transitions.

  7. The shear viscosity in anisotropic phases

    Energy Technology Data Exchange (ETDEWEB)

    Jain, Sachin [Department of Physics, Cornell University,Ithaca, New York 14853 (United States); Samanta, Rickmoy; Trivedi, Sandip P. [Department of Theoretical Physics, Tata Institute of Fundamental Research,Colaba, Mumbai 400005 (India)


    We construct anisotropic black brane solutions and analyse the behaviour of some of their metric perturbations. These solutions correspond to field theory duals in which rotational symmetry is broken due an externally applied, spatially constant, force. We find, in several examples, that when the anisotropy is sufficiently big compared to the temperature, some components of the viscosity tensor can become very small in units of the entropy density, parametrically violating the KSS bound. We obtain an expression relating these components of the viscosity, in units of the entropy density, to a ratio of metric components at the horizon of the black brane. This relation is generally valid, as long as the forcing function is translationally invariant, and it directly connects the parametric violation of the bound to the anisotropy in the metric at the horizon. Our results suggest the possibility that such small components of the viscosity tensor might also arise in anisotropic strongly coupled fluids found in nature.

  8. Polyfunctional dispersants for controlling viscosity of phyllosilicates (United States)

    Chaiko, David J.


    This invention provides phyllosilicates and polyfunctional dispersants which can be manipulated to selectively control the viscosity of phyllosilicate slurries. The polyfunctional dispersants used in the present invention, which include at least three functional groups, increase the dispersion and exfoliation of phyllosilicates in polymers and, when used in conjunction with phyllosilicate slurries, significantly reduce the viscosity of slurries having high concentrations of phyllosilicates. The functional groups of the polyfunctional dispersants are capable of associating with multivalent metal cations and low molecular weight organic polymers, which can be manipulated to substantially increase or decrease the viscosity of the slurry in a concentration dependent manner. The polyfunctional dispersants of the present invention can also impart desirable properties on the phyllosilicate dispersions including corrosion inhibition and enhanced exfoliation of the phyllosilicate platelets.

  9. Contrast Media Viscosity versus Osmolality in Kidney Injury: Lessons from Animal Studies (United States)

    Seeliger, Erdmann; Lenhard, Diana C.; Persson, Pontus B.


    Iodinated contrast media (CM) can induce acute kidney injury (AKI). CM share common iodine-related cytotoxic features but differ considerably with regard to osmolality and viscosity. Meta-analyses of clinical trials generally failed to reveal renal safety differences of modern CM with regard to these physicochemical properties. While most trials' reliance on serum creatinine as outcome measure contributes to this lack of clinical evidence, it largely relies on the nature of prospective clinical trials: effective prophylaxis by ample hydration must be employed. In everyday life, patients are often not well hydrated; here we lack clinical data. However, preclinical studies that directly measured glomerular filtration rate, intrarenal perfusion and oxygenation, and various markers of AKI have shown that the viscosity of CM is of vast importance. In the renal tubules, CM become enriched, as water is reabsorbed, but CM are not. In consequence, tubular fluid viscosity increases exponentially. This hinders glomerular filtration and tubular flow and, thereby, prolongs intrarenal retention of cytotoxic CM. Renal cells become injured, which triggers hypoperfusion and hypoxia, finally leading to AKI. Comparisons between modern CM reveal that moderately elevated osmolality has a renoprotective effect, in particular, in the dehydrated state, because it prevents excessive tubular fluid viscosity. PMID:24707482

  10. Viscosity Meaurement Technique for Metal Fuels

    Energy Technology Data Exchange (ETDEWEB)

    Ban, Heng [Utah State Univ., Logan, UT (United States). Mechanical and Aerospace Engineering; Kennedy, Rory [Idaho National Lab. (INL), Idaho Falls, ID (United States)


    Metallic fuels have exceptional transient behavior, excellent thermal conductivity, and a more straightforward reprocessing path, which does not separate out pure plutonium from the process stream. Fabrication of fuel containing minor actinides and rare earth (RE) elements for irradiation tests, for instance, U-20Pu-3Am-2Np-1.0RE-15Zr samples at the Idaho National Laboratory, is generally done by melt casting in an inert atmosphere. For the design of a casting system and further scale up development, computational modeling of the casting process is needed to provide information on melt flow and solidification for process optimization. Therefore, there is a need for melt viscosity data, the most important melt property that controls the melt flow. The goal of the project was to develop a measurement technique that uses fully sealed melt sample with no Americium vapor loss to determine the viscosity of metallic melts and at temperatures relevant to the casting process. The specific objectives of the project were to: develop mathematical models to establish the principle of the measurement method, design and build a viscosity measurement prototype system based on the established principle, and calibrate the system and quantify the uncertainty range. The result of the project indicates that the oscillation cup technique is applicable for melt viscosity measurement. Detailed mathematical models of innovative sample ampoule designs were developed to not only determine melt viscosity, but also melt density under certain designs. Measurement uncertainties were analyzed and quantified. The result of this project can be used as the initial step toward the eventual goal of establishing a viscosity measurement system for radioactive melts.

  11. Study of sorption mechanisms of europium(3) and uranium(6) ions on clays : impact of silicates; Etude des mecanismes de retention des ions U(6) et Eu(3) sur les argiles: influence des silicates

    Energy Technology Data Exchange (ETDEWEB)

    Kowal-Fouchard, A


    Bentonite clay has been selected as a potential buffer or backfill material in a number of disposal programmes for high level waste. In order to enhance the thermodynamic database of sorption phenomena at the solid-water interface, we have investigated sorption mechanisms of europium(III) and uranium(VI) ions onto montmorillonite and bentonite. Thermodynamic data were obtained for different ions concentrations, different background electrolytes and different ionic strengths. The structural identification of the surface complexes and sorption sites was carried out using two spectroscopies, XPS and TRLIFS, while sorption edges were performed using batch experiments. However, clays are complex minerals and in order to understand these sorption mechanisms we have studied europium(III) and uranium(VI) retention on a silica and an alumina because these solids are often considered as basic components of clays. The comparison of structural results shows that europium ions are significantly sorbed on permanently charged sites of clay until pH 7. But this ion is also sorbed on {identical_to}SiOH and {identical_to}AlOH sites of montmorillonite at pH higher than 6. Uranyl ions sorption on montmorillonite is mainly explained by retention of three complexes on {identical_to}SiOH sites. Moreover, we have shown that nitrate ions and dissolved silicates affect on uranium(VI) sorption mechanisms onto alumina. Nevertheless, uranyl ions sorption on montmorillonite and bentonite only decreases with increasing carbonate concentration. Finally, all the sorption edges were then modeled using these results and a surface complexation model (2 pK and constant capacitance models). (author)

  12. Shear viscosity coefficient of liquid lanthanides

    Energy Technology Data Exchange (ETDEWEB)

    Patel, H. P., E-mail:; Thakor, P. B., E-mail:; Prajapati, A. V., E-mail: [Department of Physics, Veer Narmad South Gujarat University, Surat 395 007, Gujarat (India); Sonvane, Y. A., E-mail: [Department of Applied Physics, S. V. National Institute of Technology, Surat 395 007, Gujarat (India)


    Present paper deals with the computation of shear viscosity coefficient (η) of liquid lanthanides. The effective pair potential v(r) is calculated through our newly constructed model potential. The Pair distribution function g(r) is calculated from PYHS reference system. To see the influence of local field correction function, Hartree (H), Tailor (T) and Sarkar et al (S) local field correction function are used. Present results are compared with available experimental as well as theoretical data. Lastly, we found that our newly constructed model potential successfully explains the shear viscosity coefficient (η) of liquid lanthanides.

  13. Entropy viscosity method for nonlinear conservation laws

    KAUST Repository

    Guermond, Jean-Luc


    A new class of high-order numerical methods for approximating nonlinear conservation laws is described (entropy viscosity method). The novelty is that a nonlinear viscosity based on the local size of an entropy production is added to the numerical discretization at hand. This new approach does not use any flux or slope limiters, applies to equations or systems supplemented with one or more entropy inequalities and does not depend on the mesh type and polynomial approximation. Various benchmark problems are solved with finite elements, spectral elements and Fourier series to illustrate the capability of the proposed method. © 2010 Elsevier Inc.

  14. Thermal relics in cosmology with bulk viscosity

    Energy Technology Data Exchange (ETDEWEB)

    Iorio, A. [Charles University in Prague, Faculty of Mathematics and Physics, Prague (Czech Republic); Lambiase, G. [Universita di Salerno, Dipartimento di Fisica E.R. Caianiello, Fisciano (Italy); INFN, Gruppo Collegato di Salerno, Fisciano (Italy)


    In this paper we discuss some consequences of cosmological models in which the primordial cosmic matter is described by a relativistic imperfect fluid. The latter takes into account the dissipative effects (bulk viscosity) arising from different cooling rates of the fluid components in the expanding Universe. We discuss, in particular, the effects of the bulk viscosity on Big Bang Nucleosynthesis and on the thermal relic abundance of particles, looking at recent results of PAMELA experiment. The latter has determined an anomalous excess of positron events, which cannot be explained by conventional cosmology and particle physics. (orig.)

  15. Gravimetric capillary method for kinematic viscosity measurements (United States)

    Rosenberger, Franz; Iwan, J.; Alexander, D.; Jin, Wei-Qing


    A novel version of the capillary method for viscosity measurements of liquids is presented. Viscosity data can be deduced in a straightforward way from mass transfer data obtained by differential weighing during the gravity-induced flow of the liquid between two cylindrical chambers. Tests of this technique with water, carbon tetrachloride, and ethanol suggest that this arrangement provides an accuracy of about +/- 1 percent. The technique facilitates operation under sealed, isothermal conditions and, thus can readily be applied to reactive and/or high vapor pressure liquids.

  16. On Coulomb and Viscosity damped single-degree-of-freedom vibrating systems

    DEFF Research Database (Denmark)

    Jakobsen, J.; Sivebæk, Ion Marius


    Attention on friction damping mechanisms could be of interest for vibration reduction, and appears therefore to be desirable. Presentations of textbook analyses on mechanical vibration of a viscosity damped single degree system [mass, spring and eventually damping] are numerous. Often they begin...

  17. Responsibilities and retention

    Directory of Open Access Journals (Sweden)

    Simon J Littlewood


    Full Text Available As our understanding of orthodontic relapse has improved, there is an increasing move toward long-term retention. Safely reducing relapse using appropriate long-term retention imposes considerable responsibilities on the orthodontist, the patient, and the patient's general dentist. This article will describe these responsibilities.

  18. Viscosity of Liquid Fe-17wt% Si at High Pressure and Temperature (United States)

    Yu, X.; Secco, R. A.; Wang, Y.; Ohtani, E.; Terasaki, H.; Suzuki, A.


    In situ X-ray radiography falling-sphere experiments on liquid Fe-17wt% Si viscosity were carried out from 2 GPa to 7 GPa at APS and Spring-8 in multi-anvil apparati. Video images were recorded at speeds of up to 62 frames/sec. Both Re spheres coated with alumina and composite spheres of Pt or Re core and a mechanically prepared ruby mantle were used in the high pressure melts to avoid chemical reaction between the sample and the probing metallic spheres. The viscosity at the melting temperature was calculated from activation energy, which was determined from a combination of theoretical and experimental values of viscosity at ambient pressure. At the early stages of the compression (up to ~ 5.4 GPa), the viscosity increases but later appears to approach a constant value of 69 mPa.s in the higher pressure range. The constant relating activation energy to melting temperature, g, is 6.8 from this study. Assuming that temperature varies adiabatically in the core and melting temperature Tm at the inner core boundary is 4766 K and dTm dP = 10 K/GPa, the viscosity at the core-mantle boundary, inferred from this study, decreases to a value very close to the ambient pressure viscosity of 6 mPa.s for liquid metal.

  19. High-Resolution Lithosphere Viscosity and Dynamics Revealed by Magnetotelluric Imaging (United States)

    Liu, L.; Hasterok, D. P.


    An accurate viscosity structure is critical to truthfully modeling continental lithosphere dynamics, especially at spatial scales of factors including strain rate, plastic failure, composition, and grain size. Current efforts on inferring the detailed lithosphere viscosity structure are sparse and large uncertainties and discrepancies still exist. Here we report an attempt to infer the effective lithospheric viscosity from a high-resolution magnetotelluric (MT) survey across the western United States. The high sensitivity of MT fields to the presence of electrically conductive fluids makes it a promising proxy for determining mechanical strength variations throughout the lithosphere. We demonstrate how a viscosity structure, approximated from electrical resistivity, results in a geodynamic model that successfully predicts short-wavelength surface topography, lithospheric deformation, and mantle upwelling beneath recent volcanism. The results indicate that lithosphere viscosity structure rather than the buoyancy structure is the dominant controlling factor for short-wavelength topography and intra-plate deformation in tectonically active regions. We further show that this viscosity is consistent with and more effective than that derived from laboratory-based rheology. We therefore propose that MT imaging provides a practical observational constraint for quantifying the dynamic evolution of the continental lithosphere.

  20. Lack of age-related increase in carotid artery wall viscosity in cardiorespiratory fit men. (United States)

    Kawano, Hiroshi; Yamamoto, Kenta; Gando, Yuko; Tanimoto, Michiya; Murakami, Haruka; Ohmori, Yumi; Sanada, Kiyoshi; Tabata, Izumi; Higuchi, Mitsuru; Miyachi, Motohiko


    Age-related arterial stiffening and reduction of arterial elasticity are attenuated in individuals with high levels of cardiorespiratory fitness. Viscosity is another mechanical characteristic of the arterial wall; however, the effects of age and cardiorespiratory fitness have not been determined. We examined the associations among age, cardiorespiratory fitness and carotid arterial wall viscosity. A total of 111 healthy men, aged 25-39 years (young) and 40-64 years (middle-aged), were divided into either cardiorespiratory fit or unfit groups on the basis of peak oxygen uptake. The common carotid artery was measured noninvasively by tonometry and automatic tracking of B-mode images to obtain instantaneous pressure and diameter hysteresis loops, and we calculated the effective compliance, isobaric compliance and viscosity index. In the middle-aged men, the viscosity index was larger in the unfit group than in the fit group (2533 vs. 2018 mmHg·s/mm, respectively: Pviscosity index was increased with advancing age, but these parameters were unaffected by cardiorespiratory fitness level. These results suggest that the wall viscosity in the central artery is increased with advancing age and that the age-associated increase in wall viscosity may be attenuated in cardiorespiratory fit men.

  1. Mechanisms of hydrogen retention in metallic beryllium and beryllium oxide and properties of ion-induced beryllium nitride; Rueckhaltemechanismen fuer Wasserstoff in metallischem Beryllium und Berylliumoxid sowie Eigenschaften von ioneninduziertem Berylliumnitrid

    Energy Technology Data Exchange (ETDEWEB)

    Oberkofler, Martin


    In the framework of this thesis laboratory experiments on atomically clean beryllium surfaces were performed. They aim at a basic understanding of the mechanisms occurring upon interaction of a fusion plasma with a beryllium first wall. The retention and the temperature dependent release of implanted deuterium ions are investigated. An atomistic description is developed through simulations and through the comparison with calculations based on density functional theory. The results of these investigations are compared to the behaviour of hydrogen upon implantation into thermally grown beryllium oxide layers. Furthermore, beryllium nitride is produced by implantation of nitrogen into metallic beryllium and its properties are investigated. The results are interpreted with regard to the use of beryllium in a fusion reactor. (orig.)

  2. Conformations of gelatin in trivalent chromium salt solutions: Viscosity and dynamic light scattering study (United States)

    Qiao, Congde; Zhang, Jianlong; Kong, Aiqun


    An investigation of the influences of pH, salt type, and salt concentration on the conformations of gelatin molecules in trivalent chromium salt solutions was performed by viscosity and dynamic light scattering (DLS) techniques. It was found that the viscosity behaviors as polyelectrolytes or polyampholytes depended on the charge distribution on the gelatin chains, which can be tuned by the value of pH of the gelatin solution. The intrinsic viscosity of gelatin in basic chromium sulfate aqueous solution at pH = 2.0 first decreased and then increased with increasing Cr(OH)SO4 concentration, while a monotonic decrease of the intrinsic viscosity of gelatin was observed in CrCl3 solution. However, the intrinsic viscosity of gelatin at pH = 5.0 was found to be increased first and then decreased with an increase in salt concentration in Cr(OH)SO4 solution, as well as in CrCl3 solution. We suggested that the observed viscosity behavior of gelatin in trivalent chromium salt solutions was attributed to the comprehensive effects of shielding, overcharging, and crosslinking (complexation) caused by the introduction of the different counterions. In addition, the average hydrodynamic radius ( R h ) of gelatin molecules in various salt solutions was determined by DLS. It was found that the change trend of R h with salt concentration was the same as the change of intrinsic viscosity. Based on the results of the viscosity and DLS, a possible mechanism for the conformational transition of gelatin chains with external conditions including pH, salt concentration, and salt type is proposed.

  3. Pressure-viscosity coefficient of biobased lubricants (United States)

    Film thickness is an important tribological property that is dependent on the combined effect of lubricant properties, material property of friction surfaces, and the operating conditions of the tribological process. Pressure-viscosity coefficient (PVC) is one of the lubricant properties that influe...

  4. Viscosity of endodontic irrigants: Influence of temperature

    Directory of Open Access Journals (Sweden)

    Claudio Poggio


    Full Text Available Background: The aim of this study was to assess the influence of temperature on the viscosity of different endodontic irrigants. Materials and Methods: The measurements of viscosity of 3% hydrogen peroxide, 0.9% sodium chloride, aqueous solution of 0.2% chlorhexidine (CHX and 0.2% cetrimide, 5% sodium hypochlorite (NaOCl and 17% ethylenediaminetetraacetic acid (EDTA at different temperatures (22°C, 30°C, 40°C, 50°C and 60°C were obtained using Mohr balance and Ostwald viscometer. The Shapiro-Wilk test and Mann-Whitney U-tests were used for the statistical analysis. (α = 0.05. Results: No significant differences were recorded at each temperature among 3% hydrogen peroxide, 0.9% sodium chloride and aqueous solution of 0.2% CHX and 0.2% cetrimide. 5% NaOCl and 17% EDTA showed the higher values. Viscosity statistically decreased with increasing temperature. Conclusion: Within the limitations of this study, 5% NaOCl and 17% EDTA are significantly viscous at room temperature and their viscosity reduces with elevating temperature.

  5. Effect of Viscosity on Liquid Curtain Stability (United States)

    Mohammad Karim, Alireza; Suszynski, Wieslaw; Francis, Lorraine; Carvalho, Marcio; Dow Chemical Company Collaboration; PUC Rio Collaboration; University of Minnesota, Twin Cities Collaboration


    The effect of viscosity on the stability of Newtonian liquid curtains was explored by high-speed visualization. Glycerol/water solutions with viscosity ranging from 19.1 to 210 mPa.s were used as coating liquids. The experimental set-up used a slide die delivery and steel tube edge guides. The velocity along curtain at different positions was measured by tracking small particles at different flow conditions. The measurements revealed that away from edge guides, velocity is well described by free fall effect. However, close to edge guides, liquid moves slower, revealing formation of a viscous boundary layer. The size of boundary layer and velocity near edge guides are strong function of viscosity. The critical condition was determined by examining flow rate below which curtain broke. Curtain failure was initiated by growth of a hole within liquid curtain, close to edge guides. Visualization results showed that the hole forms in a circular shape then becomes elliptical as it grows faster in vertical direction compared to horizontal direction. As viscosity rises, minimum flow rate for destabilization of curtain increased, indicating connection between interaction with edge guides and curtain stability. We would like to acknowledge the financial support from the Dow Chemical Company.

  6. Shear viscosity of an ordering latex suspension

    NARCIS (Netherlands)

    van der Vorst, A.M.; van der Vorst, B.; van den Ende, Henricus T.M.; Aelmans, N.J.J.; Mellema, J.


    The shear viscosity of a latex which is ordered at rest is studied as a function of the shear rate and volume fraction. At low shear rates and for moderate to high volume fractions, the flow curves show dynamic yield behavior which disappears below a volume fraction of 8%. At high shear rates, the

  7. Association of Plasma Viscosity with Cardiovascular Risk Factors in Obesity: As an old marker, a new insight (United States)

    Meltem, Ercan; Dildar, Konukoglu; Tijen, Yeşim Erdem


    Although obesity is related with cardiovascular disease, the exact mechanism of the relationship is not fully understood. We aim to examine the relationship between plasma viscosity and obesity as a cardiovascular disease risk factor in obese and non-obese groups. We recruited 75 obese subjects who were admitted to the Cerrahpasa Medical Faculty. Plasma viscosity and lipid profile were measured and atherogenic index was calculated as atherogenic risk factors. Plasma viscosity, total cholesterol and LDL-cholesterol levels and atherogenic index were significantly increased in obese group compared to non-obese group for each. Plasma viscosity was weakly correlated with total cholesterol and atherogenic index only in the obese group. Plasma viscosity, an early atherosclerotic risk factor, might be helpful in the assessment of cardiovascular risk in obese subjects.

  8. Retention Models on Core-Shell Columns. (United States)

    Jandera, Pavel; Hájek, Tomáš; Růžičková, Marie


    A thin, active shell layer on core-shell columns provides high efficiency in HPLC at moderately high pressures. We revisited three models of mobile phase effects on retention for core-shell columns in mixed aqueous-organic mobile phases: linear solvent strength and Snyder-Soczewiński two-parameter models and a three-parameter model. For some compounds, two-parameter models show minor deviations from linearity due to neglect of possible minor retention in pure weak solvent, which is compensated for in the three-parameter model, which does not explicitly assume either the adsorption or the partition retention mechanism in normal- or reversed-phase systems. The model retention equation can be formulated as a function of solute retention factors of nonionic compounds in pure organic solvent and in pure water (or aqueous buffer) and of the volume fraction of an either aqueous or organic solvent component in a two-component mobile phase. With core-shell columns, the impervious solid core does not participate in the retention process. Hence, the thermodynamic retention factors, defined as the ratio of the mass of the analyte mass contained in the stationary phase to its mass in the mobile phase in the column, should not include the particle core volume. The values of the thermodynamic factors are lower than the retention factors determined using a convention including the inert core in the stationary phase. However, both conventions produce correct results if consistently used to predict the effects of changing mobile phase composition on retention. We compared three types of core-shell columns with C18-, phenyl-hexyl-, and biphenyl-bonded phases. The core-shell columns with phenyl-hexyl- and biphenyl-bonded ligands provided lower errors in two-parameter model predictions for alkylbenzenes, phenolic acids, and flavonoid compounds in comparison with C18-bonded ligands.

  9. Proteinuric diseases with sodium retention: Is plasmin the link?

    DEFF Research Database (Denmark)

    Svenningsen, Per; Skøtt, Ole; Jensen, Boye L


    1. Sodium retention in disease states characterized by proteinuria, such as nephrotic syndrome, preeclampsia, and diabetic nephropathy, occurs through poorly understood mechanism(s). 2. In the nephrotic syndrome, data from experimental and clinical studies indicate that the sodium retention...... and diabetic nephropathy, which are also characterized by proteinuria and sodium retention. 7. In this review, we will examine the evidence for a role of urinary serine protease activity in the development of sodium and water retention in diseases characterised by proteinuria with a focus on the nephrotic...

  10. Effect of Ratio of Visco-Elastic Material Viscosity to Fluid Viscosity on Stability of Flexible Pipe Flow (United States)



    In the present study, a flexible pipe has been considered to study the effect of ratio of visco-elastic material viscosity to fluid viscosity on the stability of flexible laminar pipe flow with axi-symmetric disturbances. The effect of thickness of visco-elastic material on the stability of flexible pipe flow with outer rigid shroud has also been studied. The stability curves are drawn for various values of the ratio of visco-elastic material viscosity to fluid viscosity. It is observed that stability of flow is increasing by decreasing the ratio of visco-elastic material viscosity to fluid viscosity.

  11. A phase space approach to supercooled liquids and a universal collapse of their viscosity

    CERN Document Server

    Weingartner, Nicholas B; Nogueira, Flavio S; Kelton, K F; Nussinov, Zohar


    A broad fundamental understanding of the mechanisms underlying the phenomenology of supercooled liquids has remained elusive, despite decades of intense exploration. When supercooled beneath its characteristic melting temperature, a liquid sees a sharp rise in its viscosity over a narrow temperature range, eventually becoming frozen on laboratory timescales. Explaining this immense increase in viscosity is one of the principle goals of condensed matter physicists. To that end, numerous theoretical frameworks have been proposed which explain and reproduce the temperature dependence of the viscosity of supercooled liquids. Each of these frameworks appears only applicable to specific classes of glassformers and each possess a number of variable parameters. Here we describe a classical framework for explaining the dynamical behavior of supercooled liquids based on statistical mechanical considerations, and possessing only a single variable parameter. This parameter varies weakly from liquid to liquid. Furthermore...

  12. Drug Retention Times

    Energy Technology Data Exchange (ETDEWEB)

    Center for Human Reliability Studies


    The purpose of this monograph is to provide information on drug retention times in the human body. The information provided is based on plausible illegal drug use activities that might be engaged in by a recreational drug user.

  13. Liquid Effluent Retention Facility (United States)

    Federal Laboratory Consortium — The Liquid Effluent Retention Facility (LERF) is located in the central part of the Hanford Site. LERF is permitted by the State of Washington and has three liquid...

  14. Assessing bitumen and heavy oil viscosity in situ

    Energy Technology Data Exchange (ETDEWEB)

    Larter, S.; Adams, J.; Jiang, D.; Snowdon, L.; Bennett, B.; Gates, I. [Calgary Univ., AB (Canada); Gushor Inc., Calgary, AB (Canada)


    Log-based techniques for evaluating the in-situ viscosity of oil rely on dead oil viscosity measurements are conducted in laboratories. However, bitumen viscosity is impacted by water; sediment and gas loads; emulsion formation; and shear properties. This abstract discussed a method of assessing the in-situ viscosity of bitumen and heavy oils. The method was designed to simulate the viscosity of heavy oil fluid flow in process conditions. Measured appropriate dead oil viscosity was combined with estimates of solution gas content using mixing rules in order to establish in-situ live oil viscosity estimates. The method takes into account solid and water loads, procedures for correction of viscosity for core storage artifacts, and the impact of variable bitumen saturation pressures through oil columns on live oil reconstruction algorithms.

  15. Plasma Viscosity with Mass Transport in Spherical ICF Implosion Simulations

    CERN Document Server

    Vold, Erik L; Ortega, Mario I; Moll, Ryan; Fenn, Daniel; Molvig, Kim


    The effects of viscosity and small-scale atomic-level mixing on plasmas in inertial confinement fusion (ICF) currently represent challenges in ICF research. Many current ICF hydrodynamic codes ignore the effects of viscosity though recent research indicates viscosity and mixing by classical transport processes may have a substantial impact on implosion dynamics. We have implemented a Lagrange hydrodynamic code in one-dimensional spherical geometry with plasma viscosity and mass transport and including a three temperature model for ions, electrons, and radiation treated in a gray radiation diffusion approximation. The code is used to study ICF implosion differences with and without plasma viscosity and to determine the impacts of viscosity on temperature histories and neutron yield. It was found that plasma viscosity has substantial impacts on ICF shock dynamics characterized by shock burn timing, maximum burn temperatures, convergence ratio, and time history of neutron production rates. Plasma viscosity reduc...

  16. Relationship between viscosity of the ankle joint complex and functional ankle instability for inversion ankle sprain patients. (United States)

    Lin, Che-Yu; Kang, Jiunn-Horng; Wang, Chung-Li; Shau, Yio-Wha


    Measurement of viscosity of the ankle joint complex is a novel method to assess mechanical ankle instability. In order to further investigate the clinical significance of the method, this study intended to investigate the relationship between ankle viscosity and severity of functional ankle instability. Cross-sectional study. 15 participants with unilateral inversion ankle sprain and 15 controls were recruited. Their ankles were further classified into stable and unstable ankles. Ankle viscosity was measured by an instrumental anterior drawer test. Severity of functional ankle instability was measured by the Cumberland Ankle Instability Tool. Unstable ankles were compared with stable ankles. Injured ankles were compared with uninjured ankles of both groups. The spearman's rank correlation coefficient was applied to determine the relationship between ankle viscosity and severity of functional ankle instability in unstable ankles. There was a moderate relationship between ankle viscosity and severity of functional ankle instability (r=-0.64, pviscosity (pviscosity and more severe functional ankle instability than uninjured ankles (pviscosity and severity of functional ankle instability. This finding suggested that, severity of functional ankle instability may be partially attributed to mechanical insufficiencies such as the degenerative changes in ankle viscosity following the inversion ankle sprain. In clinical application, measurement of ankle viscosity could be a useful tool to evaluate severity of chronic ankle instability. Copyright © 2014 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

  17. An electron paramagnetic resonance spectroscopy investigation of the retention mechanisms of Mn and Cu in the nanopore channels of three zeolite minerals

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Daniel R.; Schulthess, Cristian P.; Amonette, James E.; Walter, Eric D.


    The adsorption mechanisms of divalent cations in zeolite nanopore channels can vary as a function of their pore dimensions. The nanopore inner-sphere enhancement (NISE) theory predicts that ions may dehydrate inside small nanopore channels in order to adsorb more closely to the mineral surface if the nanopore channel is sufficiently small. The results of an electron paramagnetic resonance (EPR) spectroscopy study of Mn and Cu adsorption on the zeolite minerals zeolite Y (large nanopores), ZSM-5 (intermediate nanopores), and mordenite (small nanopores) are presented. The Cu and Mn cations both adsorbed via an outer-sphere mechanism on zeolite Y based on the similarity between the adsorbed spectra and the aqueous spectra. Conversely, Mn and Cu adsorbed via an inner-sphere mechanism on mordenite based on spectrum asymmetry and peak broadening of the adsorbed spectra. However, Mn adsorbed via an outer-sphere mechanism on ZSM-5, whereas Cu adsorbed on ZSM-5 shows a high degree of surface interaction that indicates that it is adsorbed closer to the mineral surface. Evidence of dehydration and immobility was more readily evident in the spectrum of mordenite than ZSM-5, indicating that Cu was not as close to the surface on ZSM-5 as it was when adsorbed on mordenite. Divalent Mn cations are strongly hydrated and are held strongly only in zeolites with small nanopore channels. Divalent Cu cations are also strongly hydrated, but can dehydrate more easily, presumably due to the Jahn-Teller effect, and are held strongly in zeolites with medium sized nanopore channels or smaller.

  18. Pendulum Underwater - An Approach for Quantifying Viscosity (United States)

    Leme, José Costa; Oliveira, Agostinho


    The purpose of the experiment presented in this paper is to quantify the viscosity of a liquid. Viscous effects are important in the flow of fluids in pipes, in the bloodstream, in the lubrication of engine parts, and in many other situations. In the present paper, the authors explore the oscillations of a physical pendulum in the form of a long and lightweight wire that carries a ball at its lower end, which is totally immersed in water, so as to determine the water viscosity. The system used represents a viscous damped pendulum and we tried different theoretical models to describe it. The experimental part of the present paper is based on a very simple and low-cost image capturing apparatus that can easily be replicated in a physics classroom. Data on the pendulum's amplitude as a function of time were acquired using digital video analysis with the open source software Tracker.

  19. Bulk and shear viscosity in Hagedorn fluid

    Energy Technology Data Exchange (ETDEWEB)

    Tawfik, A.; Wahba, M. [Egyptian Center for Theoretical Physics (ECTP), MTI University, Faculty of Engineering, Cairo (Egypt)


    Assuming that the Hagedorn fluid composed of known particles and resonances with masses m <2 GeV obeys the first-order theory (Eckart) of relativistic fluid, we discuss the transport properties of QCD confined phase. Based on the relativistic kinetic theory formulated under the relaxation time approximation, expressions for bulk and shear viscosity in thermal medium of hadron resonances are derived. The relaxation time in the Hagedorn dynamical fluid exclusively takes into account the decay and eventually van der Waals processes. We comment on the in-medium thermal effects on bulk and shear viscosity and averaged relaxation time with and without the excluded-volume approach. As an application of these results, we suggest the dynamics of heavy-ion collisions, non-equilibrium thermodynamics and the cosmological models, which require thermo- and hydro-dynamics equations of state. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  20. Caldera resurgence driven by magma viscosity contrasts. (United States)

    Galetto, Federico; Acocella, Valerio; Caricchi, Luca


    Calderas are impressive volcanic depressions commonly produced by major eruptions. Equally impressive is the uplift of the caldera floor that may follow, dubbed caldera resurgence, resulting from magma accumulation and accompanied by minor eruptions. Why magma accumulates, driving resurgence instead of feeding large eruptions, is one of the least understood processes in volcanology. Here we use thermal and experimental models to define the conditions promoting resurgence. Thermal modelling suggests that a magma reservoir develops a growing transition zone with relatively low viscosity contrast with respect to any newly injected magma. Experiments show that this viscosity contrast provides a rheological barrier, impeding the propagation through dikes of the new injected magma, which stagnates and promotes resurgence. In explaining resurgence and its related features, we provide the theoretical background to account for the transition from magma eruption to accumulation, which is essential not only to develop resurgence, but also large magma reservoirs.

  1. Viscosity solution of linear regulator quadratic for degenerate diffusions

    Directory of Open Access Journals (Sweden)


    Full Text Available The paper studied a linear regulator quadratic control problem for degenerate Hamilton-Jacobi-Bellman (HJB equation. We showed the existence of viscosity properties and established a unique viscosity solution of the degenerate HJB equation associated with this problem by the technique of viscosity solutions.

  2. On the scaling of entropy viscosity in high order methods


    Kornelus, Adeline; Appelö, Daniel


    In this work, we outline the entropy viscosity method and discuss how the choice of scaling influences the size of viscosity for a simple shock problem. We present examples to illustrate the performance of the entropy viscosity method under two distinct scalings.

  3. Effect of urea formaldehyde viscosity on urea formaldehyde and ...

    African Journals Online (AJOL)

    The melting point, refractive index, density and formaldehyde emission were found to increase with increase in UF viscosity while the dry time, moisture uptake and elongation at break were found to decrease with increase in viscosity. UF viscosity below 10.82 mPa.s was found to produce UF/UP copolymer composite which ...

  4. Predicting human blood viscosity in silico (United States)

    Fedosov, Dmitry A.; Pan, Wenxiao; Caswell, Bruce; Gompper, Gerhard; Karniadakis, George E.


    The viscosity of blood has long been used as an indicator in the understanding and treatment of disease, and the advent of modern viscometers allows its measurement with ever-improving clinical convenience. However, these advances have not been matched by theoretical developments that can yield a quantitative understanding of blood’s microrheology and its possible connection to relevant biomolecules (e.g., fibrinogen). Using coarse-grained molecular dynamics and two different red blood cell models, we accurately predict the dependence of blood viscosity on shear rate and hematocrit. We explicitly represent cell–cell interactions and identify the types and sizes of reversible rouleaux structures that yield a tremendous increase of blood viscosity at low shear rates. We also present the first quantitative estimates of the magnitude of adhesive forces between red cells. In addition, our simulations support the hypothesis, previously deduced from experiments, of yield stress as an indicator of cell aggregation. This non-Newtonian behavior is analyzed and related to the suspension’s microstructure, deformation, and dynamics of single red blood cells. The most complex cell dynamics occurs in the intermediate shear rate regime, where individual cells experience severe deformation and transient folded conformations. The generality of these cell models together with single-cell measurements points to the future prediction of blood-viscosity anomalies and the corresponding microstructures associated with various diseases (e.g., malaria, AIDS, and diabetes mellitus). The models can easily be adapted to tune the properties of a much wider class of complex fluids including capsule and vesicle suspensions. PMID:21730178

  5. RELAP-7 Numerical Stabilization: Entropy Viscosity Method

    Energy Technology Data Exchange (ETDEWEB)

    R. A. Berry; M. O. Delchini; J. Ragusa


    The RELAP-7 code is the next generation nuclear reactor system safety analysis code being developed at the Idaho National Laboratory (INL). The code is based on the INL's modern scientific software development framework, MOOSE (Multi-Physics Object Oriented Simulation Environment). The overall design goal of RELAP-7 is to take advantage of the previous thirty years of advancements in computer architecture, software design, numerical integration methods, and physical models. The end result will be a reactor systems analysis capability that retains and improves upon RELAP5's capability and extends the analysis capability for all reactor system simulation scenarios. RELAP-7 utilizes a single phase and a novel seven-equation two-phase flow models as described in the RELAP-7 Theory Manual (INL/EXT-14-31366). The basic equation systems are hyperbolic, which generally require some type of stabilization (or artificial viscosity) to capture nonlinear discontinuities and to suppress advection-caused oscillations. This report documents one of the available options for this stabilization in RELAP-7 -- a new and novel approach known as the entropy viscosity method. Because the code is an ongoing development effort in which the physical sub models, numerics, and coding are evolving, so too must the specific details of the entropy viscosity stabilization method. Here the fundamentals of the method in their current state are presented.

  6. Wound dressing based on nonwoven viscose fabrics. (United States)

    Abou-Okeil, A; Sheta, A M; Amr, A; Ali, Marwa A


    Nonwoven viscose fabric was treated with chitosan/polyvinyl alcohol (PVA) using pad-dry method, using different concentrations of chitosan and PVA. Increasing the amount of PVA leads to increasing of air permeability. Water permeability increased by increasing the amount of PVA to 2 ml (10% solution) then decreased by any increase of the quantity of PVA solution. Roughness increased with increasing the amount of 10% PVA solution. It is shown that roughness, water and air permeability increased with increasing the chitosan concentration. Antibacterial properties was increased with increasing PVA/or chitosan concentration. The chitosan/PVA treated nonwoven viscose fabric was immersed in a solution of Ag nanoparticles. The chitosan/PVA/Ag nanoparticles treated nonwoven fabrics were used as wound dressings on French white Bouscat rabbits, with age ranged from 1 to 2 years. A complete healing was achieved using wound dressing consists of nonwoven viscose fabric treated with chitosan/PVA/Ag nanoparticles after 21 days. The histopathological examination confirmed the complete re-epithelialization and averagely thick epidermis formation. Copyright © 2012 Elsevier Ltd. All rights reserved.

  7. Viscosity negatively affects the nutritional value of blue lupin seeds for broilers. (United States)

    Konieczka, P; Smulikowska, S


    This study examines the impact of Lupinus angustifolius variety (C) and inclusion level (L) in broiler diets on the nutritional value, viscosity of ileal digesta and activity of gut microbiota. The experiment was conducted on 154 female 21-day-old broilers, allocated to 11 groups (kept individually). A reference lupin-free diet and 10 test diets containing one of five lupin seeds; Kadryl, Regent, Dalbor, Bojar and Tango, mixed with the reference diet at a ratio of 25 : 75 or 32 : 68 dry matter (DM) (low or high level of inclusion) were prepared. Diets were fed for 6 days, excreta were collected over last 4 days. Apparent metabolizable energy corrected to zero N balance (AMEN) of diets and AMEN of lupin seeds were calculated. Birds were sacrificed, ileal and caecal digesta were pooled by segments from two birds, and the activity of bacterial enzymes was determined. The ileal digesta viscosity was measured immediately (ileal viscosity immediate (IVI)) or after 6 days storage at -18°C (ileal viscosity frozen). AMEN of test diets were lower than the reference diet. Lupin AMEN values ranged from 6.04 MJ/kg DM for Regent at high level to 9.25 MJ/kg DM for Bojar at low level. High inclusion level numerically decreased AMEN value in all cultivars, except for Kadryl, for which it increased (significant C×L interaction). The IVI value was 2.6 mPa·s in the reference group, but ranged from 6.3 to 21.7 mPa·s in lupin-fed birds. It increased significantly with level for Regent, Dalbor and Tango but not for the other two cultivars (significant C×L interaction). There was a negative correlation between IVI and: apparent total tract N retention, fat digestibility from test diets, AMEN of diets and lupins. Ileal viscosity immediate was positively correlated with the activity of ileal α- and β-glucosidase and negatively with ileal α-galactosidase and caecal α-glucosidase. Ileal viscosity frozen ranged from 3.2 to 5 mPa·s and it was not correlated with lupins AMEN. This

  8. Influence of blood lipids on plasma and blood viscosity. (United States)

    Irace, Concetta; Carallo, Claudio; Scavelli, Faustina; Esposito, Teresa; De Franceschi, Maria Serena; Tripolino, Cesare; Gnasso, Agostino


    The relationship between hyperlipidemia and blood and plasma viscosity is not completely clear. While increasing viscosity is often reported with increasing blood lipids, lipid-lowering treatments are often unable to normalize the viscosity values. Aim of this study is to try to clarify the relationship between blood lipids and viscosity. Apparently healthy subjects were enrolled (n = 410). Smokers, diabetics, obese, and hypertriglyceridemic (above 400 mg/dl) were excluded. Blood (at shear rate 225/s) and plasma viscosity were measured at 37°C. Erythrocyte rigidity (Tk) was calculated according to Dintenfass. Blood lipids and glucose were measured by routine methods. Hyperlipidemic subjects (n = 315) had higher values of plasma viscosity (1.44 ± 0.13 vs. 1.40 ± 0.12 cP, p = 0.007), and blood viscosity (4.51 ± 0.54 vs. 4.35 ± 0.55 cP, p = 0.013), compared to normolipidemic subjects (n = 95). In simple correlation analysis, plasma viscosity was directly associated with LDL cholesterol, and inversely with Tk and HDL cholesterol. In multiple regression analysis the association with LDL and HDL was strengthened, though these two variables as a whole accounted for only 5% (adjusted R2) of the variability of plasma viscosity. Blood viscosity was significantly associated with haematocrit, plasma viscosity, Tk and all considered variables but age in simple correlation analysis, but only with haematocrit, plasma viscosity and Tk in multiple regression analysis. LDL cholesterol and HDL cholesterol influence plasma viscosity, but not blood viscosity. Triglycerides up to values of 400 mg/dl do not seem to have important effects, at least in apparently healthy subjects and at the shear rates used in the present study. The contribution of LDL and HDL cholesterol to plasma viscosity seems however quite limited.

  9. Reference Correlation for the Viscosity of Ethane

    Energy Technology Data Exchange (ETDEWEB)

    Vogel, Eckhard, E-mail: [Institut für Chemie, Universität Rostock, D-18059 Rostock (Germany); Span, Roland [Lehrstuhl für Thermodynamik, Ruhr-Universität Bochum, D-44780 Bochum (Germany); Herrmann, Sebastian [Fachgebiet Technische Thermodynamik, Hochschule Zittau/Görlitz, D-02763 Zittau (Germany)


    A new representation of the viscosity for the fluid phase of ethane includes a zero-density correlation and a contribution for the critical enhancement, initially both developed separately, but based on experimental data. The higher-density contributions are correlated as a function of the reduced density δ = ρ/ρ{sub c} and of the reciprocal reduced temperature τ = T{sub c}/T (ρ{sub c}—critical density and T{sub c}—critical temperature). The final formulation contains 14 coefficients obtained using a state-of-the-art linear optimization algorithm. The evaluation and choice of the selected primary data sets is reviewed, in particular with respect to the assessment used in earlier viscosity correlations. The new viscosity surface correlation makes use of the reference equation of state for the thermodynamic properties of ethane by Bücker and Wagner [J. Phys. Chem. Ref. Data 35, 205 (2006)] and is valid in the fluid region from the melting line to temperatures of 675 K and pressures of 100 MPa. The viscosity in the limit of zero density is described with an expanded uncertainty of 0.5% (coverage factor k = 2) for temperatures 290 < T/K < 625, increasing to 1.0% at temperatures down to 212 K. The uncertainty of the correlated values is 1.5% in the range 290 < T/K < 430 at pressures up to 30 MPa on the basis of recent measurements judged to be very reliable as well as 4.0% and 6.0% in further regions. The uncertainty in the near-critical region (1.001 < 1/τ < 1.010 and 0.8 < δ < 1.2) increases with decreasing temperature up to 3.0% considering the available reliable data. Tables of the viscosity calculated from the correlation are listed in an appendix for the single-phase region, for the vapor–liquid phase boundary, and for the near-critical region.

  10. Human sperm swimming in a high viscosity mucus analogue. (United States)

    Ishimoto, Kenta; Gadêlha, Hermes; Gaffney, Eamonn A; Smith, David J; Kirkman-Brown, Jackson


    Remarkably, mammalian sperm maintain a substantive proportion of their progressive swimming speed within highly viscous fluids, including those of the female reproductive tract. Here, we analyse the digital microscopy of a human sperm swimming in a highly viscous, weakly elastic mucus analogue. We exploit principal component analysis to simplify its flagellar beat pattern, from which boundary element calculations are used to determine the time-dependent flow field around the sperm cell. The sperm flow field is further approximated in terms of regularized point forces, and estimates of the mechanical power consumption are determined, for comparison with analogous low viscosity media studies. This highlights extensive differences in the structure of the flows surrounding human sperm in different media, indicating how the cell-cell and cell-boundary hydrodynamic interactions significantly differ with the physical microenvironment. The regularized point force decomposition also provides cell-level information that may ultimately be incorporated into sperm population models. We further observe indications that the core feature in explaining the effectiveness of sperm swimming in high viscosity media is the loss of cell yawing, which is related with a greater density of regularized point force singularities along the axis of symmetry of the flagellar beat to represent the flow field. In turn this implicates a reduction of the wavelength of the distal beat pattern - and hence dynamical wavelength selection of the flagellar beat - as the dominant feature governing the effectiveness of sperm swimming in highly viscous media. Copyright © 2018. Published by Elsevier Ltd.

  11. Measurement of viscosity of liquids using optical tweezers (United States)

    Statsenko, Anna; Inami, Wataru; Kawata, Yoshimasa


    We propose a method for measuring viscosities of unknown liquids by using optical tweezers combined with optical microscopy. We trapped 1- μm particles in water-glycerin mixtures and analyzed the dependence of the motion on viscosity. Based on our calibration with various water-glycerin mixtures, we propose a method for determination of viscosities of unknown liquids with high accuracy. We discuss how the method can be applied to measure the viscosity of liquids that are available only in small quantities. This non-invasive method of studying viscosities could be especially applicable in investigations of biological samples.

  12. Viscosity as related to dietary fiber: a review. (United States)

    Dikeman, Cheryl L; Fahey, George C


    Viscosity is a physicochemical property associated with dietary fibers, particularly soluble dietary fibers. Viscous dietary fibers thicken when mixed with fluids and include polysaccharides such as gums, pectins, psyllium, and beta-glucans. Although insoluble fiber particles may affect viscosity measurement, viscosity is not an issue regards insoluble dietary fibers. Viscous fibers have been credited for beneficial physiological responses in human, animal, and animal-alternative in vitro models. The following article provides a review of viscosity as related to dietary fiber including definitions and instrumentation, factors affecting viscosity of solutions, and effects of viscous polysaccharides on glycemic response, blood lipid attenuation, intestinal enzymatic activity, digestibility, and laxation.

  13. Effect of ceramic membrane channel diameter on limiting retentate protein concentration during skim milk microfiltration. (United States)

    Adams, Michael C; Barbano, David M


    Our objective was to determine the effect of retentate flow channel diameter (4 or 6mm) of nongraded permeability 100-nm pore size ceramic membranes operated in nonuniform transmembrane pressure mode on the limiting retentate protein concentration (LRPC) while microfiltering (MF) skim milk at a temperature of 50°C, a flux of 55 kg · m(-2) · h(-1), and an average cross-flow velocity of 7 m · s(-1). At the above conditions, the retentate true protein concentration was incrementally increased from 7 to 11.5%. When temperature, flux, and average cross-flow velocity were controlled, ceramic membrane retentate flow channel diameter did not affect the LRPC. This indicates that LRPC is not a function of the Reynolds number. Computational fluid dynamics data, which indicated that both membranes had similar radial velocity profiles within their retentate flow channels, supported this finding. Membranes with 6-mm flow channels can be operated at a lower pressure decrease from membrane inlet to membrane outlet (ΔP) or at a higher cross-flow velocity, depending on which is controlled, than membranes with 4-mm flow channels. This implies that 6-mm membranes could achieve a higher LRPC than 4-mm membranes at the same ΔP due to an increase in cross-flow velocity. In theory, the higher LRPC of the 6-mm membranes could facilitate 95% serum protein removal in 2 MF stages with diafiltration between stages if no serum protein were rejected by the membrane. At the same flux, retentate protein concentration, and average cross-flow velocity, 4-mm membranes require 21% more energy to remove a given amount of permeate than 6-mm membranes, despite the lower surface area of the 6-mm membranes. Equations to predict skim milk MF retentate viscosity as a function of protein concentration and temperature are provided. Retentate viscosity, retentate recirculation pump frequency required to maintain a given cross-flow velocity at a given retentate viscosity, and retentate protein

  14. Viscosity of Hg(0.84)Zn(0.16)Te Pseudobinary Melt (United States)

    Mazuruk, K.; Su, Ching-Hua; Sha, Yi-Gao; Lehoczky, S. L.


    An oscillating-cup viscometer was developed to measure viscosity of molten HgZnTe ternary semiconductor alloys. Data were collected for the pseudobinary Hg(0.84)Zn(0.16)Te melt between 770 and 850 C. The kinematic viscosity was found to vary from approximately 1.1 to 1.4 x 10(sup -3)sq cm/s. A slow relaxation phenomena was also observed for temperatures from the melting point of 770 to approx. 800 C. Possible mechanisms for this effect are discussed.

  15. Imaging tumor microscopic viscosity in vivo using molecular rotors (United States)

    Shimolina, Lyubov’ E.; Izquierdo, Maria Angeles; López-Duarte, Ismael; Bull, James A.; Shirmanova, Marina V.; Klapshina, Larisa G.; Zagaynova, Elena V.; Kuimova, Marina K.


    The microscopic viscosity plays an essential role in cellular biophysics by controlling the rates of diffusion and bimolecular reactions within the cell interior. While several approaches have emerged that have allowed the measurement of viscosity and diffusion on a single cell level in vitro, the in vivo viscosity monitoring has not yet been realized. Here we report the use of fluorescent molecular rotors in combination with Fluorescence Lifetime Imaging Microscopy (FLIM) to image microscopic viscosity in vivo, both on a single cell level and in connecting tissues of subcutaneous tumors in mice. We find that viscosities recorded from single tumor cells in vivo correlate well with the in vitro values from the same cancer cell line. Importantly, our new method allows both imaging and dynamic monitoring of viscosity changes in real time in live animals and thus it is particularly suitable for diagnostics and monitoring of the progress of treatments that might be accompanied by changes in microscopic viscosity. PMID:28134273

  16. [Effect of high-intensity alternating magnetic field 
on viscosity of sheep blood]. (United States)

    Tao, Pengxian; Wu, Xiangyang; Zhao, Lingzhi; Wang, Feng; Xia, Qi; Peng, Yan; Gao, Bingren


    To explore the changes of blood viscosity in high-intensity alternating magnetic field and the mechanisms.
 Methods: Five adult sheep were randomly selected and the blood samples were placed in high-intensity alternating magnetic field. Before and after exposure, the blood samples were taken and divided into 2 groups: a control group and a magnetic field group. The blood rheology and transmission electron microscopy (TEM) were performed.
 Results: Compared to the control group, the high shear viscosity of whole blood was decreased in the magnetic field group (P<0.05); the whole blood low shear viscosity and plasma viscosity were also decreased (both P<0.01). TEM showed the changes in red blood cell morphology and the double concave disc curvature. The radian of double concave disc and cell volume in the magnetic field group was larger than those in the control group.
 Conclusion: The high intensity alternating magnetic field may affect the distribution of surface charge and molecular current in blood cells, which in turn decrease the aggregation of cells and the blood viscosity.

  17. A MEMS Resonant Sensor to Measure Fluid Density and Viscosity under Flexural and Torsional Vibrating Modes. (United States)

    Zhao, Libo; Hu, Yingjie; Wang, Tongdong; Ding, Jianjun; Liu, Xixiang; Zhao, Yulong; Jiang, Zhuangde


    Methods to calculate fluid density and viscosity using a micro-cantilever and based on the resonance principle were put forward. Their measuring mechanisms were analyzed and the theoretical equations to calculate the density and viscosity were deduced. The fluid-solid coupling simulations were completed for the micro-cantilevers with different shapes. The sensing chips with micro-cantilevers were designed based on the simulation results and fabricated using the micro electromechanical systems (MEMS) technology. Finally, the MEMS resonant sensor was packaged with the sensing chip to measure the densities and viscosities of eight different fluids under the flexural and torsional vibrating modes separately. The relative errors of the measured densities from 600 kg/m³ to 900 kg/m³ and viscosities from 200 μPa·s to 1000 μPa·s were calculated and analyzed with different microcantilevers under various vibrating modes. The experimental results showed that the effects of the shape and vibrating mode of micro-cantilever on the measurement accuracies of fluid density and viscosity were analyzed in detail.

  18. A MEMS Resonant Sensor to Measure Fluid Density and Viscosity under Flexural and Torsional Vibrating Modes

    Directory of Open Access Journals (Sweden)

    Libo Zhao


    Full Text Available Methods to calculate fluid density and viscosity using a micro-cantilever and based on the resonance principle were put forward. Their measuring mechanisms were analyzed and the theoretical equations to calculate the density and viscosity were deduced. The fluid-solid coupling simulations were completed for the micro-cantilevers with different shapes. The sensing chips with micro-cantilevers were designed based on the simulation results and fabricated using the micro electromechanical systems (MEMS technology. Finally, the MEMS resonant sensor was packaged with the sensing chip to measure the densities and viscosities of eight different fluids under the flexural and torsional vibrating modes separately. The relative errors of the measured densities from 600 kg/m3 to 900 kg/m3 and viscosities from 200 μPa·s to 1000 μPa·s were calculated and analyzed with different microcantilevers under various vibrating modes. The experimental results showed that the effects of the shape and vibrating mode of micro-cantilever on the measurement accuracies of fluid density and viscosity were analyzed in detail.

  19. Shear viscosity of two-flavor inhomogenous color superconducting quark matter (United States)

    Sarkar, Sreemoyee; Sharma, Rishi


    We present the first calculation of the shear viscosity for two-flavor plane wave (FF) color superconducting quark matter. This is a member of the family of crystalline color superconducting phases of dense quark matter that may be present in the cores of neutron stars. The paired quarks in the FF phase feature gapless excitations on surfaces of crescent-shaped blocking regions in momentum space and participate in transport. We calculate their contribution to the shear viscosity. We also note that the transverse t1 , t2, t3 gluons which are undamped in the 2SC lead to dynamic screening in the FF phase. The exchange of these gluons is the most important mechanism of the scattering of the paired quarks. We find that the shear viscosity of the paired quarks is roughly a factor of 100 smaller compared to the shear viscosity of unpaired quark matter even though their spectrum is ungapped. Therefore in the two-flavor FF phase, the unpaired quarks and the electrons give the shear viscosity of the two-flavor FF phase to a very good approximation. Our results may have implications for the damping of r -modes in rapidly rotating, cold neutron stars.

  20. Radionuclide Retention in Concrete Wasteforms

    Energy Technology Data Exchange (ETDEWEB)

    Wellman, Dawn M.; Jansik, Danielle P.; Golovich, Elizabeth C.; Cordova, Elsa A.


    Assessing long-term performance of Category 3 waste cement grouts for radionuclide encasement requires knowledge of the radionuclide-cement interactions and mechanisms of retention (i.e., sorption or precipitation); the mechanism of contaminant release; the significance of contaminant release pathways; how wasteform performance is affected by the full range of environmental conditions within the disposal facility; the process of wasteform aging under conditions that are representative of processes occurring in response to changing environmental conditions within the disposal facility; the effect of wasteform aging on chemical, physical, and radiological properties; and the associated impact on contaminant release. This knowledge will enable accurate prediction of radionuclide fate when the wasteforms come in contact with groundwater. Data collected throughout the course of this work will be used to quantify the efficacy of concrete wasteforms, similar to those used in the disposal of LLW and MLLW, for the immobilization of key radionuclides (i.e., uranium, technetium, and iodine). Data collected will also be used to quantify the physical and chemical properties of the concrete affecting radionuclide retention.

  1. Idiosyncrasies of volcanic sulfur viscosity and the triggering of unheralded volcanic eruptions (United States)

    Scolamacchia, Teresa; Cronin, Shane


    Unheralded "blue-sky" eruptions from dormant volcanoes cause serious fatalities, such as at Mt. Ontake (Japan) on 27 September 2014. Could these events result from magmatic gas being trapped within hydrothermal system aquifers by elemental sulfur (Se) clogging pores, due to sharp increases in its viscosity when heated above 159oC? This mechanism was thought to prime unheralded eruptions at Mt. Ruapehu in New Zealand. Impurities in sulfur (As, Te, Se) are known to modify S-viscosity and industry experiments showed that organic compounds, H2S, and halogens dramatically influence Se viscosity under typical hydrothermal heating/cooling rates and temperature thresholds. However, the effects of complex sulfur compositions are currently ignored at volcanoes, despite its near ubiquity in long-lived volcano-hydrothermal systems. Models of impure S behavior must be urgently formulated to detect pre-eruptive warning signs before the next "blue-sky" eruption

  2. Superrotation of Earth’s Inner Core, Extraterrestrial Impacts, and the Effective Viscosity of Outer Core

    Directory of Open Access Journals (Sweden)

    Pirooz Mohazzabi


    Full Text Available The recently verified superrotation of Earth’s inner core is examined and a new model is presented which is based on the tidal despinning of the mantle and the viscosity of the outer core. The model also takes into account other damping mechanisms arising from the inner core superrotation such as magnetic and gravitational coupling as well as contribution from eddy viscosity in the outer core. The effective viscosity obtained in this model confirms a previously well constrained value of about 103 Pa s. In addition, the model shows that the currently measured superrotation of the inner core must be almost exactly equal to its asymptotic or steady-state value. The effect of extraterrestrial impacts is also investigated, and it is shown that perturbations due to such impacts can only persist over a short geological time.

  3. Meningitis retention syndrome

    Directory of Open Access Journals (Sweden)

    Abhishek Krishna


    Full Text Available A 50-year-old Caucasian woman presented with signs and symptoms of meningitis preceded by a 3 day history of flu-like symptoms and progressive difficulty with urination. Cerebrospinal Fluid (CSF analysis was consistent with aseptic meningitis. She was found to have a significant urinary retention secondary to atonic bladder. MRI of the brain and spine were normal and CSF-PCR (polymerase chain reaction was positive for HSV-2. Urinary retention in the context of meningitis and CSF pleocytosis is known as Meningitis Retention Syndrome (MRS. MRS is a rare but important complication of meningitis most commonly associated with HSV-2. Involvement of central pathways may have a role in the pathogenesis of MRS but this is poorly documented. MRS is different from Elsberg syndrome wherein patients display features of lumbosacral polyradiculitis or radiculomyelitis. Early treatment with antiviral therapy was associated with a favorable outcome in our patient.

  4. Retention in the Golgi apparatus and expression on the cell surface of Cfr/Esl-1/Glg-1/MG-160 are regulated by two distinct mechanisms. (United States)

    Miyaoka, Yuichiro; Kato, Hidenori; Ebato, Kazuki; Saito, Shigeru; Miyata, Naoko; Imamura, Toru; Miyajima, Atsushi


    Cfr (cysteine-rich fibroblast growth factor receptor) is an Fgf (fibroblast growth factor)-binding protein without a tyrosine kinase. We have shown previously that Cfr is involved in Fgf18 signalling via Fgf receptor 3c. However, as Cfr is also known as Glg (Golgi apparatus protein)-1 or MG-160 and occurs in the Golgi apparatus, it remains unknown how the distribution of Cfr is regulated. In the present study, we performed a mutagenic analysis of Cfr to show that two distinct regions contribute to its distribution and stability. First, the C-terminal region retains Cfr in the Golgi apparatus. Secondly, the Cfr repeats in the extracellular juxtamembrane region destabilizes Cfr passed through the Golgi apparatus. This destabilization does not depend on the cleavage and secretion of the extracellular domain of Cfr. Furthermore, we found that Cfr with a GPI (glycosylphosphatidylinositol) anchor was predominantly expressed on the cell surface in Ba/F3 cells and affected Fgf18 signalling in a similar manner to the full-length Cfr, indicating that the interaction of Cfr with Fgfs on the cell surface is important for its function in Fgf signalling. These results suggest that the expression of Cfr in the Golgi apparatus and on the plasma membrane is finely tuned through two distinct mechanisms for exhibiting different functions.

  5. Influence of sodium chloride and pH during acidic marination on water retention and mechanical properties of turkey breast meat. (United States)

    Goli, T; Ricci, J; Bohuon, P; Marchesseau, S; Collignan, A


    Turkey breast cubes underwent acidic marination in the presence of salt. The transfer of water, salt and acid was measured, and texture was assessed on the cooked meat. While significant mass gains were observed during marination, from 20 minutes of immersion onwards, only long durations produced an overall matter balance greater than that of non-marinated meat. From the first minutes of immersion, these transfers caused hardening, regardless of the presence of salt in the marinade. For longer durations, only in the absence of salt was significant tenderizing seen in comparison to the non-marinated control. This effect appears to be due on the one hand to passing the isoelectric pH of the meat during acidification, and on the other hand to setting up antagonistic mechanisms breaking down or reinforcing connective tissues by acid and salt respectively. The high degree of tenderization observed in a water-acid solution can be explained partly by dilution of the fiber load per section unit due to protein solubilization. © 2013. Published by Elsevier Ltd on behalf of The American Meat Science Association. All rights reserved.

  6. The effects of fluid viscosity on the kinematics and material properties of C. elegans swimming at low Reynolds number

    CERN Document Server

    Sznitman, Josue; Purohit, Prashant K; Arratia, Paulo E


    The effects of fluid viscosity on the kinematics of a small swimmer at low Reynolds number are investigated in both experiments and in a simple model. The swimmer is the nematode Caenorhabditis elegans, which is an undulating roundworm approximately 1 mm long. Experiments show that the nematode maintains a highly periodic swimming behavior as the fluid viscosity is varied from 1.0 mPa-s to 12 mPa-s. Surprisingly, the nematode's swimming speed (~0.35 mm/s) is nearly insensitive to the range of fluid viscosities investigated here. However, the nematode's beating frequency decreases to an asymptotic value (~1.7 Hz) with increasing fluid viscosity. A simple model is used to estimate the nematode's Young's modulus and tissue viscosity. Both material properties increase with increasing fluid viscosity. It is proposed that the increase in Young's modulus may be associated with muscle contraction in response to larger mechanical loading while the increase in effective tissue viscosity may be associated with the energ...

  7. Relative influence of composition and viscosity of acrylic bone cement on its apparent fracture toughness. (United States)

    Lewis, G


    The composition and viscosity of an acrylic bone cement have both been identified in the literature as being parameters that affect the mechanical properties of the material and, by extension, the in vivo longevity of cemented arthroplasties. The objective of the present study was to determine the relative influence of these parameters on a key cement mechanical property; namely, its fracture toughness. Two sets of cements were selected purposefully to allow the study objective to be achieved. Thus, one set comprised two cements with very similar compositions but very different viscosities (Cemex RX, a medium-viscosity brand, and Cemex Isoplastic, a high-viscosity brand) while the other set comprised two cements with similar viscosities but with many differences in composition (Cemex Isoplastic and CMW 1). Values of the fracture toughness (as determined using chevron-notched short rod specimens) [K(ISR)] obtained for Cemex RX and Cemex Isoplastic were 1.83 +/- 0.12 and 1.85 +/- 0.12 MPa square root(m), respectively, with the difference not being statistically significant. The K(ISR) values obtained for Cemex Isoplastic and CMW 1 were 1.85 +/- 0.12 and 1.64 +/- 0.18 MPa square root(m), respectively, with the difference being statistically significant. Thus, the influence of cement composition on its K(ISR) is more marked relative to the influence of cement viscosity. Explanations of this finding are offered, together with comments on the implications of the results for the in vivo longevity of cemented arthroplasties.

  8. From Suitable Weak Solutions to Entropy Viscosity

    KAUST Repository

    Guermond, Jean-Luc


    This paper focuses on the notion of suitable weak solutions for the three-dimensional incompressible Navier-Stokes equations and discusses the relevance of this notion to Computational Fluid Dynamics. The purpose of the paper is twofold (i) to recall basic mathematical properties of the three-dimensional incompressible Navier-Stokes equations and to show how they might relate to LES (ii) to introduce an entropy viscosity technique based on the notion of suitable weak solution and to illustrate numerically this concept. © 2010 Springer Science+Business Media, LLC.

  9. Viscosity: From air to hot nuclei

    Indian Academy of Sciences (India)

    physician and physiologist, who studied non-turbulent flow of liquids through pipes, such as blood flow in capillaries and veins: 1 P = 0.1 Pa s = 1 g/(cm s), 1 cP = 1 mPa s. = 0.001 Pa s. The values of viscosity are different for various substances: 0.02 cP for air at 18. ◦. C, 1 cP for water at 20. ◦. C, 2000–10000 cP for honey, ...

  10. Temperature dependence effect of viscosity on ultrathin lubricant film melting

    Directory of Open Access Journals (Sweden)



    Full Text Available We study the melting of an ultrathin lubricant film under friction between atomically flat surfaces at temperature dependencies of viscosity described by Vogel-Fulcher relationship and by power expression, which are observed experimentally. It is shown that the critical temperature exists in both cases the exceeding of which leads to the melting of lubricant and, as a result, the sliding mode of friction sets in. The values of characteristic parameters of lubricant are defined, which are needed for friction reduction. In the systems, where the Vogel-Fulcher dependence is fulfilled, it is possible to choose the parameters at which the melting of lubricant takes place even at zero temperature of friction surfaces. The deformational defect of the shear modulus is taken into account in describing the lubricant melting according to the mechanism of the first-order transition.

  11. Viscosity bound violation in holographic solids and the viscoelastic response

    Energy Technology Data Exchange (ETDEWEB)

    Alberte, Lasma [Abdus Salam International Centre for Theoretical Physics (ICTP),Strada Costiera 11, 34151, Trieste (Italy); Baggioli, Matteo [Institut de Física d’Altes Energies (IFAE),The Barcelona Institute of Science and Technology (BIST),Campus UAB, 08193 Bellaterra, Barcelona (Spain); Department of Physics, Institute for Condensed Matter Theory, University of Illinois,1110 W. Green Street, Urbana, IL 61801 (United States); Pujolàs, Oriol [Institut de Física d’Altes Energies (IFAE),The Barcelona Institute of Science and Technology (BIST),Campus UAB, 08193 Bellaterra, Barcelona (Spain)


    We argue that the Kovtun-Son-Starinets (KSS) lower bound on the viscosity to entropy density ratio holds in fluid systems but is violated in solid materials with a non-zero shear elastic modulus. We construct explicit examples of this by applying the standard gauge/gravity duality methods to massive gravity and show that the KSS bound is clearly violated in black brane solutions whenever the massive gravity theories are of solid type. We argue that the physical reason for the bound violation relies on the viscoelastic nature of the mechanical response in these materials. We speculate on whether any real-world materials can violate the bound and discuss a possible generalization of the bound that involves the ratio of the shear elastic modulus to the pressure.

  12. Viscosity bound violation in holographic solids and the viscoelastic response (United States)

    Alberte, Lasma; Baggioli, Matteo; Pujolàs, Oriol


    We argue that the Kovtun-Son-Starinets (KSS) lower bound on the viscosity to entropy density ratio holds in fluid systems but is violated in solid materials with a nonzero shear elastic modulus. We construct explicit examples of this by applying the standard gauge/gravity duality methods to massive gravity and show that the KSS bound is clearly violated in black brane solutions whenever the massive gravity theories are of solid type. We argue that the physical reason for the bound violation relies on the viscoelastic nature of the mechanical response in these materials. We speculate on whether any real-world materials can violate the bound and discuss a possible generalization of the bound that involves the ratio of the shear elastic modulus to the pressure.

  13. Urea encapsulation in modified starch matrix for nutrients retention (United States)

    Naz, Muhammad Yasin; Sulaiman, Shaharin Anwar; Ariff, Mohd. Hazwan Bin Mohd.; Ariwahjoedi, Bambang


    It has been estimated that 20-70% of the used urea goes to the environment via leaching, nitrification and volatilization which not only harms the environment but also reduces the urea efficiency. By coating the urea granules, the farmers can achieve high urea performance through controlling the excess release of nitrogen. Up until now, different materials have been tested for nutrients retention. However, most of them are either expensive or unfriendly to the environment. Being cheap and biodegradable materials, the starches may also be used to coat the urea fertilizer for controlling the nutrients release. However, the pure starches do not meet the standards set by many industrial processes due to their slow tacking and too low viscosities and should be modified for getting smooth, compact and mechanically stronger coatings. In these studies, the tapioca starch was modified by reacting it with urea and different masses of borax. The prepared solutions were used to coat the urea granules of 3.45 mm average diameter. Different volumes (1, 1.5 and 2 mL) of each solution were used to coat 30 g of urea fluidized above the minimum level of fluidization. It was noticed that the coating thickness, percent coating, dissolution rate and percent release follow an increasing trend with an increase of solution volume; however, some random results were obtained while investigating the solution volume effects on the percent release. It was seen that the nutrients percent release over time increases with an increase in solution volume from 1 to 1.5 mL and thereafter reaches to a steady state. It confirms that the 1.5 mL of solution for 30 g urea samples will give the optimized coating results.

  14. Viscosity dependent dual-permeability modeling of liquid manure movement in layered, macroporous, tile drained soil (United States)

    Frey, Steven K.; Rudolph, David L.; Lapen, David R.; Ball Coelho, Bonnie R.


    A scarcity of information exists on how physical processes govern the movement of liquid manure, or other viscous fluids, through layered macroporous soils. To elucidate these complex flow and transport phenomena, a viscosity dependent, two-dimensional dual-permeability model that considers macropore anisotropy is employed to simulate field experiments where liquid swine manure (LSM) was applied to silt loam with both a soil crust and plowpan layer present. Using data from the field experiment as a benchmark, the model was used to predict nutrient (NH4-N and total P) breakthrough to tile drains; and to assess the influence of reduced permeability crust and plowpan layers, and fluid viscosity, on solute movement within 48 h of LSM application. Results demonstrate the importance of viscosity on flow and transport in macroporous soils. By increasing LSM viscosity, nutrient breakthrough to tile drains can be greatly reduced, and near surface nutrient retention can increase. The presence of a nonmacroporous soil crust layer can also lead to reduced nutrient concentrations in tile discharge by reducing pressure heads in the underlying A-horizon soil matrix, resulting in reduced macropore flow; whereas a low permeability plowpan layer at the base of the A horizon can increase pressure heads in the A-horizon soil matrix and lead to increased macropore flow. Multiple target point parameter sensitivity analysis revealed that relative parameter sensitivity can be a transient characteristic, and that hydraulic properties of the A and B horizon tend to exhibit their greatest influence over the respective early and late time solute breakthrough characteristics.

  15. Improving College Freshman Retention (United States)

    Yu, Winnie Y.


    In recent years, access to higher education was greatly improved through public funding. This improvement is not matched by a similar increase in graduation rate. The purpose of this study is to examine what postsecondary institutions can do to improve college freshman retention. The conceptual framework was based on research on college student…

  16. Employment Retention Policy


    Fox, E; Stafford, B.


    This Report investigates the potential for a statutory model of employment retention leave. A Private Members Bill (HC Bill 2006-07) [79] currently in progress through Parliament would, if enacted, offer disabled employees the right to paid leave for employment assessment, rehabilitation or re-training.

  17. Tritium retention in TFTR

    Energy Technology Data Exchange (ETDEWEB)

    Dylla, H.F.; Wilson, K.L. (eds.)


    This report discusses the materials physics related to D-T operation in TFTR. Research activities are described pertaining to basic studies of hydrogenic retention in graphite, hydrogen recycling phenomena, first-wall and limiter conditioning, surface analysis of TFTR first-wall components, and estimates of the tritium inventory.

  18. Shear viscosity and out of equilibrium dynamics

    CERN Document Server

    El, Andrej; Xu, Zhe; Greiner, Carsten


    Using the Grad's method we calculate the entropy production and derive a formula for the second order shear viscosity coefficient in a one-dimensionally expanding particle system, which can also be considered out of chemical equilibrium. For a one-dimensional expansion of gluon matter with Bjorken boost invariance the shear tensor and the shear viscosity to entropy density ratio $\\eta/s$ are numerically calculated by an iterative and self-consistent prescription within the second order Israel-Stewart hydrodynamics and by a microscopic parton cascade transport theory. Compared with $\\eta/s$ obtained using the Navier-Stokes approximation, the present result is about 20% larger at a QCD coupling $\\alpha_s \\sim 0.3$(with $\\eta/s\\approx 0.18$) and is a factor of 2-3 larger at a small coupling $\\alpha_s \\sim 0.01$. We demonstrate an agreement between the viscous hydrodynamic calculations and the microscopic transport results on $\\eta/s$, except when employing a small $\\alpha_s$. On the other hand, we demonstrate th...

  19. Shear viscosity and out of equilibrium dynamics

    CERN Document Server

    El, Andrej; Xu, Zhe; Greiner, Carsten


    Using Grad’s method, we calculate the entropy production and derive a formula for the second-order shear viscosity coefficient in a one-dimensionally expanding particle system, which can also be considered out of chemical equilibrium. For a one-dimensional expansion of gluon matter with Bjorken boost invariance, the shear tensor and the shear viscosity to entropy density ratio η/s are numerically calculated by an iterative and self-consistent prescription within the second-order Israel-Stewart hydrodynamics and by a microscopic parton cascade transport theory. Compared with η/s obtained using the Navier-Stokes approximation, the present result is about 20% larger at a QCD coupling αs ∼ 0.3 (with η/s ≈ 0.18) and is a factor of 2–3 larger at a small coupling αs ∼ 0.01. We demonstrate an agreement between the viscous hydrodynamic calculations and the microscopic transport results on η/s, except when employing a small αs . On the other hand, we demonstrate that for such small αs , the gluon syst...

  20. Predicting human blood viscosity in silico

    Energy Technology Data Exchange (ETDEWEB)

    Fedosov, Dmitry A. [Inst. of Complex Systems and Inst. for Advanced Simulation, Julich (Germany); Brown Univ., Providence, RI (United States); Pan, Wenxiao [Brown Univ., Providence, RI (United States); Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Caswell, Bruce [Brown Univ., Providence, RI (United States); Gompper, Gerhard [Inst. of Complex Systems and Inst. for Advanced Simulation, Julich (Germany); Karniadakis, George E. [Brown Univ., Providence, RI (United States)


    Cellular suspensions such as blood are a part of living organisms and their rheological and flow characteristics determine and affect majority of vital functions. The rheological and flow properties of cell suspensions are determined by collective dynamics of cells, their structure or arrangement, cell properties and interactions. We study these relations for blood in silico using a mesoscopic particle-based method and two different models (multi-scale/low-dimensional) of red blood cells. The models yield accurate quantitative predictions of the dependence of blood viscosity on shear rate and hematocrit. We explicitly model cell aggregation interactions and demonstrate the formation of reversible rouleaux structures resulting in a tremendous increase of blood viscosity at low shear rates and yield stress, in agreement with experiments. The non-Newtonian behavior of such cell suspensions (e.g., shear thinning, yield stress) is analyzed and related to the suspension’s microstructure, deformation and dynamics of single cells. We provide the flrst quantitative estimates of normal stress differences and magnitude of aggregation forces in blood. Finally, the flexibility of the cell models allows them to be employed for quantitative analysis of a much wider class of complex fluids including cell, capsule, and vesicle suspensions.

  1. Textural perception of liquid emulsions: Role of oil content, oil viscosity and emulsion viscosity

    NARCIS (Netherlands)

    Aken, van G.A.; Vingerhoeds, M.H.; Wijk, de R.A.


    This work describes a study on the in-mouth textural perception of thickened liquid oil-in-water emulsions. The variables studied are oil content, oil viscosity, and the concentration of polysaccharide thickener. Gum arabic was chosen as the thickener because of the nearly Newtonian behavior of its

  2. Stellar irradiated discs and implications on migration of embedded planets. III. Viscosity transitions (United States)

    Bitsch, Bertram; Morbidelli, Alessandro; Lega, Elena; Kretke, Katherine; Crida, Aurélien


    Context. The migration strength and direction of embedded low-mass planets depends on the disc structure. In discs with an efficient radiative transport, the migration can be directed outwards for planets with more than 3-5 Earth masses. This is due to the entropy-driven corotation torque, a process that extends the lifetimes of growing planetary embryos. However, smaller mass planets are still migrating inwards and might be lost to the central star. Aims: We investigate the influence on the disc structure caused by a jump in the α parameter of the viscosity to model a dead-zone structure in the disc. We focus on Ṁ discs, which have a constant net mass flux. Using the resulting disc structure, we investigate the consequences for the formation of planetesimals and determine the regions of outward migration for proto-planets. Methods: We performed numerical hydrosimulations of Ṁ discs in the r - z-plane. We used the explicit/implicit hydrodynamical code FARGOCA that includes a full tensor viscosity and stellar irradiation as well as a two-temperature solver that includes radiation transport in the flux-limited diffusion approximation. The migration of embedded planets was studied by using torque formulae. Results: Viscosity transitions inside the disc create transitions in density that stop inward migration for small planets through the so-called "planet trap" mechanism. This mechanism also works for planets down to MP > 0.5 MEarth, while in radiative discs with no viscosity transition the lowest mass with which inward migration can be avoided is 3-5 Earth masses. Additionally, the viscosity transitions change the pressure gradient in the disc, which facilitates planetesimal formation via the streaming instability. However, a very steep transition in viscosity is needed to achieve in a pressure bump in the disc. Conclusions: The transition in viscosity facilitates planetesimal formation and can stop the migration of small-mass planets (MP > 0.5 MEarth), but

  3. Retention of Emergency Care Knowledge. (United States)

    Burckes, Mardie E.; Shao, Kung Ping Pam


    Data on the emergency care knowledge of college students were measured by a pretest, posttest, and retention test. A high relationship was found between students' posttest scores and retention test scores. Findings are discussed. (Author/DF)

  4. Designing a customer retention plan. (United States)

    DeSouza, G


    What is your company's customer retention rate? How many customers are price defectors? Have you identified barriers that prevent customers from switching to a competitor? In this article, the author outlines a game plan to increase customer retention.

  5. phosphorus retention data and metadata (United States)

    U.S. Environmental Protection Agency — phosphorus retention in wetlands data and metadata. This dataset is associated with the following publication: Lane , C., and B. Autrey. Phosphorus retention of...

  6. Modeling the viscosity of silicate melts containing manganese oxide

    Directory of Open Access Journals (Sweden)

    Kim Wan-Yi


    Full Text Available Our recently developed model for the viscosity of silicate melts is applied to describe and predict the viscosities of oxide melts containing manganese oxide. The model requires three pairs of adjustable parameters that describe the viscosities in three systems: pure MnO, MnO-SiO2 and MnO-Al2O3-SiO2. The viscosity of other ternary and multicomponent silicate melts containing MnO is then predicted by the model without any additional adjustable model parameters. Experimental viscosity data are reviewed for melts formed by MnO with SiO2, Al2O3, CaO, MgO, PbO, Na2O and K2O. The deviation of the available experimental data from the viscosities predicted by the model is shown to be within experimental error limits.

  7. Viscosity Control of Protein Solution by Small Solutes: A Review. (United States)

    Hong, Taehun; Iwashita, Kazuki; Shiraki, Kentaro


    Viscosity of protein solution is one of the most troublesome issues for the high-concentration formulation of protein drugs. In this review, we summarize the practical methods that suppress the viscosity of protein solution using small molecular additives. The small amount of salts decreases the viscosity that results from electrostatic repulsion and attraction. The chaotrope suppresses the hydrophobic attraction and cluster formation, which can lower the solution viscosity. Arginine hydrochloride (ArgHCl) also suppresses the solution viscosity due to the hydrophobic and aromatic interactions between protein molecules. The small molecular additives are the simplest resolution of the high viscosity of protein solution as well as understanding of the primary cause in complex phenomena of protein interactions. Copyright© Bentham Science Publishers; For any queries, please email at

  8. Synthesis of high-strength microcrystalline cellulose hydrogel by viscosity adjustment. (United States)

    Choe, Deokyeong; Kim, Young Min; Nam, Jae Eun; Nam, Keonwook; Shin, Chul Soo; Roh, Young Hoon


    Developing hydrogels with enhanced mechanical strength is desirable for bio-related applications. For such applications, cellulose is a notable biopolymer for hydrogel synthesis due to its inherent strength and stiffness. Here, we report the viscosity-adjusted synthesis of a high-strength hydrogel through the physical entanglement of microcrystalline cellulose (MCC) in a solvent mixture of tetrabutylammonium fluoride/dimethyl sulfoxide (TBAF/DMSO). MCC was strategically dissolved with TBAF in DMSO at a controlled ratio to induce the formation of a liquid crystalline phase (LCP), which was closely related to the viscosity of the cellulose solution. The highest viscosity was obtained at 2.5% MCC and 3.5% TBAF, leading to the strongest high-strength MCC hydrogel (strongest HS-MCC hydrogel). The resulting hydrogel exhibited a high compressive strength of 0.38MPa and a densely packed structure. Consequently, a positive linear correlation was determined between the viscosity of the cellulose solution and the mechanical strength of the HS-MCC hydrogel. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Non-invasive fluid density and viscosity measurement (United States)

    Sinha, Dipen N [Los Alamos, NM


    The noninvasively measurement of the density and viscosity of static or flowing fluids in a section of pipe such that the pipe performs as the sensing apparatus, is described. Measurement of a suitable structural vibration resonance frequency of the pipe and the width of this resonance permits the density and viscosity to be determined, respectively. The viscosity may also be measured by monitoring the decay in time of a vibration resonance in the pipe.

  10. Impact of Viscosity on Filling the Injection Mould Cavity

    Directory of Open Access Journals (Sweden)

    Satin Lukáš


    Full Text Available The aim of this paper is to look closer at the rheological properties of plastics and their impact on technology in the plastics processing industry. The paper focuses on the influence of viscosity of the material on filling the mould cavity. Four materials were tested with the settings of process parameters with different viscosity. Using simulation software of Moldex3D, we can see the effect of change in viscosity in the material to be filled.

  11. "Coulombic Viscosity" In Granular Materials: Planetary and Astrophysical Implications (United States)

    Marshall, J. R.


    The term "Coulombic viscosity" is introduced here to define an empirically observed phenomenon from experiments conducted in both microgravity, and in ground-based 1-g conditions. In the latter case, a sand attrition device was employed to test the longevity of aeolian materials by creating two intersecting grain-circulation paths or cells that would lead to most of the grain energy being expended on grain-to-grain collisions (simulating dune systems). In the areas in the device where gravitationally-driven grain-slurries recycled the sand, the slurries moved with a boundary-layer impeded motion down the chamber walls. Excessive electrostatic charging of the grains during these experiments was prevented by the use of an a.c. corona (created by a Tesla coil) through which the grains passed on every cycle. This created both positive and negative ions which neutralized the triboelectrically-generated grain charges. When the corona was switched on, the velocity of the wall-attached slurries increased by a factor of two as approximately determined by direct observation. What appeared to be a freely-flowing slurry of grains impeded only by intergranular mechanical friction, had obviously been significantly retarded in its motion by electrostatic forces between the grains; with the charging reduced, the grains were able to move past one another without a flow "viscosity" imposed by the Coulombic intergranular forces. A similar phenomenon was observed during microgravity experiments aboard Space Shuttle in USML-1 & USML-2 spacelabs where freely-suspended clouds of sand were being investigated for their potential to for-m aggregates. In this environment, the grains were also charged electrostatically (by natural processes prior to flight), but were free from the intervention of gravity in their interactions. The grains were dispersed into dense clouds by bursts of air turbulence and allowed to form aggregates as the ballistic and turbulent motions damped out. During this

  12. Journals as retention mechanisms of scientific growth

    NARCIS (Netherlands)

    Leydesdorff, L.


    Professor Loet Leydesdorff has spent the last 20 years developing an idea first posed by Derek de Solla Price in 1961. He asks whether the aggregated citation relations among journals can be used to study clusters of journals as representations of the intellectual organization of the sciences.

  13. Effect of temperature on the viscosities of mixed micellar solutions (United States)

    Prasad, C. Durga; Kumar, D. Sudheer; Sarma, G. V. S.; Ramesh, K. V.


    The effect of addition of Triton X-100 (TX-100) on the viscosities of Sodium dodecyl sulphate (SDS) micellar solution containingNaCl and Cetyltrimethylammonium bromide (CTAB) micellar solution containingKBr at various temperatures are presented. The viscosity of SDS micellar solution is found to increase on addition of TX-100 at all temperatures (25 to 45 °C). However the increase in viscosity is large up to certain % of TX-100, after that the increase in viscosity is found to be small. Where as in CTAB micelles, at lower temperatures, the viscosity of micellar solution decreased up to certain composition of TX-100 and with further addition of TX-100 the viscosity got increaed. At higher temperatures viscosity of CTAB micellar solution increased on addition of TX-100. Depending on the nature of surfactant system and temperature, the viscosity of micellar solution may increase or decrease on addition of TX-100. The thermodynamic parameters for the viscous flow of micellar solutions in the presence of TX-100 are also determined. The effect of TX-100 on the viscosity and the activation enthalpy for viscous flow of anionic micelles is tremendously large as compared to cationic micelles. This is due to transition of micellar shape from rod to elongated rod or to sphere in the presence of added TX-100.

  14. Viscosity Prediction of Hydrocarbon Mixtures Based on the Friction Theory

    DEFF Research Database (Denmark)

    Zeberg-Mikkelsen, Claus Kjær; Cisneros, Sergio; Stenby, Erling Halfdan


    The application and capability of the friction theory (f-theory) for viscosity predictions of hydrocarbon fluids is further illustrated by predicting the viscosity of binary and ternary liquid mixtures composed of n-alkanes ranging from n-pentane to n-decane for wide ranges of temperature and from...... low to high pressures. In the f-theory viscosity predictions the SRK and the PRSV EOS have respectively been used. Further, a comparison with the widely used LBC viscosity model shows that better results are obtained with the f-theory models. The obtained AAD% is within or close to the experimental...

  15. Elongational viscosity of narrow molar mass distribution polystyrene

    DEFF Research Database (Denmark)

    Bach, Anders; Almdal, Kristoffer; Rasmussen, Henrik Koblitz


    above the linear viscoelastic prediction at intermediate strains, indicating strain hardening. The steady elongational viscosities are monotone decreasing functions of elongation rate. At elongation rates larger than the inverse reptation time, the steady elongational viscosity scales linearly......Transient and steady elongational viscosity has been measured for two narrow molar mass distribution polystyrene melts of molar masses 200 000 and 390 000 by means of a filament stretching rheometer. Total Hencky strains of about five have been obtained. The transient elongational viscosity rises...... with molar mass at fixed elongation rate....

  16. Fluorescence-based Broad Dynamic Range Viscosity Probes. (United States)

    Dragan, Anatoliy; Graham, August E; Geddes, Chris D


    We introduce two new fluorescent viscosity probes, SYBR Green (SG) and PicoGreen (PG), that we have studied over a broad range of viscosity and in collagen solutions. In water, both dyes have low quantum yields and excited state lifetimes, while in viscous solvents or in complex with DNA both parameters dramatically (300-1000-fold) increase. We show that in log-log scale the dependence of the dyes' quantum yield vs. viscosity is linear, the slope of which is sensitive to temperature. Application of SG and PG, as a fluorescence-based broad dynamic range viscosity probes, to the life sciences is discussed.

  17. Viscosity of Heterogeneous Silicate Melts: A Non-Newtonian Model (United States)

    Liu, Zhuangzhuang; Blanpain, Bart; Guo, Muxing


    The recently published viscosity data of heterogeneous silicate melts with well-documented structure and experimental conditions are critically re-analyzed and tabulated. By using these data, a non-Newtonian viscosity model incorporating solid fraction, solid shape, and shear rate is proposed on the basis of the power-law equation. This model allows calculating the viscosity of the heterogeneous silicate melts with solid fraction up to 34 vol pct. The error between the calculated and measured data is evaluated to be 32 pct, which is acceptable considering the large error in viscosity measurement of the completely liquid silicate melt.

  18. Enhancing retention of partial dentures using elastomeric retention rings

    Directory of Open Access Journals (Sweden)

    Kakkirala Revathi


    Full Text Available This report presents an alternative method for the retention of partial dentures that relies on the engagement of tooth undercuts by a lining material. The lab procedures are also presented. A new maxillary and mandibular acrylic partial dentures were fabricated using elastomeric retention technique for a partially dentate patient. A partially dentate man reported difficulty in retaining his upper removable partial denture (RPD. The maxillary RPD was designed utilizing elastomeric retention technique. During follow-up, it was necessary to replace the retention rings due to wear. The replacement of the retention rings, in this case, was done through a chairside reline technique. Elastomeric retention technique provides exceptionally good retention can be indicated to stabilize, cushion, splint periodontally involved teeth, no enough undercut for clasps, eliminate extractions, single or isolated teeth.

  19. Holographic bulk viscosity: GPR vs EO

    CERN Document Server

    Buchel, Alex; Kiritsis, Elias


    Recently Eling and Oz (EO) proposed a formula for the holographic bulk viscosity, in arXiv:1103.1657, derived from the null horizon focusing equation. This formula seems different from that obtained earlier by Gubser, Pufu and Rocha (GPR) in arXiv:0806.0407 calculated from the IR limit of the two-point function of the trace of the stress tensor. The two were shown to agree only for some simple scaling cases. We point out that the two formulae agree in two non-trivial holographic theories describing RG flows. The first is the strongly coupled N=2* gauge theory plasma. The second is the semi-phenomenological model of Improved Holographic QCD.

  20. Stress relaxation and creep experiments with the atomic force microscope: a unified method to calculate elastic moduli and viscosities of biomaterials (and cells)

    CERN Document Server

    Moreno-Flores, Susana; Vivanco, Maria dM; Toca-Herrera, Jose Luis


    We show that the atomic force microscope can perform stress relaxation and creep compliance measurements on living cells. We propose a method to obtain the mechanical properties of the studied biomaterial: the relaxation time, the elastic moduli and the viscosity.

  1. Control of the Fluid Viscosity in a Mock Circulation. (United States)

    Boës, Stefan; Ochsner, Gregor; Amacher, Raffael; Petrou, Anastasios; Meboldt, Mirko; Schmid Daners, Marianne


    A mock circulation allows the in vitro investigation, development, and testing of ventricular assist devices. An aqueous-glycerol solution is commonly used to mimic the viscosity of blood. Due to evaporation and temperature changes, the viscosity of the solution drifts from its initial value and therefore, deviates substantially from the targeted viscosity of blood. Additionally, the solution needs to be exchanged to account for changing viscosities when mimicking different hematocrits. This article presents a method to control the viscosity in a mock circulation. This method makes use of the relationship between temperature and viscosity of aqueous-glycerol solutions and employs the automatic control of the viscosity of the fluid. To that end, an existing mock circulation was extended with an industrial viscometer, temperature probes, and a heating nozzle band. The results obtained with different fluid viscosities show that a viscosity controller is vital for repeatable experimental conditions on mock circulations. With a mixture ratio of 49 mass percent of aqueous-glycerol solution, the controller can mimic a viscosity range corresponding to a hematocrit between 29 and 42% in a temperature range of 30-42°C. The control response has no overshoot and the settling time is 8.4 min for a viscosity step of 0.3 cP, equivalent to a hematocrit step of 3.6%. Two rotary blood pumps that are in clinical use are tested at different viscosities. At a flow rate of 5 L/min, both show a deviation of roughly 15 and 10% in motor current for high rotor speeds. The influence of different viscosities on the measured head pressure is negligible. Viscosity control for a mock circulation thus plays an important role for assessing the required motor current of ventricular assist devices. For the investigation of the power consumption of rotary blood pumps and the development of flow estimators where the motor current is a model input, an integrated viscosity controller is a valuable

  2. The effect of viscosity, friction, and sonication on the morphology and metabolite production from Aspergillus terreus ATCC 20542. (United States)

    Rahim, Muhamad Hafiz Abd; Hasan, Hanan; Harith, Hanis H; Abbas, Ali


    This study investigates the effects of viscosity, friction, and sonication on the morphology and the production of lovastatin, (+)-geodin, and sulochrin by Aspergillus terreus ATCC 20542. Sodium alginate and gelatine were used to protect the fungal pellet from mechanical force by increasing the media viscosity. Sodium alginate stimulated the production of lovastatin by up to 329.0% and sulochrin by 128.7%, with inhibitory effect on (+)-geodin production at all concentrations used. However, the use of gelatine to increase viscosity significantly suppressed lovastatin, (+)-geodin, and sulochrin's production (maximum reduction at day 9 of 42.7, 60.8, and 68.3%, respectively), which indicated that the types of chemical play a major role in metabolite production. Higher viscosity increased both pellet biomass and size in all conditions. Friction significantly increased (+)-geodin's titre by 1527.5%, lovastatin by 511.1%, and sulochrin by 784.4% while reducing pellet biomass and size. Conversely, sonication produced disperse filamentous morphology with significantly lower metabolites. Sodium alginate-induced lovastatin and sulochrin production suggest that these metabolites are not affected by viscosity; rather, their production is affected by the specific action of certain chemicals. In contrast, low viscosity adversely affected (+)-geodin's production, while pellet disintegration can cause a significant production of (+)-geodin.

  3. Association among low whole blood viscosity, haematocrit, haemoglobin and diabetic retinopathy in subjects with type 2 diabetes. (United States)

    Irace, C; Scarinci, F; Scorcia, V; Bruzzichessi, D; Fiorentino, R; Randazzo, G; Scorcia, G; Gnasso, A


    Haemorheological variables influence endothelial function through the release of several factors. Clinical studies have described an association among blood viscosity, haematocrit, haemoglobin and macro-angiopathy. Few data are reported about the association between haemorheological variables and micro-angiopathy. The aim of the present study was to evaluate the association between these variables and retinopathy in subjects with type 2 diabetes. 111 men, 79 postmenopausal women, and 95 healthy age- and sex-matched controls were recruited. Haematocrit and haemoglobin were measured by standard methods. Blood viscosity was calculated according to the formula (0.12× haematocrit)+(0.17× (plasma proteins-2.07)). Subjects were grouped according to the presence or absence of diabetic retinopathy, while the severity of retinopathy was classified according to the Early Treatment Diabetic Retinopathy Study scale. Haemoglobin, haematocrit and whole blood viscosity were significantly lower in subjects with retinopathy compared to subjects without retinopathy in both sexes. These variables significantly decreased with increasing severity of retinopathy. A multiple logistic regression analysis confirmed the independent inverse association among viscosity, haematocrit, haemoglobin and retinopathy (p<0.01). Results demonstrate the association among low viscosity, haemoglobin, haematocrit and diabetic retinopathy. The mechanisms responsible for this association can be hypothesised. Reduced haemoglobin might cause direct organ damage. Low blood viscosity, through the reduction of shear stress, might inhibit the anti-atherogenic functions of endothelial cells.

  4. The role of meal viscosity and oat β-glucan characteristics in human appetite control: a randomized crossover trial. (United States)

    Rebello, Candida J; Chu, Yi-Fang; Johnson, William D; Martin, Corby K; Han, Hongmei; Bordenave, Nicolas; Shi, Yuhui; O'Shea, Marianne; Greenway, Frank L


    Foods that enhance satiety can help consumers to resist environmental cues to eat, and improve the nutritional quality of their diets. Viscosity generated by oat β-glucan, influences gastrointestinal mechanisms that mediate satiety. Differences in the source, processing treatments, and interactions with other constituents in the food matrix affect the amount, solubility, molecular weight, and structure of the β-glucan in products, which in turn influences the viscosity. This study examined the effect of two types of oatmeal and an oat-based ready-to-eat breakfast cereal (RTEC) on appetite, and assessed differences in meal viscosity and β-glucan characteristics among the cereals. Forty-eight individuals were enrolled in a randomized crossover trial. Subjects consumed isocaloric breakfast meals containing instant oatmeal (IO), old-fashioned oatmeal (SO) or RTEC in random order at least a week apart. Each breakfast meal contained 218 kcal (150 kcal cereal, and 68 kcal milk) Visual analogue scales measuring appetite were completed before breakfast, and over four hours, following the meal. Starch digestion kinetics, meal viscosities, and β-glucan characteristics for each meal were determined. Appetite responses were analyzed by area under the curve. Mixed models were used to analyze response changes over time. IO increased fullness (p = 0.04), suppressed desire to eat (p = 0.01) and reduced prospective intake (p viscosity, and larger hydration spheres than the RTEC, and IO had greater viscosity after oral and initial gastric digestion (initial viscosity) than the RTEC. IO and SO improved appetite control over four hours compared to RTEC. Initial viscosity of oatmeal may be especially important for reducing appetite.

  5. Near Wellbore Hydraulic Fracture Propagation from Perforations in Tight Rocks: The Roles of Fracturing Fluid Viscosity and Injection Rate

    Directory of Open Access Journals (Sweden)

    Seyed Hassan Fallahzadeh


    Full Text Available Hydraulic fracture initiation and near wellbore propagation is governed by complex failure mechanisms, especially in cased perforated wellbores. Various parameters affect such mechanisms, including fracturing fluid viscosity and injection rate. In this study, three different fracturing fluids with viscosities ranging from 20 to 600 Pa.s were used to investigate the effects of varying fracturing fluid viscosities and fluid injection rates on the fracturing mechanisms. Hydraulic fracturing tests were conducted in cased perforated boreholes made in tight 150 mm synthetic cubic samples. A true tri-axial stress cell was used to simulate real far field stress conditions. In addition, dimensional analyses were performed to correspond the results of lab experiments to field-scale operations. The results indicated that by increasing the fracturing fluid viscosity and injection rate, the fracturing energy increased, and consequently, higher fracturing pressures were observed. However, when the fracturing energy was transferred to a borehole at a faster rate, the fracture initiation angle also increased. This resulted in more curved fracture planes. Accordingly, a new parameter, called fracturing power, was introduced to relate fracture geometry to fluid viscosity and injection rate. Furthermore, it was observed that the presence of casing in the wellbore impacted the stress distribution around the casing in such a way that the fracture propagation deviated from the wellbore vicinity.

  6. Optovibrometry: tracking changes in the surface tension and viscosity of multicomponent droplets in real-time. (United States)

    Harrold, Victoria C; Sharp, James S


    An instrument was developed for measuring real time changes in the surface tension and viscosity of multicomponent droplets of miscible liquids and other soft materials. Droplets containing glycerol and water were supported on superamphiphobic surfaces and vibrated by applying a short mechanical impulse. Laser light was refracted through the droplets and allowed to fall on the surface of a photodiode. Time dependent variations in the intensity measured by the photodiode during vibration were used to monitor the decay of the droplet oscillations. The frequencies and spectral widths of the droplet vibrational resonances were then obtained from Fourier transforms of these time dependent intensity signals. A recently developed model of viscoelastic droplet vibration was used along with these values and measurements of the drop dimensions to extract the surface tension and viscosity of the drops as they evaporated. Collection of data was automated and values of frequency, spectral width, drop size, surface tension and viscosity were obtained with a time resolution of three seconds over a period of thirty minutes. The values of surface tension and viscosity obtained were shown to be in good agreement with literature values obtained from bulk glycerol/water solutions; thus validating the technique for wider application to other multicomponent liquids and soft matter systems.

  7. Pulsatile flow of blood and heat transfer with variable viscosity under magnetic and vibration environment

    Energy Technology Data Exchange (ETDEWEB)

    Shit, G.C., E-mail:; Majee, Sreeparna


    Unsteady flow of blood and heat transfer characteristics in the neighborhood of an overlapping constricted artery have been investigated in the presence of magnetic field and whole body vibration. The laminar flow of blood is taken to be incompressible and Newtonian fluid with variable viscosity depending upon temperature with an aim to provide resemblance to the real situation in the physiological system. The unsteady flow mechanism in the constricted artery is subjected to a pulsatile pressure gradient arising from systematic functioning of the heart and from the periodic body acceleration. The numerical computation has been performed using finite difference method by developing Crank–Nicolson scheme. The results show that the volumetric flow rate, skin-friction and the rate of heat transfer at the wall are significantly altered in the downstream of the constricted region. The axial velocity profile, temperature and flow rate increases with increase in temperature dependent viscosity, while the opposite trend is observed in the case of skin-friction and flow impedance. - Highlights: • We have investigated the pulsatile MHD flow of blood and heat transfer in arteries. • The influence of periodic body acceleration has been taken into account. • The temperature dependent viscosity of blood is considered. • The variable viscosity has an increasing effect on blood flow and heat transfer. • The overall temperature distribution enhances in the presence of magnetic field.

  8. Liposomal internal viscosity affects the fate of membrane deformation induced by hypertonic treatment. (United States)

    Fujiwara, Kei; Yanagisawa, Miho


    Artificial lipid membranes have been utilized to understand the physical mechanisms of the deformation patterns of live cells. However, typical artificial membrane systems contain only dilute components compared to those in the cytoplasm of live cells. By using giant unilamellar liposomes containing dense protein solutions similar to those in live cells, we here reveal that viscosity derived from internal crowding affects the deformation patterns of lipid membranes. After hypertonic treatment, liposome deformation patterns transitioned from budding to tubing when the initial internal macromolecular concentrations were increased. Remarkably, instead of observing different transition concentrations between two species of macromolecules, the viscosity at the transition concentration was found to be similar. Further analyses clearly demonstrated that the internal viscosity affects the deformation patterns of lipid membranes induced by hypertonic treatment. These results indicate that the viscosity of the cytoplasm is a key factor in determining cell deformation, and suggest the association of a process involving dynamic instability, such as a viscous fingering phenomenon, during the determination of deformation patterns by hypertonic treatment.

  9. Can More Nanoparticles Induce Larger Viscosities of Nanoparticle-Enhanced Wormlike Micellar System (NEWMS)? (United States)

    Zhao, Mingwei; Zhang, Yue; Zou, Chenwei; Dai, Caili; Gao, Mingwei; Li, Yuyang; Lv, Wenjiao; Jiang, Jianfeng; Wu, Yining


    There have been many reports about the thickening ability of nanoparticles on the wormlike micelles in the recent years. Through the addition of nanoparticles, the viscosity of wormlike micelles can be increased. There still exists a doubt: can viscosity be increased further by adding more nanoparticles? To answer this issue, in this work, the effects of silica nanoparticles and temperature on the nanoparticles-enhanced wormlike micellar system (NEWMS) were studied. The typical wormlike micelles (wormlike micelles) are prepared by 50 mM cetyltrimethyl ammonium bromide (CTAB) and 60 mM sodium salicylate (NaSal). The rheological results show the increase of viscoelasticity in NEWMS by adding nanoparticles, with the increase of zero-shear viscosity and relaxation time. However, with the further increase of nanoparticles, an interesting phenomenon appears. The zero-shear viscosity and relaxation time reach the maximum and begin to decrease. The results show a slight increasing trend for the contour length of wormlike micelles by adding nanoparticles, while no obvious effect on the entanglement and mesh size. In addition, with the increase of temperature, remarkable reduction of contour length and relaxation time can be observed from the calculation. NEWMS constantly retain better viscoelasticity compared with conventional wormlike micelles without silica nanoparticles. According to the Arrhenius equation, the activation energy Ea shows the same increase trend of NEWMS. Finally, a mechanism is proposed to explain this interesting phenomenon.

  10. Viscosity and Morphology Modification of Length Sorted Single-Walled Carbon Nanotubes in PIB Matrices

    Directory of Open Access Journals (Sweden)

    Hanxiao Huang


    Full Text Available This work evaluates the effectiveness of nanoscale particulates in producing non-Einstein-like responses in polymer matrices, to reduce their negative effects in low shear rate processing. This is of value to material processing applications which encompass extrusion, flow into cold mold, and generalized processing of nanocomposites. Through control and understanding of the structure processing relationships entailed through nanoscale additive materials, we begin to manage dispersion characteristics for more reliable and defect-free product development. In pursuit of identifying system characteristics that produce non-Einstein-like responses we isolate and characterize homogenous fractions of single-walled carbon nanotubes (SWNTs with singular lengths. This enables the definition of a well-defined nanoscale particulate phase, within the polymer matrices. The effect of nanotube length and weight fraction on the polyisobutylene (PIB matrices was evaluated with thermal and rheological testing. Our findings show that the viscosity of the produced nanocomposite systems has a length dependence and does not demonstrate the expected monotonous increases in the viscosity with an increase in weight fraction of nanotube additive within the matrix, demonstrating a non-Einstein-like viscosity response. Furthermore, we demonstrate length dependent crystallization in the studied systems, as an intermediate length nanotube initiates crystallization of polyisobutylene (PIB affecting viscosity and mechanical properties.

  11. Evaluation of Relative Blood Viscosity During Menstruation in ...

    African Journals Online (AJOL)


    ABSTRACT. The changes in blood viscosity, plasma viscosity, haematocrit and erythrocyte sedimentation rate before ... Blood samples were collected during two ..... Gynaecol., 91(7): 685–. 690. Logan, P. and Carolyn, C.(1997).Take Your. Choice. Counterbalance: Gendered. Perspectives on Writing and Language. Pp. 41.

  12. On-line measurement of food viscosity during flow

    DEFF Research Database (Denmark)

    Mason, Sarah Louise; Friis, Alan


    Sarah L. Mason and Alan Friis discuss some of the principles and equipment used to monitor food viscosity in real time.......Sarah L. Mason and Alan Friis discuss some of the principles and equipment used to monitor food viscosity in real time....

  13. The relationship between plasma viscosity and Body Mass Index in ...

    African Journals Online (AJOL)

    Plasma viscosity is one of the most important rheological parameters for assessing the health status of an individual. It is influenced by diseases with alteration in plasma protein composition and previous studies have shown that the viscosity of plasma is affected by various factors which includes body weight, fibrinogen ...

  14. Viscosity of liquids theory, estimation, experiment, and data

    CERN Document Server

    Viswanath, Dabir S; Prasad, Dasika HL; Dutt, Nidamarty VK; Rani, Kalipatnapu Y


    Single comprehensive book on viscosity of liquids, as opposed to most of the books in this area which are data books, i.e., a compilation of viscosity data from the literature, where the information is scattered and the description and analysis of the experimental methods and governing theory are not readily available in a single place.

  15. Nonlinear Eddy Viscosity Models applied to Wind Turbine Wakes

    DEFF Research Database (Denmark)

    Laan, van der, Paul Maarten; Sørensen, Niels N.; Réthoré, Pierre-Elouan


    The linear k−ε eddy viscosity model and modified versions of two existing nonlinear eddy viscosity models are applied to single wind turbine wake simulations using a Reynolds Averaged Navier-Stokes code. Results are compared with field wake measurements. The nonlinear models give better results...

  16. Effective viscosity of dispersions approached by a statistical continuum method

    NARCIS (Netherlands)

    Mellema, J.; Willemse, M.W.M.


    The problem of the determination of the effective viscosity of disperse systems (emulsions, suspensions) is considered. On the basis of the formal solution of the equations governing creeping flow in a statistically homogeneous dispersion, the effective viscosity is expressed in a series expansion

  17. Relook on fitting of viscosity with undercooling of glassy liquids

    Indian Academy of Sciences (India)

    The present approach is on the modification of viscosity fitting of undercooled liquid as a function of undercooling. The method consists of finding analytical solution of three arbitrary constants of the Vogel–Fulcher–Tamman (VFT) equation by choosing three viscosity data at three critical temperatures for an undercooled ...

  18. Evaluation of Relative Blood Viscosity During Menstruation in ...

    African Journals Online (AJOL)

    The changes in blood viscosity, plasma viscosity, haematocrit and erythrocyte sedimentation rate before and during menstruation were evaluated. Forty (40) apparently healthy reproductive female subjects (between 15 and 28 years) and resident in Benin City, Edo State, Nigeria were used for the study. The parameters ...

  19. Elongational viscosity of monodisperse and bidisperse polystyrene melts

    DEFF Research Database (Denmark)

    Nielsen, Jens Kromann; Rasmussen, Henrik K.; Hassager, Ole


    The start-up and steady uniaxial elongational viscosity have been measured for two monodisperse polystyrene melts with molecular weights of 52 and 103 kg/mole, and for three bidisperse polystyrene melts. The monodisperse melts show a maximum in the steady elongational viscosity vs. the elongational...

  20. Effect of viscosity on appetite and gastro-intestinal hormones

    NARCIS (Netherlands)

    Zijlstra, N.; Mars, M.; Wijk, de R.A.; Westerterp-Plantenga, M.S.; Holst, J.J.; Graaf, de C.


    In previous studies we showed that higher viscosity resulted in lower ad libitum intake and that eating rate is an important factor. In this study we aimed to explore the effect of viscosity on the gastro-intestinal hormones ghrelin, CCK-8 and GLP-1. Thirty-two subjects (22 ± 2 y, BMI 21.9 ± 2.2

  1. Effect of viscosity on droplet-droplet collisional interaction

    NARCIS (Netherlands)

    Finotello, Giulia; Padding, J.T.; Deen, Niels G.; Jongsma, Alfred; Innings, Fredrik; Kuipers, J.A.M.


    A complete knowledge of the effect of droplet viscosity on droplet-droplet collision outcomes is essential for industrial processes such as spray drying. When droplets with dispersed solids are dried, the apparent viscosity of the dispersed phase increases by many orders of magnitude, which

  2. Poiseuille flow to measure the viscosity of particle model fluids.

    NARCIS (Netherlands)

    Backer, J.A.; Lowe, C.P.; Hoefsloot, H.C.J.; Iedema, P.D.


    The most important property of a fluid is its viscosity, it determines the flow properties. If one simulates a fluid using a particle model, calculating the viscosity accurately is difficult because it is a collective property. In this article we describe a new method that has a better signal to

  3. A Riemann problem with small viscosity and dispersion

    Directory of Open Access Journals (Sweden)

    Kayyunnapara Thomas Joseph


    Full Text Available In this paper we prove existence of global solutions to a hyperbolic system in elastodynamics, with small viscosity and dispersion terms and derive estimates uniform in the viscosity-dispersion parameters. By passing to the limit, we prove the existence of solution the Riemann problem for the hyperbolic system with arbitrary Riemann data.

  4. Bulk viscosity, interaction and the viability of phantom solutions

    CERN Document Server

    Leyva, Yoelsy


    We study the dynamics of a bulk viscosity model in the Eckart approach for a spatially flat Friedmann-Robertson-Walker (FRW) universe. We have included radiation and dark energy, assumed as perfect fluids, and dark matter treated as an imperfect fluid having bulk viscosity. We also introduce an interaction term between the dark matter and dark energy components. Considering that the bulk viscosity is proportional to the dark matter energy density and imposing a complete cosmological dynamics, we find bounds on the bulk viscosity in order to reproduce a matter-dominated era (MDE). This constraint is independent of the interaction term. Some late time phantom solutions are mathematically possible. However, the constraint imposed by a MDE restricts the interaction parameter, in the phantom solutions, to a region consistent with a null value, eliminating the possibility of late time stable solutions with $w<-1$. From the different cases that we study, the only possible scenario, with bulk viscosity and interac...

  5. Viscosity Prediction of Natural Gas Using the Friction Theory

    DEFF Research Database (Denmark)

    Zeberg-Mikkelsen, Claus Kjær; Cisneros, Sergio; Stenby, Erling Halfdan


    Based on the concepts of the friction theory (f-theory) for viscosity modeling, a procedure is introduced for predicting the viscosity of hydrocarbon mixtures rich in one component, which is the case for natural gases. In this procedure, the mixture friction coefficients are estimated with mixing...... rules based on the values of the pure component friction coefficients. Since natural gases contain mainly methane, two f-theory models are combined, where the friction coefficients of methane are estimated by a seven-constant f-theory model directly fitted to methane viscosities, and the friction...... coefficients of the other components are estimated by the one-parameter general f-theory model. The viscosity predictions are performed with the SRK, the PR, and the PRSV equations of state, respectively. For recently measured viscosities of natural gases, the resultant AAD (0.5 to 0.8%) is in excellent...

  6. Influence of Functional Groups on the Viscosity of Organic Aerosol. (United States)

    Rothfuss, Nicholas E; Petters, Markus D


    Organic aerosols can exist in highly viscous or glassy phase states. A viscosity database for organic compounds with atmospherically relevant functional groups is compiled and analyzed to quantify the influence of number and location of functional groups on viscosity. For weakly functionalized compounds the trend in viscosity sensitivity to functional group addition is carboxylic acid (COOH) ≈ hydroxyl (OH) > nitrate (ONO2) > carbonyl (CO) ≈ ester (COO) > methylene (CH2). Sensitivities to group addition increase with greater levels of prior functionalization and decreasing temperature. For carboxylic acids a sharp increase in sensitivity is likely present already at the second addition at room temperature. Ring structures increase viscosity relative to linear structures. Sensitivities are correlated with analogously derived sensitivities of vapor pressure reduction. This may be exploited in the future to predict viscosity in numerical models by piggybacking on schemes that track the evolution of organic aerosol volatility with age.

  7. Study on lubricating oil characteristics using viscosity index

    Energy Technology Data Exchange (ETDEWEB)

    Suwanprateep, T.

    The objective of this research is to investigate the characteristics of lubricating oil sold in the market by using viscosity index. The lubricating oil of both single grade and multigrade of some trade names for gasoline engines and one without trade name are used in the test and the viscosity index is determined for each type. The test shows that every type of lubricating oil with trade name has viscosity index of more than 100, the highest standard value, and the multigrade oil has more viscosity index than the single grade oil. The oil without trade name has viscosity index rather low and therefore is not suitable for lubrication over a wide range of working temperature, such as in gasoline engines.

  8. Measurement and correlation of jet fuel viscosities at low temperatures (United States)

    Schruben, D. L.


    Apparatus and procedures were developed to measure jet fuel viscosity for eight current and future jet fuels at temperatures from ambient to near -60 C by shear viscometry. Viscosity data showed good reproducibility even at temperatures a few degrees below the measured freezing point. The viscosity-temperature relationship could be correlated by two linear segments when plotted as a standard log-log type representation (ASTM D 341). At high temperatures, the viscosity-temperature slope is low. At low temperatures, where wax precipitation is significant, the slope is higher. The breakpoint between temperature regions is the filter flow temperature, a fuel characteristic approximated by the freezing point. A generalization of the representation for the eight experimental fuels provided a predictive correlation for low-temperature viscosity, considered sufficiently accurate for many design or performance calculations.

  9. Measuring Solution Viscosity and its Effect on Enzyme Activity

    Directory of Open Access Journals (Sweden)

    Uribe Salvador


    Full Text Available In proteins, some processes require conformational changes involving structural domain diffusion. Among these processes are protein folding, unfolding and enzyme catalysis. During catalysis some enzymes undergo large conformational changes as they progress through the catalytic cycle. According to Kramers theory, solvent viscosity results in friction against proteins in solution, and this should result in decreased motion, inhibiting catalysis in motile enzymes. Solution viscosity was increased by adding increasing concentrations of glycerol, sucrose and trehalose, resulting in a decrease in the reaction rate of the H+-ATPase from the plasma membrane of Kluyveromyces lactis. A direct correlation was found between viscosity (&eegr; and the inhibition of the maximum rate of catalysis (V max. The protocol used to measure viscosity by means of a falling ball type viscometer is described, together with the determination of enzyme kinetics and the application of Kramers’ equation to evaluate the effect of viscosity on the rate of ATP hydrolysis by the H+-ATPase.

  10. Bulk viscosity of spin-one color superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Sa' d, Basil A.


    The bulk viscosity of several quark matter phases is calculated. It is found that the effect of color superconductivity is not trivial, it may suppress, or enhance the bulk viscosity depending on the critical temperature and the temperature at which the bulk viscosity is calculated. Also, is it found that the effect of neutrino-emitting Urca processes cannot be neglected in the consideration of the bulk viscosity of strange quark matter. The results for the bulk viscosity of strange quark matter are used to calculate the r-mode instability window of quark stars with several possible phases. It is shown that each possible phase has a different structure for the r-mode instability window. (orig.)

  11. Integrated Solvent Design for CO2 Capture and Viscosity Tuning

    Energy Technology Data Exchange (ETDEWEB)

    Cantu Cantu, David; Malhotra, Deepika; Koech, Phillip K.; Heldebrant, David J.; Zheng, Feng; Freeman, Charles J.; Rousseau, Roger J.; Glezakou, Vassiliki-Alexandra


    We present novel design strategies for reduced viscosity single-component, water-lean CO2 capture organic solvent systems. Through molecular simulation, we identify the main molecular-level descriptor that influences bulk solvent viscosity. Upon loading, a zwitterionic structure forms with a small activation energy of ca 16 kJ/mol and a small stabilization of ca 6 kJ/mol. Viscosity increases exponentially with CO2 loading due to hydrogen-bonding between neighboring Zwitterions. We find that molecular structures that promote internal hydrogen bonding (within the same molecule) and suppress interactions with neighboring molecules have low viscosities. In addition, tuning the acid/base properties leads to a shift of the equilibrium toward a non-charged (acid) form that further reduces the viscosity. Based on the above structural criteria, a reduced order model is also presented that allows for the quick screening of large compound libraries and down selection of promising candidates for synthesis and testing.

  12. Effects of fluid viscosity on a moving sonoluminescing bubble. (United States)

    Sadighi-Bonabi, Rasoul; Mirheydari, Mona; Rezaee, Nastaran; Ebrahimi, Homa


    Based on the quasi-adiabatic model, the parameters of the bubble interior for a moving single bubble sonoluminescence in water, adiponitrile, and N-methylformamide are calculated for various fluid viscosities. By using a complete form of the hydrodynamic force, the bubble trajectory is calculated for a moving single bubble sonoluminescence (m-SBSL). It is found that as the fluid viscosity increases, the unique circular path changes to an ellipsoidal and then linear form and along this incrementally increase of viscosity the light intensity increases. By using the Bremsstrahlung model to describe the bubble radiation, gradual increase of the viscosity results in brighter emissions. It is found that in fluids with higher viscosity the light intensity decreases as time passes.

  13. Comparison and experimental validation of two potential resonant viscosity sensors in the kilohertz range (United States)

    Lemaire, Etienne; Heinisch, Martin; Caillard, Benjamin; Jakoby, Bernhard; Dufour, Isabelle


    Oscillating microstructures are well established and find application in many fields. These include force sensors, e.g. AFM micro-cantilevers or accelerometers based on resonant suspended plates. This contribution presents two vibrating mechanical structures acting as force sensors in liquid media in order to measure hydrodynamic interactions. Rectangular cross section microcantilevers as well as circular cross section wires are investigated. Each structure features specific benefits, which are discussed in detail. Furthermore, their mechanical parameters and their deflection in liquids are characterized. Finally, an inverse analytical model is applied to calculate the complex viscosity near the resonant frequency for both types of structures. With this approach it is possible to determine rheological parameters in the kilohertz range in situ within a few seconds. The monitoring of the complex viscosity of yogurt during the fermentation process is used as a proof of concept to qualify at least one of the two sensors in opaque mixtures.

  14. Variation of the apparent viscosity of thickened drinks. (United States)

    O'Leary, Mark; Hanson, Ben; Smith, Christina H


    In dysphagia care, thickening powders are widely added to drinks to slow their flow speed by increasing their viscosity. Current practice relies on subjective evaluation of viscosity using verbal descriptors. Several brands of thickener are available, with differences in constituent ingredients and instructions for use. Some thickened fluids have previously been shown to exhibit time-varying non-Newtonian flow behaviour, which may complicate attempts at subjective viscosity judgement. The aims were to quantify the apparent viscosity over time produced by thickeners having a range of constituent ingredients, and to relate the results to clinical practice. A comparative evaluation of currently available thickener products, including two which have recently been reformulated, was performed. Their subjective compliance to the National Descriptors standards was assessed, and their apparent viscosity was measured using a rheometer at shear rates representative of situations from slow tipping in a beaker (0.1 s⁻¹) to a fast swallow (100 s⁻¹). Testing was performed repeatedly up to 3 h from mixing. When mixed with water, it was found that most products compared well with subjective National Descriptors at three thickness levels. The fluids were all highly non-Newtonian; their apparent viscosity was strongly dependent on the rate of testing, typically decreasing by a factor of almost 100 as shear rate increased. All fluids showed some change in viscosity with time from mixing; this varied between products from -34% to 37% in the tests. This magnitude was less than the difference between thickness levels specified by the National Descriptors. The apparent viscosity of thickened fluids depends strongly on the shear rate at which it is examined. This inherent behaviour is likely to hinder subjective evaluation of viscosity. If quantitative measures of viscosity are required (for example, for standardization purposes), they must therefore be qualified with information of

  15. Relating chromatographic retention and electrophoretic mobility to the ion distribution within electrosprayed droplets. (United States)

    Bökman, C Fredrik; Bylund, Dan; Markides, Karin E; Sjöberg, Per J R


    Ions that are observed in a mass spectrum obtained with electrospray mass spectrometry can be assumed to originate preferentially from ions that have a high distribution to the surface of the charged droplets. In this study, a relation between chromatographic retention and electrophoretic mobility to the ion distribution (derived from measured signal intensities in mass spectra and electrospray current) within electrosprayed droplets for a series of tetraalkylammonium ions, ranging from tetramethyl to tetrapentyl, is presented. Chromatographic retention in a reversed-phase system was taken as a measure of the analyte's surface activity, which was found to have a large influence on the ion distribution within electrosprayed droplets. In addition, different transport mechanisms such as electrophoretic migration and diffusion can influence the surface partitioning coefficient. The viscosity of the solvent system is affected by the methanol content and will influence both diffusion and ion mobility. However, as diffusion and ion mobility are proportional to each other, we have, in this study, chosen to focus on the ion mobility parameter. It was found that the influence of ion mobility relative to surface activity on the droplet surface partitioning of analyte ions decreases with increasing methanol content. This effect is most probably coupled to the decrease in droplet size caused by the decreased surface tension at increasing methanol content. The same observation was made upon increasing the ionic strength of the solvent system, which is also known to give rise to a decreased initial droplet size. The observed effect of ionic strength on the droplet surface partitioning of analyte ions could also be explained by the fact that at higher ionic strength, a larger number of ions are initially closer to the droplet surface and, thus, the contribution of ionic transport from the bulk liquid to the liquid/air surface interface (jet and droplet surface), attributable to

  16. Intron retention as a component of regulated gene expression programs. (United States)

    Jacob, Aishwarya G; Smith, Christopher W J


    Intron retention has long been an exemplar of regulated splicing with case studies of individual events serving as models that provided key mechanistic insights into the process of splicing control. In organisms such as plants and budding yeast, intron retention is well understood as a major mechanism of gene expression regulation. In contrast, in mammalian systems, the extent and functional significance of intron retention have, until recently, remained greatly underappreciated. Technical challenges to the global detection and quantitation of transcripts with retained introns have often led to intron retention being overlooked or dismissed as "noise". Now, however, with the wealth of information available from high-throughput deep sequencing, combined with focused computational and statistical analyses, we are able to distinguish clear intron retention patterns in various physiological and pathological contexts. Several recent studies have demonstrated intron retention as a central component of gene expression programs during normal development as well as in response to stress and disease. Furthermore, these studies revealed various ways in which intron retention regulates protein isoform production, RNA stability and translation efficiency, and rapid induction of expression via post-transcriptional splicing of retained introns. In this review, we highlight critical findings from these transcriptomic studies and discuss commonalties in the patterns prevalent in intron retention networks at the functional and regulatory levels.

  17. Membrane bioreactor sludge rheology at different solid retention times. (United States)

    Laera, G; Giordano, C; Pollice, A; Saturno, D; Mininni, G


    Rheological characterization is of crucial importance in sludge management both in terms of biomass dewatering and stabilization properties and in terms of design parameters for sludge handling operations. The sludge retention time (SRT) has a significant influence on biomass properties in biological wastewater treatment systems and in particular in membrane bioreactors (MBRs). The aim of this work is to compare the rheological behaviour of the biomass in a MBR operated under different SRTs. A bench-scale MBR was operated for 4 years under the same conditions except for the SRT, which ranged from 20 days to complete sludge retention. The rheological properties were measured over time and the apparent viscosity was correlated with the concentration of solid material when equilibrium conditions were reached and maintained. The three models most commonly adopted for rheological simulations were evaluated and compared in terms of their parameters. Then, steady-state average values of these parameters were related to the equilibrium biomass concentration (MLSS). The models were tested to select the one better fitting the experimental data in terms of mean root square error (MRSE). The relationship between the apparent viscosity and the shear rate, as a function of solid concentration, was determined and is proposed here. Statistical analysis showed that, in general, the Bingham model provided slightly better results than the Ostwald one. However, considering that a strong correlation between the two parameters of the Ostwald model was found for all the SRTs tested, both in the transient growth phases and under steady-state conditions, this model might be used more conveniently. This feature suggests that the latter model is easier to be used for the determination of the sludge apparent viscosity.

  18. Heteropoly acid catalytic treatment for reactivity enhancement and viscosity control of dissolving pulp. (United States)

    Wang, Xinqi; Duan, Chao; Zhao, Chengxin; Meng, Jingru; Qin, Xiaoyu; Xu, Yongjian; Ni, Yonghao


    The reactivity enhancement and viscosity control are of practical importance during the manufacture of high-quality cellulose (also known as dissolving pulp). In the study, the concept of using phosphotungstic acid (HPW) for this purpose was demonstrated. The Fock reactivity of resultant pulp increased from 49.1% to 74.1% after the HPW catalytic treatment at a dosage of 86.4 mg HPW/g odp. The improved results can be attributed to the increased fiber accessibility, thanks to the favorable fiber morphologic changes, such as increased pore volume/size, water retention value and specific surface area. HPW can be readily recycled/reused by evaporating method, where maintaining 87.1% catalytic activity after six recycle times. The HPW catalytic treatment concept may provide a green alternative for the manufacture of high-quality dissolving pulp. Copyright © 2018 Elsevier Ltd. All rights reserved.

  19. Effective Viscosity in Porous Media and Applicable Limitations for Polymer Flooding of an Associative Polymer

    Directory of Open Access Journals (Sweden)

    Zhang Peng


    Full Text Available Hydrophobically associating polyacrylamide (HAPAM is considered to be a promising candidate for polymer flooding because of its excellent apparent viscosifying capability. Compared with partially hydrolyzed polyacrylamide (HPAM, the resistance factor and residual resistance factor caused by HAPAM tend to be higher. However, the effective viscosity of HAPAM is lower than that of conventional polymer at a concentration of 2 000 mg/L. The dynamic retention capacity of HAPAM is about 2.3 times that of HPAM. The oil displacement efficiency of HAPAM is lower than that of conventional polymer at a concentration of 2 000 mg/L in the homogeneous sandpack model. The oil displacement efficiency of HAPAM is higher than that of HPAM only in the heterogeneous model (permeability ratio 2.8. Neither high nor low permeability ratios are good for the oil displacement efficiency of HAPAM.

  20. Effects of Metal Ions on Viscosity of Aqueous Sodium Carboxylmethylcellulose Solution and Development of Dropping Ball Method on Viscosity (United States)

    Set, Seng; Ford, David; Kita, Masakazu


    This research revealed that metal ions with different charges could significantly affect the viscosity of aqueous sodium carboxylmethylcellulose (CMC) solution. On the basis of an Ostwald viscometer, an improvised apparatus using a dropping ball for examining the viscosity of liquids/solutions has been developed. The results indicate that the…

  1. Viscosity jump in the lower mantle inferred from melting curves of ferropericlase. (United States)

    Deng, Jie; Lee, Kanani K M


    Convection provides the mechanism behind plate tectonics, which allows oceanic lithosphere to be subducted into the mantle as "slabs" and new rock to be generated by volcanism. Stagnation of subducting slabs and deflection of rising plumes in Earth's shallow lower mantle have been suggested to result from a viscosity increase at those depths. However, the mechanism for this increase remains elusive. Here, we examine the melting behavior in the MgO-FeO binary system at high pressures using the laser-heated diamond-anvil cell and show that the liquidus and solidus of (Mg x Fe 1-x )O ferropericlase (x = ~0.52-0.98), exhibit a local maximum at ~40 GPa, likely caused by the spin transition of iron. We calculate the relative viscosity profiles of ferropericlase using homologous temperature scaling and find that viscosity increases 10-100 times from ~750 km to ~1000-1250 km, with a smaller decrease at deeper depths, pointing to a single mechanism for slab stagnation and plume deflection.

  2. Kinematic viscosity of unstimulated whole saliva in healthy young adults. (United States)

    Foglio-Bonda, A; Pattarino, F; Foglio-Bonda, P L


    To analyze kinematic viscosity and pH of unstimulated whole saliva, evaluate possible variations after sampling, identify any gender differences and detect possible correlations between them. The sample consisted of sixty-four healthy young adults (37 females and 27 males, mean age 25.2 years). Saliva was collected using the spitting method at 11:00 am. Kinematic viscosity was determined with a capillary viscometer (ViscoClock, Schott-Geräte Mainz, Germany) equipped with a micro-Ubbelohde capillary. Viscosity and pH were measured at a temperature of 36 °C in a thermostatic bath. Viscosity and pH data were evaluated almost simultaneously at six different times after sampling in order to identify any variations due to aging. The data were statistically analyzed using Student's t test and Wilcoxon-Mann-Whitney test. In total sample kinematic viscosity was 1.40 cSt (SD = 0.39; RSD % = 27.81), in the male and female groups was 1.33 cSt (SD = 0.35, RSD% = 26.31) and 1.45 cSt (SD = 0.41, RSD % = 28.45) respectively; the difference was not statistically significant. Viscosity decreased exponentially as a function of time after sampling then reaching a plateau around 1.12 cSt, while the pH values increased linearly. There was a trend of pH to decrease while viscosity decreases. Kinematic viscometry could be a valid tool to evaluate salivary viscosity. Degradation of saliva after sampling affects viscosity and slightly pH. The use of capillary viscometer to evaluate salivary aging needs more improvements. Further studies are required to investigate and explain the effects of different techniques to reduce the film forming on the air/liquid interface during measurement.

  3. Numerical solutions of Williamson fluid with pressure dependent viscosity

    Directory of Open Access Journals (Sweden)

    Iffat Zehra


    Full Text Available In the present paper, we have examined the flow of Williamson fluid in an inclined channel with pressure dependent viscosity. The governing equations of motion for Williamson fluid model under the effects of pressure dependent viscosity and pressure dependent porosity are modeled and then solved numerically by the shooting method with Runge Kutta Fehlberg for two types of geometries i.e., (i Poiseuille flow and (ii Couette flow. Four different cases for pressure dependent viscosity and pressure dependent porosity are assumed and the physical features of pertinent parameters are discussed through graphs.

  4. Elongational viscosity of multiarm (Pom-Pom) polystyrene

    DEFF Research Database (Denmark)

    Nielsen, Jens Kromann; Rasmussen, Henrik K.; Almdal, Kristoffer


    -Pom was estimated to have 2.5 arms on average, while the estimate is 3.3 for the asymmetric star. The molar mass of each arm is about 27 kg/mol. The melts were characterized in the linear viscoelastic regime and in non-linear elongational rheometry. The transient elongational viscosity for the Pom-Pom molecule...... it corresponds well with an estimate of the maximum stretchability of the backbone. Time-strain separability was not observed for the 'Asymmetric star' molecule at the elongation rates investigated. The transient elongational viscosity for the 'Pom-Pom' molecule went through a reproducible maximum...... in the viscosity at the highest elongational rate....

  5. Structural Origin of Shear Viscosity of Liquid Water. (United States)

    Yamaguchi, Tsuyoshi


    The relation between the microscopic structure and shear viscosity of liquid water was analyzed by calculating the cross-correlation between the shear stress and the two-body density using the molecular dynamics simulation. The slow viscoelastic relaxation that dominates the steady-state shear viscosity was ascribed to the destruction of the hydrogen-bonding network structure along the compression axis of the shear distortion, which resembles the structural change under isotropic hydrostatic compression. It means that the shear viscosity of liquid water reflects the anisotropic destruction-formation dynamics of the hydrogen-bonding network.

  6. Chebyshev super spectral viscosity method for water hammer analysis

    Directory of Open Access Journals (Sweden)

    Hongyu Chen


    Full Text Available In this paper, a new fast and efficient algorithm, Chebyshev super spectral viscosity (SSV method, is introduced to solve the water hammer equations. Compared with standard spectral method, the method's advantage essentially consists in adding a super spectral viscosity to the equations for the high wave numbers of the numerical solution. It can stabilize the numerical oscillation (Gibbs phenomenon and improve the computational efficiency while discontinuities appear in the solution. Results obtained from the Chebyshev super spectral viscosity method exhibit greater consistency with conventional water hammer calculations. It shows that this new numerical method offers an alternative way to investigate the behavior of the water hammer in propellant pipelines.

  7. Plasma viscosity increase with progression of peripheral arterial atherosclerotic disease. (United States)

    Poredos, P; Zizek, B


    Increased blood and plasma viscosity has been described in patients with coronary and peripheral arterial disease. However, the relation of viscosity to the extent of arterial wall deterioration--the most important determinant of clinical manifestation and prognosis of the disease--is not well known. Therefore, the authors studied plasma viscosity as one of the major determinants of blood viscosity in patients with different stages of arterial disease of lower limbs (according to Fontaine) and its relation to the presence of some risk factors of atherosclerosis. The study encompassed four groups of subjects: 19 healthy volunteers (group A), 18 patients with intermittent claudication up to 200 m (stage II; group B), 15 patients with critical ischemia of lower limbs (stage III and IV; group C), and 16 patients with recanalization procedures on peripheral arteries. Venous blood samples were collected from an antecubital vein without stasis for the determination of plasma viscosity (with a rotational capillary microviscometer, PAAR), fibrinogen, total cholesterol, alpha-2-macroglobulin, and glucose concentrations. In patients with recanalization procedure local plasma viscosity was also determined from blood samples taken from a vein on the dorsum of the foot. Plasma viscosity was most significantly elevated in the patients with critical ischemia (1.78 mPa.sec) and was significantly higher than in the claudicants (1.68 mPa.sec), and the claudicants also had significantly higher viscosity than the controls (1.58 mPa.sec). In patients in whom a recanalization procedure was performed, no differences in systemic and local plasma viscosity were detected, neither before nor after recanalization of the diseased artery. In all groups plasma viscosity was correlated with fibrinogen concentration (r=0.70, P < 0.01) and total cholesterol concentration (r=0.24, P < 0.05), but in group C (critical ischemia) plasma viscosity was most closely linked to the concentration of alpha-2

  8. High shear rate rheometry of low-viscosity liquids (United States)

    Lodge, Arthur S.


    A new instrument called LODGE STRESSMETER was developed to measure the shear elasticity and viscosity of general and multigrade oils at high shear rates. This will make possible the measurements of normal stress difference N1 for values of shear rate up to 5 x 10 to the 5th power is temperature of 150 C. New surprising data show (as yet unexplained) the the N1 contribution to the minimum oil film thickness could be as much as 75 percent of the contribution from viscosity. This raises hope for the use of oils with lower viscosity, leading to improved fuel economy and an increase in the range of motorized vehicles.

  9. Intrinsic viscosity of bead models for macromolecules and bioparticles. (United States)

    Gmachowski, L


    A new method based on the fractal dimension dependence of the hydrodynamic radius is proposed for calculation of the intrinsic viscosity of bead models. The method describes properly the viscosity increment except for elongated structures such as linear aggregates and ellipsoids. It is expected to be useful for very compact structures, for which the volume correction does not improve the results calculated by the modified Oseen tensor. The results obtained for the viscosity increment lie between the volume corrected ones and those determined by the cubic substitution procedure. They are close to the values recalculated from the falling velocities of the models analyzed.

  10. Mechanics

    CERN Document Server

    Hartog, J P Den


    First published over 40 years ago, this work has achieved the status of a classic among introductory texts on mechanics. Den Hartog is known for his lively, discursive and often witty presentations of all the fundamental material of both statics and dynamics (and considerable more advanced material) in new, original ways that provide students with insights into mechanical relationships that other books do not always succeed in conveying. On the other hand, the work is so replete with engineering applications and actual design problems that it is as valuable as a reference to the practicing e

  11. Drug Retention Times

    Energy Technology Data Exchange (ETDEWEB)

    None, None


    The purpose of this monograph is to provide information on drug retention times in the human body. The information provided is based on plausible illegal drug use activities that might be engaged in by a recreational drug user. Based on anecdotal evidence, most people “party” during extended time away from the work environment. Therefore, the following scenarios were envisioned: (1) a person uses an illicit drug at a party on Saturday night (infrequent user); (2) a person uses a drug one time on Friday night and once again on Saturday night (infrequent user); and (3) a person uses a drug on Friday night, uses a drug twice on Saturday night, and once again on Sunday (frequent user).


    National Research Council Canada - National Science Library

    I. V. Makeev; I. Y. Popov; I. V. Blinova


    .... We suggest exact particular solutions of Stokes and continuity equations with variable viscosity and density in spherical coordinates for the case of spherically symmetric viscosity and density distributions...

  13. Research Synopsis: Spring 1983 Retention. (United States)

    Peralta Community Coll. District, Oakland, CA. Office of Research, Planning and Development.

    An analysis of spring 1983 retention rates and grade distributions within the Peralta Community College District (PCCD) revealed: (1) College of Alameda had the highest successful retention rate in the PCCD, defined as the total of all students who completed the term with a grade of A, B, C, D, or CR (credit); (2) the PCCD's successful retention…

  14. Reversing direction of galvanotaxis by controlled increases in boundary layer viscosity. (United States)

    Kobylkevich, Brian M; Sarkar, Anyesha; Carlberg, Brady R; Huang, Ling; Ranjit, Suman; Graham, David M; Messerli, Mark A


    Weak external electric fields (EFs) polarize cellular structure and direct most migrating cells (galvanotaxis) toward the cathode, making it a useful tool during tissue engineering and healing of epidermal wounds. However, the biophysical mechanisms for sensing weak EFs remain elusive. We have reinvestigated the mechanism of cathode-directed water flow (electro-osmosis) in the boundary layer of cells, by reducing it with neutral, viscous polymers. We report that increasing viscosity with low molecular weight polymers decreases cathodal migration and promotes anodal migration in a concentration dependent manner. In contrast, increased viscosity with high molecular weight polymers does not affect directionality. We explain the contradictory results in terms of porosity and hydraulic permeability between the polymers rather than in terms of bulk viscosity. These results provide the first evidence for controlled reversal of galvanotaxis using viscous agents and position the field closer to identifying the putative electric field receptor, a fundamental, outside-in signaling receptor that controls cellular polarity for different cell types. © 2018 IOP Publishing Ltd.

  15. Effect of MnO on High-Alumina Slag Viscosity and Corrosion Behavior of Refractory in Slags

    National Research Council Canada - National Science Library

    Xu, Renze; Zhang, Jianliang; Fan, Xiaoyue; Zheng, Weiwei; Zhao, Yongan


    The influence of MnO on viscosities of CaO–SiO2–MgO–Al2O3–Cr2O3-based slags and the corrosion mechanism of carbon composite brick used in blast furnace hearth by slags was investigated in this work...

  16. Linear viscoelasticity of emulsions : I. The effect of an interfacial film on the dynamic viscosity of nondilute emulsions

    NARCIS (Netherlands)

    Oosterbroek, M.; Mellema, J.


    The dynamic viscosity of nondilute monodisperse emulsions is calculated by using a cell model. Two possibilities for describing the mechanical properties of the interfacial film between the internal and the external phase are considered: (A) the film is assigned a two-dimensional linear viscoelastic

  17. Military Retention. A Comparative Outlook

    Directory of Open Access Journals (Sweden)

    Vasile Sminchise


    Full Text Available One of the main goals for human resources management structures and for armed forces leaders is to maintain all necessary personnel, both qualitatively and quantitatively for operational needs or for full required capabilities. The retention of military personnel is essential to keep morale and unit readiness and to reduce the costs for recruiting, training, replacement of manpower. Retention rates depend not only on money or other social measures. The goal for retention is to keep in use the most valuable resource that belongs to an organization: the human beings and their knowledge. The aim pf this paper is to provide a comparative analysis of retention measures in various countries based on Research and Technology Organisation report released in 2007 and, thus, provide more examples of retention measures as far as the Romanian military system is concerned.

  18. Lattice Boltzmann simulations of immiscible displacement process with large viscosity ratios (United States)

    Rao, Parthib; Schaefer, Laura


    Immiscible displacement is a key physical mechanism involved in enhanced oil recovery and carbon sequestration processes. This multiphase flow phenomenon involves a complex interplay of viscous, capillary, inertial and wettability effects. The lattice Boltzmann (LB) method is an accurate and efficient technique for modeling and simulating multiphase/multicomponent flows especially in complex flow configurations and media. In this presentation we present numerical simulation results of displacement process in thin long channels. The results are based on a new psuedo-potential multicomponent LB model with multiple relaxation time collision (MRT) model and explicit forcing scheme. We demonstrate that the proposed model is capable of accurately simulating the displacement process involving fluids with a wider range of viscosity ratios (>100) and which also leads to viscosity-independent interfacial tension and reduction of some important numerical artifacts.

  19. Hall viscosity: A link between quantum Hall systems, plasmas and liquid crystals

    Energy Technology Data Exchange (ETDEWEB)

    Lingam, Manasvi, E-mail:


    In this Letter, the assumption of two simple postulates is shown to give rise to a Hall viscosity term via an action principle formulation. The rationale behind the two postulates is clearly delineated, and the connections to an intrinsic angular momentum are emphasized. By employing this methodology, it is shown that Hall viscosity appears in a wide range of fields, and the interconnectedness of quantum Hall systems, plasmas and nematic liquid crystals is hypothesized. Potential avenues for experimental and theoretical work arising from this cross-fertilization are also indicated. - Highlights: • Connections between simple 2D fluid models in different fields of physics presented. • Structure emerges via varied physical mechanisms driven by internal angular momentum. • Properties of these models such as Casimirs, equilibria and stability are analyzed.

  20. Low-melt Viscosity Polyimide Resins for Resin Transfer Molding (RTM) II (United States)

    Chuang, Kathy C.; Criss, Jim M.; Mintz, Eric A.; Scheiman, Daniel A.; Nguyen, Baochau N.; McCorkle, Linda S.


    A series of polyimide resins with low-melt viscosities in the range of 10-30 poise and high glass transition temperatures (Tg s) of 330-370 C were developed for resin transfer molding (RTM) applications. These polyimide resins were formulated from 2,3,3 ,4 -biphenyltetracarboxylic dianhydride (a-BPDA) with 4-phenylethynylphthalic anhydride endcaps along with either 3,4 - oxyaniline (3,4 -ODA), 3,4 -methylenedianiline, (3,4 -MDA) or 3,3 -methylenedianiline (3,3 -MDA). These polyimides had pot lives of 30-60 minutes at 260-280 C, enabling the successful fabrication of T650-35 carbon fiber reinforced composites via RTM process. The viscosity profiles of the polyimide resins and the mechanical properties of the polyimide carbon fiber composites will be discussed.

  1. Measuring viscosity with nonlinear self-excited microcantilevers (United States)

    Mouro, J.; Tiribilli, B.; Paoletti, P.


    A viscosity sensor based on the nonlinear behaviour of a microcantilever embedded in a self-excitation loop with an adjustable phase-shifter is proposed. The self-sustained oscillation frequencies of the cantilever are experimentally and theoretically investigated as functions of the fluid viscosity and of the imposed phase shift of the signal along the self-excitation loop. The sensor performance is validated experimentally using different water-glycerol solutions. In contrast to existing rheological sensors, the proposed platform can be tuned to work in two different modes: a high-sensitivity device whose oscillation frequency changes smoothly with the rheological properties of the fluid or a critical viscosity threshold detector, where, for small changes in fluid viscosity, there is a step change in oscillation frequency.

  2. PVT characterization and viscosity modeling and prediction of crude oils

    DEFF Research Database (Denmark)

    Cisneros, Eduardo Salvador P.; Dalberg, Anders; Stenby, Erling Halfdan


    In previous works, the general, one-parameter friction theory (f-theory), models have been applied to the accurate viscosity modeling of reservoir fluids. As a base, the f-theory approach requires a compositional characterization procedure for the application of an equation of state (EOS), in most...... pressure, is also presented. The combination of the mass characterization scheme presented in this work and the f-theory, can also deliver accurate viscosity modeling results. Additionally, depending on how extensive the compositional characterization is, the approach,presented in this work may also...... deliver accurate viscosity predictions. The modeling approach presented in this work can deliver accurate viscosity and density modeling and prediction results over wide ranges of reservoir conditions, including the compositional changes induced by recovery processes such as gas injection....

  3. Poiseuille Flow of Fluid Whose Viscosity is Temperature Dependent ...

    African Journals Online (AJOL)

    We discuss a fluid flowing between two parallel plates. We assume a Poiseuille flow. Furthermore, we assume that the viscosity μ, depends on temperature T. We show that the velocity equation has two solutions. Graph features prominently in the presentation.

  4. Density and viscosity modeling and characterization of heavy oils

    DEFF Research Database (Denmark)

    Cisneros, Sergio; Andersen, Simon Ivar; Creek, J


    Viscosity and density are key properties for the evaluation, simulation, and development of petroleum reservoirs. Previously, the friction theory (f-theory) was shown to be capable of delivering simple and accurate viscosity models for petroleum reservoir fluids with molecular weights up to similar...... to 200 g/mol and viscosities up to similar to 10 mPa s, under usual reservoir conditions. As a basis, the f-theory approach requires a compositional characterization procedure that is used in conjunction with a van der Waals type of equation of state (EOS). This is achieved using simple cubic EOSs, which...... are widely used within the oil industry. Further work also established the basis for extending the approach to heavy oils. Thus, in this work, the extended f-theory approach is further discussed with the study and modeling of a wider set of representative heavy reservoir fluids with viscosities up...

  5. Viscosity and density tables of sodium chloride solutions

    Energy Technology Data Exchange (ETDEWEB)

    Fair, J.A.; Ozbek, H. (comps.)


    A file is presented containing tabulated data extracted from the scientific literature on the density and viscosity of aqueous sodium chloride solutions. Also included is a bibliography of the properties of aqueous sodium chloride solutions. (MHR)

  6. Rotational and spin viscosities of water: Application to nanofluidics

    DEFF Research Database (Denmark)

    Hansen, Jesper Søndergaard; Bruus, Henrik; Todd, B.D.


    In this paper we evaluate the rotational viscosity and the two spin viscosities for liquid water using equilibrium molecular dynamics. Water is modeled via the flexible SPC/Fw model where the Coulomb interactions are calculated via the Wolf method which enables the long simulation times required....... We find that the rotational viscosity is independent of the temperature in the range from 284 to 319 K. The two spin viscosities, on the other hand, decrease with increasing temperature and are found to be two orders of magnitude larger than that estimated by Bonthuis et al. [Phys. Rev. Lett. 103...... geometries. The coupling also enables conversion of rotational electrical energy into fluid linear momentum and we find that in order to obtain measurable flow rates the electrical field strength must be in the order of 0.1 MV m(-1) and rotate with a frequency of more than 100 MHz....

  7. Quetol 651: Not just a low viscosity resin. (United States)

    Ellis, E Ann


    Quetol 651, a low viscosity epoxy resin, is miscible with alcohols, acetone, and water. It is versatile and can be used as a single epoxide or mixed with other epoxides and anhydrides. The most important characteristic is that the addition of Quetol 651 to a formulation results in a lower viscosity embedding medium and allows for good detection of antigenic activity. Properly formulated and mixed resins containing Quetol 651 have excellent sectioning properties and good beam stability. The decrease in viscosity lends to lower specific gravity of the embedding medium and less interfering electron density between specimen elements resulting in better spatial resolution. New formulations and viscosity data are presented and compared to long used, embedding formulations and the extensive uses of Quetol 651 are reviewed. © 2015 Wiley Periodicals, Inc.

  8. Viscosity Measurements and Correlation of the Squalane + CO2 Mixture (United States)

    Tomida, D.; Kumagai, A.; Yokoyama, C.


    Experimental results for the viscosity of squalane + CO2 mixtures are reported. The viscosities were measured using a rolling ball viscometer. The experimental temperatures were 293.15, 313.15, 333.15, and 353.15 K, and pressures were 10.0, 15.0, and 20.0 MPa. The CO2 mole fraction of the mixtures varied from 0 to 0.417. The experimental uncertainties in viscosity were estimated to be within ±3.0%. The viscosity of the mixtures decreased with an increase in the CO2 mole fraction. The experimental data were compared with predictions from the Grunberg-Nissan and McAllister equations, which correlated the experimental data with maximum deviations of 10 and 8.7%, respectively.

  9. An investigation on the rheological and sulfur-retention characteristics of desulfurizing coal water slurry with calcium-based additives

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jianzhong; Zhao, Weidong; Zhou, Junhu; Cheng, Jun; Zhang, Guangxue; Feng, Yungang; Cen, Kefa [State Key Laboratory of Clean Energy Utilization, Institute for Thermal Power Engineering, Zhejiang University, Hangzhou 310027 (China)


    Desulphurizing coal water slurry is a kind of new clean coal water slurry(CWS), which has good performance on SO{sub 2} emission during combustion and gasification process. But, the addition of sulfur-retention agents have some effects on the stability and fluid characters of the coal water slurry. In this paper, the viscosity, stability and rheology of Xinwen coal water slurry have been studied by adding different kinds of calcium-based sulfur-retention agents and different dosage. The results show that the sulfur-retention agents have little effect on rheological nature of CWS, which still presents pseudoplastic fluid. The addition of sulfur-retention agents will increase the viscosity of CWS, but the stability will decrease a little. The results also show that inorganic calcium has less negative effect on the performance of CWS than the organic calcium. The viscosity of the CWS with organic calcium agent keeps 1000-1200 mPa s when Ca/S molar ratio is 2. Sulfur release of the CWS with CaCO{sub 3} reduces to 52% at Ca/S = 2 compared to original of 98%. (author)

  10. Viscosity measurements of crystallizing andesite from Tungurahua volcano (Ecuador). (United States)

    Chevrel, Magdalena Oryaëlle; Cimarelli, Corrado; deBiasi, Lea; Hanson, Jonathan B; Lavallée, Yan; Arzilli, Fabio; Dingwell, Donald B


    Viscosity has been determined during isothermal crystallization of an andesite from Tungurahua volcano (Ecuador). Viscosity was continuously recorded using the concentric cylinder method and employing a Pt-sheathed alumina spindle at 1 bar and from 1400°C to subliquidus temperatures to track rheological changes during crystallization. The disposable spindle was not extracted from the sample but rather left in the sample during quenching thus preserving an undisturbed textural configuration of the crystals. The inspection of products quenched during the crystallization process reveals evidence for heterogeneous crystal nucleation at the spindle and near the crucible wall, as well as crystal alignment in the flow field. At the end of the crystallization, defined when viscosity is constant, plagioclase is homogeneously distributed throughout the crucible (with the single exception of experiment performed at the lowest temperature). In this experiments, the crystallization kinetics appear to be strongly affected by the stirring conditions of the viscosity determinations. A TTT (Time-Temperature-Transformation) diagram illustrating the crystallization "nose" for this andesite under stirring conditions and at ambient pressure has been constructed. We further note that at a given crystal content and distribution, the high aspect ratio of the acicular plagioclase yields a shear-thinning rheology at crystal contents as low as 13 vol %, and that the relative viscosity is higher than predicted from existing viscosity models. These viscosity experiments hold the potential for delivering insights into the relative influences of the cooling path, undercooling, and deformation on crystallization kinetics and resultant crystal morphologies, as well as their impact on magmatic viscosity.

  11. Imaging viscosity of intragranular mucin matrix in cystic fibrosis cells. (United States)

    Requena, Sebastian; Ponomarchuk, Olga; Castillo, Marlius; Rebik, Jonathan; Brochiero, Emmanuelle; Borejdo, Julian; Gryczynski, Ignacy; Dzyuba, Sergei V; Gryczynski, Zygmunt; Grygorczyk, Ryszard; Fudala, Rafal


    Abnormalities of mucus viscosity play a critical role in the pathogenesis of several respiratory diseases, including cystic fibrosis. Currently, there are no approaches to assess the rheological properties of mucin granule matrices in live cells. This is the first example of the use of a molecular rotor, a BODIPY dye, to quantitatively visualize the viscosity of intragranular mucin matrices in a large population of individual granules in differentiated primary bronchial epithelial cells using fluorescence lifetime imaging microscopy.

  12. Chebyshev super spectral viscosity method for a fluidized bed model

    CERN Document Server

    Sarra, S A


    A Chebyshev super spectral viscosity method and operator splitting are used to solve a hyperbolic system of conservation laws with a source term modeling a fluidized bed. The fluidized bed displays a slugging behavior which corresponds to shocks in the solution. A modified Gegenbauer postprocessing procedure is used to obtain a solution which is free of oscillations caused by the Gibbs-Wilbraham phenomenon in the spectral viscosity solution. Conservation is maintained by working with unphysical negative particle concentrations.

  13. Comment on "Accelerating cosmological expansion from shear and bulk viscosity"

    CERN Document Server

    Giovannini, Massimo


    In a recent Letter [Phys. Rev. Lett. 114 091301 (2105)] the cause of the acceleration of the present Universe has been identified with the shear viscosity of an imperfect relativistic fluid even in the absence of any bulk viscous contribution. The gist of this comment is that the shear viscosity, if anything, can only lead to an accelerated expansion over sufficiently small scales well inside the Hubble radius.

  14. Convergence of a residual based artificial viscosity finite element method

    KAUST Repository

    Nazarov, Murtazo


    We present a residual based artificial viscosity finite element method to solve conservation laws. The Galerkin approximation is stabilized by only residual based artificial viscosity, without any least-squares, SUPG, or streamline diffusion terms. We prove convergence of the method, applied to a scalar conservation law in two space dimensions, toward an unique entropy solution for implicit time stepping schemes. © 2012 Elsevier B.V. All rights reserved.

  15. Viscosity measurements of crystallizing andesite from Tungurahua volcano (Ecuador) (United States)

    Cimarelli, Corrado; deBiasi, Lea; Hanson, Jonathan B.; Lavallée, Yan; Arzilli, Fabio; Dingwell, Donald B.


    Abstract Viscosity has been determined during isothermal crystallization of an andesite from Tungurahua volcano (Ecuador). Viscosity was continuously recorded using the concentric cylinder method and employing a Pt‐sheathed alumina spindle at 1 bar and from 1400°C to subliquidus temperatures to track rheological changes during crystallization. The disposable spindle was not extracted from the sample but rather left in the sample during quenching thus preserving an undisturbed textural configuration of the crystals. The inspection of products quenched during the crystallization process reveals evidence for heterogeneous crystal nucleation at the spindle and near the crucible wall, as well as crystal alignment in the flow field. At the end of the crystallization, defined when viscosity is constant, plagioclase is homogeneously distributed throughout the crucible (with the single exception of experiment performed at the lowest temperature). In this experiments, the crystallization kinetics appear to be strongly affected by the stirring conditions of the viscosity determinations. A TTT (Time‐Temperature‐Transformation) diagram illustrating the crystallization “nose” for this andesite under stirring conditions and at ambient pressure has been constructed. We further note that at a given crystal content and distribution, the high aspect ratio of the acicular plagioclase yields a shear‐thinning rheology at crystal contents as low as 13 vol %, and that the relative viscosity is higher than predicted from existing viscosity models. These viscosity experiments hold the potential for delivering insights into the relative influences of the cooling path, undercooling, and deformation on crystallization kinetics and resultant crystal morphologies, as well as their impact on magmatic viscosity. PMID:27656114

  16. Viscosity of α-pinene secondary organic material and implications for particle growth and reactivity

    Energy Technology Data Exchange (ETDEWEB)

    Renbaum-Wolff, Lindsay; Grayson, James W.; Bateman, Adam P.; Kuwata, Mikinori; Sellier, Mathieu; Murray, Benjamin J.; Shilling, John E.; Martin, Scot T.; Bertram, Allan K.


    Particles composed of secondary organic material (SOM) are abundant in the lower troposphere and play important roles in climate, air quality, and health. The viscosity of these particles is a fundamental property that is presently poorly quantified for conditions relevant to the lower troposphere. Using two new techniques, namely a bead-mobility technique and a poke-flow technique, in conjunction with simulations of fluid flow, we measure the viscosity of the watersoluble component of SOM produced by α-pinene ozonolysis. The viscosity is comparable to that of honey at 90% relative humidity (RH), comparable to that of peanut butter at 70% RH and greater than or comparable to that of bitumen for ≤ 30% RH, implying that the studied SOM ranges from liquid to semisolid/solid at ambient relative humidities. With the Stokes-Einstein relation, the measured viscosities further imply that the growth and evaporation of SOM by the exchange of organic molecules between the gas and condensed phases may be confined to the surface region when RH ≤ 30%, suggesting the importance of an adsorption-type mechanism for partitioning in this regime. By comparison, for RH ≥ 70% partitioning of organic molecules may effectively occur by an absorption mechanism throughout the bulk of the particle. Finally, the net uptake rates of semi-reactive atmospheric oxidants such as O3 are expected to decrease by two to five orders of magnitude for a change in RH from 90% to ≤ 30% RH, with possible implications for the rates of chemical aging of SOM particles in the atmosphere.

  17. Determination of fluid viscosity and femto Newton forces of Leishmania amazonensis using optical tweezers (United States)

    Fontes, Adriana; Giorgio, Selma; de Castro, Archimedes, Jr.; Neto, Vivaldo M.; de Y. Pozzo, Liliana; de Thomaz, Andre A.; Barbosa, Luiz C.; Cesar, Carlos L.


    The displacements of a polystyrene microsphere trapped by an optical tweezers (OT) can be used as a force transducer for mechanical measurements in life sciences such as the measurement of forces of living microorganisms or the viscosity of local fluids. The technique we used allowed us to measure forces on the 200 femto Newtons to 4 pico Newtons range of the protozoa Leishmania amazonensis, responsible for a serious tropical disease. These observations can be used to understand the infection mechanism and chemotaxis of these parasites. The same technique was used to measure viscosities of few microliters sample with agreement with known samples better than 5%. To calibrate the force as a function of the microsphere displacement we first dragged the microsphere in a fluid at known velocity for a broad range of different optical and hydrodynamical parameters. The hydrodynamical model took into account the presence of two walls and the force depends on drag velocity, fluid viscosity and walls proximities, while the optical model in the geometric optics regime depends on the particle and fluid refractive indexes and laser power. To measure the high numerical (NA) aperture laser beam power after the objective we used an integration sphere to avoid the systematic errors of usual power meters for high NA beams. After this careful laser power measurement we obtained an almost 45 degrees straight line for the plot of the optical force (calculated by the particle horizontal displacement) versus hydrodynamic force (calculated by the drag velocity) under variation of all the parameters described below. This means that hydrodynamic models can be used to calibrate optical forces, as we have done for the parasite force measurement, or vice-versa, as we did for the viscosity measurements.

  18. Leukocyte rolling on P-selectin: a three-dimensional numerical study of the effect of cytoplasmic viscosity. (United States)

    Khismatullin, Damir B; Truskey, George A


    Rolling leukocytes deform and show a large area of contact with endothelium under physiological flow conditions. We studied the effect of cytoplasmic viscosity on leukocyte rolling using our three-dimensional numerical algorithm that treats leukocyte as a compound droplet in which the core phase (nucleus) and the shell phase (cytoplasm) are viscoelastic fluids. The algorithm includes the mechanical properties of the cell cortex by cortical tension and considers leukocyte microvilli that deform viscoelastically and form viscous tethers at supercritical force. Stochastic binding kinetics describes binding of adhesion molecules. The leukocyte cytoplasmic viscosity plays a critical role in leukocyte rolling on an adhesive substrate. High-viscosity cells are characterized by high mean rolling velocities, increased temporal fluctuations in the instantaneous velocity, and a high probability for detachment from the substrate. A decrease in the rolling velocity, drag, and torque with the formation of a large, flat contact area in low-viscosity cells leads to a dramatic decrease in the bond force and stable rolling. Using values of viscosity consistent with step aspiration studies of human neutrophils (5-30 Pa·s), our computational model predicts the velocities and shape changes of rolling leukocytes as observed in vitro and in vivo. Copyright © 2012 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  19. Leukocyte Rolling on P-Selectin: A Three-Dimensional Numerical Study of the Effect of Cytoplasmic Viscosity (United States)

    Khismatullin, Damir B.; Truskey, George A.


    Rolling leukocytes deform and show a large area of contact with endothelium under physiological flow conditions. We studied the effect of cytoplasmic viscosity on leukocyte rolling using our three-dimensional numerical algorithm that treats leukocyte as a compound droplet in which the core phase (nucleus) and the shell phase (cytoplasm) are viscoelastic fluids. The algorithm includes the mechanical properties of the cell cortex by cortical tension and considers leukocyte microvilli that deform viscoelastically and form viscous tethers at supercritical force. Stochastic binding kinetics describes binding of adhesion molecules. The leukocyte cytoplasmic viscosity plays a critical role in leukocyte rolling on an adhesive substrate. High-viscosity cells are characterized by high mean rolling velocities, increased temporal fluctuations in the instantaneous velocity, and a high probability for detachment from the substrate. A decrease in the rolling velocity, drag, and torque with the formation of a large, flat contact area in low-viscosity cells leads to a dramatic decrease in the bond force and stable rolling. Using values of viscosity consistent with step aspiration studies of human neutrophils (5–30 Pa·s), our computational model predicts the velocities and shape changes of rolling leukocytes as observed in vitro and in vivo. PMID:22768931

  20. Friction Reduction Tested for a Downsized Diesel Engine with Low-Viscosity Lubricants Including a Novel Polyalkylene Glycol

    Directory of Open Access Journals (Sweden)

    David E. Sander


    Full Text Available With the increasing pressure to reduce emissions, friction reduction is always an up-to-date topic in the automotive industry. Among the various possibilities to reduce mechanical friction, the usage of a low-viscosity lubricant in the engine is one of the most effective and most economic options. Therefore, lubricants of continuously lower viscosity are being developed and offered on the market that promise to reduce engine friction while avoiding deleterious mixed lubrication and wear. In this work, a 1.6 L downsized Diesel engine is used on a highly accurate engine friction test-rig to determine the potential for friction reduction using low viscosity lubricants under realistic operating conditions including high engine loads. In particular, two hydrocarbon-based lubricants, 0W30 and 0W20, are investigated as well as a novel experimental lubricant, which is based on a polyalkylene glycol base stock. Total engine friction is measured for all three lubricants, which show a general 5% advantage for the 0W20 in comparison to the 0W30 lubricant. The polyalkylene glycol-based lubricant, however, shows strongly reduced friction losses, which are about 25% smaller than for the 0W20 lubricant. As the 0W20 and the polyalkylene glycol-based lubricant have the same HTHS-viscosity , the findings contradict the common understanding that the HTHS-viscosity is the dominant driver related to the friction losses.

  1. Effects of nano-sized metals on viscosity reduction of heavy oil/bitumen during thermal applications

    Energy Technology Data Exchange (ETDEWEB)

    Hamedi Shokrfu, Y.; Babadagli, T. [Alberta Univ., Edmonton, AB (Canada)


    The efficiency of heavy oil and bitumen recovery methods can be increased by improving energy transfer to the oil for increased viscosity reduction. Studies have shown that micron-sized metal particles improve the efficiency of ex situ processes such as coal liquefaction and pyrolysis. This study investigated the mechanics of additional viscosity reduction using nano-sized metals during thermal applications. Experiments were conducted to investigate the exothermic chemical reactions and thermal conductivity of iron, nickel and copper particles. The viscosity of oil samples mixed with the particles was measured, and the tests were repeated at different temperatures. The effect of the metal particles on heat transfer enhancement was also investigated. The studies showed that the metal nanoparticles significantly improved heavy oil and bitumen recovery rates. However, the percentage of the viscosity reduction and the optimum concentration of metal nanoparticles was highly dependent on the oil sample composition and the metal type. Different types of metals reduced heavy oil and bitumen viscosity with different series of exothermic reactions. The thermal conductivity of the metal must also be considered. Further studies are need to determine reactions when the nanoparticles are introduced into reservoirs. 24 refs., 4 tabs., 7 figs.

  2. Solution viscosity – molar mass relationships for poly(butylene succinate and discussion on molar mass analysis

    Directory of Open Access Journals (Sweden)

    Q. Charlier


    Full Text Available Poly(butylene succinate (PBS is currently developing due to its biodegradability and the similarity of its mechanical properties to those of polyolefins. Relationships between the number average molar mass, Mn, and solution viscosity such as [η] and ηred were derived for this aliphatic polyester. Mn values were determined by end-group analysis and size exclusion chromatography (SEC. Mark-Houwink-Sakurada (MHS parameters were proposed in two solvents and for the different molar masses and viscosity measurement methods. As an example, the MHS equations were respectively, [η] =6.4•10–4•Mn0.67 in chloroform and [η] = 7.1•10–4•Mn0.69 in 50/50 wt% 1,2-dichlorobenzene/phenol at 25°C for molar masses measured by SEC in hexafluoro isopropanol (HFIP with poly(methyl methacrylate (PMMA standards. Empirical relationships were also suggested to derive Mn directly from reduced viscosity, ηred, which is much easier to determine than intrinsic viscosity. With these data, the number average molar mass of PBS can be conveniently estimated from a single viscosity measurement. In addition, it was shown that PBS contains 1–2 wt% of cyclic oligomers produced during esterification and that molar masses determined by taking this fraction into account or not were significantly different, especially for long chains.

  3. Bulk viscosity of accretion disks around non rotating black holes (United States)

    Moeen Moghaddas, M.


    In this paper, we study the Keplerian, relativistic accretion disks around the non rotating black holes with the bulk viscosity. Many of authors studied the relativistic accretion disks around the black holes, but they ignored the bulk viscosity. We introduce a simple method to calculate the bulk in these disks. We use the simple form for the radial component of the four velocity in the Schwarzschild metric, then the other components of the four velocity and the components of the shear and the bulk tensor are calculated. Also all components of the bulk viscosity, the shear viscosity and stress tensor are calculated. It is seen that some components of the bulk tensor are comparable with the shear tensor. We calculate some of the thermodynamic quantities of the relativistic disks. Comparison of thermodynamic quantities shows that in some states influences of the bulk viscosity are important, especially in the inner radiuses. All calculations are done analytically and we do not use the boundary conditions. Finally, we find that in the relativistic disks around the black holes, the bulk viscosity is non-negligible in all the states.

  4. Measuring Lipid Membrane Viscosity Using Rotational and Translational Tracer Diffusion (United States)

    Hormel, Tristan; Kurihara, Sarah; Reyer, Matthew; Parthasarathy, Raghuveer


    The two-dimensional fluidity of lipid membranes enables the motion of membrane-bound macromolecules and is therefore crucial to biological function. However, current methods of measuring membrane viscosity rely on particular membrane lipid compositions or geometries, making the comparison of different measurements difficult. We address this with a new technique for measuring lipid membrane viscosity, in which determination of both the rotational and translational diffusion coefficients of tracer particles enables quantification of viscosity as well as the effective size of the tracers. This technique is general, and can be applied to different model membrane systems to determine the effects of membrane composition and protein modulation. We present measurements of lipid membrane viscosity for two different lipids with phosphatidylcholine headgroups, finding a surprisingly wide distribution of effective tracer sizes, due presumably to a large variety of couplings to the membrane. We also compare the effective viscosity of two different structures - black lipid membranes and membrane multilayers - as well as changes in viscosity induced by peripheral protein binding.

  5. Relaxation-based viscosity mapping for magnetic particle imaging. (United States)

    Utkur, M; Muslu, Y; Saritas, E U


    Magnetic particle imaging (MPI) has been shown to provide remarkable contrast for imaging applications such as angiography, stem cell tracking, and cancer imaging. Recently, there is growing interest in the functional imaging capabilities of MPI, where 'color MPI' techniques have explored separating different nanoparticles, which could potentially be used to distinguish nanoparticles in different states or environments. Viscosity mapping is a promising functional imaging application for MPI, as increased viscosity levels in vivo have been associated with numerous diseases such as hypertension, atherosclerosis, and cancer. In this work, we propose a viscosity mapping technique for MPI through the estimation of the relaxation time constant of the nanoparticles. Importantly, the proposed time constant estimation scheme does not require any prior information regarding the nanoparticles. We validate this method with extensive experiments in an in-house magnetic particle spectroscopy (MPS) setup at four different frequencies (between 250 Hz and 10.8 kHz) and at three different field strengths (between 5 mT and 15 mT) for viscosities ranging between 0.89 mPa · s-15.33 mPa · s. Our results demonstrate the viscosity mapping ability of MPI in the biologically relevant viscosity range.

  6. Saliva viscosity as a potential risk factor for oral malodor. (United States)

    Ueno, Masayuki; Takeuchi, Susumu; Takehara, Sachiko; Kawaguchi, Yoko


    The objective of this study was to assess whether saliva viscosity, measured by a viscometer, was a predictor of oral malodor. The subjects were 617 patients who visited an oral malodor clinic. The organoleptic test (OT) was used for diagnosis of oral malodor. An oral examination assessed the numbers of teeth present and decayed teeth as well as the presence or absence of dentures. Further, periodontal pocket depths (PD), gingival bleeding, dental plaque and tongue coating were investigated. Unstimulated saliva were collected for 5 min. Saliva viscosity was measured with a viscometer. Logistic regression analysis with oral malodor status by OT as a dependent variable was performed. Possible confounders including age, gender, number of teeth present, number of decayed teeth, number of teeth with PD ≥ 4 mm, number of teeth with bleeding on probing, presence or absence of dentures, plaque index, area of tongue coating, saliva flow rate, saliva pH and saliva viscosity were used as independent variables. Saliva viscosity (p = 0.047) along with the number of teeth with PD ≥4 mm (p = 0.001), plaque index (p = 0.037) and area of tongue coating (p viscosity (OR = 1.10) were more likely to have oral malodor compared to those with lower values. The results suggested that high saliva viscosity could be a potential risk factor for oral malodor.

  7. Impact of aggregate formation on the viscosity of protein solutions. (United States)

    Nicoud, Lucrèce; Lattuada, Marco; Yates, Andrew; Morbidelli, Massimo


    Gaining knowledge on the stability and viscosity of concentrated therapeutic protein solutions is of great relevance to the pharmaceutical industry. In this work, we borrow key concepts from colloid science to rationalize the impact of aggregate formation on the changes in viscosity of a concentrated monoclonal antibody solution. In particular, we monitor the kinetics of aggregate growth under thermal stress by static and dynamic light scattering, and we follow the rise in solution viscosity by measuring the diffusion coefficient of tracer nanoparticles with dynamic light scattering. Moreover, we characterize aggregate morphology in the frame of the fractal geometry. We show that the curves of the increase in viscosity with time monitored at three different protein concentrations collapse on one single master curve when the reaction profiles are normalized based on an effective volume fraction occupied by the aggregates, which depends on the aggregate size, concentration and morphology. Importantly, we find that the viscosity of an aggregate sample is lower than the viscosity of a monomeric sample of a similar occupied volume fraction due to the polydispersity of the aggregate distribution.

  8. Modeling of complex viscosity changes in the curing of epoxy resins from near-infrared spectroscopy and multivariate regression analysis. (United States)

    Garrido, M; Larrechi, M S; Rius, F X


    The present study investigates the relationship between the changes in complex viscosity and near-infrared spectra. Principal component regression analysis is applied to a near-infrared data set obtained from the in situ monitoring of the curing of diglycidyl ether of bisphenol A with the diamine 4,4'-diaminodiphenylmethane. The values of complex viscosity obtained by dynamic mechanical analysis during the cure process were used as a reference. The near-infrared spectra recorded throughout the reaction, unlike the univariate data analysis at some wavelengths of the spectra, contain a sufficient amount of information to estimate the complex viscosity. The relationship found was high and the results demonstrate the quality of the fitted model. Also, a simple user-friendly procedure for applying the model, focused on the user, is shown.

  9. Influence of clay particles on Al{sub 2}O{sub 3} and TiO{sub 2} nanoparticles transport and retention through limestone porous media: measurements and mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Bayat, Ali Esfandyari, E-mail:; Junin, Radzuan [Universiti Teknologi Malaysia, Department of Petroleum Engineering, Faculty of Petroleum and Renewable Energy Engineering (Malaysia); Mohsin, Rahmat [Universiti Teknologi Malaysia, UTM-MPRC Institute for Oil and Gas, N29A, Lengkuk Suria (Malaysia); Hokmabadi, Mehrdad [Universiti Teknologi Malaysia, Department of Petroleum Engineering, Faculty of Petroleum and Renewable Energy Engineering (Malaysia); Shamshirband, Shahaboddin [University of Malaya, Department of Computer System and Information Technology, Faculty of Computer System and Information Technology (Malaysia)


    Utilization of nanoparticles (NPs) for a broad range of applications has caused considerable quantities of these materials to be released into the environment. Issues of how and where the NPs are distributed into the subsurface aquatic environments are questions for those in environmental engineering. This study investigated the influence of three abundant clay minerals namely kaolinite, montmorillonite, and illite in the subsurface natural aquatic systems on the transport and retention of aluminum oxide (Al{sub 2}O{sub 3}, 40 nm) and titanium dioxide (TiO{sub 2}, 10–30 nm) NPs through saturated limestone porous media. The clay concentrations in porous media were set at 2 and 4 vol% of the holder capacity. Breakthrough curves in the columns outlets were measured using a UV–Vis spectrophotometer. It was found that the maximum NPs recoveries were obtained when there was no clay particle in the porous medium. On the other hand, increase in concentration of clay particles has resulted in the NPs recoveries being significantly declined. Due to fibrous structure of illite, it was found to be more effective for NPs retention in comparison to montmorillonite and kaolinite. Overall, the position of clay particles in the porous media pores and their morphologies were found to be two main reasons for increase of NPs retention in porous media.

  10. Effect of Liquid Viscosity on a Liquid Jet Produced by the Collapse of a Laser-Induced Bubble near a Rigid Boundary (United States)

    Liu, Xiu-mei; He, Jie; Lu, Jian; Ni, Xiao-wu


    The collapse of a laser-induced cavitation bubble near a rigid boundary and its dependence on liquid (kinematic) viscosity are investigated experimentally by fiber-coupling optical beam deflection (OBD). Cavitation bubble tests are performed using a mixture of glycerin and water of various concentrations, and the viscosity ranges from 1.004×10-6 to 51.30×10-6 m2/s. Combining the detection principles of this detector with a widely used laser ablation model, actual liquid-jet impact forces are presented for the mentioned viscosity range. In addition, based on the model of a collapsing bubble, some characteristic parameters, such as bubble lifetime, the maximum bubble radius, and liquid-jet impact pressure, are also obtained as a function of liquid viscosity. The main conclusion is that the liquid jet is a dominant factor in cavitation damage and can be modified by liquid viscosity. A high viscosity reduces the liquid-jet impact force and cavitation erosion markedly. The mechanism of the liquid viscosity effect on cavitation erosion has also been discussed.

  11. "Microencapsulation of Matricine by a dehydrating liquid and assessment of its retention "

    Directory of Open Access Journals (Sweden)

    "Gharavi SM


    Full Text Available Matricine of flowers of cultivated Matricaria chamomilla L. was isolated and identified by TLC, IR, UV and ¹H-NMR and quantified by HPLC. One of the lopophylic materials of this plant (matricine has been used as antispasmodic and anti-inflammatory. Retention of matricine by microencapsulation technique was one of the objectives of this study. Encapsulation was carried out by cold dehydrating liquid method and effects of the various process parameters on retention of the matricine were evaluated. To achieve high retention values it was necessary to employ low core to shell material ratio, high solid concentration, high viscosity of the emulsion continuous phase, the use of absolute ethanol as desiccant, short contact times between capsules and desiccant, and low air pressure in the formation of microcapsules. Results suggested that the process might be much more efficient if continuous coextrusion of the emulsion and desiccant were used.

  12. Effects of xylanase and citric acid on the performance, nutrient retention, and characteristics of gastrointestinal tract of broilers fed low-phosphorus wheat-based diets

    NARCIS (Netherlands)

    Esmaeilipour, O.; Shivazad, M.; Moravej, H.; Aminzadeh, S.; Rezaian, M.; Krimpen, van M.M.


    An experiment was conducted to study the effects of xylanase and citric acid on the performance, nutrient retention, jejunal viscosity, and size and pH of the gastrointestinal tract of broilers fed a low-P wheat-based diet. The experiment was conducted as a 2 × 3 factorial arrangement with 2 levels

  13. Retention of resin-based filled and unfilled pit and fissure sealants: A comparative clinical study. (United States)

    Reddy, V Rajashekar; Chowdhary, Nagalakshmi; Mukunda, K S; Kiran, N K; Kavyarani, B S; Pradeep, M C


    The most caries-susceptible period of a permanent first molar tooth is the eruption phase, during which the enamel is not fully matured and it is usually difficult for the child to clean the erupting tooth surfaces. Sealing occlusal pits and fissures with resin-based pit and fissure sealants is a proven method to prevent occlusal caries. The difference in the viscosity of the sealants differs in the penetration into pit and fissures and abrasive wear resistance property due to the addition of filler particles. The present study was conducted to evaluate and compare the retention of the resin-based filled (Helioseal F, Ivoclar Vivadent) and unfilled (Clinpro, 3M ESPE) pit and fissure sealants, which is important for their effectiveness. Fifty-six children between the age group of 6 and 9 years, with all four newly erupted permanent first molars were selected. Sealants were applied randomly using split mouth design technique on permanent first molars. Evaluation of sealant retention was performed at regular intervals over 12 months, using Simonsen's criteria at 2(nd), 4(th), 6(th), 8(th), 10(th) and 12(th) month. The results were subjected to statistical analysis. At the end of our study period (12(th) month), 53.57% showed complete retention, 37.50% showed partial retention, and 8.83% showed complete missing of resin-based filled (Helioseal F) pit and fissure sealant. And, 64.29% showed complete retention, 32.14% showed partial retention, and 3.57% showed complete missing of resin-based unfilled (Clinpro) pit and fissure sealant. This difference in retention rates between filled and unfilled pit and fissure sealants was not statistically significant. The difference in retention rates between Helioseal F and Clinpro was not statistically significant, but Clinpro (unfilled) sealant showed slightly higher retention rates and clinically better performance than Helioseal F (filled).

  14. Retention of resin-based filled and unfilled pit and fissure sealants: A comparative clinical study

    Directory of Open Access Journals (Sweden)

    V Rajashekar Reddy


    Full Text Available Background and Objectives: The most caries-susceptible period of a permanent first molar tooth is the eruption phase, during which the enamel is not fully matured and it is usually difficult for the child to clean the erupting tooth surfaces. Sealing occlusal pits and fissures with resin-based pit and fissure sealants is a proven method to prevent occlusal caries. The difference in the viscosity of the sealants differs in the penetration into pit and fissures and abrasive wear resistance property due to the addition of filler particles. The present study was conducted to evaluate and compare the retention of the resin-based filled (Helioseal F, Ivoclar Vivadent and unfilled (Clinpro, 3M ESPE pit and fissure sealants, which is important for their effectiveness. Materials and Methods: Fifty-six children between the age group of 6 and 9 years, with all four newly erupted permanent first molars were selected. Sealants were applied randomly using split mouth design technique on permanent first molars. Evaluation of sealant retention was performed at regular intervals over 12 months, using Simonsen′s criteria at 2 nd , 4 th , 6 th , 8 th , 10 th and 12 th month. The results were subjected to statistical analysis. Results: At the end of our study period (12 th month, 53.57% showed complete retention, 37.50% showed partial retention, and 8.83% showed complete missing of resin-based filled (Helioseal F pit and fissure sealant. And, 64.29% showed complete retention, 32.14% showed partial retention, and 3.57% showed complete missing of resin-based unfilled (Clinpro pit and fissure sealant. This difference in retention rates between filled and unfilled pit and fissure sealants was not statistically significant. Conclusion: The difference in retention rates between Helioseal F and Clinpro was not statistically significant, but Clinpro (unfilled sealant showed slightly higher retention rates and clinically better performance than Helioseal F (filled.

  15. Avaliação da resistência da união metal-resina usando sistemas de retenção mecânico e químico Evaluation of the resistance of metal-resin bond using mechanical and chemical retention systems

    Directory of Open Access Journals (Sweden)

    Luciana Silva Andrade TAROZZO


    Full Text Available O objetivo deste trabalho foi avaliar a resistência ao cisalhamento da união metal-resina empregando-se cinco tipos de retenção na estrutura metálica, em três ligas comerciais de Ni-Cr: Duceranium U, Wiron 99 e Wirocer. Um total de 90 corpos-de-prova foi submetido ao ensaio de cisalhamento e os resultados obtidos foram analisados estatisticamente, o que permitiu concluir que a interação retenção versus ligas foi estatisticamente significante em nível de 1% de probabilidade, sendo que o maior valor médio de resistência foi obtido com a liga Wirocer com retenção mecânica 0,6 mm, e o menor foi obtido com a liga Wiron 99 com retenção química.The objective of the present investigation was to evaluate the resistance of metal-resin bonding using the Silicoater® MD system (Kulzer, five types of retention in the metal structure, and three commercial Ni-Cr alloys: Duceranium U, Wiron 99 and Wirocer. A total of 90 samples were submitted to the shearing test. Statistical analysis of the results permitted us to conclude that retention versus alloy interaction was statistically significant at a 1% level of probability, the highest mean value being obtained with the Wirocer alloy with mechanical retention with 0.6 mm spheres. The lowest mean values were observed with the Wiron 99 alloy with chemical retention.

  16. Effectiveness of two new types of sealants: retention after 2 years. (United States)

    Chen, Xi; Du, Minquan; Fan, Mingwen; Mulder, Jan; Huysmans, Marie-Charlotte; Frencken, Jo E


    The hypotheses tested were: survival rate of fully and partially retained glass-carbomer sealants is higher than those of high-viscosity glass-ionomer, with and without energy supplied, and that of resin composite; survival rate of fully and partially retained sealants of high-viscosity glass-ionomer with energy supplied is higher than those without energy supplied. The randomized clinical trial covered 407 children, with a mean age of 8 years. The evaluation took place after 0.5, 1 and 2 years. Survival of sealant material in occlusal and in smooth surfaces, using the traditional categorization (fully and partially retained versus completely lost sealants) and the modified categorization (fully and more than 2/3 of the sealant retained versus completely lost sealants), were dependent variables. The Kaplan-Meier survival method was used. According to both categorizations of partially retained sealants, the survival of completely and partially retained resin composite sealants in occlusal and in smooth tooth surfaces was statistically significantly higher, and those of glass-carbomer sealants lower, than those of sealants of the other three groups. There was no statistically significant difference in the survival rates of completely and partially retained high-viscosity glass-ionomer sealants with and without energy supplied in occlusal and in smooth surfaces. After 2 years, glass-carbomer sealant retention was the poorest, adding energy to high-viscosity glass-ionomer sealant did not increase the retention rate and resin composite sealants were retained the longest. We suggest the use of the modified categorization of partially retained sealants in future studies. It seems not necessary to cure high-viscosity glass-ionomer sealants. The use of glass-carbomer sealants cannot be recommended yet.

  17. Comparison the clinical outcomes and complications of high-viscosity versus low-viscosity in osteoporotic vertebral compression fractures. (United States)

    Guo, Zhao; Wang, Wei; Gao, Wen-Shan; Gao, Fei; Wang, Hui; Ding, Wen-Yuan


    To compare the clinical outcomes and complications of high viscosity and low viscosity bone cement percutaneous vertebroplasty (PVP) for osteoporotic vertebral compression fractures (OVCF).From September 2009 to September 2015, 100 patients with OVCF were randomly divided into 2 groups: group H, using high viscosity cement (n = 50) or group L, using low viscosity cement (n = 50). The clinical outcomes were assessed by the visual analog scale (VAS), Oswestry Disability Index (ODI), kyphosis Cobb angle, vertebral height, and complications.Significant improvements in the VAS, ODI, kyphosis Cobb angle, and vertebral height were noted in both groups, and the VAS score in the H group showed greater benefit than in the L group. Cement leakage was observed less in group H. Postoperative assessment using computed tomography identified cement leakage in 27 of 98 (27.6%) vertebrae in group H and in 63 of 86 (73.3%) vertebrae in group L (P = .025).Compared with PVP using low viscosity bone cement, PVP using high viscosity bone cement can provide the same clinical outcomes with fewer complications and is recommended for routine clinical use.

  18. A comparison of high viscosity bone cement and low viscosity bone cement vertebroplasty for severe osteoporotic vertebral compression fractures. (United States)

    Zhang, Liang; Wang, Jingcheng; Feng, Xinmin; Tao, Yuping; Yang, Jiandong; Wang, Yongxiang; Zhang, Shengfei; Cai, Jun; Huang, Jijun


    To compare the clinical outcome and complications of high viscosity and low viscosity poly-methyl methacrylate bone cement PVP for severe OVCFs. From December 2010 to December 2012, 32 patients with severe OVCFs were randomly assigned to either group H using high viscosity cement (n=14) or group L using low viscosity cement (n=18). The clinical outcomes were assessed by the Visual Analog Scale (VAS), Oswestry Disability Index (ODI), Short Form-36 General Health Survey (SF-36), kyphosis Cobb's angle, vertebral height, and complications. Significant improvement in the VAS, ODI, SF-36 scores, kyphosis Cobb's angle, and vertebral height were noted in both the groups, and there were no significant differences between the two groups. Cement leakage was seen less in group H. Postoperative assessment using computed tomography identified cement leakage in 5 of 17 (29.4%) vertebrae in group H and in 15 of 22 (68.2%) vertebrae in group L (P=0.025). The PVP using high viscosity bone cement can provide the same clinical outcome and fewer complications compared with PVP using low viscosity bone cement. Copyright © 2014. Published by Elsevier B.V.

  19. The influence of tongue strength on oral viscosity discrimination acuity. (United States)

    Steele, Catriona M


    The ability to generate tongue pressures is widely considered to be critical for liquid bolus propulsion in swallowing. It has been proposed that the application of tongue pressure may also serve the function of collecting sensory information regarding bolus viscosity (resistance to flow). In this study, we explored the impact of age-related reductions in tongue strength on oral viscosity discrimination acuity. The experiment employed a triangle test discrimination protocol with an array of xanthan-gum thickened liquids in the mildly to moderately thick consistency range. A sample of 346 healthy volunteers was recruited, with age ranging from 12 to 86 (164 men, 182 women). On average, participants were able to detect a 0.29-fold increase in xanthan-gum concentration, corresponding to a 0.5-fold increase in viscosity at 50/s. Despite having significantly reduced tongue strength on maximum isometric tongue-palate pressure tasks, and regardless of sex, older participants in this study showed no reductions in viscosity discrimination acuity. In this article, the relationship between tongue strength and the ability to discriminate small differences in liquid viscosity during oral processing is explored. Given that tongue strength declines with age in healthy adults and is also reduced in individuals with dysphagia, it is interesting to determine whether reduced tongue strength might contribute to difficulties in evaluating liquid viscosity during the oral stage of swallowing. Using an array of mildly to moderately thick xanthan-gum thickened liquids, this experiment failed to find any evidence that reductions in tongue strength influence oral viscosity discrimination acuity. © 2017 Wiley Periodicals, Inc.

  20. Demonstrating the Importance of Bubbles and Viscosity on Volcanic Eruptions (United States)

    Namiki, A.


    The behavior of bubbles (exsolved volatile from magma) and viscosity of magma are important parameters that influence volcanic eruptions. Exsolved volatiles increase the volume of magma and reduce its density so that magma has sufficient volume and buoyancy force to erupt. Volatiles exsolve through nucleation and growth by diffusion and bubbles can expand as pressure is reduced. The time scale of diffusion depends on the viscosity of surrounding magma, and the expansion time scale of a bubble is also depends on the viscosity of magma. These control the time scale for volume change. If bubbles segregate from magma and collapse, the magma might not able to expand sufficiently to erupt violently. Whether a bubble can segregate from the liquid part of magma is also depends on viscosity of magma. In this poster, I introduce a straightforward demonstration to show the importance of bubbles and viscosity of magma on volcanic eruptions. To make bubbles, I use baking soda (NaHCO3) and citric acid. Reaction between them generates carbon dioxide (CO2) to make bubbles. I make citric acid solution gel by using agar at the bottom of a transparent glass and pour baking soda disolved corn syrup on top of the agar. This situation is a model of basally heated magma chamber. When water disolved magma (baking soda disolved corn syrup) receives sufficient heat (citric acid) bubbles are generated. I can change viscosity of corn syrup by varying the concentration of water. This demonstration shows how viscosity controls the time scale of volume change of bubbly magma and the distribution of bubbles in the fluid. In addition it helps to understand the important physical processes in volcanic eruption: bubble nucleation, diffusion grows, expansion, and bubble driving convection. I will perform a live demonstration at the site of the poster.

  1. Intrinsic viscosity of polymers and biopolymers measured by microchip. (United States)

    Lee, Jinkee; Tripathi, Anubhav


    Intrinsic viscosity provides insight to molecular structure and interactions in solution. A new microchip method is described for fast and accurate measurements of viscosity and intrinsic viscosity of polymer and biopolymer solutions. Polymer samples are diluted with solvent in the microfluidic chip by imposing pressure gradients across the channel network. The concentration and flow dilutions of the polymer sample are calculated from the fluorescent signals recorded over a range of dilutions. The viscosities at various polymer dilutions are evaluated using mass and momentum balances in the pressure-driven microchannel flow. The technique is particularly important to many chemical, biological, and medical applications where sample is available in very small quantities. The intrinsic viscosity experiments were performed for three classes of polymer solutions: (a) poly(ethylene glycol), polymers with linear hydrocarbon chains; (b) bovine serum albumin, biopolymer chains with hydrophobic and hydrophilic amino acids, and (c) DNA fragments, biological macromolecules with double-stranded polymeric chains. The measured values of intrinsic viscosity agree remarkably well with the available data obtained using different methods. The data exhibit power law behavior for molecular weight as described by the Mark-Houwink-Sakurada equation. Experiments were performed to understand the effect of solvent quality and salt concentration on molecular conformations and the intrinsic viscosity of the polymers. This method offers a new way to study the conformational changes in proteins and DNA solutions in various buffer conditions such as pH, ionic strength, and surfactants. The effects of shear rate in the microchannel and mixing time on the accuracy and limitation of the measurement method are discussed.

  2. Normal swallowing acoustics across age, gender, bolus viscosity, and bolus volume. (United States)

    Youmans, Scott R; Stierwalt, Julie A G


    Cervical auscultation has been proposed as an augmentative procedure for the subjective clinical swallowing examination due to the tangible differences between normal and dysphagic swallowing sounds. However, the research is incomplete regarding cervical auscultation and swallowing acoustics in that the differences between the sounds of normal versus dysphagic swallowing have yet to be fully understood or quantified. The swallows of 96 reportedly healthy adults, balanced for gender and divided into younger, middle, and older age groups, were audio-recorded while ingesting several boluses of varying viscosity and volume. The audio signals were then analyzed to determine their temporal and acoustic characteristics. Results indicated increasing pharyngeal swallowing duration with increasing age, bolus viscosity, and bolus volume. In addition, an increased duration to peak intensity with increasing age was found in one of our two analyses, as well as with some of the more viscous versus less viscous boluses. Men and older persons produced higher peak intensities and peak frequencies than women and younger persons. Thin liquids were produced with more intensity than honey or more viscous boluses, and with greater frequency than mechanical soft solids. Larger volumes resulted in greater peak frequency values. Some of the acoustic measurements appear to be more useful than others, including the duration of the acoustic swallowing signal and the within-subjects peak intensity variable. We noted that differences in swallowing acoustics were more related to changes in viscosity rather than volume. Finally, within-participant observations were more useful than between-participant observations.

  3. Perspective: interesterified triglycerides, the recent increase in deaths from heart disease, and elevated blood viscosity. (United States)

    Sloop, Gregory D; Weidman, Joseph J; St Cyr, John A


    The authors hypothesize that consumption of interesterified fats may be the cause of the continuous increase in cardiovascular deaths in the United States which began in 2011. Interesterification is a method of producing solid fats from vegetable oil and began to supplant partial hydrogenation for this purpose upon recognition of the danger of trans fats to cardiovascular health. Long, straight carbon chains, as are present in saturated and trans fatty acids, decrease the fluidity of the erythrocyte cell membrane, which decreases erythrocyte deformability and increases blood viscosity. This decrease in cell membrane fluidity is caused by increased van der Waals interactions, which also solidify dietary fats. Elevated blood viscosity is favored as the pathogenic mechanism by which trans fats increase cardiovascular mortality because changes in lipoprotein levels do not account for all the mortality attributable to their consumption. The rapid changes in cardiovascular mortality noted with the introduction and withdrawal of trans fats from the food supply are reviewed. The evidence implicating elevated blood viscosity in cardiovascular disease is also reviewed. Data regarding the production and consumption of interesterified fats in the US should be released in order to determine if there is an association with the observed increase in cardiovascular deaths.

  4. Faster in-plane switching and reduced rotational viscosity characteristics in a graphene-nematic suspension

    Energy Technology Data Exchange (ETDEWEB)

    Basu, Rajratan, E-mail:; Kinnamon, Daniel; Skaggs, Nicole; Womack, James [Soft Matter and Nanomaterials Laboratory, Department of Physics, The United States Naval Academy, Annapolis, Maryland 21402 (United States)


    The in-plane switching (IPS) for a nematic liquid crystal (LC) was found to be considerably faster when the LC was doped with dilute concentrations of monolayer graphene flakes. Additional studies revealed that the presence of graphene reduced the rotational viscosity of the LC, permitting the nematic director to respond quicker in IPS mode on turning the electric field on. The studies were carried out with several graphene concentrations in the LC, and the experimental results coherently suggest that there exists an optimal concentration of graphene, allowing a reduction in the IPS response time and rotational viscosity in the LC. Above this optimal graphene concentration, the rotational viscosity was found to increase, and consequently, the LC no longer switched faster in IPS mode. The presence of graphene suspension was also found to decrease the LC's pretilt angle significantly due to the π-π electron stacking between the LC molecules and graphene flakes. To understand the π-π stacking interaction, the anchoring mechanism of the LC on a CVD grown monolayer graphene film on copper substrate was studied by reflected crossed polarized microscopy. Optical microphotographs revealed that the LC alignment direction depended on monolayer graphene's hexagonal crystal structure and its orientation.

  5. Faster in-plane switching and reduced rotational viscosity characteristics in a graphene-nematic suspension (United States)

    Basu, Rajratan; Kinnamon, Daniel; Skaggs, Nicole; Womack, James


    The in-plane switching (IPS) for a nematic liquid crystal (LC) was found to be considerably faster when the LC was doped with dilute concentrations of monolayer graphene flakes. Additional studies revealed that the presence of graphene reduced the rotational viscosity of the LC, permitting the nematic director to respond quicker in IPS mode on turning the electric field on. The studies were carried out with several graphene concentrations in the LC, and the experimental results coherently suggest that there exists an optimal concentration of graphene, allowing a reduction in the IPS response time and rotational viscosity in the LC. Above this optimal graphene concentration, the rotational viscosity was found to increase, and consequently, the LC no longer switched faster in IPS mode. The presence of graphene suspension was also found to decrease the LC's pretilt angle significantly due to the π-π electron stacking between the LC molecules and graphene flakes. To understand the π-π stacking interaction, the anchoring mechanism of the LC on a CVD grown monolayer graphene film on copper substrate was studied by reflected crossed polarized microscopy. Optical microphotographs revealed that the LC alignment direction depended on monolayer graphene's hexagonal crystal structure and its orientation.

  6. Geometry Properties of Porosity Waves during Magma Migration: The Influence of Viscosities and Damage (United States)

    Cai, Z.; Bercovici, D.


    Partial melting occurs along grain boundaries and migrates through porous flow, leading to magma segregation in the mantle. Solitary porosity waves created by a perturbation in melting have been studied in the flow of a low viscosity fluid in a deformable matrix (McKenzie 1984, Scott and Stevenson 1986, Barcilon and Richter 1986, Spiegelman 1993, Wiggins and Spiegelman 1995). However, in a fairly complicated multi-physics, multi-scale process of magma migration, the geometry and instability of porosity waves can be affected by both mechanical and thermal factors, leaving different propagation signatures. In this work we develop a two-dimensional, two-phase damage model of magma-fracturing, and study the influence of viscosities and damage (void generation and microcracking) on the geometry properties of porosity waves. We first benchmark our solitary solutions with previous works and solve 2-D finite-amplitude waves numerically using spectral and semi-spectral method. We show that damage, decompaction weakening of the matrix and porosity-driven viscosities can alter the geometry of stable porosity waves, and result in an elongated or flattened wave front with a trail of smaller porosity. Such trails may localize subsequent waves and form porosity passage in the matrix. Scaling analysis of the time-dependent porosity waves are conducted and amount of magma reaching to the top of the melting region are estimated. Future work will include evaluating the thermal and seismic signatures during and after melt migration in two-phase porous flow.

  7. Temperature dependence of interfacial properties and viscosity of nanofluids for droplet-based microfluidics

    Energy Technology Data Exchange (ETDEWEB)

    Murshed, S M Sohel; Tan, Say-Hwa; Nguyen, Nam-Trung [School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore 639798 (Singapore)], E-mail:


    Interfacial tension and viscosity of a liquid play an important role in microfluidic systems. In this study, temperature dependence of surface tension, interfacial tension and viscosity of a nanofluid are investigated for its applicability in droplet-based microfluidics. Experimental results show that nanofluids having TiO{sub 2} nanoparticles of 15 nm diameter in deionized water exhibit substantially smaller surface tension and oil-based interfacial tension than those of the base fluid (i.e. deionized water). These surface and interfacial tensions of this nanofluid were found to decrease almost linearly with increasing temperature. The Brownian motion of nanoparticles in the base fluid was identified as a possible mechanism for reduced surface and interfacial tensions of the nanofluid. The measured effective viscosity of the nanofluid was found to be insignificantly higher than that of the base fluid and to decrease with increasing fluid temperature. The dependence on the temperature of the droplet formation at the T-junction of a microfluidic device is also studied and the nanofluid shows larger droplet size compared with its base fluid.

  8. A parametric study of helium retention in beryllium and its effect on deuterium retention (United States)

    Alegre, D.; Baldwin, M. J.; Simmonds, M.; Nishijima, D.; Hollmann, E. M.; Brezinsek, S.; Doerner, R. P.


    Beryllium samples have been exposed in the PISCES-B linear plasma device to conditions relevant to the International Thermonuclear Experimental Reactor (ITER) in pure He, D, and D/He mixed plasmas. Except at intermediate sample exposure temperatures (573–673 K) He addition to a D plasma is found to have a beneficial effect as it reduces the D retention in Be (up to ∼55%), although the mechanism is unclear. Retention of He is typically around 1020–1021 He m‑2, and is affected primarily by the Be surface temperature during exposition, by the ion fluence at <500 K exposure, but not by the ion impact energy at 573 K. Contamination of the Be surface with high-Z elements from the mask of the sample holder in pure He plasmas is also observed under certain conditions, and leads to unexpectedly large He retention values, as well as changes in the surface morphology. An estimation of the tritium retention in the Be first wall of ITER is provided, being sufficiently low to allow a safe operation of ITER.

  9. Determination of Viscosity Versus Pressure by Means of a Clearance Seal

    DEFF Research Database (Denmark)

    Christiansen, Peter; Schmidt Hansen, Niels; Lund, Martin Thomas Overdahl


    This paper describes the construction and testing of a simple, experimental tool setup that enables determination of the pressure–viscosity relationship for high viscosity oils. Comparing the determined pressure–viscosity relationship with a reference rheometer measuring the viscosity at ambient ...

  10. Increasing Army Retention Through Incentives

    National Research Council Canada - National Science Library

    Beerman, Kevin


    .... This study examines current retention issues and the Army Incentive Model. The model appears to offer a range of benefits that may retain a segment of what demographers have labeled as the Millennium Generation...

  11. Fuzzy indicators for customer retention

    National Research Council Canada - National Science Library

    Valenzuela-Fernández, Leslier; Nicolas, Carolina; Gil-Lafuente, Jaime; Merigó, José M


    .... Nevertheless, one cannot ignore the existence of a gap on how to measure this relationship. Following this idea, this study proposes six fuzzy key performance indicators that aims to measure customer retention and loyalty of the portfolio...

  12. Mechanics

    CERN Document Server

    Chester, W


    When I began to write this book, I originally had in mind the needs of university students in their first year. May aim was to keep the mathematics simple. No advanced techniques are used and there are no complicated applications. The emphasis is on an understanding of the basic ideas and problems which require expertise but do not contribute to this understanding are not discussed. How­ ever, the presentation is more sophisticated than might be considered appropri­ ate for someone with no previous knowledge of the subject so that, although it is developed from the beginning, some previous acquaintance with the elements of the subject would be an advantage. In addition, some familiarity with element­ ary calculus is assumed but not with the elementary theory of differential equations, although knowledge of the latter would again be an advantage. It is my opinion that mechanics is best introduced through the motion of a particle, with rigid body problems left until the subject is more fully developed. Howev...

  13. Strong synergistic effects in PLA/PCL blends: Impact of PLA matrix viscosity. (United States)

    Ostafinska, Aleksandra; Fortelný, Ivan; Hodan, Jiří; Krejčíková, Sabina; Nevoralová, Martina; Kredatusová, Jana; Kruliš, Zdeněk; Kotek, Jiří; Šlouf, Miroslav


    Blends of two biodegradable polymers, poly(lactic acid) (PLA) and poly(ϵ-caprolactone) (PCL), with strong synergistic improvement in mechanical performance were prepared by melt-mixing using the optimized composition (80/20) and the optimized preparation procedure (a melt-mixing followed by a compression molding) according to our previous study. Three different PLA polymers were employed, whose viscosity decreased in the following order: PLC ≈ PLA1 > PLA2 > PLA3. The blends with the highest viscosity matrix (PLA1/PCL) exhibited the smallest PCL particles (d∼0.6μm), an elastic-plastic stable fracture (as determined from instrumented impact testing) and the strongest synergistic improvement in toughness (>16× with respect to pure PLA, exceeding even the toughness of pure PCL). According to the available literature, this was the highest toughness improvement in non-compatiblized PLA/PCL blends ever achieved. The decrease in the matrix viscosity resulted in an increase in the average PCL particle size and a dramatic decrease in the overall toughness: the completely stable fracture (for PLA1/PCL) changed to the stable fracture followed by unstable crack propagation (for PLA2/PCL) and finally to the completely brittle fracture (for PLA3/PCL). The stiffness of all blends remained at well acceptable level, slightly above the theoretical predictions based on the equivalent box model. Despite several previous studies, the results confirmed that PLA and PCL could behave as compatible polymers, but the final PLA/PCL toughness is extremely sensitive to the PCL particle size distribution, which is influenced by both processing conditions and PLA viscosity. PLA/PCL blends with high stiffness (due to PLA) and toughness (due to PCL) are very promising materials for medical applications, namely for the bone tissue engineering. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Effect of temperature and viscosity on swimming velocity of the copepod Acartia tonsa, brine shrimp Artemia salina and rotifer Brachionus plicatilis

    DEFF Research Database (Denmark)

    Larsen, Poul Scheel; Madsen, C.V.; Riisgard, H.U.


    that the temperature-dependent viscosity of seawater is the key physical/mechanical factor that controls the beat frequency of water-pumping cilia in mussels and the swimming velocity in a ciliate. The present study on the swimming velocity of 3 zooplankton organisms, however, shows that the response of swimming...... velocity to a change in viscosity is different when due to a change in temperature or, at constant temperature, due to a manipulation of viscosity by addition of a high-molecular-weight polymer (polyvinyl pyrrolidone, PVP) to the ambient seawater. There is a biological effect (fraction of total reduction......) due to change in kinematic viscosity (v) be correlated in terms of a power law, V proportional to v(-m). The present data on swimming velocity of copepods, brine shrimps and rotifers show values of exponent m approximate to 1.5 to 3, with a trend of decreasing values for increasing size of species...

  15. Air Force Pilot Retention-1988. (United States)


    Politica l Science from Texas A&M University in 1973. He earned his commission S’- ,t the same time. This project will fulfill partial r(,quir(,m,nts...12 years of Air Force pilot retention rates , (2:12: 5:2). 0>. _ , FISCAL YEAR PILOT RETENTION RATES 1976 50.6% 1977 47.9% 1978 39.6% 1979 26.0% 1980

  16. Shear viscosity of shocked metals at mega-bar pressures (United States)

    Liu, Fu-Sheng


    Viscosity of metals at high pressures and temperatures has been one of the most concerned problems in weapon physics and geophysics, e.g., the shear viscosity coefficients of substances in earth's mantle and earth's core at mega-bar pressures are needed for understanding the core mantle convection in deep earth. But the experimental data is very scarce because the conventional measurement methods can hardly be applied to such compression conditions [1]. In this talk, the principle of small-disturbance perturbation method [2] is re-investigated based on both the analytic solution and the numerical solution of the two-dimentional shock flow of sinusoidal distubance on front. In numerical solution, the real viscosity, which governs the flow behind the shock front and the perturbation damping feature, and the artificial viscosity, whick controls the numerical oscillation, separately treated. The relation between the viscosity of flow and the damping features of perturbation amplitude is quantitatively established for the loading situations of Sakharov's [3] and a flyer-impact situation with a finite disturbance. The later is the theoretical basis to develop a new experimental method, called the flyer-impact small-disturbance method [4]. In the flyer-impact small-disturbance method, the two-stage light-gas gun is used to launch a metal flyer. When the flyer directly impacts on the wedge-shaped sample with a sinusoidal surface, a two-dimensional shock flow of sinusoidal distubance on its front is generated. The amplitude of disturbance and its dependance with propagation distance is measured by use of an electric pin-array probe or a fibre-array probe. Correspondingly, the solution of the flow is given by numerically solving the hydrodynamic equations by the finite difference technique to find out the quantative correlations among the amplitude decay, the initial distribution of flow, the amplitude of initial disturbance, the shear viscosity of the flow, and the material

  17. The influence of magnetic fields on crude oils viscosity

    Energy Technology Data Exchange (ETDEWEB)

    Goncalves, Jose L.; Bombard, Antonio J. F. [Universidade Federal de Itajuba (UNIFEI), Itajuba, MG (Brazil). Instituto de Ciencias Exatas. Lab. de Reologia


    The crystallization of paraffin causes serious problems in the process of transportation of petroleum. This phenomenon increases the crude oil viscosity and implies an organic resin accumulation on pipeline wall, resulting in a reduced flux area or totally blocked pipes. One of the most challenging tasks for pipeline maintenance is solving this problem at low cost. Therefore, a method that inhibits the crystallization of paraffin and reduces the viscosity of crude oil could have many useful applications within the petroleum industry. Recent studies showed that magnetic fields reduce the Wax Appearance Temperature (WAT) and the viscosity of paraffin-based crude oil. For better understanding of this discovery, a series of tests was performed. This paper will show the influence of a DC magnetic field on rheological proprieties of three crude oils with different paraffin concentrations: a crude oil sample with 11 % p/p of paraffin concentration (sample 1); a crude oil sample with 6 % p/p of paraffin concentration (sample 2); a mixture of paraffin plus light crude oil with a total of 11 % p/p of paraffin concentration. These samples were placed in an electromagnet that generates a magnetic field of 1.3 Tesla. The samples' temperatures were conditioned around their Wax Appearance Temperature (WAT), and they were exposed to the field. As the viscosity of crude oil is very sensitive to the changes in temperature, it was ensured that the temperature has remained constant throughout the process. The sample 1 revealed a considerable reduction of viscosity: its original viscosity was 66 cP before magnetic field exposure, after that its viscosity was reduced to 39 cP. The other samples showed the same viscosity, before and after the magnetic field exposure. Since the samples 1 and 3 have the same paraffin concentrations, the viscosity reduction is not due only to the presence of paraffin; there must be other factors responsible for the interaction of sample 1 with the

  18. Investigation of viscosity of whole hydrolyze sweetened condensed milk

    Directory of Open Access Journals (Sweden)

    O. Kalinina


    Full Text Available Introduction. Рaper is aimed at developing of low-lactose (hydrolyzed sweetened condensed milk products technology for lactose intolerant people and for the whole population. Materials and methods: Rheological characteristics were determined on a Reotest device by the 2 nd method of viscometry Results and discussion. Reasonability of ß-galactosidase use for milk lactose hydrolyze during the production of canned products with sugar was proved in the previous works. This technology gives possibility to increase the quality of condensed canned foods, to reduce sugar concentration till 50 %, to increase dietary properties. Due to the reducing of saccharose mass part till 22 and 31 % the products had a liquid consistency that’s why was a necessity to increase the viscosity properties of condensed products. One of method to increase the product viscosity is inoculation of stabilization systems. Reasonability of the usage of stabilization system Bivicioc 1L was proved. The researches of viscosity determination in whole hydrolyzed sweetened condensed milk were shown in the work. Relations of viscosity of whole hydrolyzed condensed milk to the deformation rate were presented. Conclusions Viscosity indices of experimental samples in the fresh produced products and during storage are determined and justified.

  19. Universality of the shear viscosity of alkali metals (United States)

    Meyer, N.; Xu, H.; Wax, J.-F.


    The universality of the shear viscosity of alkali metals is studied up to high pressure. Equilibrium molecular dynamics simulations are used to calculate the stress autocorrelation function, which allows us to obtain the value of shear viscosity using the Green-Kubo formula. Atomic interactions are computed from Fiolhais pseudopotential and are validated by comparison between pair distribution functions and mean-squared displacements obtained from classical and ab initio molecular dynamics simulations. The description of the interactions is accurate at least up to 12 GPa, 9.4 GPa, 6.6 GPa, and 3 GPa for Na, K, Rb, and Cs, respectively, and to a lesser extent up to 4.8 GPa for Li. A good agreement between simulation and experimental viscosity results along the liquid-gas coexistence curve is found. The viscosity appears to be a universal property over a wide range of the liquid phase of the phase diagram, between 0.85 and 1.5 times the ambient melting density and up to seven times the ambient melting temperature. Scaling laws are proposed following relations formulated in [Meyer, Xu, and Wax, Phys. Rev. B 93, 214203 (2016), 10.1103/PhysRevB.93.214203] so that it is possible to predict the viscosity value of any alkali metal with an accuracy better than 10% over the corresponding density and temperature range.

  20. The effect of gasses on the viscosity of dimethyl ether

    DEFF Research Database (Denmark)

    Sivebæk, Ion Marius; Jakobsen, Jørgen


    media, but their effect on DME viscosity is unknown. Argon (Ar), nitrogen (NA carbon dioxide (CO2), hydrogen (H-2) and propane (C3H8) have been investigated at pressure levels of 12-15 bar. A Cannon-Manning semi-micro capillary glass viscometer, size 25, enclosed in a cylindrical pressure container......, of glass, submerged completely in a constant temperature bath, has been used. A distinct reduction of efflux times was found only for the gas, CO2. The reduction in efflux time was about 9%. The kinematic viscosity of pure DME was determined to be: 0.188 +/- 0.001 cSt, 25 degrees C. A previously reported...... viscosity of pure DME has been corrected for the surface tension effect. Viscosity determination was initially based on a direct comparison of efflux times of DME with that of distilled water. The calculation gave a revised viscosity of 0.186 +/- 0.002 cSt, 25 degrees C, consistent with the above...

  1. Bulk viscosity, interaction and the viability of phantom solutions

    Energy Technology Data Exchange (ETDEWEB)

    Leyva, Yoelsy; Sepulveda, Mirko [Universidad de Tarapaca, Departamento de Fisica, Facultad de Ciencias, Arica (Chile)


    We study the dynamics of a bulk viscosity model in the Eckart approach for a spatially flat Friedmann-Robertson-Walker (FRW) Universe. We have included radiation and dark energy, assumed as perfect fluids, and dark matter treated as an imperfect fluid having bulk viscosity. We also introduce an interaction term between the dark matter and dark energy components. Considering that the bulk viscosity is proportional to the dark matter energy density and imposing a complete cosmological dynamics, we find bounds on the bulk viscosity in order to reproduce a matter-dominated era (MDE). This constraint is independent of the interaction term. Some late time phantom solutions are mathematically possible. However, the constraint imposed by a MDE restricts the interaction parameter, in the phantom solutions, to a region consistent with a null value, eliminating the possibility of late time stable solutions with w < -1. From the different cases that we study, the only possible scenario, with bulk viscosity and interaction term, belongs to the quintessence region. In the latter case, we find bounds on the interaction parameter compatible with latest observational data. (orig.)

  2. Dark goo: Bulk viscosity as an alternative to dark energy

    CERN Document Server

    Gagnon, Jean-Sebastien


    We present a simple (microscopic) model in which bulk viscosity plays a role in explaining the present acceleration of the universe. The effect of bulk viscosity on the Friedmann equations is to turn the pressure into an "effective" pressure containing the bulk viscosity. For a sufficiently large bulk viscosity, the effective pressure becomes negative and could mimic a dark energy equation of state. Our microscopic model includes self-interacting spin-zero particles (for which the bulk viscosity is known) that are added to the usual energy content of the universe. We study both background equations and linear perturbations in this model. We show that a dark energy behavior is obtained for reasonable values of the two parameters of the model (i.e. the mass and coupling of the spin-zero particles) and that linear perturbations are well-behaved. There is no apparent fine tuning involved. We also discuss the conditions under which hydrodynamics holds, in particular that the spin-zero particles must be in local eq...

  3. Dynamic viscosity study of barley malt and chicory concentrates

    Directory of Open Access Journals (Sweden)

    G. O. Magomedov


    Full Text Available The purpose of research is to find optimal conditions for dispersing and subsequent dehydration of liquid food environments in the nozzle spray drying chamber through the study of dynamic changes in viscosity according to temperature, velocities gradients and dry residue content. The objects of study were roasted chicory and malt barley concentrates with dry residue content of 20, 40, 60 and 80%. Research of dynamic viscosity were carried out at the measuring complex based on the rotational viscometer Rheotest II, analog-to-digital converter, module Laurent and a personal computer with a unique software that allows to record in real time (not only on a tape recorder, but also in the form of graphic files the behavior of the viscosity characteristics of concentrates. Registration of changes of dynamic viscosity was carried out at a shear rate gradient from 1,0 с -1 to 27,0 с -1 and the products temperature thermostating : 35, 55, 75˚ C. The research results are presented in the form of graphic dependences of effective viscosity on shear rate and flow curves (dependencies of shear stresses on the velocity gradient, which defined flow regimes, the optimal modes of dispersion concentrates into spray dryer chambers in obtaining of powdered semi-finished products and instanting were found: dry residue content - 40 %, concentrate temperature - 75 ˚C, velocity gradient in the air channel of the nozzle at least 20 c-1

  4. Association between blood viscosity and common carotid artery elasticity. (United States)

    Tripolino, Cesare; Irace, Concetta; Carallo, Claudio; De Franceschi, Maria Serena; Scavelli, Faustina; Della Valle, Elisabetta; Gnasso, Agostino


    Elastic properties of the vessel wall are associated with atherosclerosis and major cardiovascular events. Several physiological and pathological conditions can affect arterial elasticity, but few studies have considered the role of hemorheological parameters. The present study aimed to investigate the relationship between hemorheological parameters and vascular stiffness in the carotid artery district. One hundred and two individuals were enrolled. Blood and plasma viscosity were measured by a cone-plate viscometer (Wells-Brookfield DV-III, Stoughton, U.S.A.). Echo-Doppler evaluation of carotid arteries was performed in order to calculate elastic indexes (strain, β-stiffness index and distensibility). The association between hemorheological parameters and carotid elasticity indexes was assessed by simple and multiple regression analyses. In simple correlation analysis, only blood viscosity was directly associated with β-stiffness index (r = 0.20, p = 0.05) and inversely with strain (r =-0.26, p = 0.01) and distensibility (r =-0.34, p = 0.001). After adjusting for cardiovascular risk factors, blood viscosity, but not plasma viscosity or hematocrit, was independently associated carotid arterial measures, together with age, obesity, hypertension, and dyslipidemia. The results of the present study demonstrate a strong association between blood viscosity and common carotid elasticity indexes.

  5. Effect of viscosity on droplet-droplet collisional interaction (United States)

    Finotello, Giulia; Padding, Johan T.; Deen, Niels G.; Jongsma, Alfred; Innings, Fredrik; Kuipers, J. A. M.


    A complete knowledge of the effect of droplet viscosity on droplet-droplet collision outcomes is essential for industrial processes such as spray drying. When droplets with dispersed solids are dried, the apparent viscosity of the dispersed phase increases by many orders of magnitude, which drastically changes the outcome of a droplet-droplet collision. However, the effect of viscosity on the droplet collision regime boundaries demarcating coalescence and reflexive and stretching separation is still not entirely understood and a general model for collision outcome boundaries is not available. In this work, the effect of viscosity on the droplet-droplet collision outcome is studied using direct numerical simulations employing the volume of fluid method. The role of viscous energy dissipation is analysed in collisions of droplets with different sizes and different physical properties. From the simulations results, a general phenomenological model depending on the capillary number (Ca, accounting for viscosity), the impact parameter (B), the Weber number (We), and the size ratio (Δ) is proposed.

  6. Viscosity of diluted suspensions of vegetal particles in water

    Directory of Open Access Journals (Sweden)

    Szydłowska Adriana


    Full Text Available Viscosity and rheological behaviour of sewage as well as sludge are essential while designing apparatuses and operations employed in the sewage treatment process and its processing. With reference to these substances, the bio-suspensions samples of three size fractions ((i 150÷212 μm, (ii 106÷150 μm and (iii below106 μm of dry grass in water with solid volume fraction 8%, 10% and 11% were prepared. After twenty four hours prior to their preparation time, the suspension samples underwent rheometeric measurements with the use of a rotational rheometer with coaxial cylinders. On the basis of the obtained results, flow curves were plotted and described with both the power model and Herschel-Bulkley model. Moreover, the viscosity of the studied substances was determined that allowed to conclude that the studied bio-suspensions display features of viscoelastic fluids. The experimentally established viscosity was compared to the calculated one according to Manley and Manson equation, recommended in the literature. It occurred that the measured viscosity values substantially exceed the calculation viscosity values, even by 105 times. The observations suggest that it stems from water imbibition of fibrous vegetal particles, which causes their swelling and decreases the amount of liquid phase in the suspension.

  7. Viscosity changes in hyaluronic acid: Irradiation and rheological studies

    Energy Technology Data Exchange (ETDEWEB)

    Daar, Eman [Department of Physics, University of Surrey, Guildford, Surrey GU2 7XH (United Kingdom)], E-mail:; King, L.; Nisbet, A. [Department of Physics, University of Surrey, Guildford, Surrey GU2 7XH (United Kingdom); Thorpe, R.B. [Fluids and Systems Centre, University of Surrey, Guildford, Surrey GU2 7XH (United Kingdom); Bradley, D.A. [Department of Physics, University of Surrey, Guildford, Surrey GU2 7XH (United Kingdom)


    Hyaluronic acid (HA) is a significant component of the extracellular matrix (ECM), particular interest being shown herein in synovial fluid. The present study aims to investigate the degrading effects of X-ray radiation on HA at radiotherapy doses. Measurements of viscosity and shear stresses on HA solutions have been made at different shear rates using various types of viscometer for different concentrations in the range 0.01-1% w/v of HA. The HA has been subjected to doses of 6 MV photon radiation ranging from 0 to 20 Gy, the major emphasis being on doses below 5 Gy. It is found that there is a dose-dependent relationship between viscosity and shear rate, viscosity reducing with radiation dose, this being related to polymer scissions via the action of radiation-induced free radicals. The dependency appears to become weaker at higher concentrations, possibly due to the contribution to viscosity from polymer entanglement becoming dominant over that from mean molecular weight. Present results, for HA solutions in the concentration range 0.01% to 1% w/v, show reduced viscosity with dose over the range 0-4 Gy, the latter covering the dose regime of interest in fractionated radiotherapy. The work also shows agreement with previous Raman microspectrometry findings by others, the possible bond alterations being defined by comparison with available published data.

  8. Detection of Liposome Membrane Viscosity Perturbations with Ratiometric Molecular Rotors (United States)

    Nipper, Matthew E.; Dakanali, Marianna; Theodorakis, Emmanuel


    Molecular rotors are a form of fluorescent intramolecular charge-transfer complexes that can undergo intramolecular twisting motion upon photoexcitation. Twisted-state formation leads to non-radiative relaxation that competes with fluorescence emission. In bulk solutions, these molecules exhibit a viscosity-dependent quantum yield. On the molecular scale, the fluorescence emission is a function of the local free volume, which in turn is related to the local microviscosity. Membrane viscosity, and the inverse; fluidity, are characteristic terms used to describe the ease of movement withing the membrane. Often, changes in membrane viscosity govern intracellular processes and are indicative of a disease state. Molecular rotors have been used to investigate viscosity changes in liposomes and cells, but accuracy is affected by local concentration gradients and sample optical properties. We have developed self-calibrating ratiometric molecular rotors to overcome this challenge and integrated the new molecules into a DLPC liposome model exposed to the membrane-fluidizing agent propanol. We show that the ratiometric emission intensity linearly decreases with the pentanol exposure and that the ratiometric intensity is widely independent of the total liposome concentration. Conversely, dye concentration inside liposomes influences the sensitivity of the system. We suggest that the new self-calibrating dyes can be used for real-time viscosity sensing in liposome systems with the advantages of lifetime measurements, but with low-cost steady-state instrumentation. PMID:21354253

  9. Probing large viscosities in glass-formers with nonequilibrium simulations (United States)

    Jadhao, Vikram; Robbins, Mark O.


    For decades, scientists have debated whether supercooled liquids stop flowing below a glass transition temperature Tg0 or whether motion continues to slow gradually down to zero temperature. Answering this question is challenging because human time scales set a limit on the largest measurable viscosity, and available data are equally well fit to models with opposite conclusions. Here, we use short simulations to determine the nonequilibrium shear response of a typical glass-former, squalane. Fits of the data to an Eyring model allow us to extrapolate predictions for the equilibrium Newtonian viscosity ηN over a range of pressures and temperatures that change ηN by 25 orders of magnitude. The results agree with the unusually large set of equilibrium and nonequilibrium experiments on squalane and extend them to higher ηN. Studies at different pressures and temperatures are inconsistent with a diverging viscosity at finite temperature. At all pressures, the predicted viscosity becomes Arrhenius with a single temperature-independent activation barrier at low temperatures and high viscosities (ηN>103 Pa ṡs). Possible experimental tests of our results are outlined.

  10. Thermophysical properties of fluids: dynamic viscosity and thermal conductivity (United States)

    Latini, G.


    Thermophysical properties of fluids strongly depend upon atomic and molecular structure, complex systems governed by physics laws providing the time evolution. Theoretically the knowledge of the initial position and velocity of each atom, of the interaction forces and of the boundary conditions, leads to the solution; actually this approach contains too many variables and it is generally impossible to obtain an acceptable solution. In many cases it is only possible to calculate or to measure some macroscopic properties of fluids (pressure, temperature, molar volume, heat capacities...). The ideal gas “law,” PV = nRT, was one of the first important correlations of properties and the deviations from this law for real gases were usefully proposed. Moreover the statistical mechanics leads for example to the “hard-sphere” model providing the link between the transport properties and the molecular size and speed of the molecules. Further approximations take into account the intermolecular interactions (the potential functions) which can be used to describe attractions and repulsions. In any case thermodynamics reduces experimental or theoretical efforts by relating one physical property to another: the Clausius-Clapeyron equation provides a classical example of this method and the PVT function must be known accurately. However, in spite of the useful developments in molecular theory and computers technology, often it is usual to search for physical properties when the existing theories are not reliable and experimental data are not available: the required value of the physical or thermophysical property must be estimated or predicted (very often estimation and prediction are improperly used as synonymous). In some cases empirical correlations are useful, if it is clearly defined the range of conditions on which they are based. This work is concerned with dynamic viscosity µ and thermal conductivity λ and is based on clear and important rules to be respected

  11. LARES Mission: Separation and Retention Subsystem (United States)

    Bursi, Alessandro; Camilli, Pierluigi; Piredda, Claudio; Babini, Gianni; Mangraviti, Elio


    As part of the Lares (LAser RElativity Satellite) mission, an all-Italian scientific mission launched with the Vega maiden flight in February 2012, a mechanical separation and retention subsystem (SSEP) has been developed to retain the LARES satellite during launch and release it in the final orbit. The design flow was based on the identification of the driving requirements and critical areas to guide the trade-off, design, analysis and test activities. In particular, the SSEP had to face very high environmental loads and to minimize the contact areas with the satellite that had a spherical shape. The test activity overview is provided.

  12. Cooking utensil with improved heat retention (United States)

    Potter, Thomas F.; Benson, David K.; Burch, Steven D.


    A cooking utensil with improved heat retention includes an inner pot received within an outer pot and separated in a closely spaced-apart relationship to form a volume or chamber therebetween. The chamber is evacuated and sealed with foil leaves at the upper edges of the inner and outer pot. The vacuum created between the inner and outer pot, along with the minimum of thermal contact between the inner and outer pot, and the reduced radiative heat transfer due to low emissivity coatings on the inner and outer pot, provide for a highly insulated cooking utensil. Any combination of a plurality of mechanisms for selectively disabling and re-enabling the insulating properties of the pot are provided within the chamber. These mechanisms may include: a hydrogen gas producing and reabsorbing device such as a metal hydride, a plurality of metal contacts which can be adjusted to bridge the gap between the inner and outer pot, and a plurality of bimetallic switches which can selectively bridge the gap between the inner and outer pot. In addition, phase change materials with superior heat retention characteristics may be provided within the cooking utensil. Further, automatic and programmable control of the cooking utensil can be provided through a microprocessor and associated hardware for controlling the vacuum disable/enable mechanisms to automatically cook and save food.

  13. Long-time stability effects of quadrature and artificial viscosity on nodal discontinuous Galerkin methods for gas dynamics (United States)

    Durant, Bradford; Hackl, Jason; Balachandar, Sivaramakrishnan


    Nodal discontinuous Galerkin schemes present an attractive approach to robust high-order solution of the equations of fluid mechanics, but remain accompanied by subtle challenges in their consistent stabilization. The effect of quadrature choices (full mass matrix vs spectral elements), over-integration to manage aliasing errors, and explicit artificial viscosity on the numerical solution of a steady homentropic vortex are assessed over a wide range of resolutions and polynomial orders using quadrilateral elements. In both stagnant and advected vortices in periodic and non-periodic domains the need arises for explicit stabilization beyond the numerical surface fluxes of discontinuous Galerkin spectral elements. Artificial viscosity via the entropy viscosity method is assessed as a stabilizing mechanism. It is shown that the regularity of the artificial viscosity field is essential to its use for long-time stabilization of small-scale features in nodal discontinuous Galerkin solutions of the Euler equations of gas dynamics. Supported by the Department of Energy Predictive Science Academic Alliance Program Contract DE-NA0002378.

  14. Influence of processing conditions on apparent viscosity and system parameters during extrusion of distiller's dried grains-based snacks. (United States)

    Singha, Poonam; Muthukumarappan, Kasiviswanathan; Krishnan, Padmanaban


    A combination of different levels of distillers dried grains processed for food application (FDDG), garbanzo flour and corn grits were chosen as a source of high-protein and high-fiber extruded snacks. A four-factor central composite rotatable design was adopted to study the effect of FDDG level, moisture content of blends, extrusion temperature, and screw speed on the apparent viscosity, mass flow rate or MFR, torque, and specific mechanical energy or SME during the extrusion process. With increase in the extrusion temperature from 100 to 140°C, apparent viscosity, specific mechanical energy, and torque value decreased. Increase in FDDG level resulted in increase in apparent viscosity, SME and torque. FDDG had no significant effect (p > .5) on mass flow rate. SME also increased with increase in the screw speed which could be due to the higher shear rates at higher screw speeds. Screw speed and moisture content had significant negative effect ( p  <   .05) on the torque. The apparent viscosity of dough inside the extruder and the system parameters were affected by the processing conditions. This study will be useful for control of extrusion process of blends containing these ingredients for the development of high-protein high-fiber extruded snacks.

  15. Viscosity of neutron star matter and r -modes in rotating pulsars (United States)

    Kolomeitsev, E. E.; Voskresensky, D. N.


    up to 5 n0 (corresponding to the star mass M ≃1.9 M⊙ ). Computed with account of in-medium effects, the frequency boundary of the r -mode stability for the stars with the mass ≳1.8 M⊙ proves to be above the frequencies of all rotating young pulsars. However, none of the conventional contributions to the viscosity are able to explain the stability of rapid rotation of old recycled pulsars in x-ray binaries. To solve this problem we propose a novel efficient mechanism associated with the appearance of condensates of low-lying modes of bosonic excitations with finite momentum and/or with an enhancement of the inhomogeneous pion/kaon condensates in some parts of the star, if the angular velocity exceeds a critical value.

  16. Experimental viscosity measurements of biodiesels at high pressure

    Directory of Open Access Journals (Sweden)

    Schaschke C.J.


    Full Text Available The viscosity of biodiesels of soybean and rapeseed biodiesels blended with mineral diesel fuel were measured at pressures of up to 200 MPa. Using a falling sinker-type viscometer reproducible viscosity data were obtained based on the time taken for a sinker to descend a fixed distance down an enclosed tube under the influence of gravity. Measurements were taken using pressures which correspond to those of interest in automotive common rail diesel engines, and at temperatures of between 25ºC and 80ºC. In all cases, the viscosity of the biodiesel blends were found to increase exponentially for which the blends were noted as being more viscous than pure mineral fuels. A pressure-freezing effect was not observed for the blends.

  17. Measurement of Viscosity of Hydrocarbon Liquids Using a Microviscometer

    DEFF Research Database (Denmark)

    Dandekar, Abhijit; Andersen, Simon Ivar; Stenby, Erling Halfdan


    The viscosity of normal alkanes, their mixtures, and true boiling point (TBP) fractions (C (sub 6) -C (sub 19)) of four North Sea petroleum reservoir fluids have been measured by use of an automatic rolling ball mixroviscometer at 20°C. The equipment is specially suited for samples of limited...... amount as only 120 to 2500 micro l. is required depending on the viscosity range. The densities of the fluids were also determined. The accuracy of these measurements is ascertained and compared with literature data on n-alkane mixtures. The data reported for reservoir fluids includes molecular weights...... as well as density. Finally, generalized viscosity correlations for the C (sub 6) to C (sub 19) fractions are discussed....

  18. Effect of viscosity on appetite and gastro-intestinal hormones

    DEFF Research Database (Denmark)

    Zijlstra, Nicolien; Mars, Monica; de Wijk, René A


    In previous studies we showed that higher viscosity resulted in lower ad libitum intake and that eating rate is an important factor. In this study we aimed to explore the effect of viscosity on the gastro-intestinal hormones ghrelin, CCK-8 and GLP-1. Thirty-two subjects (22+/-2 y, BMI 21.9+/-2.2 kg...... than the liquid. There was a significant product effect for fullness (p 0.03), desire to eat (p 0.04), appetite something sweet (p 0.002) and prospective consumption (p 0.0009). We observed no clear effect of viscosity on gastro-intestinal hormones. Only for desacyl ghrelin there was a significant...

  19. Viscosity Measurement via Drop Coalescence: A Space Station Experiment (United States)

    Antar, Basil; Ethridge, Edwin C.


    The concept of using low gravity experimental data together with CFD simulations for measuring the viscosity of highly viscous liquids was recently validated on onboard the International Space Station (ISS). A series of microgravity tests were conducted for this purpose on the ISS in July, 2004 and in May of 2005. In these experiments two liquid drops were brought manually together until they touched and were allowed to coalesce under the action of the capillary force alone. The coalescence process was recorded photographically from which the contact radius speed of the merging drops was measured. The liquid viscosity was determined by fitting the measured data with accurate numerical simulation of the coalescence process. Several liquids were tested and for each liquid several drop diameters were employed. Experimental and numerical results will be presented in which the viscosity of several highly viscous liquids were determined using this technique.

  20. On the Role of Viscosity in the Eyring Equation. (United States)

    Kistemaker, Jos C M; Lubbe, Anouk S; Bloemsma, Erik A; Feringa, Ben L


    Transition-state theory allows for the characterization of kinetic processes in terms of enthalpy and entropy of activation by using the Eyring equation. However, for reactions in solution, it fails to take the change of viscosity of solvents with temperature into account. A second-generation unidirectional rotary molecular motor was used as a probe to study the effects of temperature-dependent viscosity changes upon unimolecular thermal isomerization processes. By combining the free-volume model with transition-state theory, a modified version of the Eyring equation was derived, in which the rate is expressed in terms of both temperature and viscosity. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Temperature Dependence of the Viscosity of Isotropic Liquids (United States)

    Jadzyn, J.; Czechowski, G.; Lech, T.


    Temperature dependence of the shear viscosity measured for isotropic liquids belonging to the three homologous series: 4-(trans-4'-n-alkylcyclohexyl) isothiocyanatobenzenes (Cn H2n+1 CyHx Ph NCS; nCHBT, n=0-12), n-alkylcyanobiphenyls (CnH2n+1 Ph Ph CN; nCB, n=2-12) and 1,n-alkanediols (HO(CH2)nOH; 1,nAD, n=2-10) were analysed with the use of Arrhenius equation and its two modifications: Vogel--Fulcher and proposed in this paper. The extrapolation of the isothermal viscosity of 1,n-alkanediols (n=2-10) to n=1 leads to an interesting conclusion concerning the expected viscosity of methanediol, HOCH2OH, the compound strongly unstable in a pure state.

  2. Diffusivities and Viscosities of Poly(ethylene oxide) Oligomers †

    KAUST Repository

    Hong, Bingbing


    Diffusivities and viscosities of poly(ethylene oxide) (PEO) oligomer melts with 1 to 12 repeat units have been obtained from equilibrium molecular dynamics simulations using the TraPPE-UA force field. The simulations generated diffusion coefficients with high accuracy for all of the molar masses studied, but the statistical uncertainties in the viscosity calculations were significantly larger for longer chains. There is good agreement of the calculated viscosities and densities with available experimental data, and thus, the simulations can be used to bridge gaps in the data and for extrapolations with respect to chain length, temperature, and pressure. We explored the convergence characteristics of the Green-Kubo formulas for different chain lengths and propose minimal production times required for convergence of the transport properties. The chain-length dependence of the transport properties suggests that neither Rouse nor reptation models are applicable in the short-chain regime investigated. © 2010 American Chemical Society.

  3. The viscosity window of the silicate glass foam production

    DEFF Research Database (Denmark)

    Petersen, Rasmus Rosenlund; König, Jakob; Yue, Yuanzheng


    The production of silicate glass foam allows diverse resources and waste materials to be used in the production. Testing of such large palette of materials complicates and prolongs the optimisation process. Therefore, it is crucial to find a universal criterion for foaming silicate glass melts...... which can offer a practical starting point for the optimisation procedure. The melt viscosity might be the most important parameter for controlling the foaming process and the glass foam density. In this work, we attempt to define a viscosity range in which foaming of different glasses results...... in a maximum of foam expansion. The expansion maximum is obtained for different glasses (labware, E-glass, CRT panel, soda-lime-silica) by foaming with CaCO3 at isokom temperature and from literature data. In general, the viscosity window was found to be within 104–106 Pa s when foaming with MnO2 or metal...

  4. Bulk viscosity of low-temperature strongly interacting matter

    Energy Technology Data Exchange (ETDEWEB)

    Dobado, Antonio [Departamento de Fisica Teorica I, Universidad Complutense de Madrid, 28040 Madrid (Spain); Llanes-Estrada, Felipe J., E-mail: [Departamento de Fisica Teorica I, Universidad Complutense de Madrid, 28040 Madrid (Spain); Torres-Rincon, Juan M. [Departamento de Fisica Teorica I, Universidad Complutense de Madrid, 28040 Madrid (Spain)


    We study the bulk viscosity of a pion gas in unitarized Chiral Perturbation Theory at low and moderate temperatures, below any phase transition to a quark-gluon plasma phase. We argue that inelastic processes are irrelevant and exponentially suppressed at low temperatures. Since the system falls out of chemical equilibrium upon expansion, a pion chemical potential must be introduced, so we extend the existing theories that include it. We control the zero modes of the collision operator and Landau's conditions of fit when solving the Boltzmann equation with the elastic collision kernel. The dependence of the bulk viscosity with temperature is reminiscent of the findings of Fernandez-Fraile and Gomez Nicola (2009) , while the numerical value is closer to that of Davesne (1996) . In the zero-temperature limit we correctly recover the vanishing viscosity associated to a non-relativistic monoatomic gas.

  5. Mapping microbubble viscosity using fluorescence lifetime imaging of molecular rotors (United States)

    Hosny, Neveen A.; Mohamedi, Graciela; Rademeyer, Paul; Owen, Joshua; Wu, Yilei; Tang, Meng-Xing; Eckersley, Robert J.; Stride, Eleanor; Kuimova, Marina K.


    Encapsulated microbubbles are well established as highly effective contrast agents for ultrasound imaging. There remain, however, some significant challenges to fully realize the potential of microbubbles in advanced applications such as perfusion mapping, targeted drug delivery, and gene therapy. A key requirement is accurate characterization of the viscoelastic surface properties of the microbubbles, but methods for independent, nondestructive quantification and mapping of these properties are currently lacking. We present here a strategy for performing these measurements that uses a small fluorophore termed a “molecular rotor” embedded in the microbubble surface, whose fluorescence lifetime is directly related to the viscosity of its surroundings. We apply fluorescence lifetime imaging to show that shell viscosities vary widely across the population of the microbubbles and are influenced by the shell composition and the manufacturing process. We also demonstrate that heterogeneous viscosity distributions exist within individual microbubble shells even with a single surfactant component. PMID:23690599


    Directory of Open Access Journals (Sweden)

    Z.S. Nazirah


    Full Text Available Empty fruit bunches (EFB are one of the solid wastes produced by the palm oil industry, which is increasing rapidly. The aim of this paper is to analyse the viscosity of empty fruit bunch (EFB bio-oil that can be extracted from all solid waste EFB as a sample, and a few processes were executed. The samples underwent two processes, which were pre-treatment and pyrolysis. The pre-treatment involved three processes, namely, cutting, shredding and sieving, which were necessary in order to prepare EFB into a particle size suitable for the reactor. After that, the samples were fed into the feedback reactor as feedstock for the pyrolysis process to produce bio-oil. Once the bio-oil was produced, its viscosity was tested using the Brookfield Viscometer in two conditions: before and after the chemical reaction. The bio-oil was treated by adding 10 ml and 20 ml of acetone respectively through the chemical reaction. The viscosity test was carried out at different temperatures, which were 25°C, 30°C, 35°C, 40°C, 45°C and 50°C respectively. The observed viscosity of the EFB bio-oil varied and was higher as the temperature decreased. In addition, the viscosity of the EFB bio-oil was higher when it reacted chemically with the acetone added. Therefore, the results showed that the chemical reaction with acetone has the potential to increase the viscosity of EFB bio-oil.

  7. Understanding and optimizing the floating body retention in FDSOI UTBOX (United States)

    Aoulaiche, M.; Simoen, E.; Caillat, C.; Witters, L.; Bourdelle, K. K.; Nguyen, B.-Y.; Martino, J.; Claeys, C.; Fazan, P.; Jurczak, M.


    The floating body retention time is investigated on fully depleted SOI devices with UTBOX. The retention is occurring through the junctions and strongly assisted by defects in the junction space charge region during the holding state at a negative gate voltage. For standard devices with a gate overlap, the junction field is high and the dominant mechanism in this case is the generation by band-to-band tunneling. For optimized extensionless devices with lower junction field, the Shockley-Read-Hall generation enhanced by the field and Poole-Frenkel mechanism takes over the band-to-band tunneling. Therefore, reducing the concentration of Si impurities closer to the junctions is the key to approach an ideal retention time only due to band-to-band tunneling with the Si bandgap as the energy barrier for tunneling.

  8. A memory-based model for blood viscosity (United States)

    Ionescu, Clara M.


    This paper presents a comparison between existing models for non-Newtonian fluid viscosity as a function of shear rate variations. A novel model is introduced whose parameters are linked to physiological phenomena in the blood. The end use of such models is to predict changes in viscosity to adapt the speed of a nanorobot device for targeted drug delivery purposes. Simulation results show the agreement between the proposed model and available models from literature. A laboratory scale validation of the proposed model for a fluid mimicking non-Newtonian properties has been performed. Conceptual perspectives are also given in this work.

  9. Analytical shear viscosity in hyperscaling violating black brane (United States)

    Kuang, Xiao-Mei; Wu, Jian-Pin


    In this letter, with the use of matching method, we investigate the shear viscosity in a non-relativistic boundary filed theory without hyperscaling symmetry, which is dual to a bulk charged hyperscaling violating black brane. By matching the solutions to the inner region and outer region at the matching region, we analytically obtain that the ratio of shear viscosity and the entropy density is alway 1 / 4 π at zero temperature and finite temperatures. Our results satisfy the Kovtun-Starinets-Son (KSS) bound.

  10. Viscosity-Induced Crossing of the Phantom Barrier

    Directory of Open Access Journals (Sweden)

    Iver Brevik


    Full Text Available We show explicitly, by using astrophysical data plus reasonable assumptions for the bulk viscosity in the cosmic fluid, how the magnitude of this viscosity may be high enough to drive the fluid from its position in the quintessence region at present time t = 0 across the barrier w = −1 into the phantom region in the late universe. The phantom barrier is accordingly not a sharp mathematical divide, but rather a fuzzy concept. We also calculate the limiting forms of various thermodynamical quantities, including the rate of entropy production, for a dark energy fluid near the future Big Rip singularity.

  11. Time Dependent and Steady Uni-axial Elongational Viscosity

    DEFF Research Database (Denmark)

    Nielsen, Jens K.; Rasmussen, Henrik Koblitz; Hassager, Ole


    Here we present measurements of transient and steady uni-axial elongational viscosity, using the Filament Stretching Rheometer1 or FSR1 (see Fig. 1) of the following melts: Four narrow MMD polystyrene (PS) samples with weight-average molar mass Mw in the range of 50k to 390k. Three different bi......-disperse samples, mixed from the narrow MMD PS. Two low-density polyethylene (LDPE) melts (Lupolen 1840D and 3020D). A steady-state viscosity was kept for 1-2.5 Hencky strain units in all measurements....

  12. Viscosities in the Gluon-Plasma within a Quasiparticle Model

    CERN Document Server

    Bluhm, M; Redlich, K


    A phenomenological quasiparticle model, featuring dynamically generated self-energies of excitation modes, successfully describes lattice QCD results relevant for the QCD equation of state and related quantities both at zero and non-zero net baryon density. Here, this model is extended to study bulk and shear viscosities of the gluon-plasma within an effective kinetic theory approach. In this way, the compatibility of the employed quasiparticle ansatz with the apparent low viscosities of the strongly coupled deconfined gluonic medium is shown.

  13. NVP melt/magma viscosity: insight on Mercury lava flows (United States)

    Rossi, Stefano; Morgavi, Daniele; Namur, Olivier; Vetere, Francesco; Perugini, Diego; Mancinelli, Paolo; Pauselli, Cristina


    After more than four years of orbiting Mercury, NASA's MESSENGER spacecraft came to an end in late April 2015. MESSENGER has provided many new and surprising results. This session will again highlight the latest results on Mercury based on MESSENGER observations or updated modelling. The session will further address instrument calibration and science performance both retrospective on MESSENGER and on the ESA/JAXA BepiColombo mission. Papers covering additional themes related to Mercury are also welcomed. Please be aware that this session will be held as a PICO session. This will allow an intensive exchange of expertise and experience between the individual instruments and mission. NVP melt/magma viscosity: insight on Mercury lava flows S. Rossi1, D. Morgavi1, O. Namur2, D. Perugini1, F.Vetere1, P. Mancinelli1 and C. Pauselli1 1 Dipartimento di Fisica e Geologia, Università di Perugia, piazza Università 1, 06123 Perugia, Italy 2 Uni Hannover Institut für Mineralogie, Leibniz Universität Hannover, Callinstraβe 3, 30167 Hannover, Germany In this contribution we report new measurements of viscosity of synthetic komatitic melts, used the behaviour of silicate melts erupted at the surface of Mercury. Composition of Mercurian surface magmas was calculated using the most recent maps produced from MESSENGER XRS data (Weider et al., 2015). We focused on the northern hemisphere (Northern Volcanic Province, NVP, the largest lava flow on Mercury and possibly in the Solar System) for which the spatial resolution of MESSENGER measurements is high and individual maps of Mg/Si, Ca/Si, Al/Si and S/Si were combined. The experimental starting material contains high Na2O content (≈7 wt.%) that strongly influences viscosity. High temperature viscosity measurements were carried out at 1 atm using a concentric cylinder apparatus equipped with an Anton Paar RheolabQC viscometer head at the Department of Physics and Geology (PVRG_lab) at the University of Perugia (Perugia, Italy

  14. Analytical shear viscosity in hyperscaling violating black brane

    Directory of Open Access Journals (Sweden)

    Xiao-Mei Kuang


    Full Text Available In this letter, with the use of matching method, we investigate the shear viscosity in a non-relativistic boundary filed theory without hyperscaling symmetry, which is dual to a bulk charged hyperscaling violating black brane. By matching the solutions to the inner region and outer region at the matching region, we analytically obtain that the ratio of shear viscosity and the entropy density is alway 1/4π at zero temperature and finite temperatures. Our results satisfy the Kovtun–Starinets–Son (KSS bound.

  15. Viscosity of interfacial water regulates ice nucleation

    Energy Technology Data Exchange (ETDEWEB)

    Li, Kaiyong; Chen, Jing; Zhang, Qiaolan; Zhang, Yifan [Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Green Printing, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Xu, Shun; Zhou, Xin [School of Physics, University of Chinese Academy of Sciences, Beijing 100049 (China); Cui, Dapeng; Wang, Jianjun, E-mail:; Song, Yanlin [Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Green Printing, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190 (China)


    Ice formation on solid surfaces is an important phenomenon in many fields, such as cloud formation and atmospheric icing, and a key factor for applications in preventing freezing. Here, we report temperature-dependent nucleation rates of ice for hydrophilic and hydrophobic surfaces. The results show that hydrophilic surface presents a lower ice nucleation rate. We develop a strategy to extract the thermodynamic parameters, J{sub 0} and Γ, in the context of classical nucleation theory. From the extracted J{sub 0} and Γ, we reveal the dominant role played by interfacial water. The results provide an insight into freezing mechanism on solid surfaces.

  16. Heat transport and coupling modes in Rayleigh-Bénard convection occurring between two layers with largely different viscosities (United States)

    Yoshida, Masaki; Iwamori, Hikaru; Hamano, Yozo; Suetsugu, Daisuke


    A high-resolution numerical simulation model in two-dimensional cylindrical geometry was used to discuss the heat transport and coupling modes in two-layer Rayleigh-Bénard convection with a high Rayleigh number (up to the order of 109), an infinite Prandtl number, and large viscosity contrasts (up to 10-3) between an outer, highly viscous layer (HVL) and an inner, low-viscosity layer (LVL). In addition to mechanical and thermal interaction across the HVL-LVL interface, which has been investigated by Yoshida and Hamano ["Numerical studies on the dynamics of two-layer Rayleigh-Bénard convection with an infinite Prandtl number and large viscosity contrasts," Phys. Fluids 28(11), 116601 (2016)], the spatiotemporal analysis in this study provides new insights into (1) heat transport over the entire system between the bottom of the LVL and the top of the HVL, in particular that associated with thermal plumes, and (2) the convection regime and coupling mode of the two layers, including the transition mechanism between the mechanical coupling mode at relatively low viscosity contrasts and the thermal coupling mode at higher viscosity contrasts. Although flow in the LVL is highly time-dependent, it shares the spatially opposite/same flow pattern synchronized to the nearly stationary upwelling and downwelling plumes in the HVL, corresponding to the mechanical/thermal coupling mode. In the transitional regime between the mechanical and thermal coupling modes, the LVL exhibits periodical switching between the two phases (i.e., the mechanical and thermal coupling phases) with a stagnant period. A detailed inspection revealed that the switching was initiated by the instability in the uppermost boundary layer of the LVL. These results suggest that convection in the highly viscous mantle of the Earth controls that of the extremely low-viscosity outer core in a top-down manner under the thermal coupling mode, which may support a scenario of top-down hemispherical dynamics

  17. Evidence for a Role of Vascular Endothelium in the Control of Arterial Wall Viscosity in Humans. (United States)

    Roca, Frederic; Iacob, Michele; Remy-Jouet, Isabelle; Bellien, Jeremy; Joannides, Robinson


    Arterial wall viscosity (AWV) is a major cause of energy dissipation along the arterial tree. Its determinants remain controversial but an active endothelial regulation has been suggested. Our objective was to assess in humans the physiological role of endothelium-derived nitric oxide (NO), epoxyeicosatrienoic acids and the effect of modulating smooth muscle tone in the regulation of AWV. We simultaneously measured radial artery diameter, wall thickness, and arterial pressure in healthy volunteers during the local infusion of inhibitors of NO-synthase ( N G -monomethyl-l-arginine), epoxyeicosatrienoic acids synthesis by cytochrome P450 (fluconazole), the epoxyeicosatrienoic acids cellular targets calcium-activated potassium channels (tetraethylammonium), alone and in combination. AWV was estimated from the relative viscosity expressed as the ratio of the area of the hysteresis loop of the pressure-diameter relationship to the area under the loading phase. Arterial tone was assessed by measuring change in wall stiffness and midwall stress. N G -monomethyl-l-arginine paradoxically reduced relative viscosity (34.9±8.9%-28.9±8.6%). Conversely, relative viscosity was not modified by fluconazole (33.5±15.5%-32.0±13.6%) but increased by tetraethylammonium (31.7±6.6%-35.7±8.0%). This increase was more marked with N G -monomethyl-l-arginine+fluconazole (31.1±10.7%-43.3±13.2%) and N G -monomethyl-l-arginine+tetraethylammonium (29.5±2.3%-41.5±11.1%) compared with inhibitors alone. Sodium nitroprusside decreased AWV (35.4±2.9%-28.7±2.0%). These effects were associated with parallel change in tone but of different magnitude for similar variations in viscosity, suggesting tone-dependent and independent mechanisms. In conclusion, this is the first demonstration that the endothelial factors, NO and epoxyeicosatrienoic acids, regulate AWV in humans and support the role of arterial tone in this regulation. URL: Unique identifier: RCB2007-A

  18. Radionuclide Retention in Concrete Waste Forms

    Energy Technology Data Exchange (ETDEWEB)

    Mattigod, Shas V.; Bovaird, Chase C.; Wellman, Dawn M.; Wood, Marcus I.


    Assessing long-term performance of Category 3 waste cement grouts for radionuclide encasement requires knowledge of the radionuclide-cement interactions and mechanisms of retention (i.e., sorption or precipitation); the mechanism of contaminant release; the significance of contaminant release pathways; how waste form performance is affected by the full range of environmental conditions within the disposal facility; the process of waste form aging under conditions that are representative of processes occurring in response to changing environmental conditions within the disposal facility; the effect of waste form aging on chemical, physical, and radiological properties; and the associated impact on contaminant release. This knowledge will enable accurate prediction of radionuclide fate when the waste forms come in contact with groundwater. The information presented in the report provides data that 1) quantify radionuclide retention within concrete waste form materials similar to those used to encapsulate waste in the Low-Level Waste Burial Grounds (LLBG); 2) measure the effect of concrete waste form properties likely to influence radionuclide migration; and 3) quantify the stability of uranium-bearing solid phases of limited solubility in concrete.

  19. Radionuclide Retention in Concrete Wasteforms - FY13

    Energy Technology Data Exchange (ETDEWEB)

    Snyder, Michelle MV; Golovich, Elizabeth C.; Wellman, Dawn M.; Crum, Jarrod V.; Lapierre, Robert; Dage, Denomy C.; Parker, Kent E.; Cordova, Elsa A.


    Assessing long-term performance of Category 3 waste cement grouts for radionuclide encasement requires knowledge of the radionuclide-cement interactions and mechanisms of retention (i.e., sorption or precipitation); the mechanism of contaminant release; the significance of contaminant release pathways; how wasteform performance is affected by the full range of environmental conditions within the disposal facility; the process of wasteform aging under conditions that are representative of processes occurring in response to changing environmental conditions within the disposal facility; the effect of wasteform aging on chemical, physical, and radiological properties; and the associated impact on contaminant release. This knowledge will enable accurate prediction of radionuclide fate when the wasteforms come in contact with groundwater. Data collected throughout the course of this work will be used to quantify the efficacy of concrete wasteforms, similar to those used in the disposal of low-level waste and mixed low-level waste, for the immobilization of key radionuclides (i.e., uranium, technetium, and iodine). Data collected will also be used to quantify the physical and chemical properties of the concrete affecting radionuclide retention.

  20. Effect of Retention Time on Biogas Production from Poultry ...

    African Journals Online (AJOL)


    nitrogen and volatile acids were measured by Pearson method (Perason, 1976). Gas production in different retention time: Gas production was measured daily using the system of water displacement. A gas compressor is a mechanical device that increases the pressure of gas by reducing its volume, which obeys Boyle's ...

  1. Sodium retention by insulin may depend on decreased plasma potassium

    NARCIS (Netherlands)

    Friedberg, C. E.; Koomans, H. A.; Bijlsma, J. A.; Rabelink, T. J.; Dorhout Mees, E. J.


    Evidence is accumulating that insulin is a hypertensive factor in humans. The involved mechanism may be its sodium-retaining effect. We examined whether insulin causes sodium retention through a direct action on the kidney, as is generally assumed, or indirectly through hypokalemia. Insulin was

  2. Morphological transformations of native petroleum emulsions. I. Viscosity studies. (United States)

    Evdokimov, Igor N; Efimov, Yaroslav O; Losev, Aleksandr P; Novikov, Mikhail A


    Emulsions of water in as-recovered native crude oils of diverse geographical origin evidently possess some common morphological features. At low volume fractions varphi of water, the viscosity behavior of emulsions is governed by the presence of flocculated clusters of water droplets, whereas characteristic tight gels, composed of visually monodisperse small droplets, are responsible for the viscosity anomaly at varphi approximately 0.4-0.5. Once formed, small-droplet gel domains apparently retain their structural integrity at higher varphi, incorporating/stabilizing new portions of water as larger-sized droplets. The maximum hold-up of disperse water evidently is the close-packing limit of varphi approximately 0.74. At higher water contents (up to varphi approximately 0.83), no inversion to O/W morphology takes place, but additional water emerges as a separate phase. The onset of stratified flow (W/O emulsion gel + free water) is the cause of the observed viscosity decrease, contrary to the conventional interpretation of the viscosity maximum as a reliable indicator of the emulsion inversion point.

  3. Effect of electrochemical oxidation of a viscose rayon based ...

    African Journals Online (AJOL)

    A viscose rayon based activated carbon cloth (ACC) was electrochemically oxidised to enhance its cation sorption capacity for comparison with as-received ACC. ACCs were characterised by sodium capacity measurement, pH titration, zeta potential measurement, elemental analysis, Brunauer-Emmet- Teller surface area ...

  4. The effect of viscosity on ad libitum food intake

    NARCIS (Netherlands)

    Zijlstra, N.; Mars, M.; Wijk, de R.A.; Westerterp-Plantenga, M.; Graaf, de C.


    Background: Energy-yielding liquids elicit weak suppressive appetite responses and weak compensatory responses, suggesting that liquid calories might lead to a positive energy balance. However, data is often derived from foods differing in many characteristics other than viscosity. Objective: To

  5. Upper mantle viscosity and lithospheric thickness under Iceland

    NARCIS (Netherlands)

    Barnhoorn, A.; Wal, W. van der; Drury, M.R.


    Deglaciation during the Holocene on Iceland caused uplift due to glacial isostatic adjustment. Relatively low estimates for the upper mantle viscosity and lithospheric thickness result in rapid uplift responses to the deglaciation cycles on Iceland. The relatively high temperatures of the upper

  6. The effects of gold nanoparticles size and concentration on viscosity ...

    African Journals Online (AJOL)

    This study was carried out to investigate viscosity in relation with the temperature, flow activation energy and dielectric properties for 10, 20 and 50 nm gold nanoparticles size (GNPs) in addition to absorption and fluorescence spectra at different concentrations (0.2 × 10-3 to 1 × 10-2%) in an attempt to cover and understand ...

  7. Viscosity and Electrical Conductivity of Concentrated Solutions of Soluble Coffee

    Czech Academy of Sciences Publication Activity Database

    Sobolík, Václav; Žitný, R.; Tovčigrečko, Valentin; Delgado, M.; Allaf, K.


    Roč. 51, č. 2 (2002), s. 93-98 ISSN 0260-8774 Institutional research plan: CEZ:AV0Z4072921; CEZ:MSM 212200008 Keywords : coffee extract * soluble coffee * viscosity Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 1.085, year: 2002

  8. On the Role of Viscosity in the Eyring Equation

    NARCIS (Netherlands)

    Kistemaker, Jos C. M.; Lubbe, Anouk S.; Bloemsma, Erik A.; Feringa, Ben L.


    Transition-state theory allows for the characterization of kinetic processes in terms of enthalpy and entropy of activation by using the Eyring equation. However, for reactions in solution, it fails to take the change of viscosity of solvents with temperature into account. A second-generation

  9. Effect of fluid viscosity on fault frictional behavior (United States)

    Cornelio, Chiara; Violay, Marie; Spagnuolo, Elena; Di Toro, Giulio


    Fluids play an important role in fault zone and in earthquakes generation. Fluid pressure reduces the normal effective stress, lowering the frictional strength of the fault, potentially triggering earthquake ruptures. Fluid injection induced earthquakes, such as in geothermal reservoir, are direct evidence of the effect of fluid pressure on the fault strength. However, the frictional fault strength may also vary due to the chemical and physical characteristics of the fluid as discussed here. Here we performed two series of experiments on precut samples of Westerly granite to investigate the role of fluid viscosity on fault frictional behavior. In the first series, we performed 20 rotary shear experiments with the machine SHIVA (INGV, Rome) on cylindrical (50 mm external diameter), at slip rate (V) ranging from 10 μ m/s to 1 m/s effective normal stress (P) of 10 MPa and pore pressure varying from 0 ( i.e., dry conditions) to 2 MPa. Three different fluid viscosities were tested using pure distilled water (η=1 mPa\\cdot s), 40{%}water/60{%}glycerol (η =10.5 mPa\\cdot s) and 15{%}water/85{%}glycerol (η=109 mPa\\cdot s) mixtures (all reported viscosities at 20 rC). In agreement with theoretical argumentations (Stribeck curve) we distinguished three lubrication regimes. At low product of slip-rate per fluid viscosity (S= η\\cdot V/P

  10. Changes in the viscosity and energy density of weaning maize ...

    African Journals Online (AJOL)

    The effect of replacing 25% of the basic maize flour with groundnut paste (w/w) and/or 10% of the liquid ingredients with fresh dairy milk (v/v) on the viscosity and energy density of weaning maize porridge was investigated in a 2• fractional factorial experiment. Other factors investigated included (i) particle size of the flour (ii) ...

  11. Does polar interaction influence medium viscosity? A computer ...

    Indian Academy of Sciences (India)

    Abstract. Molecular dynamics simulations of model liquids interacting via Lennard–Jones (L–J) and. Stockmayer (SM) interactions have been carried out to explore the effects of the longer-ranged dipole–dipole interaction on solvent viscosity and diffusion. Switching on of the dipolar interaction at a fixed density and tem-.

  12. A comparative study of regenerated bamboo, cotton and viscose ...

    African Journals Online (AJOL)

    Apart from the claimed “cool feeling”, the comfort properties referred to in the promotion of bamboo viscose fabrics can generally be ascribed to most cellulose fibres or fabrics. The purpose of this study was to investigate whether the moisture management and thermo-physiological properties of regenerated bamboo fabrics ...

  13. The Asymptotic Solution for the Steady Variable-Viscosity Free ...

    African Journals Online (AJOL)

    Under an arbitrary time-dependent heating of an infinite vertical plate (or wall), the steady viscosity-dependent free convection flow of a viscous incompressible fluid is investigated. Using the asymptotic method of solution on the governing equations of motion and energy, the resulting Ordinary differential equations were ...

  14. The Unsteady Variable – Viscosity Free Convection Flow on a ...

    African Journals Online (AJOL)

    The unsteady variable-viscosity free convection flow of a viscous incompressible fluid near an infinite vertical plate (or wall) is investigated under an arbitrary timedependent heating of the plates, and the governing equations of motion and energy transformed into ordinary differential equations. Employing asymptotic ...

  15. Highly Branched Polyethylenes as Lubricant Viscosity and Friction Modifiers

    Energy Technology Data Exchange (ETDEWEB)

    Robinson, Joshua W.; Zhou, Yan; Qu, Jun; Bays, John T.; Cosimbescu, Lelia


    A series of highly branched polyethylenes (BPE) were prepared and used in a Group I base oil as potential viscosity and friction modifiers. The lubricating performance of these BPEs supports the expected dual functionality. Changes in polarity, topology, and molecular weight of the BPEs showed significant effects on the lubricants’ performance, which provide scientific insights for polymer design in future lubricant development.

  16. Origin of apparent viscosity in yield stress fluids below yielding

    NARCIS (Netherlands)

    Møller, P.C.F.; Fall, A.; Bonn, D.


    For more than 20 years it has been debated if yield stress fluids are solid below the yield stress or actually flow; whether true yield stress fluids exist or not. Advocates of the true yield stress picture have demonstrated that the effective viscosity increases very rapidly as the stress is

  17. Does polar interaction influence medium viscosity? A computer ...

    Indian Academy of Sciences (India)

    L-J) and Stockmayer (SM) interactions have been carried out to explore the effects of the longer-ranged dipole-dipole interaction on solvent viscosity and diffusion. Switching on of the dipolar interaction at a fixed density and temperature has ...

  18. Bulk viscosity of strange quark matter in density dependent quark ...

    Indian Academy of Sciences (India)

    Abstract. We have studied the bulk viscosity of strange quark matter in the density dependent quark mass model (DDQM) and compared results with calculations done earlier in the MIT bag model where u, d masses were neglected and first order interactions were taken into account. We find that at low temperatures and ...

  19. Intrinsic viscosity of guar gum in sweeteners solutions | Samavati ...

    African Journals Online (AJOL)

    Rheological methods were applied to study the effect of sweeteners on the rheological behavior of guar gum in dilute solutions. The concentration of the sweeteners were 0.1, 0.2%w/v for aspartame, acesulfame-k and cyclamate, and 0.001, 0.002%w/v for neotame. Gum was evaluated for intrinsic viscosity by various ...

  20. Pendulum Underwater--An Approach for Quantifying Viscosity (United States)

    Leme, José Costa; Oliveira, Agostinho


    The purpose of the experiment presented in this paper is to quantify the viscosity of a liquid. Viscous effects are important in the flow of fluids in pipes, in the bloodstream, in the lubrication of engine parts, and in many other situations. In the present paper, the authors explore the oscillations of a physical pendulum in the form of a long…

  1. Phase and viscosity behaviour of refrigerant-lubricant mixtures

    DEFF Research Database (Denmark)

    Cisneros, Sergio; Garcia, J.; Fernandez, J.


    , mainly as a function of the molecular asymmetry. This also has a profound effect in the mixture transport properties. Thus, in this work the general aspects of phase and viscosity behaviour linked to the type of asymmetry found in refrigerant-lubricant mixtures are discussed in the context of phase...

  2. Electrical conductivity and viscosity of borosilicate glasses and melts

    DEFF Research Database (Denmark)

    Ehrt, Doris; Keding, Ralf


    by impedance measurements in a wide temperature range (250 to 1450°C). The activation energies were calculated by Arrhenius plots in various temperature regions: below the glass transition temperature, Tg, above the melting point, Tl, and between Tg and Tl. Viscosity measurements were carried out...

  3. Measuring Viscosity with a Levitating Magnet: Application to Complex Fluids (United States)

    Even, C.; Bouquet, F.; Remond, J.; Deloche, B.


    As an experimental project proposed to students in fourth year of university, a viscometer was developed, consisting of a small magnet levitating in a viscous fluid. The viscous force acting on the magnet is directly measured: viscosities in the range 10-10[superscript 6] mPa s are obtained. This experiment is used as an introduction to complex…

  4. Viscosity solutions of fully nonlinear functional parabolic PDE

    Directory of Open Access Journals (Sweden)

    Liu Wei-an


    Full Text Available By the technique of coupled solutions, the notion of viscosity solutions is extended to fully nonlinear retarded parabolic equations. Such equations involve many models arising from optimal control theory, economy and finance, biology, and so forth. The comparison principle is shown. Then the existence and uniqueness are established by the fixed point theory.

  5. Prothrombin time and relative plasma viscosity of hypertensive ...

    African Journals Online (AJOL)

    A study of the prothrombin time and relative plasma viscosity of hypertensive patients attending University of Calabar Teaching Hospital was conducted. Three hundred (300) male and female subjects aged 25 - 65 years were enrolled for the study. Two hundred (200) subjects were hypertensive, while 100 apparently ...

  6. Elongational viscosity of monodisperse and bidisperse polystyrene melts

    DEFF Research Database (Denmark)

    Nielsen, Jens Kromann; Rasmussen, Henrik Koblitz; Hassager, Ole


    The startup and steady uniaxial elongational viscosity have been measured for two monodisperse polystyrene melts with molecular weights of 52 kg/mole (PS52K) and 103 kg/mole (PS103K), and for three bidisperse polystyrene melts. The bidisperse melts consist of PS103K or PS52K and a monodisperse...... (closed loop proportional regulator) using the laser in such a way that the stretch rate at the neck is kept constant. The rheometer has been described in more detail in (A. Bach, H.K. Rasmussen and O. Hassager, Journal of Rheology, 47 (2003) 429). PS390K show a decrease in the steady viscosity as a power......-law function of the elongational rate (A. Bach, K. Almdal, H.K. Rasmussen and O. Hassager, Macromolecules 36 (2003) 5174). PS52K and PS103K show that the steady viscosity has a maximum that is respectively 100% and 50% above 3 times the zero-shear-rate viscosity. The bidisperse melts show a significant...

  7. Variable viscosity effects on mixed convection heat and mass ...

    African Journals Online (AJOL)

    An analysis is carried out to study the viscous dissipation and variable viscosity effects on the flow, heat and mass transfer characteristics in a viscous fluid over a semi-infinite vertical porous plate in the presence of chemical reaction. The governing boundary layer equations are written into a dimensionless form by similarity ...

  8. Viscosity solutions to delay differential equations in demo-economy


    Fabbri, Giorgio


    Economic and demographic models governed by linear delay differential equations are expressed as optimal control problems in infinite dimensions. A general objective function is considered and the concavity of the Hamiltonian is not required. The value function is a viscosity solution of the Hamilton-Jacobi-Bellman (HJB) equation and a verification theorem is proved.

  9. Effects of iron oxidation state on viscosity, lunar composition 15555 (United States)

    Cukierman, M.; Uhlmann, D. R.


    The viscous flow behavior of a 9.6-kg lunar rock containing 22.5 wt.% FeO was studied in the temperature ranges from 620 to 700 C and from 1215 to 1400 C. The material was synthesized under mildy reducing conditions to simulate the Fe(2+)/total Fe ratio of the lunar environment. The effect of iron oxidation state on flow behavior in the high viscosity region is studied for specimens of the 15555 composition with Fe(2+) concentration ratios of 0.94, 0.76, and 0.20. A change in ratio from 0.94 to 0.76 had no observable effect on viscosity, whereas a change from 0.76 to 0.20 was accompanied by a drastic increase in viscosity (some three orders of magnitude) at a given temperature, but without changing the form of the variation of viscosity with temperature. The flow behavior is analyzed as a function of the structural features of the glasses.

  10. Passive non-linear microrheology for determining extensional viscosity (United States)

    Hsiao, Kai-Wen; Dinic, Jelena; Ren, Yi; Sharma, Vivek; Schroeder, Charles M.


    Extensional viscosity is a key property of complex fluids that greatly influences the non-equilibrium behavior and processing of polymer solutions, melts, and colloidal suspensions. In this work, we use microfluidics to determine steady extensional viscosity for polymer solutions by directly observing particle migration in planar extensional flow. Tracer particles are suspended in semi-dilute solutions of DNA and polyethylene oxide, and a Stokes trap is used to confine single particles in extensional flows of polymer solutions in a cross-slot device. Particles are observed to migrate in the direction transverse to flow due to normal stresses, and particle migration is tracked and quantified using a piezo-nanopositioning stage during the microfluidic flow experiment. Particle migration trajectories are then analyzed using a second-order fluid model that accurately predicts that migration arises due to normal stress differences. Using this analytical framework, extensional viscosities can be determined from particle migration experiments, and the results are in reasonable agreement with bulk rheological measurements of extensional viscosity based on a dripping-onto-substrate method. Overall, this work demonstrates that non-equilibrium properties of complex fluids can be determined by passive yet non-linear microrheology.

  11. Measurement of gas viscosity using photonic crystal fiber (United States)

    Gao, R.-K.; Sheehe, S. L.; Kurtz, J.; O'Byrne, S.


    A new measurement technique for gas viscosity coefficient is designed and demonstrated using the technique of tunable diode laser absorption spectroscopy (TDLAS). Gas flow is driven by a pressure gradient between two gas cells, through a photonic crystal fiber (PCF) surrounded by a furnace for temperature adjustment. PCF with 20-micron diameter affords physical space for gas-light interaction and provides a basis for gas viscosity measurement by determining the time for flow to exit a capillary tube under the influence of a pressure gradient. Infrared radiation from a diode laser is coupled into the fiber to be guided through the gas, and the light attenuation due to absorption from the molecular absorbing species is measured by a photo detector placed at the exit of the fiber. A numerical model from Sharipov and Graur describing local number density distribution in a unsteady state is applied for the determination of gas viscosity, based on the number density of gas measured by the absorption of the laser light, using the Beer-Lambert law. The measurement system is confirmed by measuring the viscosity of CO2 as a reference gas.

  12. Density and viscosity of magnesium sulphate in formamide + ...

    Indian Academy of Sciences (India)

    Abstract. Densities (ρ) and viscosities (η) of different strengths of magnesium sulphate (MgSO4) in varying proportions of formamide (FA) + ethylene glycol as mixed solvents were measured at room temperature. The experimental values of ρ and η were used to calculate the values of the apparent molar volume, (φv), partial ...

  13. Estimation of the viscosities of liquid binary alloys (United States)

    Wu, Min; Su, Xiang-Yu


    As one of the most important physical and chemical properties, viscosity plays a critical role in physics and materials as a key parameter to quantitatively understanding the fluid transport process and reaction kinetics in metallurgical process design. Experimental and theoretical studies on liquid metals are problematic. Today, there are many empirical and semi-empirical models available with which to evaluate the viscosity of liquid metals and alloys. However, the parameter of mixed energy in these models is not easily determined, and most predictive models have been poorly applied. In the present study, a new thermodynamic parameter Δ G is proposed to predict liquid alloy viscosity. The prediction equation depends on basic physical and thermodynamic parameters, namely density, melting temperature, absolute atomic mass, electro-negativity, electron density, molar volume, Pauling radius, and mixing enthalpy. Our results show that the liquid alloy viscosity predicted using the proposed model is closely in line with the experimental values. In addition, if the component radius difference is greater than 0.03 nm at a certain temperature, the atomic size factor has a significant effect on the interaction of the binary liquid metal atoms. The proposed thermodynamic parameter Δ G also facilitates the study of other physical properties of liquid metals.

  14. Variable viscosity effects on mixed convection heat and mass ...

    African Journals Online (AJOL)

    DR OKE

    porous medium, Physics Letters A, Vol. 372, 14, pp 2355-2358. Jayanthi S. and Kumari M., 2007. Effect of variable viscosity on non-Darcy free or mixed convection flow on a vertical surface in a fluid saturated porous medium, Applied Mathematics and Computations, Vol.186, 2, pp 1643-1659. Kafoussius N.G. and Williams ...

  15. Effects of Nattokinase on Whole Blood Viscosity and Mortality

    Directory of Open Access Journals (Sweden)

    Melike Cengiz


    Full Text Available Objective: Nattokinase is a serin protease having potent fibrinolytic effect derived from fermentation of boiled soy bean by the use of Basillus Subtilis Natto. The aim of this experimental study is to investigate the effects of intragastric Nattokinase (6 mg/day administration for 7 days prior to formation of sepsis on plasma fibrinogen levels, whole blood viscosity and mortality in rats. Materials and Methods: Intraabdominal sepsis were performed by cecal ligation and puncture in rats supplemented with nattokinase or olive oil for 7 days prior to sepsis formation. Plasma fibrinogen, whole blood viscosity analysis and survival analysis was performed after intraabdominal sepsis formation. Results: Mean blood viscosity of rats was lower in Nattokinase and cecal ligation group at lowest shear rate (p<0.05. However, the differences between groups were not significant at higher shear rates. No difference was found in survival rates and survival times of Nattokinase and cecal ligation and cecal ligation and puncture groups. Conclusion: Our results were unable to show the effects of intragastric nattokinase supplementation prior to sepsis on plasma fibrinogen levels or whole blood viscosity, except low shear rate. Nattokinase did not altered survival in septic rats. (Journal of the Turkish Society Intensive Care 2011; 9: 85-9

  16. The adhesive strength and initial viscosity of denture adhesives. (United States)

    Han, Jian-Min; Hong, Guang; Dilinuer, Maimaitishawuti; Lin, Hong; Zheng, Gang; Wang, Xin-Zhi; Sasaki, Keiichi


    To examine the initial viscosity and adhesive strength of modern denture adhesives in vitro. Three cream-type denture adhesives (Poligrip S, Corect Cream, Liodent Cream; PGS, CRC, LDC) and three powder-type denture adhesives (Poligrip Powder, New Faston, Zanfton; PGP, FSN, ZFN) were used in this study. The initial viscosity was measured using a controlled-stress rheometer. The adhesive strength was measured according to ISO-10873 recommended procedures. All data were analyzed independently by one-way analysis of variance combined with a Student-Newman-Keuls multiple comparison test at a 5% level of significance. The initial viscosity of all the cream-type denture adhesives was lower than the powder-type adhesives. Before immersion in water, all the powder-type adhesives exhibited higher adhesive strength than the cream-type adhesives. However, the adhesive strength of cream-type denture adhesives increased significantly and exceeded the powder-type denture adhesives after immersion in water. For powder-type adhesives, the adhesive strength significantly decreased after immersion in water for 60 min, while the adhesive strength of the cream-type adhesives significantly decreased after immersion in water for 180 min. Cream-type denture adhesives have lower initial viscosity and higher adhesive strength than powder type adhesives, which may offer better manipulation properties and greater efficacy during application.

  17. Anisotropic cosmological models with bulk viscosity and particle ...

    Indian Academy of Sciences (India)

    equations in two types of cosmologies, one with power-law expansion and the other with expo- nential expansion. Cosmological model with power-law expansion has a Big-Bang singularity at time t = 0, whereas the model with exponential expansion has no finite singularity. We study bulk viscosity and particle creation in ...

  18. Anisotropic cosmological models with bulk viscosity and particle ...

    Indian Academy of Sciences (India)

    Particle creation and bulk viscosity are considered as separate irreversible processes. The energy–momentum tensor is modified to accommodate the viscous pressure and creation pressure which is associated with the creation of matter out of gravitational field. A special law of variation of Hubble parameter is applied to ...

  19. Steady shear viscosity of stirred yoghurts with varying ropiness

    NARCIS (Netherlands)

    van Marle, M.E.; van Marle, M.E.; van den Ende, Henricus T.M.; de Kruif, C.G.; de Kruif, C.G.; Mellema, J.


    Stirred yogurt was viewed as a concentrated dispersion of aggregates consisting of protein particles. The steady-shear behavior of three types of stirred yogurt with varying ropiness was investigated experimentally. To describe the shear-dependent viscosity, a microrheological model was used which

  20. A comparative study of regenerated bamboo, cotton and viscose ...

    African Journals Online (AJOL)

    Since regenerated bamboo fibres (also referred to as bamboo viscose) became commercially available in 2006, consumers have been bombarded with contradictory information regarding products made of these fibres, their potential end-uses and their properties. On the one hand, manufacturers and marketers make ...

  1. Sensitivity of viscosity Arrhenius parameters to polarity of liquids (United States)

    Kacem, R. B. H.; Alzamel, N. O.; Ouerfelli, N.


    Several empirical and semi-empirical equations have been proposed in the literature to estimate the liquid viscosity upon temperature. In this context, this paper aims to study the effect of polarity of liquids on the modeling of the viscosity-temperature dependence, considering particularly the Arrhenius type equations. To achieve this purpose, the solvents are classified into three groups: nonpolar, borderline polar and polar solvents. Based on adequate statistical tests, we found that there is strong evidence that the polarity of solvents affects significantly the distribution of the Arrhenius-type equation parameters and consequently the modeling of the viscosity-temperature dependence. Thus, specific estimated values of parameters for each group of liquids are proposed in this paper. In addition, the comparison of the accuracy of approximation with and without classification of liquids, using the Wilcoxon signed-rank test, shows a significant discrepancy of the borderline polar solvents. For that, we suggested in this paper new specific coefficient values of the simplified Arrhenius-type equation for better estimation accuracy. This result is important given that the accuracy in the estimation of the viscosity-temperature dependence may affect considerably the design and the optimization of several industrial processes.

  2. Acute urinary retention in a young man secondary to colonic irrigation: a case report

    Directory of Open Access Journals (Sweden)

    Raheem Omer A


    Full Text Available Abstract Introduction Autonomic innervation of the bladder is complex and regulated by a hierarchy of mechanisms of the central nervous system. Any dysfunction in these regulatory mechanisms can lead to acute urinary retention. Case presentation A 36-year-old Caucasian man presented with acute urinary retention following extensive bowel irrigation. His urinary bladder was decompressed and his normal voiding mechanism was restored thereafter. Conclusion We postulate that prolonged anorectal and sigmoid dilatation can stimulate the recto-vesicourethral reflex and lead to acute urinary retention via autonomic dysfunction.

  3. Magmatic Focusing to Mid-Ocean Ridges: The Role of Grain-Size Variability and Non-Newtonian Viscosity (United States)

    Turner, Andrew J.; Katz, Richard F.; Behn, Mark D.; Keller, Tobias


    Melting beneath mid-ocean ridges occurs over a region that is much broader than the zone of magmatic emplacement that forms the oceanic crust. Magma is focused into this zone by lateral transport. This focusing has typically been explained by dynamic pressure gradients associated with corner flow, or by a sublithospheric channel sloping upward toward the ridge axis. Here we discuss a novel mechanism for magmatic focusing: lateral transport driven by gradients in compaction pressure within the asthenosphere. These gradients arise from the covariation of melting rate and compaction viscosity. The compaction viscosity, in previous models, was given as a function of melt fraction and temperature. In contrast, we show that the viscosity variations relevant to melt focusing arise from grain-size variability and non-Newtonian creep. The asthenospheric distribution of melt fraction predicted by our models provides an improved explanation of the electrical resistivity structure beneath one location on the East Pacific Rise. More generally, we find that although grain-size and non-Newtonian viscosity are properties of the solid phase, their effect on melt transport beneath mid-ocean ridges is more profound than their effect on the mantle corner flow.

  4. Effect of Boric Acid Concentration on Viscosity of Slag and Property of Weld Metal Obtained from Underwater Wet Welding (United States)

    Guo, Ning; Guo, Wei; Xu, Changsheng; Du, Yongpeng; Feng, Jicai


    Underwater wet welding is a crucial repair and maintenance technology for nuclear plant. A boric acid environment raises a new challenge for the underwater welding maintenance of nuclear plant. This paper places emphasis on studying the influence of a boric acid environment in nuclear plant on the underwater welding process. Several groups of underwater wet welding experiments have been conducted in boric acid aqueous solution with different concentration (0-35000 ppm). The viscosity of the welding slag and the mechanical properties of welds, such as the hardness, strength, and elongation, have been studied. The results show that with increasing boric acid concentration, the viscosity of the slag decreases first and then increases at a lower temperature (less than 1441 °C). However, when the temperature is above 1480 °C, the differences between the viscosity measurements become less pronounced, and the viscosity tends to a constant value. The hardness and ductility of the joints can be enhanced significantly, and the maximum strength of the weld metal can be reached at 2300 ppm.

  5. Universality of the high-temperature viscosity limit of silicate liquids

    DEFF Research Database (Denmark)

    Zheng, Qiuju; Mauro, John C.; Ellison, Adam J.


    We investigate the high-temperature limit of liquid viscosity by analyzing measured viscosity curves for 946 silicate liquids and 31 other liquids including metallic, molecular, and ionic systems. Our results show no systematic dependence of the high-temperature viscosity limit on chemical...... composition for the studied liquids. Based on theMauro-Yue-Ellison-Gupta-Allan (MYEGA) model of liquid viscosity, the high-temperature viscosity limit of silicate liquids is 10−2.93 Pa·s. Having established this value, there are only two independent parameters governing the viscosity-temperature relation...

  6. Research on viscosity of metal at high pressure (United States)

    Li, Y.; Liu, F.; Ma, X.; Zhang, M.


    A new experimental technique, the flyer-impact method, is proposed in this article to investigate the viscosity coefficient of shocked metals. In this technique, a shock wave with a sinusoidal perturbation on the front is induced by the sinusoidal profile of the impact surface of the sample by use of a two-stage light-gas gun, and the oscillatory damping process of the perturbation amplitude is monitored by electric pins. The damping processes of aluminum at 78 and 101 GPa and iron at 159 and 103 GPa are obtained by this technique, which supplement the existing data by measuring the viscosity coefficient via a dynamic high-pressure method. Applying the formula of Miller and Ahrens to fit the experimental data, the shear viscosity coefficients of aluminum at 78 and 101 GPa are 1350 ± 500 and 1200 ± 500 Pa s, respectively, and those of iron at 159 and 103 GPa are 1150 ± 1000 and 4800 ± 1000 Pa s, respectively. The values measured by the flyer-impact method, approximately 103 Pa s, are consistent with those measured by Sakharov's method, while still greatly differing from those measured by static high-pressure methods. In dynamic high-pressure experiments, the shear viscosity is related to dislocation motion in the solid material, while that in static high-pressure experiments is related to the diffusion motion of atoms or molecules in liquids. Therefore, there are different physical meanings of shear viscosity in dynamic and static high-pressure experiments, and there is no comparability among these results.

  7. Shear viscosity in an anisotropic unitary Fermi gas (United States)

    Samanta, Rickmoy; Sharma, Rishi; Trivedi, Sandip P.


    We consider a system consisting of a strongly interacting, ultracold unitary Fermi gas under harmonic confinement. Our analysis suggests the possibility of experimentally studying, in this system, an anisotropic shear viscosity tensor driven by the anisotropy in the trapping potential. In particular, we suggest that this experimental setup could mimic some features of anisotropic geometries that have recently been studied for strongly coupled field theories which have a dual gravitational description. Results using the AdS/CFT (anti-de Sitter/conformal field theory correspondence) in these theories show that in systems with a background linear potential, certain viscosity components can be made much smaller than the entropy density, parametrically violating the bound proposed by Kovtun, Son, and Starinets (KSS). This intuition, along with results from a Boltzmann analysis that we perform, suggests that a violation of the KSS bound can perhaps occur in the unitary Fermi gas system when it is subjected to a suitable anisotropic trapping potential which may be approximated to be linear in a suitable range of parameters. We give a concrete proposal for an experimental setup where an anisotropic shear viscosity tensor may arise. In such situations, it may also be possible to observe a reduction in the spin-1 component of the shear viscosity from its lowest value observed so far in ultracold Fermi gases. In extreme anisotropic situations, the reduction may be enough to reduce the shear viscosity to entropy ratio below the proposed KSS bound, although this regime is difficult to analyze in a theoretically controlled manner.

  8. Computing the viscosity of supercooled liquids: Markov Network model.

    Directory of Open Access Journals (Sweden)

    Ju Li

    Full Text Available The microscopic origin of glass transition, when liquid viscosity changes continuously by more than ten orders of magnitude, is challenging to explain from first principles. Here we describe the detailed derivation and implementation of a Markovian Network model to calculate the shear viscosity of deeply supercooled liquids based on numerical sampling of an atomistic energy landscape, which sheds some light on this transition. Shear stress relaxation is calculated from a master-equation description in which the system follows a transition-state pathway trajectory of hopping among local energy minima separated by activation barriers, which is in turn sampled by a metadynamics-based algorithm. Quantitative connection is established between the temperature variation of the calculated viscosity and the underlying potential energy and inherent stress landscape, showing a different landscape topography or "terrain" is needed for low-temperature viscosity (of order 10(7 Pa·s from that associated with high-temperature viscosity (10(-5 Pa·s. Within this range our results clearly indicate the crossover from an essentially Arrhenius scaling behavior at high temperatures to a low-temperature behavior that is clearly super-Arrhenius (fragile for a Kob-Andersen model of binary liquid. Experimentally the manifestation of this crossover in atomic dynamics continues to raise questions concerning its fundamental origin. In this context this work explicitly demonstrates that a temperature-dependent "terrain" characterizing different parts of the same potential energy surface is sufficient to explain the signature behavior of vitrification, at the same time the notion of a temperature-dependent effective activation barrier is quantified.

  9. Low Melt Viscosity Resins for Resin Transfer Molding (United States)

    Harris, Frank W.


    In recent years, resin transfer molding (RTM) has become one of the methods of choice for high performance composites. Its cost effectiveness and ease of fabrication are major advantages of RTM. RTM process usually requires resins with very low melt viscosity (less than 10 Poise). The optimum RTM resins also need to display high thennal-oxidative stability, high glass transition temperature (T(sub g)), and good toughness. The traditional PMR-type polyimides (e.g. PMR-15) do not fit this requirement, because the viscosities are too high and the nadic endcap cures too fast. High T(sub g), low-melt viscosity resins are highly desirable for aerospace applications and NASA s Reusable Launch Vehicle (RLV) program. The objective of this work is to prepare low-melt viscosity polyimide resins for RTM or resin film infusion (RFI) processes. The approach involves the synthesis of phenylethynyl-terminated imide oligomers. These materials have been designed to minimize their melt viscosity so that they can be readily processed. During the cure, the oligomers undergo both chain extension and crosslinking via the thermal polymerization of the phenylethynyl groups. The Phenylethynyl endcap is preferred over the nadic group due to its high curing temperature, which provides broader processing windows. This work involved the synthesis and polymerization of oligomers containing zig-zag backbones and twisted biphenyl structures. Some A-B type precursors which possessed both nitro and anhydride functionality, or both nitro and amine functionality, were also synthesized in order to obtain the well defined oligomers. The resulting zig-zag structured oligomers were then end-capped with 4-phenylethynylphthalic anhydride (PEPA) for further cure. The properties of these novel imide oligomers are evaluated.

  10. Individual lipid encapsulated microbubble radial oscillations: Effects of fluid viscosity. (United States)

    Helfield, Brandon; Chen, Xucai; Qin, Bin; Villanueva, Flordeliza S


    Ultrasound-stimulated microbubble dynamics have been shown to be dependent on intrinsic bubble properties, including size and shell characteristics. The effect of the surrounding environment on microbubble response, however, has been less investigated. In particular, microbubble optimization studies are generally conducted in water/saline, characterized by a 1 cP viscosity, for application in the vasculature (i.e., 4 cP). In this study, ultra-high speed microscopy was employed to investigate fluid viscosity effects on phospholipid encapsulated microbubble oscillations at 1 MHz, using a single, eight-cycle pulse at peak negative pressures of 100 and 250 kPa. Microbubble oscillations were shown to be affected by fluid viscosity in a size- and pressure-dependent manner. In general, the oscillation amplitudes exhibited by microbubbles between 3 and 6 μm in 1 cP fluid were larger than in 4 cP fluid, reaching a maximum of 1.7-fold at 100 kPa for microbubbles 3.8 μm in diameter and 1.35-fold at 250 kPa for microbubbles 4.8 μm in diameter. Simulation results were in broad agreement at 250 kPa, however generally underestimated the effect of fluid viscosity at 100 kPa. This is the first experimental demonstration documenting the effects of surrounding fluid viscosity on microbubble oscillations, resulting in behavior not entirely predicted by current microbubble models.

  11. Intermolecular potential parameters and combining rules determined from viscosity data

    Energy Technology Data Exchange (ETDEWEB)

    Bastien, Lucas A.J.; Price, Phillip N.; Brown, Nancy J.


    The Law of Corresponding States has been demonstrated for a number of pure substances and binary mixtures, and provides evidence that the transport properties viscosity and diffusion can be determined from a molecular shape function, often taken to be a Lennard-Jones 12-6 potential, that requires two scaling parameters: a well depth {var_epsilon}{sub ij} and a collision diameter {sigma}{sub ij}, both of which depend on the interacting species i and j. We obtain estimates for {var_epsilon}{sub ij} and {sigma}{sub ij} of interacting species by finding the values that provide the best fit to viscosity data for binary mixtures, and compare these to calculated parameters using several 'combining rules' that have been suggested for determining parameter values for binary collisions from parameter values that describe collisions of like molecules. Different combining rules give different values for {sigma}{sub ij} and {var_epsilon}{sub ij} and for some mixtures the differences between these values and the best-fit parameter values are rather large. There is a curve in ({var_epsilon}{sub ij}, {sigma}{sub ij}) space such that parameter values on the curve generate a calculated viscosity in good agreement with measurements for a pure gas or a binary mixture. The various combining rules produce couples of parameters {var_epsilon}{sub ij}, {sigma}{sub ij} that lie close to the curve and therefore generate predicted mixture viscosities in satisfactory agreement with experiment. Although the combining rules were found to underpredict the viscosity in most of the cases, Kong's rule was found to work better than the others, but none of the combining rules consistently yields parameter values near the best-fit values, suggesting that improved rules could be developed.

  12. Individual lipid encapsulated microbubble radial oscillations: Effects of fluid viscosity (United States)

    Helfield, Brandon; Chen, Xucai; Qin, Bin; Villanueva, Flordeliza S.


    Ultrasound-stimulated microbubble dynamics have been shown to be dependent on intrinsic bubble properties, including size and shell characteristics. The effect of the surrounding environment on microbubble response, however, has been less investigated. In particular, microbubble optimization studies are generally conducted in water/saline, characterized by a 1 cP viscosity, for application in the vasculature (i.e., 4 cP). In this study, ultra-high speed microscopy was employed to investigate fluid viscosity effects on phospholipid encapsulated microbubble oscillations at 1 MHz, using a single, eight-cycle pulse at peak negative pressures of 100 and 250 kPa. Microbubble oscillations were shown to be affected by fluid viscosity in a size- and pressure-dependent manner. In general, the oscillation amplitudes exhibited by microbubbles between 3 and 6 μm in 1 cP fluid were larger than in 4 cP fluid, reaching a maximum of 1.7-fold at 100 kPa for microbubbles 3.8 μm in diameter and 1.35-fold at 250 kPa for microbubbles 4.8 μm in diameter. Simulation results were in broad agreement at 250 kPa, however generally underestimated the effect of fluid viscosity at 100 kPa. This is the first experimental demonstration documenting the effects of surrounding fluid viscosity on microbubble oscillations, resulting in behavior not entirely predicted by current microbubble models. PMID:26827018

  13. Mercury Retention by Fly Ashes from Oxy-fuel Processes


    Fernández Miranda, Nuria; Villamil Rumayor, Marta; López Antón, María Antonia; Díaz Somoano, Mercedes; Martínez Tarazona, María Rosa


    The objective of this study is to determine the mechanism of mercury retention in fly ashes, the main solid waste from coal combustion power plants, and to evaluate the interactions between the type of mercury and fly ashes. The work was based on the results of mercury speciation in the gas and the solid fly ash before and after mercury retention. The identification of the mercury species in the gas was performed using previously validated methods, but the speciation of the mercury retained i...


    Energy Technology Data Exchange (ETDEWEB)

    Carciofi, Alex C.; Bjorkman, Jon E.; Haubois, Xavier [Instituto de Astronomia, Geofisica e Ciencias Atmosfericas, Universidade de Sao Paulo, Rua do Matao 1226, Cidade Universitaria, 05508-900, Sao Paulo, SP (Brazil); Otero, Sebastian A. [American Association of Variable Star Observers, 49 Bay State Road, Cambridge, MA 02138 (United States); Okazaki, Atsuo T. [Faculty of Engineering, Hokkai-Gakuen University, Toyohira-ku, Sapporo 062-8605 (Japan); Stefl, Stanislav; Rivinius, Thomas [European Organisation for Astronomical Research in the Southern Hemisphere, Casilla 19001, Santiago 19 (Chile); Baade, Dietrich, E-mail:, E-mail: [European Organisation for Astronomical Research in the Southern Hemisphere, Karl-Schwarzschild-Str. 2, 85748 Garching bei Muenchen (Germany)


    Be stars possess gaseous circumstellar decretion disks, which are well described using standard {alpha}-disk theory. The Be star 28 CMa recently underwent a long outburst followed by a long period of quiescence, during which the disk dissipated. Here we present the first time-dependent models of the dissipation of a viscous decretion disk. By modeling the rate of decline of the V-band excess, we determine that the viscosity parameter {alpha} = 1.0 {+-} 0.2, corresponding to a mass injection rate M-dot =(3.5{+-}1.3) Multiplication-Sign 10{sup -8} M{sub Sun} yr{sup -1}. Such a large value of {alpha} suggests that the origin of the turbulent viscosity is an instability in the disk whose growth is limited by shock dissipation. The mass injection rate is more than an order of magnitude larger than the wind mass-loss rate inferred from UV observations, implying that the mass injection mechanism most likely is not the stellar wind, but some other mechanism.

  15. Strategies for improving employee retention. (United States)

    Verlander, Edward G; Evans, Martin R


    This article proposes a solution to the perennial problem of talent retention in the clinical laboratory. It includes the presentation of 12 strategies that may be used to significantly improve institutional identity formation and establishment of the psychological contract that employees form with laboratory management. Identity formation and psychological contracting are deemed as essential in helping reduce employee turnover and increase retention. The 12 conversational strategies may be used as a set of best practices for all employees, but most importantly for new employees, and should be implemented at the critical moment when employees first join the laboratory. This time is referred to as "retention on-boarding"--the period of induction and laboratory orientation. Retention on-boarding involves a dialogue between employees and management that is focused on the psychological, practical, cultural, and political dimensions of the laboratory. It is placed in the context of the modern clinical laboratory, which is faced with employing and managing Generation X knowledge workers. Specific topics and broad content areas of those conversations are outlined.

  16. Exploring General Education Development Retention (United States)

    Grover, Sharon D.


    According to the instructors and administrators at a local adult education (AE) program in Houston, Texas, retaining and graduating general education development (GED) students has been a constant challenge. Locating GED attendance barriers could enable AE programs to develop techniques that increase student retention and graduation rates. The…

  17. Maslow's Hierarchy and Student Retention. (United States)

    Brookman, David M.


    Abraham Maslow's hierarchy of needs offers perspective on student motivation and a rationale for college retention programing. Student affairs and faculty interventions addressing student safety needs and engaging students' sense of purpose reinforce persistence. A mentor program is a possible cooperative effort between student personnel and…

  18. Evaluation of the synergistic effects of milk proteins in a rapid viscosity analyzer

    National Research Council Canada - National Science Library

    Stephani, Rodrigo; Borges de Souza, Alisson; Leal de Oliveira, Marcone Augusto; Perrone, Ítalo Tuler; Fernandes de Carvalho, Antônio; Cappa de Oliveira, Luiz Fernando


    .... Here, using a rapid viscosity analyzer, we observed the rheological changes in the startup viscosities of 5 PS obtained by combining varying proportions of milk protein concentrate and whey protein...

  19. Viscosity of egg white from hens of different strains fed with commercial and natural additives

    Directory of Open Access Journals (Sweden)

    Fernanda Papa Spada


    Full Text Available Yolk color and egg white (albumen cleanliness and viscosity are important parameters by which consumers judge the quality of eggs. This study aimed to investigate changes in albumen viscosity during storage of eggs for up to 36 days from two different commercial laying hen strains (Carijo Barbada and Isa Brown fed a diet containing annatto (1.5 and 2.0% or a synthetic additive without synthetic colorants (control. Analyses of humidity, albumen height, pH, viscosity, foam formation, and stability were carried out on eggs. Carijo Barbada strain had smaller albumen, lower humidity and higher egg white viscosity than Isa Brown strain; however, with storage, viscosity lowered significantly on both strains. Initially, the addition of 2.0% of annatto or a synthetic additive increased viscosity in both strains, but with storage only the control maintained longer viscosity. Lower viscosity did not change foam density and stability.

  20. Mantle Viscosity in the Kuril Subduction Zone from Postseismic GPS Monitoring of Great 2006/2007 Earthquakes (United States)

    Kogan, M. G.; Vasilenko, N. F.; Frolov, D. I.; Freymueller, J. T.; Steblov, G. M.; Ekstrom, G.; Prytkov, A. S.


    This study is based on 10 years of ongoing GPS measurements of postseismic deformation following a pair of great earthquakes in the Kuril subduction zone. The study area is one of only a handful to capture a magnitude >8 signal and its postseismic signature with continuous GPS. The Kuril GPS Array was installed a few months prior to a 2006/2007 earthquake doublet and has been recording postseismic displacements in the near and far fields since that time. For a decade, the near field stations are moving trenchward, towards the seismic source at a speed of several tens of millimeters per year initially and an order of magnitude slower currently. Our modeling of viscoelastic relaxation explores realistic 3D subduction structures accounting for the dipping slab and for a low-viscosity mantle wedge above it (software RELAX of S. Barbot). We test linear (Maxwell) and nonlinear (power-law) rheologies of the asthenosphere, assuming that the viscoelastic relaxation is the dominant signal compared to afterslip after a year since the earthquakes. The data are best fit by the Maxwell asthenospheric viscosity 1 × 1018 Pa s for an interval 2007.5-2016.5. This viscosity is about ten times smaller than for two M9 events (Chile 1960 and Alaska 1964) from postseismic GPS displacements observed several decades later. This suggests a power-law rheology predicting the growth of apparent viscosity with time. From laboratory experiments with olivine, two alternative power-law mechanisms are possible: dislocation creep (stress power-law exponent n = 3.4-4.5) or diffusion creep (n = 0.9-1.5). Our numerical tests spanned the expected range of n, as well as a range of values of the initial apparent viscosity. The data are best fit by diffusion creep with n = 1.2 although the fit is not as good as for the Maxwell model.