A Comparison of Streaming and Microelectrophoresis Methods for Obtaining the zeta Potential of Granular Porous Media Surfaces.

PubMed

Johnson

1999-01-01

The electrokinetic behavior of granular quartz sand in aqueous solution is investigated by both microelectrophoresis and streaming potential methods. zeta potentials of surfaces composed of granular quartz obtained via streaming potential methods are compared to electrophoretic mobility zeta potential values of colloid-sized quartz fragments. The zeta values generated by these alternate methods are in close agreement over a wide pH range and electrolyte concentrations spanning several orders of magnitude. Streaming measurements performed on chemically heterogeneous mixtures of physically homogeneous sand are shown to obey a simple mixing model based on the surface area-weighted average of the streaming potentials associated with the individual end members. These experimental results support the applicability of the streaming potential method as a means of determining the zeta potential of granular porous media surfaces. Copyright 1999 Academic Press.

Cursory examination of the zeta potential behaviors of two optical materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tesar, A.; Oja, T.

1992-01-02

When an oxide surface is placed in water, a difference in potential across the interface occurs due to dipole orientation. Hydroxyl groups or bound oxygen atoms on the oxide surface will orient adjacent water molecules which balance the dipole charge. This occurs over some small distance called the electrical double layer. Trace amounts of high field strength ions present in the vicinity of the double layer can have significant effects on the double layer. When there is movement of the oxide surface with respect to the water, a shearing of the double layer occurs. The electrical potential at this surfacemore » of shear is termed the zeta potential. The impetus for this study was to document the zeta potential behavior in water of two optical materials. (1) a multicomponent phosphate glass; and (2) Zerodur, a silicate glass-ceramic.« less

Zeta potential in ceramic industry

NASA Technical Reports Server (NTRS)

Lecuit, M.

1984-01-01

Deflocculation, electrical conductivity and zeta potential (ZP) are studied for the addition of 0 to 10000 ppm Na2SiO3 deflocculator to slips obtained from three argillaceous materials (kaolin d'Arvor, ball clay Hyplas 64, and/or Granger Clay No. 10). The quantity of Na2SO3 required to deflocculate a slip is independent of the density but differes for each clay. The ZP is directly related to the density of the slip. The higher the ZP the more stable a slip is; the value of the ZP of a mixture does not follow a simple law but the electrical resistance of a mixture does follow a simple additive law. The ZP appears to have linear relation with the specific surface of the argillaceous material.

Estimation of zeta potential of electroosmotic flow in a microchannel using a reduced-order model.

PubMed

Park, H M; Hong, S M; Lee, J S

2007-10-01

A reduced-order model is derived for electroosmotic flow in a microchannel of nonuniform cross section using the Karhunen-Loève Galerkin (KLG) procedure. The resulting reduced-order model is shown to predict electroosmotic flows accurately with minimal consumption of computer time for a wide range of zeta potential zeta and dielectric constant epsilon. Using the reduced-order model, a practical method is devised to estimate zeta from the velocity measurements of the electroosmotic flow in the microchannel. The proposed method is found to estimate zeta with reasonable accuracy even with noisy velocity measurements.

Zeta potential orientation dependence of sapphire substrates.

PubMed

Kershner, Ryan J; Bullard, Joseph W; Cima, Michael J

2004-05-11

The zeta potential of planar sapphire substrates for three different crystallographic orientations was measured by a streaming potential technique in the presence of KCl and (CH3)4NCl electrolytes. The streaming potential was measured for large single crystalline C-plane (0001), A-plane (1120), and R-plane (1102) wafers over a full pH range at three or more ionic strengths ranging from 1 to 100 mM. The roughness of the epi-polished wafers was verified using atomic force microscopy to be on the order of atomic scale, and X-ray photoelectron spectroscopy (XPS) was used to ensure that the samples were free of silica and other contaminants. The results reveal a shift in the isoelectric point (iep) of the three samples by as much as two pH units, with the R-plane surface exhibiting the most acidic behavior and the C-plane samples having the highest iep. The iep at all ionic strengths was tightly centered around a single pH for each wafer. These values of iep are substantially different from the range of pH 8-10 consistently reported in the literature for alpha-Al2O3 particles. Particle zeta potential measurements were performed on a model powder using phase analysis light scattering, and the iep was confirmed to occur at pH 8. Modified Auger parameters (MAP) were calculated from XPS spectra of a monolayer of iridium metal deposited on the sapphire by electron beam deposition. A shift in MAP consistent with the observed differences in iep of the surfaces confirms the effect of surface structure on the transfer of charge between the Ir and sapphire, hence accounting for the changes in acidity as a function of crystallographic orientation.

Effect of polymer viscosity on physicochemical properties and ocular tolerance of FB-loaded PLGA nanospheres.

PubMed

Araújo, J; Vega, E; Lopes, C; Egea, M A; Garcia, M L; Souto, E B

2009-08-01

Poly(lactide-co-glycolide) acid (PLGA) nanospheres incorporating flurbiprofen (FB) were produced by the solvent displacement technique, for ocular applications aiming to avoid/minimize inflammation induced by surgical trauma. In this work, a PLGA of low viscosity has been tested and the results obtained were compared with those previously reported by Vega et al. The physicochemical properties of the developed formulations were evaluated by measuring particle size, zeta potential and FB entrapment efficiency, showing no significant differences. Release studies demonstrated that the formulation produced with PLGA of higher viscosity revealed a slower drug release rate. Stability analysis, for a period of 75 days, was performed using three complementary methods: (i) turbidity experiments using a Turbiscan optical analyzer, (ii) particle size measurements, and (iii) zeta potential analysis. The results revealed long-term physicochemical stability suitability for ophthalmic use, being independent from the polymer viscosity. The ocular tolerance was assessed by an alternative in vitro method to animal experimentation, the HET-CAM. For all developed formulations no ocular irritancy has been detected.

Electrokinetically driven active micro-mixers utilizing zeta potential variation induced by field effect

NASA Astrophysics Data System (ADS)

Lee, Chia-Yen; Lee, Gwo-Bin; Fu, Lung-Ming; Lee, Kuo-Hoong; Yang, Ruey-Jen

2004-10-01

This paper presents a new electrokinetically driven active micro-mixer which uses localized capacitance effects to induce zeta potential variations along the surface of silica-based microchannels. The mixer is fabricated by etching bulk flow and shielding electrode channels into glass substrates and then depositing Au/Cr thin films within the latter to form capacitor electrodes, which establish localized zeta potential variations near the electrical double layer (EDL) region of the electroosmotic flow (EOF) within the microchannels. The potential variations induce flow velocity changes within a homogeneous fluid and a rapid mixing effect if an alternating electric field is provided. The current experimental data confirm that the fluid velocity can be actively controlled by using the capacitance effect of the buried shielding electrodes to vary the zeta potential along the channel walls. While compared with commonly used planar electrodes across the microchannels, the buried shielding electrodes prevent current leakage caused by bad bonding and allow direct optical observation during operation. It also shows that the buried shielding electrodes can significantly induce the field effect, resulting in higher variations of zeta potential. Computational fluid dynamic simulations are also used to study the fluid characteristics of the developed active mixers. The numerical and experimental results demonstrate that the developed microfluidic device permits a high degree of control over the fluid flow and an efficient mixing effect. Moreover, the developed device could be used as a pumping device as well. The development of the active electrokinetically driven micro-mixer could be crucial for micro-total-analysis-systems.

Coagulation-flocculation mechanisms in wastewater treatment plants through zeta potential measurements.

PubMed

López-Maldonado, E A; Oropeza-Guzman, M T; Jurado-Baizaval, J L; Ochoa-Terán, A

2014-08-30

Based on the polyelectrolyte-contaminant physical and chemical interactions at the molecular level, this article analyzed and discussed the coagulation-flocculation and chemical precipitation processes in order to improve their efficiency. Bench experiments indicate that water pH, polyelectrolyte (PE) dosing strategy and cationic polyelectrolyte addition are key parameters for the stability of metal-PE complexes. The coagulation-flocculation mechanism is proposed based on zeta potential (ζ) measurement as the criteria to define the electrostatic interaction between pollutants and coagulant-flocculant agents. Polyelectrolyte and wastewater dispersions are exposed to an electrophoretic effect to determine ζ. Finally, zeta potential values are compared at pH 9, suggesting the optimum coagulant dose at 162mg/L polydadmac and 67mg/L of flocculant, since a complete removal of TSS and turbidity is achieved. Based on the concentration of heavy metals (0.931mg/L Sn, 0.7mg/L Fe and 0.63mg/L Pb), treated water met the Mexican maximum permissible limits. In addition, the treated water has 45mg O2/L chemical oxygen demand (COD) and 45mg C/L total organic carbon (TOC). The coagulation-flocculation mechanism is proposed taking into account both: zeta potential (ζ)-pH measurement and chemical affinity, as the criteria to define the electrostatic and chemical interaction between pollutants and polyelectrolytes. Copyright © 2014 Elsevier B.V. All rights reserved.

Zeta potential in oil-brine-sandstone system and its role in oil recovery during controlled salinity waterflooding

NASA Astrophysics Data System (ADS)

Li, S.; Jackson, M.

2017-12-01

Wettability alteration is widely recognised as a primary role in improved oil recovery (IOR) during controlled salinity waterflooding (CSW) by modifying brine composition. The change of wettability of core sample depends on adsorption of polar oil compounds into the mineral surface which influences its surface charge density and zeta potential. It has been proved that zeta potentials can be useful to quantify the wettability and incremental oil recovery in natural carbonates. However, the study of zeta potential in oil-brine-sandstone system has not investigated yet. In this experimental study, the zeta potential is used to examine the controlled salinity effects on IOR in nature sandstone (Doddington) aged with two types of crude oils (Oil T and Oil D) over 4 weeks at 80 °C. Results show that the zeta potential measured in the Oil T-brine-sandstone system following primary waterflooding decreases compared to that in fully water saturation, which is consistent with the negative oil found in carbonates study, and IOR response during secondary waterflooding using diluted seawater was observed. In the case of negative oil, the injected low salinity brine induces a more repulsive electrostatic force between the mineral-brine interface and oil-brine interface, which results in an increase disjoining pressure and alters the rock surface to be more water-wet. For Oil D with a positive oil-brine interface, the zeta potential becomes more positive compared to that under single phase condition. The conventional waterflooding fails to observe the IOR in Oil D-brine-sandstone system due to a less repulsive electrostatic force built up between the two interfaces. After switching the injection brine from low salinity brine to formation brine, the IOR was observed. Measured zeta potentials shed some light on the mechanism of wettability alteration in the oil-brine-sandstone system and oil recovery during CSW.

Influence of the Dukhin and Reynolds numbers on the apparent zeta potential of granular porous media.

PubMed

Crespy, A; Bolève, A; Revil, A

2007-01-01

The Helmholtz-Smoluchowski (HS) equation is widely used to determine the apparent zeta potential of porous materials using the streaming potential method. We present a model able to correct this apparent zeta potential of granular media of the influence of the Dukhin and Reynolds numbers. The Dukhin number represents the ratio between the surface conductivity (mainly occurring in the Stern layer) and the pore water conductivity. The Reynolds number represents the ratio between inertial and viscous forces in the Navier-Stokes equation. We show here that the HS equation can lead to serious errors if it is used to predict the dependence of zeta potential on flow in the inertial laminar flow regime without taking into account these corrections. For indifferent 1:1 electrolytes (such as sodium chloride), we derived two simple scaling laws for the dependence of the streaming potential coupling coefficient (or the apparent zeta potential) on the Dukhin and Reynolds numbers. Our model is compared with a new set of experimental data obtained on glass bead packs saturated with NaCl solutions at different salinities and pH. We find fairly good agreement between the model and these experimental data.

The zeta potential of extended dielectrics and conductors in terms of streaming potential and streaming current measurements.

PubMed

Gallardo-Moreno, Amparo M; Vadillo-Rodríguez, Virginia; Perera-Núñez, Julia; Bruque, José M; González-Martín, M Luisa

2012-07-21

The electrical characterization of surfaces in terms of the zeta potential (ζ), i.e., the electric potential contributing to the interaction potential energy, is of major importance in a wide variety of industrial, environmental and biomedical applications in which the integration of any material with the surrounding media is initially mediated by the physico-chemical properties of its outer surface layer. Among the different existing electrokinetic techniques for obtaining ζ, streaming potential (V(str)) and streaming current (I(str)) are important when dealing with flat-extended samples. Mostly dielectric materials have been subjected to this type of analysis and only a few papers can be found in the literature regarding the electrokinetic characterization of conducting materials. Nevertheless, a standardized procedure is typically followed to calculate ζ from the measured data and, importantly, it is shown in this paper that such a procedure leads to incorrect zeta potential values when conductors are investigated. In any case, assessment of a reliable numerical value of ζ requires careful consideration of the origin of the input data and the characteristics of the experimental setup. In particular, it is shown that the cell resistance (R) typically obtained through a.c. signals (R(a.c.)), and needed for the calculations of ζ, always underestimates the zeta potential values obtained from streaming potential measurements. The consideration of R(EK), derived from the V(str)/I(str) ratio, leads to reliable values of ζ when dielectrics are investigated. For metals, the contribution of conductivity of the sample to the cell resistance provokes an underestimation of R(EK), which leads to unrealistic values of ζ. For the electrical characterization of conducting samples I(str) measurements constitute a better choice. In general, the findings gathered in this manuscript establish a measurement protocol for obtaining reliable zeta potentials of dielectrics and

Estimation of the zeta potential and the dielectric constant using velocity measurements in the electroosmotic flows.

PubMed

Park, H M; Hong, S M

2006-12-15

In this paper we develop a method for the determination of the zeta potential zeta and the dielectric constant epsilon by exploiting velocity measurements of the electroosmotic flow in microchannels. The inverse problem is solved through the minimization of a performance function utilizing the conjugate gradient method. The present method is found to estimate zeta and epsilon with reasonable accuracy even with noisy velocity measurements.

Stimulation and inhibition of enzymatic hydrolysis by organosolv lignins as determined by zeta potential and hydrophobicity.

PubMed

Huang, Yang; Sun, Shaolong; Huang, Chen; Yong, Qiang; Elder, Thomas; Tu, Maobing

2017-01-01

Lignin typically inhibits enzymatic hydrolysis of cellulosic biomass, but certain organosolv lignins or lignosulfonates enhance enzymatic hydrolysis. The hydrophobic and electrostatic interactions between lignin and cellulases play critical roles in the enzymatic hydrolysis process. However, how to incorporate these two interactions into the consideration of lignin effects has not been investigated. We examined the physicochemical properties and the structures of ethanol organosolv lignins (EOL) from hardwood and softwood and ascertained the association between lignin properties and their inhibitory and stimulatory effects on enzymatic hydrolysis. The zeta potential and hydrophobicity of EOL lignin samples, isolated from organosolv pretreatment of cottonwood (CW), black willow (BW), aspen (AS), eucalyptus (EH), and loblolly pine (LP), were determined and correlated with their effects on enzymatic hydrolysis of Avicel. EOLs from CW, BW, and AS improved the 72 h hydrolysis yield by 8-12%, while EOLs from EH and LP decreased the 72 h hydrolysis yield by 6 and 16%, respectively. The results showed a strong correlation between the 72 h hydrolysis yield with hydrophobicity and zeta potential. The correlation indicated that the hydrophobicity of EOL had a negative effect and the negative zeta potential of EOL had a positive effect. HSQC NMR spectra showed that β- O -4 linkages in lignin react with ethanol to form an α -ethoxylated β- O -4' substructure (A') during organosolv pretreatment. Considerable amounts of C 2,6 -H 2,6 correlation in p -hydroxybenzoate (PB) units were observed for EOL-CW, EOL-BW, and EOL-AS, but not for EOL-EH and EOL-LP. This study revealed that the effect of lignin on enzymatic hydrolysis is a function of both hydrophobic interactions and electrostatic repulsions. The lignin inhibition is controlled by lignin hydrophobicity and the lignin stimulation is governed by the negative zeta potential. The net effect of lignin depends on the combined

Effect of additive on Zeta potential and particle size of nickel nanoparticles

NASA Astrophysics Data System (ADS)

Sharma, Vikash; Tarachand, Chotia, Chandrabhan; Okram, G. S.

2017-05-01

Nickel nanoparticles (NPs) were prepared by thermal decomposition method using Oleylamine (OLY) as a solvent and Trioctylphosphine (TOP) as a surfactant. We have investigated the effect of pH and addition of Ethylenediamine tetraacetic acid (EDTA) on the stability and particle size of Ni NPs using zeta potential and particle size analyser. Coating of the surfactants on the surface of Ni NPs was confirmed by Fourier transform infrared (FTIR) spectroscopy. Autotitration study of zeta potential of these NPs in ethanol by dynamic light scattering (DLS) at different pH values confirmed an isoelectric point (IEP) at pH = 3.64 in ethanol and pH = 3.04 after addition of EDTA in ethanol. It was observed that addition of EDTA in nanosuspension enhances stability of Ni-NPs significantly.

Electrokinetic mixing at high zeta potentials: ionic size effects on cross stream diffusion.

PubMed

Ahmadian Yazdi, Alireza; Sadeghi, Arman; Saidi, Mohammad Hassan

2015-03-15

The electrokinetic phenomena at high zeta potentials may show several unique features which are not normally observed. One of these features is the ionic size (steric) effect associated with the solutions of high ionic concentration. In the present work, attention is given to the influences of finite ionic size on the cross stream diffusion process in an electrokinetically actuated Y-shaped micromixer. The method consists of a finite difference based numerical approach for non-uniform grid which is applied to the dimensionless form of the governing equations, including the modified Poisson-Boltzmann equation. The results reveal that, neglecting the ionic size at high zeta potentials gives rise to the overestimation of the mixing length, because the steric effects retard liquid flow, thereby enhancing the mixing efficiency. The importance of steric effects is found to be more intense for channels of smaller width to height ratio. It is also observed that, in sharp contrast to the conditions that the ions are treated as point charges, increasing the zeta potential improves the cross stream diffusion when incorporating the ionic size. Moreover, increasing the EDL thickness decreases the mixing length, whereas the opposite is true for the channel aspect ratio. Copyright © 2014 Elsevier Inc. All rights reserved.

Hydrodynamic dispersion in a combined magnetohydrodynamic- electroosmotic-driven flow through a microchannel with slowly varying wall zeta potentials

NASA Astrophysics Data System (ADS)

Vargas, C.; Arcos, J.; Bautista, O.; Méndez, F.

2017-09-01

The effective dispersion coefficient of a neutral solute in the combined electroosmotic (EO) and magnetohydrodynamic (MHD)-driven flow of a Newtonian fluid through a parallel flat plate microchannel is studied. The walls of the microchannel are assumed to have modulated and low zeta potentials that vary slowly in the axial direction in a sinusoidal manner. The flow field required to obtain the dispersion coefficient is solved using the lubrication approximation theory. The solution of the electrical potential is based on the Debye-Hückel approximation for a symmetric (Z :Z ) electrolyte solution. The EO and MHD effects, together with the variations in the zeta potentials of the walls, are observed to notably modify the axial distribution of the effective dispersion coefficient. The problem is formulated for two cases of the zeta potential function. Note that the dispersion coefficient primarily depends on the Hartmann number, on the ratio of the half height of the microchannel to the Debye length, and on the assumed variation in the zeta potentials of the walls.

Binding of phosphoinositide-specific phospholipase C-zeta (PLC-zeta) to phospholipid membranes: potential role of an unstructured cluster of basic residues.

PubMed

Nomikos, Michail; Mulgrew-Nesbitt, Anna; Pallavi, Payal; Mihalyne, Gyongyi; Zaitseva, Irina; Swann, Karl; Lai, F Anthony; Murray, Diana; McLaughlin, Stuart

2007-06-01

Phospholipase C-zeta (PLC-zeta) is a sperm-specific enzyme that initiates the Ca2+ oscillations in mammalian eggs that activate embryo development. It shares considerable sequence homology with PLC-delta1, but lacks the PH domain that anchors PLC-delta1 to phosphatidylinositol 4,5-bisphosphate, PIP2. Thus it is unclear how PLC-zeta interacts with membranes. The linker region between the X and Y catalytic domains of PLC-zeta, however, contains a cluster of basic residues not present in PLC-delta1. Application of electrostatic theory to a homology model of PLC-zeta suggests this basic cluster could interact with acidic lipids. We measured the binding of catalytically competent mouse PLC-zeta to phospholipid vesicles: for 2:1 phosphatidylcholine/phosphatidylserine (PC/PS) vesicles, the molar partition coefficient, K, is too weak to be of physiological significance. Incorporating 1% PIP2 into the 2:1 PC/PS vesicles increases K about 10-fold, to 5x10(3) M-1, a biologically relevant value. Expressed fragments corresponding to the PLC-zeta X-Y linker region also bind with higher affinity to polyvalent than monovalent phosphoinositides on nitrocellulose filters. A peptide corresponding to the basic cluster (charge=+7) within the linker region, PLC-zeta-(374-385), binds to PC/PS vesicles with higher affinity than PLC-zeta, but its binding is less sensitive to incorporating PIP2. The acidic residues flanking this basic cluster in PLC-zeta may account for both these phenomena. FRET experiments suggest the basic cluster could not only anchor the protein to the membrane, but also enhance the local concentration of PIP2 adjacent to the catalytic domain.

Effective flocculation of Chlorella vulgaris using chitosan with zeta potential measurement

NASA Astrophysics Data System (ADS)

Low, Y. J.; Lau, S. W.

2017-06-01

Microalgae are considered as one promising source of third-generation biofuels due to their fast growth rates, potentially higher yield rates and wide ranges of growth conditions. However, the extremely low biomass concentration in microalgae cultures presents a great challenge to the harvesting of microalgae because a large volume of water needs to be removed to obtain dry microalgal cells for the subsequent oil extraction process. In this study, the fresh water microalgae Chlorella vulgaris (C. vulgaris) was effectively harvested using both low molecular weight (MW) and high MW chitosan flocculants. The flocculation efficiency was evaluated by physical appearance, supernatant absorbance, zeta potential and solids content after centrifugal dewatering. High flocculation efficiency of 98.0-99.0% was achieved at the optimal dosage of 30-40 mg/g with formation of large microalgae flocs. This study suggests that the polymer bridging mechanism was governing the flocculation behaviour of C. vulgaris using high MW chitosan. Besides, charge patch neutralisation mechanism prevailed at low MW chitosan where lower dosage was sufficient to reach near-zero zeta potential compared with the high MW chitosan. The amount of chitosan polymer present in the culture may also affect the mechanism of flocculation.

Zeta potentials of the rare earth element fluorcarbonate minerals focusing on bastnäsite and parisite.

PubMed

Owens, C L; Nash, G R; Hadler, K; Fitzpatrick, R S; Anderson, C G; Wall, F

2018-06-01

Rare earth elements (REE) are critical to a wide range of technologies ranging from mobile phones to wind turbines. Processing and extraction of REE minerals from ore bodies is, however, both challenging and relatively poorly understood, as the majority of deposits contain only limited enrichment of REEs. An improved understanding of the surface properties of the minerals is important in informing and optimising their processing, in particular for separation by froth flotation. The measurement of zeta potential can be used to extract information regarding the electrical double layer, and hence surface properties of these minerals. There are over 34 REE fluorcarbonate minerals currently identified, however bastnäsite, synchysite and parisite are of most economic importance. Bastnäsite-(Ce), the most common REE fluorcarbonate, supplies over 50% of the world's REE. Previous studies of bastnäsite have showed a wide range of surface behaviour, with the iso-electric point (IEP), being measured between pH values of 4.6 and 9.3. In contrast, no values of IEP have been reported for parisite or synchysite. In this work, we review previous studies of the zeta potentials of bastnäsite to investigate the effects of different methodologies and sample preparation. In addition, measurements of zeta potentials of parisite under water, collector and supernatant conditions were conducted, the first to be reported. These results showed an iso-electric point for parisite of 5.6 under water, with a shift to a more negative zeta potential with both collector (hydroxamic and fatty acids) and supernatant conditions. The IEP with collectors and supernatant was <3.5. As zeta potential measurements in the presence of reagents and supernatants are the most rigorous way of determining the efficiency of a flotation reagent, the agreement between parisite zeta potentials obtained here and previous work on bastnäsite suggests that parisite may be processed using similar reagent schemes to

Entrapment of ovalbumin into liposomes--factors affecting entrapment efficiency, liposome size, and zeta potential.

PubMed

Brgles, Marija; Jurasin, Darija; Sikirić, Maja Dutour; Frkanec, Ruza; Tomasić, Jelka

2008-01-01

Various amounts of Ovalbumin (OVA) were encapsulated into positively and negatively charged multilamellar liposomes, with the aim to investigate the entrapment efficiency in different buffers and to study their effects on the liposome size and zeta potential. Results showed that the entrapment efficiency of OVA in anionic liposomes was the same in 10 mM Phosphate Buffer (PB) as in Phosphate-Buffered Saline (PBS; PB + 0.15 M NaCl). Also, liposome size was approximately 1200 nm for all anionic liposomes incorporating OVA. The entrapment efficiency of OVA in cationic liposomes was highly dependent on ionic strength. The size of cationic liposomes was approximately 1200 nm in PBS, regardless of protein content, but increased with the amount of the incorporated protein in PB. Aggregation of cationic liposomes in PB was observed when the mass of the protein was 2.5 mg or greater. The zeta potential of anionic liposomes was negative and of cationic liposomes positive in the whole range of protein mass tested. These results show how different compositions of lipid and aqueous phases can be used to vary the entrapment efficiency, liposome size, and zeta potential--the factors that are of great importance for the use of liposomes as drug carriers.

Study of a binary interpenetrated polymeric complex by correlation of rheological parameters with zeta potential and conductivity.

PubMed

Nita, Loredana Elena; Chiriac, Aurica P; Neamtu, Iordana; Bercea, Maria

2010-03-01

The interpenetrated macromolecular chains complexation between poly(aspartic acid) and poly(vinyl alcohol) in aqueous solution it was investigated. The interpolymer complexation process was evaluated through dynamic rheology. The aspects concerning the stability of the tested homopolymers and the prepared interpolymeric complex there were achieved from the evaluation of the aqueous solutions'zeta potential and also by determining the pH influence upon the zeta potential and the conductivity. The data obtained through the rheological dynamic measurements were correlated with the composition of the polymeric mixture, the dependence of zeta potential and conductivity. The study reveals the conditions for the formation of interpenetrated polymeric complex as being a ratio of 70wt.% PAS to 30wt.% PVA at 22 degrees C and 50/50 PAS/PVA ratio at 37 degrees C temperature. From the pH influence upon the zeta potential values it was evidenced the PAS aqueous solution does not reach the isoelectric point. At the same time, PVA solution and the complex PAS/PVA reaches the isoelectric point at strongly acid pH. The better stability of PAS, PVA and their mixture in solution is recorded in the alkaline domain (7.5or=12). The conductivity increases with the rising of the PAS content, pH and temperature. Other characteristics of the prepared interpenetrated polymeric structure, as for example thermal stability, there are also presented.

EFFECT OF AQUEOUS PHASE PROPERTIES ON CLAY PARTICLE ZETA POTENTIAL AND ELECTRO-OSMOTIC PERMEABILITY: IMPLICATIONS FOR ELECTRO-KINETIC SOIL REMEDIATION PROCESSES

EPA Science Inventory

The influence of aqueous phase properties (pH, ionic strength and divalent metal ion concentration) on clay particle zeta potential and packed-bed electro-osmotic permeability was quantified. Although pH strongly altered the zeta potential of a Georgia kaolinite, it did not signi...

Investigation of the influence of the zeta-potential on the filtration rate in the presence of collectors

NASA Technical Reports Server (NTRS)

Provirnina, E. V.; Barbin, M. B.

1984-01-01

The value of the zeta-potential does not have an explicit effect, which is expressed by a simple math correlation, on filtration rate when a solution of the tested collector is filtered through a cake prepared under standard conditions from the examined particulate material. The zeta-potential measurements and filtration tests were carried out on silica and galena with solutions contg. a cationic container ANP and Et xanthane, resp. at PH = 6.5, varying concentration of the agent (0-2500 g/ton), and under a vacuum of 100 to 600 mm Hg.

Implementation of the Baldwin-Barth turbulence model into the ZETA code and its diagnosis. M.S. Thesis

NASA Technical Reports Server (NTRS)

Low, Scott L.

1993-01-01

The Baldwin-Barth turbulence model was implemented into Zeta, a time-accurate, zonal, integro-differential code for incompressible laminar and turbulent flows. The implementation procedure is patterned after the model subroutine in ARC2D. The results of ZETA with the Baldwin-Barth turbulence model were compared with experimental data, with ZETA using Baldwin-Lomax model, and with ARC2D using the Baldwin-Barth model. The Baldwin-Barth model subroutine was tested by inputting an ARC2D velocity solution of an NACA-0012 airfoil at R(sub e) = 3.9 x 10(exp 6) and alpha = 5 deg. The resultant turbulent viscosity and Reynolds stresses compared favorably with the original data. For the same grid having grid points inside the laminar sublayer, which is necessary due to the one-equation nature of the model, ZETA however predicts early separation. It was found that the current ZETA has problem with such a fine grid. Further work is in progress to solve this problem.

Development of a novel in silico model of zeta potential for metal oxide nanoparticles: a nano-QSPR approach

NASA Astrophysics Data System (ADS)

Wyrzykowska, Ewelina; Mikolajczyk, Alicja; Sikorska, Celina; Puzyn, Tomasz

2016-11-01

Once released into the aquatic environment, nanoparticles (NPs) are expected to interact (e.g. dissolve, agglomerate/aggregate, settle), with important consequences for NP fate and toxicity. A clear understanding of how internal and environmental factors influence the NP toxicity and fate in the environment is still in its infancy. In this study, a quantitative structure-property relationship (QSPR) approach was employed to systematically explore factors that affect surface charge (zeta potential) under environmentally realistic conditions. The nano-QSPR model developed with multiple linear regression (MLR) was characterized by high robustness ({{{Q}}{{2}}}{{CV}}=0.90) and external predictivity ({{{Q}}{{2}}}{{EXT}}=0.93). The results clearly showed that zeta potential values varied markedly as functions of the ionic radius of the metal atom in the metal oxides, confirming that agglomeration and the extent of release of free MexOy largely depend on their intrinsic properties. A developed nano-QSPR model was successfully applied to predict zeta potential in an ionized solution of NPs for which experimentally determined values of response have been unavailable. Hence, the application of our model is possible when the values of zeta potential in the ionized solution for metal oxide nanoparticles are undetermined, without the necessity of performing more time consuming and expensive experiments. We believe that our studies will be helpful in predicting the conditions under which MexOy is likely to become problematic for the environment and human health.

Directional flow induced by synchronized longitudinal and zeta-potential controlling AC-electrical fields.

PubMed

van der Wouden, E J; Hermes, D C; Gardeniers, J G E; van den Berg, A

2006-10-01

Electroosmotic flow (EOF) in a microchannel can be controlled by electronic control of the surface charge using an electrode embedded in the wall of the channel. By setting a voltage to the electrode, the zeta-potential at the wall can be changed locally. Thus, the electrode acts as a "gate" for liquid flow, in analogy with a gate in a field-effect transistor. In this paper we will show three aspects of a Field Effect Flow Control (FEFC) structure. We demonstrate the induction of directional flow by the synchronized switching of the gate potential with the channel axial potential. The advantage of this procedure is that potential gas formation by electrolysis at the electrodes that provide the axial electric field is suppressed at sufficiently large switching frequencies, while the direction and magnitude of the EOF can be maintained. Furthermore we will give an analysis of the time constants involved in the charging of the insulator, and thus the switching of the zeta potential, in order to predict the maximum operating frequency. For this purpose an equivalent electrical circuit is presented and analyzed. It is shown that in order to accurately describe the charging dynamics and pH dependency the traditionally used three capacitor model should be expanded with an element describing the buffer capacitance of the silica wall surface.

Optimal aluminum/zirconium: Protein interactions for predicting antiperspirant efficacy using zeta potential measurements.

PubMed

Yuan, Shaotang; Vaughn, John; Pappas, Iraklis; Fitzgerald, Michael; Masters, James G; Pan, Long

2015-01-01

The interactions between commercial antiperspirant (AP) salts [aluminum chlorohydrate (ACH), activated ACH, aluminum sesquichlorohydrate (ASCH), zirconium aluminum glycine (ZAG), activated ZAG), pure aluminum polyoxocations (Al13-mer, Al30-mer), and the zirconium(IV)-glycine complex Zr6 (O)4 (OH)4 (H2O)8 (Gly)8]12+(-) (CP-2 or ZG) with Bovine serum albumin (BSA) were studied using zeta potential and turbidity measurements. The maximal turbidity, which revealed the optimal interactions between protein and metal salts, for all protein-metal salt samples was observed at the isoelectric point (IEP), where the zeta potential of the solution was zero. Efficacy of AP salts was determined via three parameters: the amount of salt required to flocculate BSA to reach IEP, the turbidity of solution at the IEP, and the pH range over which the turbidity of the solution remains sufficiently high. By comparing active salt performance from this work to traditional prescreening methods, this methodology was able to provide a consistent efficacy assessment for metal actives in APs or in water treatment.

Stability of fenbendazole suspensions for veterinary use. Correlation between zeta potential and sedimentation.

PubMed

Arias, José L; López-Viota, Margarita; Clares, Beatriz; Ruiz, Ma Adolfina

2008-08-07

In this paper we have carried out a detailed investigation of the stability and redispersibility characteristics of fenbendazole aqueous suspensions, through a thermodynamic and electrokinetic characterization, considering the effect of both pH and ionic strength. The hydrophobic character of the drug, and the surface charge and electrical double-layer thickness play an essential role in the stability of the system, hence the need for a full characterization of fenbendazole. It was found that the drug suspensions displays "delayed" or "hindered" sedimentation, determined by their hydrophobic character and their low zeta potential (indicating a small electrokinetic charge on the particles). The electrostatic repulsion between the particles is responsible for the low sedimentation volume and poor redispersibility of the drug. However, only low concentrations of AlCl(3) induced a significant effect on both the zeta potential and stability of the drug, leading to a "free-layered" sedimentation and a very easy redispersion which could be of great interest in the design of an oral pharmaceutical dosage form for veterinary.

zeta 1 and zeta 2 Reticuli and the existence of the zeta Herculis group

NASA Astrophysics Data System (ADS)

del Peloso, E. F.; da Silva, L.; Porto de Mello, G. F.

2000-06-01

We report the detailed analysis of the solar type stars zeta 1 and zeta 2 Reticuli. We obtained accurate effective temperatures (T_eff = 5746 +/- 27 K and 5859 +/- 27 K respectively) and surface gravities (log g = 4.54 +/- 0.02 and 4.46 +/- 0.01 respectively). Both stars are slightly metal deficient ([Fe/H] = -0.22 +/- 0.05) and their element abundance patterns are compatible with one another and with the Sun. The hypothesis, suggested by previous detailed analyses, that these stars could be helium rich relative to the Sun, was investigated. The stars were found to have a normal, solar helium abundance. We analysed the stars' membership of the zeta Herculis stellar kinematic group (SKG). Some probable members have nearly the same galactic orbital parameters, chemical composition and evolutionary states, which confirm the existence of a metal deficient SKG. Since we determined that zeta Herculis does not belong to this group, we propose it be renamed zeta Reticuli SKG. Based on observations collected at the European Southern Observatory, La Silla, Chile, and at the Observatório do Pico dos Dias, operated by the Laboratório Nacional de Astrofísica, CNPq, Brazil.

Nanoparticle Tracking Analysis for Determination of Hydrodynamic Diameter, Concentration, and Zeta-Potential of Polyplex Nanoparticles.

PubMed

Wilson, David R; Green, Jordan J

2017-01-01

Nanoparticle tracking analysis (NTA) is a recently developed nanoparticle characterization technique that offers certain advantages over dynamic light scattering for characterizing polyplex nanoparticles in particular. Dynamic light scattering results in intensity-weighted average measurements of nanoparticle characteristics. In contrast, NTA directly tracks individual particles, enabling concentration measurements as well as the direct determination of number-weighted particle size and zeta-potential. A direct number-weighted assessment of nanoparticle characteristics is particularly useful for polydisperse samples of particles, including many varieties of gene delivery particles that can be prone to aggregation. Here, we describe the synthesis of poly(beta-amino ester)/deoxyribonucleic acid (PBAE/DNA) polyplex nanoparticles and their characterization using NTA to determine hydrodynamic diameter, zeta-potential, and concentration. Additionally, we detail methods of labeling nucleic acids with fluorophores to assess only those polyplex nanoparticles containing plasmids via NTA. Polymeric gene delivery of exogenous plasmid DNA has great potential for treating a wide variety of diseases by inducing cells to express a gene of interest.

Effects of image charges, interfacial charge discreteness, and surface roughness on the zeta potential of spherical electric double layers.

PubMed

Gan, Zecheng; Xing, Xiangjun; Xu, Zhenli

2012-07-21

We investigate the effects of image charges, interfacial charge discreteness, and surface roughness on spherical electric double layer structures in electrolyte solutions with divalent counterions in the setting of the primitive model. By using Monte Carlo simulations and the image charge method, the zeta potential profile and the integrated charge distribution function are computed for varying surface charge strengths and salt concentrations. Systematic comparisons were carried out between three distinct models for interfacial charges: (1) SURF1 with uniform surface charges, (2) SURF2 with discrete point charges on the interface, and (3) SURF3 with discrete interfacial charges and finite excluded volume. By comparing the integrated charge distribution function and the zeta potential profile, we argue that the potential at the distance of one ion diameter from the macroion surface is a suitable location to define the zeta potential. In SURF2 model, we find that image charge effects strongly enhance charge inversion for monovalent interfacial charges, and strongly suppress charge inversion for multivalent interfacial charges. For SURF3, the image charge effect becomes much smaller. Finally, with image charges in action, we find that excluded volumes (in SURF3) suppress charge inversion for monovalent interfacial charges and enhance charge inversion for multivalent interfacial charges. Overall, our results demonstrate that all these aspects, i.e., image charges, interfacial charge discreteness, their excluding volumes, have significant impacts on zeta potentials of electric double layers.

Investigating the clinical potential for 14-3-3 zeta protein to serve as a biomarker for epithelial ovarian cancer

PubMed Central

2013-01-01

Objective Recently, 14-3-3 zeta protein was identified as a potential serum biomarker of epithelial ovarian cancer (EOC). The goal of this study was to investigate the clinical potential of 14-3-3 zeta protein for monitoring EOC progression compared with CA-125 and HE4. Design Prospective follow-up study. Setting University of Pecs Medical Center Department of Obstetrics and Gynecology/Oncology (Pecs, Hungary). Population Thirteen EOC patients with advanced stage (FIGO IIb-IIIc) epithelial ovarian cancer that underwent radical surgery and received six consecutive cycles of first line chemotherapy (paclitaxel, carboplatin) in 21-day intervals. Methods Pre- and post-chemotherapy computed tomography (CT) scans were performed. Serum levels of CA-125, HE4, and 14-3-3 zeta protein were detected by enzyme-linked immunosorbent assay (ELISA) and quantitative electrochemiluminescence assay (ECLIA). Main outcome measures Serum levels of CA-125, HE4, and 14-3-3 zeta protein, as well as lesion size according to pre- and post-chemotherapy CT scans. Results Serum levels of CA-125 and HE4 were found to significantly decrease following chemotherapy, and this was consistent with the decrease in lesion size detected post-chemotherapy. In contrast, 14-3-3 zeta protein levels did not significantly differ in healthy postmenopausal patients versus EOC patients. Conclusions Determination of CA-125 and HE4 serum levels for the determination of the risk of ovarian malignancy algorithm (ROMA) represents a useful tool for the prediction of chemotherapy efficacy for EOC patients. However, levels of 14-3-3 zeta protein were not found to vary significantly as a consequence of treatment. Therefore we question if 14-3-3 zeta protein is a reliable biomarker, which correlates with the clinical behavior of EOC. PMID:24238270

Zeta potential study of Sb2S3 nanoparticles synthesized by a facile polyol method in various surfactants

NASA Astrophysics Data System (ADS)

Saxena, Monika; Okram, Gunadhor Singh

2018-05-01

In the present work, we report the successful synthesis of stibnite Sb2S3 nanoparticles (NPs) by a facile polyol method using various surfactant. The structural and optical properties were investigated by X-ray diffraction (XRD), Raman spectroscopy and Zeta potential. Rietveld refinement of XRD data confirms the single phase orthorhombic crystal structure of stibnite Sb2S3. Presence of six obvious Raman modes further confirmed their stoichiometric formation. Effect of different surfactants on the surface charge of Sb2S3 NPs was studied using Zeta potential measurement in deionized water at different pH values. They reveal that these NPs are more stable when it was synthesized in presence of EDTA than that of CTAB or without surfactant samples with high zeta potential. The isoelectronic point was found at pH = 6.4 for pure sample, 3.5 and 7.2 for CTAB and not found for EDTA Sb2S3 samples. This information can be useful for many industrial applications like pharmaceuticals, ceramics, waste water treatment and medicines.

Acoustic Experiment to Measure the Bulk Viscosity of Near-Critical Xenon in Microgravity

NASA Technical Reports Server (NTRS)

Gillis, K. A.; Shinder, I.; Moldover, M. R.; Zimmerli, G. A.

2002-01-01

We plan a rigorous test of the theory of dynamic scaling by accurately measuring the bulk viscosity of xenon in microgravity 50 times closer to the critical temperature T(sub c) than previous experiments. The bulk viscosity zeta (or "second viscosity" or "dilational viscosity") will be determined by measuring the attenuation length of sound alpha lambda and also measuring the frequency-dependence of the speed of sound. For these measurements, we developed a unique Helmholtz resonator and specialized electro-acoustic transducers. We describe the resonator, the transducers, their performance on Earth, and their expected performance in microgravity.

The adsorption of cationic and amphoteric copolymers on glass surfaces: zeta potential measurements, adsorption isotherm determination, and FT Raman characterization.

PubMed

Tartakovsky, Alla; Drutis, Dane M; Carnali, Joseph O

2003-07-15

The adsorption of cationic and amphoteric copolymers onto controlled pore glass (CPG) powders has been studied by measurement of the powder particle zeta (zeta) potential, by determination of the adsorption isotherm, and by FT Raman measurements of the polymer-coated powder. The cationic polymers consisted chiefly of homopolymers of dimethyldiallylammonium chloride (DMDAAC) or copolymers of DMDAAC and acrylamide. The amphoteric polymers studied included copolymers of DMDAAC and acrylic acid. The comonomer ratio was varied to explore the dependence of cationic charge density on the extent and effect of adsorption. Both types of polymers adsorb onto the anionic glass surface via an ion-exchange mechanism. Consequently, a correspondingly higher mass of a low-charge-density copolymer adsorbs than of a cationic homopolymer. The presence of the anionic portion in the amphoteric polymers does not significantly alter this picture. The zeta potential, however, reflects the overall nature of the polymer. Cationic polymers effectively neutralize the glass surface, while amphoteric polymers leave the zeta potential net negative. Adsorption isotherms, determined via the depletion technique using colloidal titration, were used to "calibrate" a FT Raman method. The latter was used to determined the amount of adsorbed polymer under solution conditions in which colloidal titration could not be performed.

Zeta-potential and particle size studies of silver sulphide nanoparticles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sharma, Vikash, E-mail: vikash@csr.res.in; Tarachand,; Ganesan, V.

Silver sulfide (Ag{sub 2}S) nanoparticles (NPs) were prepared successfully for the first time using diethylene glycol (DEG) as a surfactant. X-ray diffraction (XRD) data revealed single phase nature of the compound and energy-dispersive X-ray (EDX) confirmed its nominal composition. Their sizes were 43 nm from XRD, 50 nm from atomic force microscopy (AFM) and 19 nm & 213 nm from dynamic light scattering (DLS); their differences have been discussed. Autotitration study of zeta potential of these NPs in deionized water by DLS at different pH values confirmed an isoelectric point at pH = 5.14 and their very unstable nature in deionized water.

Zeta potential in oil-water-carbonate systems and its impact on oil recovery during controlled salinity water-flooding

PubMed Central

Jackson, Matthew D.; Al-Mahrouqi, Dawoud; Vinogradov, Jan

2016-01-01

Laboratory experiments and field trials have shown that oil recovery from carbonate reservoirs can be increased by modifying the brine composition injected during recovery in a process termed controlled salinity water-flooding (CSW). However, CSW remains poorly understood and there is no method to predict the optimum CSW composition. This work demonstrates for the first time that improved oil recovery (IOR) during CSW is strongly correlated to changes in zeta potential at both the mineral-water and oil-water interfaces. We report experiments in which IOR during CSW occurs only when the change in brine composition induces a repulsive electrostatic force between the oil-brine and mineral-brine interfaces. The polarity of the zeta potential at both interfaces must be determined when designing the optimum CSW composition. A new experimental method is presented that allows this. Results also show for the first time that the zeta potential at the oil-water interface may be positive at conditions relevant to carbonate reservoirs. A key challenge for any model of CSW is to explain why IOR is not always observed. Here we suggest that failures using the conventional (dilution) approach to CSW may have been caused by a positively charged oil-water interface that had not been identified. PMID:27876833

Dynamic Light Scattering and Zeta Potential of Colloidal Mixtures of Amelogenin and Hydroxyapatite in Calcium and Phosphate Rich Ionic Milieus

PubMed Central

Uskoković, Vuk; Odsinada, Roselyn; Djordjevic, Sonia; Habelitz, Stefan

2011-01-01

The concept of zeta-potential has been used for more than a century as a basic parameter in controlling the stability of colloidal suspensions, irrespective of the nature of their particulate ingredients – organic or inorganic. There are prospects that self-assembly of peptide species and the protein-mineral interactions related to biomineralization may be controlled using this fundamental physicochemical parameter. In this study, we have analyzed the particle size and zeta-potential of the full-length recombinant human amelogenin (rH174), the main protein of the developing enamel matrix, in the presence of calcium and phosphate ions and hydroxyapatite (HAP) particles. As calcium and phosphate salts are introduced to rH174 sols in increments, zeta-potential of the rH174 nanospheres is more affected by negatively charged ions, suggesting their tendency to locate within the double charge layer. Phosphate ions have a more pronounced effect on both the zeta-potential and aggregation propensity of rH174 nanospheres compared to calcium ions. The isoelectric point of amelogenin was independent on the ionic strength of the solution and the concentration of calcium and/or phosphate ions. Whereas rH174 shows a higher affinity for phosphate than for calcium, HAP attracts both of these ions to the shear plane of the double layer. The parallel size and zeta-potential analysis of HAP and rH174 colloidal mixtures indicated that at pH 7.4, despite both HAP and rH174 particles being negatively charged, rH174 adsorbs well onto HAP particles. The process is slower at pH 7.4 than at pH 4.5 when the HAP surface is negatively charged and the rH174 nanosphere carries an overall positive charge. The results presented hereby demonstrate that electrostatic interactions can affect the kinetics of the adsorption of rH174 onto HAP. PMID:21146151

Influence of temperature, anions and size distribution on the zeta potential of DMPC, DPPC and DMPE lipid vesicles.

PubMed

Morini, M A; Sierra, M B; Pedroni, V I; Alarcon, L M; Appignanesi, G A; Disalvo, E A

2015-07-01

The purpose of the work is to compare the influence of the multilamellarity, phase state, lipid head groups and ionic media on the origin of the surface potential of lipid membranes. With this aim, we present a new analysis of the zeta potential of multilamellar and unilamellar vesicles composed by phosphatidylcholines (PC) and phosphatidylethanolamines (PE) dispersed in water and ionic solutions of polarizable anions, at temperatures below and above the phase transition. In general, the adsorption of anions seems to explain the origin of the zeta potential in vesicles only above the transition temperature (Tc). In this case, the sign of the surface potential is ascribed to a partial orientation of head group moiety toward the aqueous phase. This is noticeable in PC head groups but not in PEs, due to the strong lateral interaction between PO and NH group in PE. Copyright © 2015 Elsevier B.V. All rights reserved.

Understanding and modulating opalescence and viscosity in a monoclonal antibody formulation

PubMed Central

Salinas, Branden A; Sathish, Hasige A; Bishop, Steven M; Harn, Nick; Carpenter, John F; Randolph, Theodore W

2014-01-01

Opalescence and high viscosities can pose challenges for high concentration formulation of antibodies. Both phenomena result from protein-protein intermolecular interactions that can be modulated with solution ionic strength. We studied a therapeutic monoclonal antibody that exhibits high viscosity in solutions at low ionic strength (~20 centipoise (cP) at 90 mg/mL and 23°C) and significant opalescence at isotonic ionic strength (approximately 100 nephelometric turbidity units at 90 mg/mL and 23°C). The intermolecular interactions responsible for these effects were characterized using membrane osmometry, static light scattering and zeta potential measurements. The net protein-protein interactions were repulsive at low ionic strength (~4 mM) and attractive at isotonic ionic strengths. The high viscosities are attributed to electroviscous forces at low ionic strength and the significant opalescence at isotonic ionic strength is correlated with attractive antibody interactions. Furthermore there appears to be a connection to critical phenomena and it is suggested that the extent of opalescence is dependent on the proximity to the critical point. We demonstrate that by balancing the repulsive and attractive forces via intermediate ionic strengths and by increasing the mAb concentration above the apparent critical concentration both opalescence and viscosity can be simultaneously minimized. PMID:19475558

Surface electrochemical properties of red mud (bauxite residue): zeta potential and surface charge density.

PubMed

Liu, Yanju; Naidu, Ravendra; Ming, Hui

2013-03-15

The surface electrochemical properties of red mud (bauxite residue) from different alumina refineries in Australia and China were studied by electrophoresis and measuring surface charge density obtained from acid/base potentiometric titrations. The electrophoretic properties were measured from zeta potentials obtained in the presence of 0.01 and 0.001 M KNO(3) over a wide pH range (3.5-10) by titration. The isoelectric point (IEP) values were found to vary from 6.35 to 8.70 for the red mud samples. Further investigation into the surface charge density of one sample (RRM) by acid/base potentiometric titration showed similar results for pH(PZC) with pH(IEP) obtained from electrokinetic measurements. The pH(IEP) determined from zeta potential measurements can be used as a characteristic property of red mud. The minerals contained in red mud contributed to the different values of pH(IEP) of samples obtained from different refineries. Different relationships of pH(IEP) with Al/Fe and Al/Si ratios (molar basis) were also found for different red mud samples. Copyright © 2012 Elsevier Inc. All rights reserved.

Interlaboratory comparison for the measurement of particle size and zeta potential of silica nanoparticles in an aqueous suspension

NASA Astrophysics Data System (ADS)

Lamberty, Andrée; Franks, Katrin; Braun, Adelina; Kestens, Vikram; Roebben, Gert; Linsinger, Thomas P. J.

2011-12-01

The Institute for Reference Materials and Measurements has organised an interlaboratory comparison (ILC) to allow the participating laboratories to demonstrate their proficiency in particle size and zeta potential measurements on monomodal aqueous suspensions of silica nanoparticles in the 10-100 nm size range. The main goal of this ILC was to identify competent collaborators for the production of certified nanoparticle reference materials. 38 laboratories from four different continents participated in the ILC with different methods for particle sizing and determination of zeta potential. Most of the laboratories submitted particle size results obtained with centrifugal liquid sedimentation (CLS), dynamic light scattering (DLS) or electron microscopy (EM), or zeta potential values obtained via electrophoretic light scattering (ELS). The results of the laboratories were evaluated using method-specific z scores, calculated on the basis of consensus values from the ILC. For CLS (13 results) and EM (13 results), all reported values were within the ±2 | z| interval. For DLS, 25 of the 27 results reported were within the ±2 | z| interval, the two other results were within the ±3 | z| interval. The standard deviations of the corresponding laboratory mean values varied between 3.7 and 6.5%, which demonstrates satisfactory interlaboratory comparability of CLS, DLS and EM particle size values. From the received test reports, a large discrepancy was observed in terms of the laboratory's quality assurance systems, which are equally important for the selection of collaborators in reference material certification projects. Only a minority of the participating laboratories is aware of all the items that are mandatory in test reports compliant to ISO/IEC 17025 (ISO General requirements for the competence of testing and calibration laboratories. International Organisation for Standardization, Geneva, 2005b). The absence of measurement uncertainty values in the reports, for

Reduced Zeta potential through use of cationic adhesion promoter for improved resist process performance and minimizing material consumption

NASA Astrophysics Data System (ADS)

Hodgson, Lorna; Thompson, Andrew

2012-03-01

This paper presents the results of a non-HMDS (non-silane) adhesion promoter that was used to reduce the zeta potential for very thin (proprietary) polymer on silicon. By reducing the zeta potential, as measured by the minimum sample required to fully coat a wafer, the amount of polymer required to coat silicon substrates was significantly reduced in the manufacture of X-ray windows used for high transmission of low-energy X-rays. Moreover, this approach used aqueous based adhesion promoter described as a cationic surface active agent that has been shown to improve adhesion of photoresists (positive, negative, epoxy [SU8], e-beam and dry film). As well as reducing the amount of polymer required to coat substrates, this aqueous adhesion promoter is nonhazardous, and contains non-volatile solvents.

Protein adsorption on dopamine-melanin films: role of electrostatic interactions inferred from zeta-potential measurements versus chemisorption.

PubMed

Bernsmann, Falk; Frisch, Benoît; Ringwald, Christian; Ball, Vincent

2010-04-01

We recently showed the possibility to build dopamine-melanin films of controlled thickness by successive immersions of a substrate in alkaline solutions of dopamine [F. Bernsmann, A. Ponche, C. Ringwald, J. Hemmerlé, J. Raya, B. Bechinger, J.-C. Voegel, P. Schaaf, V. Ball, J. Phys. Chem. C 113 (2009) 8234-8242]. In this work the structure and properties of such films are further explored. The zeta-potential of dopamine-melanin films is measured as a function of the total immersion time to build the film. It appears that the film bears a constant zeta-potential of (-39+/-3) mV after 12 immersion steps. These data are used to calculate the surface density of charged groups of the dopamine-melanin films at pH 8.5 that are mostly catechol or quinone imine chemical groups. Furthermore the zeta-potential is used to explain the adsorption of three model proteins (lysozyme, myoglobin, alpha-lactalbumin), which is monitored by quartz crystal microbalance. We come to the conclusion that protein adsorption on dopamine-melanin is not only determined by possible covalent binding between amino groups of the proteins and catechol groups of dopamine-melanin but that electrostatic interactions contribute to protein binding. Part of the adsorbed proteins can be desorbed by sodium dodecylsulfate solutions at the critical micellar concentration. The fraction of weakly bound proteins decreases with their isoelectric point. Additionally the number of available sites for covalent binding of amino groups on melanin grains is quantified. Copyright 2009 Elsevier Inc. All rights reserved.

Retention of membrane charge attributes by cryopreserved-thawed sperm and zeta selection.

PubMed

Kam, Tricia L; Jacobson, John D; Patton, William C; Corselli, Johannah U; Chan, Philip J

2007-09-01

Mature sperm can be selected based on their negative zeta electrokinetic potential. The zeta selection of cryopreserved sperm is unknown. The objective was to study the effect of zeta processing on the morphology and kinematic parameters of cryopreserved-thawed sperm. Colloid-washed sperm (N = 9 cases) were cryopreserved for 24 h, thawed and diluted in serum-free medium in positive-charged tubes. After centrifugation, the tubes were decanted, serum-supplemented medium was added and the resuspended sperm were analyzed. Untreated sperm and fresh sperm served as the controls. There were improvements in strict normal morphology in fresh (11.8 +/- 0.3 versus control 8.8 +/- 0.3 %, mean +/- SEM) and thawed (8.7 +/- 0.2 versus control 5.4 +/- 0.2%) sperm after zeta processing. Percent sperm necrosis was reduced after zeta processing (66.0 +/- 0.6 versus unprocessed 74.6 +/- 0.3%). Progression decreased by 50% but not total motility after zeta processing of thawed sperm. The results suggested that the cryopreservation process did not impact the sperm membrane net zeta potential and higher percentages of sperm with normal strict morphology, acrosome integrity and reduced necrosis were recovered. The zeta method was simple and improved the selection of quality sperm after cryopreservation but more studies would be needed before routine clinical application.

Flotation of algae for water reuse and biomass production: role of zeta potential and surfactant to separate algal particles.

PubMed

Kwak, Dong-Heui; Kim, Mi-Sug

2015-01-01

The effect of chemical coagulation and biological auto-flocculation relative to zeta potential was examined to compare flotation and sedimentation separation processes for algae harvesting. Experiments revealed that microalgae separation is related to auto-flocculation of Anabaena spp. and requires chemical coagulation for the whole period of microalgae cultivation. In addition, microalgae separation characteristics which are associated with surfactants demonstrated optimal microalgae cultivation time and separation efficiency of dissolved CO2 flotation (DCF) as an alternative to dissolved air flotation (DAF). Microalgae were significantly separated in response to anionic surfactant rather than cationic surfactant as a function of bubble size and zeta potential. DAF and DCF both showed slightly efficient flotation; however, application of anionic surfactant was required when using DCF.

Bulk viscosity and relaxation time of causal dissipative relativistic fluid dynamics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang Xuguang; Rischke, Dirk H.; Institut fuer Theoretische Physik, J.W. Goethe-Universitaet, D-60438 Frankfurt am Main

2011-02-15

The microscopic formulas of the bulk viscosity {zeta} and the corresponding relaxation time {tau}{sub {Pi}} in causal dissipative relativistic fluid dynamics are derived by using the projection operator method. In applying these formulas to the pionic fluid, we find that the renormalizable energy-momentum tensor should be employed to obtain consistent results. In the leading-order approximation in the chiral perturbation theory, the relaxation time is enhanced near the QCD phase transition, and {tau}{sub {Pi}} and {zeta} are related as {tau}{sub {Pi}={zeta}}/[{beta}{l_brace}(1/3-c{sub s}{sup 2})({epsilon}+P)-2({epsilon}-3P)/9{r_brace}], where {epsilon}, P, and c{sub s} are the energy density, pressure, and velocity of sound, respectively. The predictedmore » {zeta} and {tau}{sub {Pi}} should satisfy the so-called causality condition. We compare our result with the results of the kinetic calculation by Israel and Stewart and the string theory, and confirm that all three approaches are consistent with the causality condition.« less

The role of zeta potential in the adhesion of E. coli to suspended intertidal sediments.

PubMed

Wyness, Adam J; Paterson, David M; Defew, Emma C; Stutter, Marc I; Avery, Lisa M

2018-05-29

The extent of pathogen transport to and within aquatic systems depends heavily on whether the bacterial cells are freely suspended or in association with suspended particles. The surface charge of both bacterial cells and suspended particles affects cell-particle adhesion and subsequent transport and exposure pathways through settling and resuspension cycles. This study investigated the adhesion of Faecal Indicator Organisms (FIOs) to natural suspended intertidal sediments over the salinity gradient encountered at the transition zone from freshwater to marine environments. Phenotypic characteristics of three E. coli strains, and the zeta potential (surface charge) of the E. coli strains and 3 physically different types of intertidal sediments was measured over a salinity gradient from 0 to 5 Practical Salinity Units (PSU). A batch adhesion microcosm experiment was constructed with each combination of E. coli strain, intertidal sediment and 0, 2, 3.5 and 5 PSU. The zeta potential profile of one E. coli strain had a low negative charge and did not change in response to an increase in salinity, and the remaining E. coli strains and the sediments exhibited a more negative charge that decreased with an increase in salinity. Strain type was the most important factor in explaining cell-particle adhesion, however adhesion was also dependant on sediment type and salinity (2, 3.5 PSU > 0, 5 PSU). Contrary to traditional colloidal (Derjaguin, Landau, Vervey, and Overbeek (DLVO)) theory, zeta potential of strain or sediment did not correlate with cell-particle adhesion. E. coli strain characteristics were the defining factor in cell-particle adhesion, implying that diverse strain-specific transport and exposure pathways may exist. Further research applying these findings on a catchment scale is necessary to elucidate these pathways in order to improve accuracy of FIO fate and transport models. Copyright © 2018 Elsevier Ltd. All rights reserved.

A zeta potential value determines the aggregate's size of penta-substituted [60]fullerene derivatives in aqueous suspension whereas positive charge is required for toxicity against bacterial cells.

PubMed

Deryabin, Dmitry G; Efremova, Ludmila V; Vasilchenko, Alexey S; Saidakova, Evgeniya V; Sizova, Elena A; Troshin, Pavel A; Zhilenkov, Alexander V; Khakina, Ekaterina A; Khakina, Ekaterina E

2015-08-08

The cause-effect relationships between physicochemical properties of amphiphilic [60]fullerene derivatives and their toxicity against bacterial cells have not yet been clarified. In this study, we report how the differences in the chemical structure of organic addends in 10 originally synthesized penta-substituted [60]fullerene derivatives modulate their zeta potential and aggregate's size in salt-free and salt-added aqueous suspensions as well as how these physicochemical characteristics affect the bioenergetics of freshwater Escherichia coli and marine Photobacterium phosphoreum bacteria. Dynamic light scattering, laser Doppler micro-electrophoresis, agarose gel electrophoresis, atomic force microscopy, and bioluminescence inhibition assay were used to characterize the fullerene aggregation behavior in aqueous solution and their interaction with the bacterial cell surface, following zeta potential changes and toxic effects. Dynamic light scattering results indicated the formation of self-assembled [60]fullerene aggregates in aqueous suspensions. The measurement of the zeta potential of the particles revealed that they have different surface charges. The relationship between these physicochemical characteristics was presented as an exponential regression that correctly described the dependence of the aggregate's size of penta-substituted [60]fullerene derivatives in salt-free aqueous suspension from zeta potential value. The prevalence of DLVO-related effects was shown in salt-added aqueous suspension that decreased zeta potential values and affected the aggregation of [60]fullerene derivatives expressed differently for individual compounds. A bioluminescence inhibition assay demonstrated that the toxic effect of [60]fullerene derivatives against E. coli cells was strictly determined by their positive zeta potential charge value being weakened against P. phosphoreum cells in an aquatic system of high salinity. Atomic force microscopy data suggested that the

Ion Viscosity Mediated by Tangled Magnetic Fields: An Application to Black Hole Accretion Disks

NASA Technical Reports Server (NTRS)

Subramanian, Prasad; Becker, Peter A.; Kafatos, Menas

1996-01-01

We examine the viscosity associated with the shear stress exerted by ions in the presence of a tangled magnetic field. As an application, we consider the effect of this mechanism on the structure of black hole accretion disks. We do not attempt to include a self-consistent description of the magnetic field. Instead, we assume the existence of a tangled field with coherence length lambda(sub coh), which is the average distance between the magnetic 'kinks' that scatter the particles. For simplicity, we assume that the field is self-similar, and take lambda(sub coh) to be a fixed fraction zeta of the local disk height H. Ion viscosity in the presence of magnetic fields is generally taken to be the cross-field viscosity, wherein the effective mean free path is the ion Larmor radius lambda(sub L), which is much less than the ion-ion Coulomb mean free path A(sub ii) in hot accretion disks. However, we arrive at a formulation for a 'hybrid' viscosity in which the tangled magnetic field acts as an intermediary in the transfer of momentum between different layers in the shear flow. The hybrid viscosity greatly exceeds the standard cross-field viscosity when (lambda/lambda(sub L)) much greater than (lambda(sub L)/lambda(sub ii)), where lambda = ((lambda(sub ii)(sup -1) + lambda(sub (coh)(sup -1))(sup -1) is the effective mean free path for the ions. This inequality is well satisfied in hot accretion disks, which suggests that the ions may play a much larger role in the momentum transfer process in the presence of magnetic fields than was previously thought. The effect of the hybrid viscosity on the structure of a steady-state, two-temperature, quasi-Keplerian accretion disk is analyzed. The hybrid viscosity is influenced by the degree to which the magnetic field is tangled (represented by zeta = lambda(sub coh)), and also by the relative accretion rate M/M(sub E), where M(sub E) = L(sub E)/c(sup 2) and L(sub E) is the Eddington luminosity. We find that ion viscosity in the

Rheological behavior, zeta potential, and accelerated stability tests of Buriti oil (Mauritia flexuosa) emulsions containing lyotropic liquid crystals.

PubMed

Zanatta, Cinthia Fernanda; de Faria Sato, Anne Miwa Callejón; de Camargo, Flavio Bueno; Campos, Patrícia Maria Berardo Gonçalves Maia; Rocha-Filho, Pedro Alves

2010-01-01

It is well known that the Amazon region presents a huge biodiversity; therefore, countless natural resources are being employed in the production of phytocosmetics and phytomedicines. The purpose of this work was to obtain emulsions produced with Buriti oil and non-ionic surfactants. Two surfactant systems were employed (Steareth-2 associated to Ceteareth-5 and to Ceteareth-20) to produce the emulsions using phase diagram method. Emulsions were obtained by echo-planar imaging method at 75°C. Rheological behavior and zeta potential were evaluated, and accelerated stability tests were performed. All emulsions analyzed presented pseudoplastic behavior. Zeta potential values were obtained between -14.2 and -53.3 mV. The formulations did not show changes in either physical stability, pH, or rheological behavior after accelerated stability tests. Significant differences were observed only after temperature cycling test. Based on these results, the emulsions obtained could be considered as promising delivery systems.

Saliva viscosity as a potential risk factor for oral malodor.

PubMed

Ueno, Masayuki; Takeuchi, Susumu; Takehara, Sachiko; Kawaguchi, Yoko

2014-11-01

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 < 0.001) were significant variables for oral malodor. Subjects with a higher number of teeth with PD ≥ 4 mm (OR = 1.32), plaque index (OR = 2.13), area of tongue coating (OR = 3.17) and saliva 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.

Zeta potentials in the flotation of oxide and silicate minerals.

PubMed

Fuerstenau, D W; Pradip

2005-06-30

Adsorption of collectors and modifying reagents in the flotation of oxide and silicate minerals is controlled by the electrical double layer at the mineral-water interface. In systems where the collector is physically adsorbed, flotation with anionic or cationic collectors depends on the mineral surface being charged oppositely. Adjusting the pH of the system can enhance or prevent the flotation of a mineral. Thus, the point of zero charge (PZC) of the mineral is the most important property of a mineral in such systems. The length of the hydrocarbon chain of the collector is important because of chain-chain association enhances the adsorption once the surfactant ions aggregate to form hemimicelles at the surface. Strongly chemisorbing collectors are able to induce flotation even when collector and the mineral surface are charged similarly, but raising the pH sufficiently above the PZC can repel chemisorbing collectors from the mineral surface. Zeta potentials can be used to delineate interfacial phenomena in these various systems.

Viscosity Analysis of Dual Variable Domain Immunoglobulin Protein Solutions: Role of Size, Electroviscous Effect and Protein-Protein Interactions.

PubMed

Raut, Ashlesha S; Kalonia, Devendra S

2016-01-01

Increased solution viscosity results in difficulties in manufacturing and delivery of therapeutic protein formulations, increasing both the time and production costs, and leading to patient inconvenience. The solution viscosity is affected by the molecular properties of both the solute and the solvent. The purpose of this work was to investigate the effect of size, charge and protein-protein interactions on the viscosity of Dual Variable Domain Immunoglobulin (DVD-Ig(TM)) protein solutions. The effect of size of the protein molecule on solution viscosity was investigated by measuring intrinsic viscosity and excluded volume calculations for monoclonal antibody (mAb) and DVD-Ig(TM) protein solutions. The role of the electrostatic charge resulting in electroviscous effects for DVD-Ig(TM) protein was assessed by measuring zeta potential. Light scattering measurements were performed to detect protein-protein interactions affecting solution viscosity. DVD-Ig(TM) protein exhibited significantly higher viscosity compared to mAb. Intrinsic viscosity and excluded volume calculations indicated that the size of the molecule affects viscosity significantly at higher concentrations, while the effect was minimal at intermediate concentrations. Electroviscous contribution to the viscosity of DVD-Ig(TM) protein varied depending on the presence or absence of ions in the solution. In buffered solutions, negative k D and B 2 values indicated the presence of attractive interactions which resulted in high viscosity for DVD-Ig(TM) protein at certain pH and ionic strength conditions. Results show that more than one factor contributes to the increased viscosity of DVD-Ig(TM) protein and interplay of these factors modulates the overall viscosity behavior of the solution, especially at higher concentrations.

Zeta potential and Raman studies of PVP capped Bi2S3 nanoparticles synthesized by polyol method

NASA Astrophysics Data System (ADS)

Tarachand, Sathe, Vasant G.; Okram, Gunadhor S.

2018-05-01

Here we report the synthesis and characterisation of polyvinylpyrrolidone (PVP) capped Bi2S3 nanoparticles via one step catalyst-free polyol method. Raman spectroscopy, dynamic light scattering and zeta potential analysis were performed on it. Rietveld refinement of powder XRD of PVP capped samples confirmed the formation of single phase orthorhombic Bi2S3 for all PVP capped samples. The presence of eight obvious Raman modes further confirmed the formation of stoichiometric Bi2S3. Dynamic light scattering (DLS) studies show a clear increase in hydrodynamic diameter for samples made with increasing PVP concentration. Particle size obtained from DLS and XRD (using Scherrer's formula) combine with change in full width half maxima of Raman modes collectively suggest overall improvement in crystallinity and quality of product on introducing PVP. In zeta potential (ζ) measurement, steric hindrance of carbon chains plays very crucial role and a systematic reduction of ζ value is observed for samples made with decreasing PVP concentration. An isoelectric point is obtained for sample made with low PVP (1g). Present results are likely to open a window for its medical and catalytic applications.

Interrelationship between the zeta potential and viscoelastic properties in coacervates complexes.

PubMed

Espinosa-Andrews, Hugo; Enríquez-Ramírez, Karina Esmeralda; García-Márquez, Eristeo; Ramírez-Santiago, Cesar; Lobato-Calleros, Consuelo; Vernon-Carter, Jaime

2013-06-05

The formation of the complex coacervate (CC) phases between gum Arabic (GA) and low molecular weight chitosan (Ch) and the interrelationship between the zeta-potential and viscoelastic properties of the coacervate phase were investigated. The maximum charge difference of biopolymers stock dispersion was displayed in a range of pH between 4.0 and 5.5. Titration experiment between the oppositely charged biopolymers showed that the isoelectric point was found at a biopolymers mass ratio (R[GA:Ch]) of R[5.5:1]. Turbidity, size and ζ-potential of the soluble complexes (SC) showed an interrelation with the complex coacervate yield (CCY). Higher CCY values (82.2-88.1%) were obtained in the range from R[3:1] to R[5.5:1]. Change the R[GA:Ch] in dispersion, make possible to produce CC's phases exhibiting cationic (R[1:1] and R[3:1]), neutral (R[5.5:1]) or anionic (R[9:1] and R[7:1]) charged. All CC's exhibited liquid-viscoelastic behavior at lower frequencies and a crossover between G″ and G' at higher frequencies. Copyright © 2013 Elsevier Ltd. All rights reserved.

Hydrogen bonding and interparticle forces in platelet alpha-Al2O3 dispersions: yield stress and zeta potential.

PubMed

Khoo, Kay-Sen; Teh, E-Jen; Leong, Yee-Kwong; Ong, Ban Choon

2009-04-09

Adsorbed phosphate on smooth platelet alpha-Al2O3 particles at saturation surface coverage gives rise to strong interparticle attractive forces in dispersion. The maximum yield stress at the point of zero charge was increased by 2-fold. This was attributed to a high density of intermolecular hydrogen bonding between the adsorbed phosphate layers of the interacting particles. Adsorbed citrate at saturation surface coverage, however, reduced the maximum yield stress by 50%. It adsorbed to form a very effective steric barrier as intramolecular hydrogen bonding between -OH and the free terminal carboxylic group prevented strong interactions with other adsorbed citrate molecules residing on the second interacting particle. This steric barrier kept the interacting platelet particles further apart, thereby weakening the van der Waals attraction. The platelet alpha-Al2O3 dispersions were flocculated at all pH level. These dispersions displayed a maximum yield stress at the point of zero zeta potential at the pH approximately 8.0. They also obeyed the yield stress-DLVO force model as characterized by a linear decrease in the yield stress with the square of the zeta potential.

Effect of zeta potential on the performance of a ring-type electroosmotic mixer.

PubMed

Kim, T A; Koo, K H; Kim, Y J

2009-12-01

In order to achieve faster mixing, a new type of electrokinetic mixer with a T-type channel is introduced. The proposed mixer takes two fluids from different inlets and combines them into a single channel. The fluids then enter a mixing chamber with different inner and outer radii. Four microelectrodes are positioned on the outer wall of the mixing chamber. The electric potentials on the four microelectrodes are sinusoidal with respect to time and have various maximum voltages, zeta potentials and frequency values. The working fluid is water and each inlet has a different initial concentration values. The incompressible Navier-Stokes equation is solved in the channel, with a slip boundary condition on the inner and outer walls of the mixing chamber. The convection-diffusion equation is used to describe the concentration of the dissolved substances in the fluid. The pressure, concentration and flow fields in the channel are calculated and the results are graphically depicted for various flow and electric conditions.

An estimate of the bulk viscosity of the hadronic medium

NASA Astrophysics Data System (ADS)

Sarwar, Golam; Chatterjee, Sandeep; Alam, Jane

2017-05-01

The bulk viscosity (ζ) of the hadronic medium has been estimated within the ambit of the Hadron Resonance Gas (HRG) model including the Hagedorn density of states. The HRG thermodynamics within a grand canonical ensemble provides the mean hadron number as well as its fluctuation. The fluctuation in the chemical composition of the hadronic medium in the grand canonical ensemble can result in non-zero divergence of the hadronic fluid flow velocity, allowing us to estimate the ζ of the hadronic matter up to a relaxation time. We study the influence of the hadronic spectrum on ζ and find its correlation with the conformal symmetry breaking measure, ε -3P. We estimate ζ along the contours with constant, S/{N}B (total entropy/net baryon number) in the T-μ plane (temperature-baryonic chemical potential) for S/{N}B=30,45 and 300. We also assess the value of ζ on the chemical freeze-out curve for various centers of mass energy (\\sqrt{{s}{NN}}) and find that the bulk viscosity to entropy density ratio, \\zeta /s is larger in the energy range of the beam energy scan program of RHIC, low energy SPS run, AGS, NICA and FAIR, than LHC energies.

Surfactants, not size or zeta-potential influence blood-brain barrier passage of polymeric nanoparticles.

PubMed

Voigt, Nadine; Henrich-Noack, Petra; Kockentiedt, Sarah; Hintz, Werner; Tomas, Jürgen; Sabel, Bernhard A

2014-05-01

Nanoparticles (NP) can deliver drugs across the blood-brain barrier (BBB), but little is known which of the factors surfactant, size and zeta-potential are essential for allowing BBB passage. To this end we designed purpose-built fluorescent polybutylcyanoacrylate (PBCA) NP and imaged the NP's passage over the blood-retina barrier - which is a model of the BBB - in live animals. Rats received intravenous injections of fluorescent PBCA-NP fabricated by mini-emulsion polymerisation to obtain various NP's compositions that varied in surfactants (non-ionic, anionic, cationic), size (67-464nm) and zeta-potential. Real-time imaging of retinal blood vessels and retinal tissue was carried out with in vivo confocal neuroimaging (ICON) before, during and after NP's injection. Successful BBB passage with subsequent cellular labelling was achieved if NP were fabricated with non-ionic surfactants or cationic stabilizers but not when anionic compounds were added. NP's size and charge had no influence on BBB passage and cell labelling. This transport was not caused by an unspecific opening of the BBB because control experiments with injections of unlabelled NP and fluorescent dye (to test a "door-opener" effect) did not lead to parenchymal labelling. Thus, neither NP's size nor chemo-electric charge, but particle surface is the key factor determining BBB passage. This result has important implications for NP engineering in medicine: depending on the surfactant, NP can serve one of two opposite functions: while non-ionic tensides enhance brain up-take, addition of anionic tensides prevents it. NP can now be designed to specifically enhance drug delivery to the brain or, alternatively, to prevent brain penetration so to reduce unwanted psychoactive effects of drugs or prevent environmental nanoparticles from entering tissue of the central nervous system. Copyright © 2014 Elsevier B.V. All rights reserved.

Generation of nanobubbles by ceramic membrane filters: The dependence of bubble size and zeta potential on surface coating, pore size and injected gas pressure.

PubMed

Ahmed, Ahmed Khaled Abdella; Sun, Cuizhen; Hua, Likun; Zhang, Zhibin; Zhang, Yanhao; Zhang, Wen; Marhaba, Taha

2018-07-01

Generation of gaseous nanobubbles (NBs) by simple, efficient, and scalable methods is critical for industrialization and applications of nanobubbles. Traditional generation methods mainly rely on hydrodynamic, acoustic, particle, and optical cavitation. These generation processes render issues such as high energy consumption, non-flexibility, and complexity. This research investigated the use of tubular ceramic nanofiltration membranes to generate NBs in water with air, nitrogen and oxygen gases. This system injects pressurized gases through a tubular ceramic membrane with nanopores to create NBs. The effects of membrane pores size, surface energy, and the injected gas pressures on the bubble size and zeta potential were examined. The results show that the gas injection pressure had considerable effects on the bubble size, zeta potential, pH, and dissolved oxygen of the produced NBs. For example, increasing the injection air pressure from 69 kPa to 414 kPa, the air bubble size was reduced from 600 to 340 nm respectively. Membrane pores size and surface energy also had significant effects on sizes and zeta potentials of NBs. The results presented here aim to fill out the gaps of fundamental knowledge about NBs and development of efficient generation methods. Copyright © 2018 Elsevier Ltd. All rights reserved.

Cellular internalization of polycation-coated microparticles and its dependence on their zeta potential

NASA Astrophysics Data System (ADS)

Kato, Noritaka; Kondo, Ryosuke

2018-03-01

By applying microparticles to HeLa cells, the number of particles adhered on the cell and that of the ones internalized in the cells were evaluated. Three-dimensional tomographic images of the cells with the particles were obtained by multiphoton excitation laser scanning microscopy, and the adhered and internalized particles were counted separately. When the surface charge of the particles was reversed from negative to positive by coating the particles with polycations, both numbers significantly increased owing to the electrostatic attraction between the cells and the polycation-coated particles. Four different positively charged particles were prepared using four different polycations, and the numbers of adhered and internalized particles were compared. Our results suggest that these numbers depended on the zeta potential rather than the molecular structure of the polycation.

Zeta Potential Measurements on Solid Surfaces for in Vitro Biomaterials Testing: Surface Charge, Reactivity Upon Contact With Fluids and Protein Absorption

PubMed Central

Ferraris, Sara; Cazzola, Martina; Peretti, Veronica; Stella, Barbara; Spriano, Silvia

2018-01-01

Surface properties of biomaterials (e.g., roughness, chemical composition, charge, wettability, and hydroxylation degree) are key features to understand and control the complex interface phenomena that happens upon contact with physiological fluids. Numerous physico-chemical techniques can be used in order to investigate in depth these crucial material features. Among them, zeta potential measurements are widely used for the characterization of colloidal suspensions, but actually poorly explored in the study of solid surfaces, even if they can give significant information about surface charge in function of pH and indirectly about surface functional groups and reactivity. The aim of the present research is application of zeta potential measurements of solid surfaces for the in vitro testing of biomaterials. In particular, bare and surface modified Ti6Al4V samples have been compared in order to evaluate their isoelectric points (IEPs), surface charge at physiological pH, in vitro bioactivity [in simulated body fluid (SBF)] and protein absorption. Zeta potential titration was demonstrated as a suitable technique for the surface characterization of surface treated Ti6Al4V substrates. Significant shift of the isoelectric point was recorded after a chemical surface treatment (because of the exposition of hydroxyl groups), SBF soaking (because of apatite precipitation IEP moves close to apatite one) and protein absorption (IEP moves close to protein ones). Moreover, the shape of the curve gives information about exposed functional groups (e.g., a plateau in the basic range appears due to the exposition of acidic OH groups and in the acidic range due to exposition of basic NH2 groups). PMID:29868575

MISCIBILITY, SOLUBILITY, AND VISCOSITY MEASUREMENTS FOR R-236EA WITH POTENTIAL LUBRICANTS

EPA Science Inventory

The report gives results of miscibility, solubility, and viscosity measurements of refrigerant R-236ea with three potential lubricants. (NOTE: The data were needed to determine the suitability of refrigerant/lubricant combinations for use in refrigeration systems.) The lubricants...

The Isolation of DNA by Polycharged Magnetic Particles: An Analysis of the Interaction by Zeta Potential and Particle Size

PubMed Central

Haddad, Yazan; Xhaxhiu, Kledi; Kopel, Pavel; Hynek, David; Zitka, Ondrej; Adam, Vojtech

2016-01-01

Magnetic isolation of biological targets is in major demand in the biotechnology industry today. This study considers the interaction of four surface-modified magnetic micro- and nanoparticles with selected DNA fragments. Different surface modifications of nanomaghemite precursors were investigated: MAN37 (silica-coated), MAN127 (polyvinylpyrrolidone-coated), MAN158 (phosphate-coated), and MAN164 (tripolyphosphate-coated). All particles were positive polycharged agglomerated monodispersed systems. Mean particle sizes were 0.48, 2.97, 2.93, and 3.67 μm for MAN37, MAN127, MAN164, and MAN158, respectively. DNA fragments exhibited negative zeta potential of −0.22 mV under binding conditions (high ionic strength, low pH, and dehydration). A decrease in zeta potential of particles upon exposure to DNA was observed with exception of MAN158 particles. The measured particle size of MAN164 particles increased by nearly twofold upon exposure to DNA. Quantitative PCR isolation of DNA with a high retrieval rate was observed by magnetic particles MAN127 and MAN164. Interaction between polycharged magnetic particles and DNA is mediated by various binding mechanisms such as hydrophobic and electrostatic interactions. Future development of DNA isolation technology requires an understanding of the physical and biochemical conditions of this process. PMID:27104527

Joule heating effects on electromagnetohydrodynamic flow through a peristaltically induced micro-channel with different zeta potential and wall slip

NASA Astrophysics Data System (ADS)

Ranjit, N. K.; Shit, G. C.

2017-09-01

This paper aims to develop a mathematical model for magnetohydrodynamic flow of biofluids through a hydrophobic micro-channel with periodically contracting and expanding walls under the influence of an axially applied electric field. The velocity slip effects have been taken into account at the channel walls by employing different slip lengths due to hydrophobic gating. Different temperature jump factors have also been used to investigate the thermomechanical interactions at the fluid-solid interface. The electromagnetohydrodynamic flow in a microchannel is simplified under the framework of Debye-Hückel linearization approximation. We have derived the closed-form solutions for the linearized dimensionless boundary value problem under the assumptions of long wave length and low Reynolds number. The axial velocity, temperature, pressure distribution, stream function, wall shear stress and the Nusselt number have been appraised for diverse values of the parameters approaching into the problem. Our main focus is to determine the effects of different zeta potential on the axial velocity and temperature distribution under electromagnetic environment. This study puts forward an important observation that the different zeta potential plays an important role in controlling fluid velocity. The study further reveals that the temperature increases significantly with the Joule heating parameter and the Brinkman number (arises due to the dissipation of energy).

The Isolation of DNA by Polycharged Magnetic Particles: An Analysis of the Interaction by Zeta Potential and Particle Size.

PubMed

Haddad, Yazan; Xhaxhiu, Kledi; Kopel, Pavel; Hynek, David; Zitka, Ondrej; Adam, Vojtech

2016-04-20

Magnetic isolation of biological targets is in major demand in the biotechnology industry today. This study considers the interaction of four surface-modified magnetic micro- and nanoparticles with selected DNA fragments. Different surface modifications of nanomaghemite precursors were investigated: MAN37 (silica-coated), MAN127 (polyvinylpyrrolidone-coated), MAN158 (phosphate-coated), and MAN164 (tripolyphosphate-coated). All particles were positive polycharged agglomerated monodispersed systems. Mean particle sizes were 0.48, 2.97, 2.93, and 3.67 μm for MAN37, MAN127, MAN164, and MAN158, respectively. DNA fragments exhibited negative zeta potential of -0.22 mV under binding conditions (high ionic strength, low pH, and dehydration). A decrease in zeta potential of particles upon exposure to DNA was observed with exception of MAN158 particles. The measured particle size of MAN164 particles increased by nearly twofold upon exposure to DNA. Quantitative PCR isolation of DNA with a high retrieval rate was observed by magnetic particles MAN127 and MAN164. Interaction between polycharged magnetic particles and DNA is mediated by various binding mechanisms such as hydrophobic and electrostatic interactions. Future development of DNA isolation technology requires an understanding of the physical and biochemical conditions of this process.

A new biphasic osteoinductive calcium composite material with a negative Zeta potential for bone augmentation

PubMed Central

Smeets, Ralf; Kolk, Andreas; Gerressen, Marcus; Driemel, Oliver; Maciejewski, Oliver; Hermanns-Sachweh, Benita; Riediger, Dieter; Stein, Jamal M

2009-01-01

The aim of the present study was to analyze the osteogenic potential of a biphasic calcium composite material (BCC) with a negative surface charge for maxillary sinus floor augmentation. In a 61 year old patient, the BCC material was used in a bilateral sinus floor augmentation procedure. Six months postoperative, a bone sample was taken from the augmented regions before two titanium implants were inserted at each side. We analyzed bone neoformation by histology, bone density by computed tomography, and measured the activity of voltage-activated calcium currents of osteoblasts and surface charge effects. Control orthopantomograms were carried out five months after implant insertion. The BCC was biocompatible and replaced by new mineralized bone after being resorbed completely. The material demonstrated a negative surface charge (negative Zeta potential) which was found to be favorable for bone regeneration and osseointegration of dental implants. PMID:19523239

Earthing (grounding) the human body reduces blood viscosity-a major factor in cardiovascular disease.

PubMed

Chevalier, Gaétan; Sinatra, Stephen T; Oschman, James L; Delany, Richard M

2013-02-01

Emerging research is revealing that direct physical contact of the human body with the surface of the earth (grounding or earthing) has intriguing effects on human physiology and health, including beneficial effects on various cardiovascular risk factors. This study examined effects of 2 hours of grounding on the electrical charge (zeta potential) on red blood cells (RBCs) and the effects on the extent of RBC clumping. SUBJECTS were grounded with conductive patches on the soles of their feet and palms of their hands. Wires connected the patches to a stainless-steel rod inserted in the earth outdoors. Small fingertip pinprick blood samples were placed on microscope slides and an electric field was applied to them. Electrophoretic mobility of the RBCs was determined by measuring terminal velocities of the cells in video recordings taken through a microscope. RBC aggregation was measured by counting the numbers of clustered cells in each sample. Each subject sat in a comfortable reclining chair in a soundproof experiment room with the lights dimmed or off. Ten (10) healthy adult subjects were recruited by word-of-mouth. Earthing or grounding increased zeta potentials in all samples by an average of 2.70 and significantly reduced RBC aggregation. Grounding increases the surface charge on RBCs and thereby reduces blood viscosity and clumping. Grounding appears to be one of the simplest and yet most profound interventions for helping reduce cardiovascular risk and cardiovascular events.

Shear and bulk viscosity of high-temperature gluon plasma

NASA Astrophysics Data System (ADS)

Zhang, Le; Hou, De-Fu

2018-05-01

We calculate the shear viscosity (η) and bulk viscosity (ζ) to entropy density (s) ratios η/s and ζ/s of a gluon plasma system in kinetic theory, including both the elastic {gg}≤ftrightarrow {gg} forward scattering and the inelastic soft gluon bremsstrahlung {gg}≤ftrightarrow {ggg} processes. Due to the suppressed contribution to η and ζ in the {gg}≤ftrightarrow {gg} forward scattering and the effective g≤ftrightarrow {gg} gluon splitting, Arnold, Moore and Yaffe (AMY) and Arnold, Dogan and Moore (ADM) have got the leading order computations for η and ζ in high-temperature QCD matter. In this paper, we calculate the correction to η and ζ in the soft gluon bremsstrahlung {gg}≤ftrightarrow {ggg} process with an analytic method. We find that the contribution of the collision term from the {gg}≤ftrightarrow {ggg} soft gluon bremsstrahlung process is just a small perturbation to the {gg}≤ftrightarrow {gg} scattering process and that the correction is at ∼5% level. Then, we obtain the bulk viscosity of the gluon plasma for the number-changing process. Furthermore, our leading-order result for bulk viscosity is the formula \\zeta \\propto \\tfrac{{α }s2{T}3}{ln}{α }s-1} in high-temperature gluon plasma. Supported by Ministry of Science and Technology of China (MSTC) under the “973” Project (2015CB856904(4)) and National Natural Science Foundation of China (11735007, 11521064)

Optimal MEMS device for mobility and zeta potential measurements using DC electrophoresis.

PubMed

Karam, Pascal R; Dukhin, Andrei; Pennathur, Sumita

2017-05-01

We have developed a novel microchannel geometry that allows us to perform simple DC electrophoresis to measure the electrophoretic mobility and zeta potential of analytes and particles. In standard capillary geometries, mobility measurements using DC fields are difficult to perform. Specifically, measurements in open capillaries require knowledge of the hard to measure and often dynamic wall surface potential. Although measurements in closed capillaries eliminate this requirement, the measurements must be performed at infinitesimally small regions of zero flow where the pressure driven-flow completely cancels the electroosmotic flow (Komagata Planes). Furthermore, applied DC fields lead to electrode polarization, further questioning the reliability and accuracy of the measurement. In contrast, our geometry expands and moves the Komagata planes to where velocity gradients are at a minimum, and thus knowledge of the precise location of a Komagata plane is not necessary. Additionally, our microfluidic device prevents electrode polarization because of fluid recirculation around the electrodes. We fabricated our device using standard MEMS fabrication techniques and performed electrophoretic mobility measurements on 500 nm fluorescently tagged polystyrene particles at various buffer concentrations. Results are comparable to two different commercial dynamic light scattering based particle sizing instruments. We conclude with guidelines to further develop this robust electrophoretic tool that allows for facile and efficient particle characterization. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

MISCIBILITY, SOLUBILITY, VISCOSITY, AND DENSITY MEASUREMENTS FOR R-236FA WITH POTENTIAL LUBRICANTS

EPA Science Inventory

The report gives results of miscibility, solubility, viscosity, and density measurements for refrigerant R-236fa and two potential lubricants . (The data are needed to determine the suitability of refrigerant/lubricant combinations for use in refrigeration systems.) The tested oi...

Design and assembly of ternary Pt/Re/SnO2 NPs by controlling the zeta potential of individual Pt, Re, and SnO2 NPs

NASA Astrophysics Data System (ADS)

Drzymała, Elżbieta; Gruzeł, Grzegorz; Pajor-Świerzy, Anna; Depciuch, Joanna; Socha, Robert; Kowal, Andrzej; Warszyński, Piotr; Parlinska-Wojtan, Magdalena

2018-05-01

In this study Pt, Re, and SnO2 nanoparticles (NPs) were combined in a controlled manner into binary and ternary combinations for a possible application for ethanol oxidation. For this purpose, zeta potentials as a function of the pH of the individual NPs solutions were measured. In order to successfully combine the NPs into Pt/SnO2 and Re/SnO2 NPs, the solutions were mixed together at a pH guaranteeing opposite zeta potentials of the metal and oxide NPs. The individually synthesized NPs and their binary/ternary combinations were characterized by Fourier transform infrared spectroscopy (FTIR) and scanning transmission electron microscopy (STEM) combined with energy dispersive X-ray spectroscopy (EDS) analysis. FTIR and XPS spectroscopy showed that the individually synthesized Pt and Re NPs are metallic and the Sn component was oxidized to SnO2. STEM showed that all NPs are well crystallized and the sizes of the Pt, Re, and SnO2 NPs were 2.2, 1.0, and 3.4 nm, respectively. Moreover, EDS analysis confirmed the successful formation of binary Pt/SnO2 and Re/SnO2 NP, as well as ternary Pt/Re/SnO2 NP combinations. This study shows that by controlling the zeta potential of individual metal and oxide NPs, it is possible to assemble them into binary and ternary combinations. [Figure not available: see fulltext.

Variability in Bioreactivity Linked to Changes in Size and Zeta Potential of Diesel Exhaust Particles in Human Immune Cells

PubMed Central

Sarkar, Srijata; Zhang, Lin; Subramaniam, Prasad; Lee, Ki-Bum; Garfunkel, Eric; Strickland, Pamela A. Ohman.; Mainelis, Gediminas; Lioy, Paul J.; Tetley, Teresa D.; Chung, Kian Fan; Zhang, Junfeng; Ryan, Mary; Porter, Alex; Schwander, Stephan

2014-01-01

Acting as fuel combustion catalysts to increase fuel economy, cerium dioxide (ceria, CeO2) nanoparticles have been used in Europe as diesel fuel additives (Envirox™). We attempted to examine the effects of particles emitted from a diesel engine burning either diesel (diesel exhaust particles, DEP) or diesel doped with various concentrations of CeO2 (DEP-Env) on innate immune responses in THP-1 and primary human peripheral blood mononuclear cells (PBMC). Batches of DEP and DEP-Env were obtained on three separate occasions using identical collection and extraction protocols with the aim of determining the reproducibility of particles generated at different times. However, we observed significant differences in size and surface charge (zeta potential) of the DEP and DEP-Env across the three batches. We also observed that exposure of THP-1 cells and PBMC to identical concentrations of DEP and DEP-Env from the three batches resulted in statistically significant differences in bioreactivity as determined by IL-1β, TNF-α, IL-6, IFN-γ, and IL-12p40 mRNA (by qRT-PCR) and protein expression (by ELISPOT assays). Importantly, bioreactivity was noted in very tight ranges of DEP size (60 to 120 nm) and zeta potential (−37 to −41 mV). Thus, these physical properties of DEP and DEP-Env were found to be the primary determinants of the bioreactivity measured in this study. Our findings also point to the potential risk of over- or under- estimation of expected bioreactivity effects (and by inference of public health risks) from bulk DEP use without taking into account potential batch-to-batch variations in physical (and possibly chemical) properties. PMID:24825358

Progression towards optimization of viscosity of highly concentrated carbonaceous solid-water slurries by incorporating and modifying surface chemistry parameters with and without additives

NASA Astrophysics Data System (ADS)

Mukherjee, Amrita

Carbonaceous solid-water slurries (CSWS) are concentrated suspensions of coal, petcoke bitumen, pitch etc. in water which are used as feedstock for gasifiers. The high solid loading (60-75 wt.%) in the slurry increases CSWS viscosity. For easier handling and pumping of these highly loaded mixtures, low viscosities are desirable. Depending on the nature of the carbonaceous solid, solids loading in the slurry and the particle size distribution, viscosity of a slurry can vary significantly. Ability to accurately predict the viscosity of a slurry will provide a better control over the design of slurry transport system and for viscosity optimization. The existing viscosity prediction models were originally developed for hard-sphere suspensions and therefore do not take into account surface chemistry. As a result, the viscosity predictions using these models for CSWS are not very accurate. Additives are commonly added to decrease viscosity of the CSWS by altering the surface chemistry. Since additives are specific to CSWS, selection of appropriate additives is crucial. The goal of this research was to aid in optimization of CSWS viscosity through improved prediction and selection of appropriate additive. To incorporate effect of surface chemistry in the models predicting suspension viscosity, the effect of the different interfacial interactions caused by different surface chemistries has to be accounted for. Slurries of five carbonaceous solids with varying O/C ratio (to represent different surface chemistry parameters) were used for the study. To determine the interparticle interactions of the carbonaceous solids in water, interfacial energies were calculated on the basis of surface chemistries, characterized by contact angles and zeta potential measurements. The carbonaceous solid particles in the slurries were assumed to be spherical. Polar interaction energy (hydrophobic/hydrophilic interaction energy), which was observed to be 5-6 orders of magnitude higher than the

Characterization of gold nanoparticles with different hydrophilic coatings via capillary electrophoresis and Taylor dispersion analysis. Part I: determination of the zeta potential employing a modified analytic approximation.

PubMed

Pyell, Ute; Jalil, Alaa H; Pfeiffer, Christian; Pelaz, Beatriz; Parak, Wolfgang J

2015-07-15

Taking gold nanoparticles with different hydrophilic coatings as an example, it is investigated whether capillary electrophoresis in combination with Taylor dispersion analysis allows for the precise determination of mean electrophoretic mobilities, electrophoretic mobility distributions, and zeta potentials in a matrix of exactly known composition and the calibration-free determination of number-weighted mean hydrodynamic radii. Our experimental data confirm that the calculation of the zeta potential for colloidal nanoparticles with ζ>25 mV requires to take the relaxation effect into account. Because of the requirement to avoid particle-wall interactions, a solution of disodiumtetraborate decahydrate (borax) in deionized water had been selected as suitable electrolyte. Measurements of the electrophoretic mobility at different ionic strength and application of the analytic approximation developed by Ohshima show that in the present case of a buffered solution with a weak electrolyte co-ion and a strong electrolyte counterion, the effective ionic drag coefficient should be approximated with the ionic drag coefficient of the counterion. The obtained results are in good agreement with theoretical expectations regarding the dependence of the zeta potential and the electrokinetic surface charge density on the ionic strength. We also show that Taylor dispersion analysis (besides estimation of the number-weighted mean hydrodynamic radius) provides additional information on the type and width of the number-weighted particle distribution. Copyright © 2015 Elsevier Inc. All rights reserved.

The receptor protein tyrosine phosphatase (RPTP){beta}/{zeta} is expressed in different subtypes of human breast cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Perez-Pinera, Pablo; Garcia-Suarez, Olivia; Instituto Universitario de Oncologia del Principado de Asturias, Oviedo

2007-10-12

Increasing evidence suggests mutations in human breast cancer cells that induce inappropriate expression of the 18-kDa cytokine pleiotrophin (PTN, Ptn) initiate progression of breast cancers to a more malignant phenotype. Pleiotrophin signals through inactivating its receptor, the receptor protein tyrosine phosphatase (RPTP){beta}/{zeta}, leading to increased tyrosine phosphorylation of different substrate proteins of RPTP{beta}/{zeta}, including {beta}-catenin, {beta}-adducin, Fyn, GIT1/Cat-1, and P190RhoGAP. PTN signaling thus has wide impact on different important cellular systems. Recently, PTN was found to activate anaplastic lymphoma kinase (ALK) through the PTN/RPTP{beta}/{zeta} signaling pathway; this discovery potentially is very important, since constitutive ALK activity of nucleophosmin (NPM)-ALK fusionmore » protein is causative of anaplastic large cell lymphomas, and, activated ALK is found in other malignant cancers. Recently ALK was identified in each of 63 human breast cancers from 22 subjects. We now demonstrate that RPTP{beta}/{zeta} is expressed in each of these same 63 human breast cancers that previously were found to express ALK and in 10 additional samples of human breast cancer. RPTP{beta}/{zeta} furthermore was localized not only in its normal association with the cell membrane but also scattered in cytoplasm and in nuclei in different breast cancer cells and, in the case of infiltrating ductal carcinomas, the distribution of RPTP{beta}/{zeta} changes as the breast cancer become more malignant. The data suggest that the PTN/RPTP{beta}/{zeta} signaling pathway may be constitutively activated and potentially function to constitutively activate ALK in human breast cancer.« less

Project SQUID: The Viscosity of the Isotopes of Hydrogen and Their Intermolecular Force Potentials

DTIC Science & Technology

1963-12-01

values of the pseudo- Lennard - Jones potential for either hydrogen o- deuteriua. On the present evidence, and cn the present evidence alone, it would...W4drogesror deuterium forces the conclusion that neither gas obeys a lenrArd- Jones six- twelve potential , it is, nevertheless, useful to discuss the values...VISCOSITY OF THE ISOTOPES OF HYDROGEN AND THEIR INTERMOLECULAR FORCE POTENTIALS * by S. Kestir and A Nagashima Broow University December 1963 PROJECT SQUID

Zeta Ophiuchi -- Runaway Star Plowing through Space Dust

NASA Image and Video Library

2011-01-24

The blue star near the center of this image is Zeta Ophiuchi. Zeta Ophiuchi is actually a very massive, hot, bright blue star plowing its way through a large cloud of interstellar dust and gas in this image from NASA Wide-field Infrared Survey Explorer.

In vitro evaluation of the erosive potential of viscosity-modified soft acidic drinks on enamel.

PubMed

Aykut-Yetkiner, Arzu; Wiegand, Annette; Ronay, Valerie; Attin, Rengin; Becker, Klaus; Attin, Thomas

2014-04-01

The objective of this in vitro study was to investigate the effect of viscosity-modified soft acidic drinks on enamel erosion. A total of 108 bovine enamel samples (∅ = 3 mm) were embedded in acrylic resin and allocated into six groups (n = 18). Soft acidic drinks (orange juice, Coca-Cola, Sprite) were used both in their regular forms and at a kinetic viscositiy of 5 mm(2)/s, which was adjusted by adding hydroxypropyl cellulose. All solutions were pumped over the enamel surface from a reservoir with a drop rate of 3 ml/min. Each specimen was eroded for 10 min at 20 °C. Erosion of enamel surfaces was measured using profilometry. Data were analyzed using independent t tests and one-way ANOVAs (p < 0.05). Enamel loss was significantly higher for the regular (Coca-Cola, 5.60 ± 1.04 μm; Sprite, 5.49 ± 0.94 μm; orange juice, 1.35 ± 0.4 μm) than for the viscosity-modified drinks (Coca-Cola, 4.90 ± 0.34 μm; Sprite, 4.46 ± 0.39 μm; orange juice, 1.10 ± 0.22 μm). For both regular and viscosity-modified forms, Coca-Cola and Sprite caused higher enamel loss than orange juice. Increasing the viscosity of acidic soft drinks to 5 mm(2)/s reduced enamel erosion by 12.6-18.7 %. The erosive potential of soft acidic drinks is not only dependent on various chemical properties but also on the viscosity of the acidic solution and can be reduced by viscosity modification.

Characterization of the startup transient electrokinetic flow in rectangular channels of arbitrary dimensions, zeta potential distribution, and time-varying pressure gradient.

PubMed

Miller, Andrew; Villegas, Arturo; Diez, F Javier

2015-03-01

The solution to the startup transient EOF in an arbitrary rectangular microchannel is derived analytically and validated experimentally. This full 2D transient solution describes the evolution of the flow through five distinct periods until reaching a final steady state. The derived analytical velocity solution is validated experimentally for different channel sizes and aspect ratios under time-varying pressure gradients. The experiments used a time resolved micro particle image velocimetry technique to calculate the startup transient velocity profiles. The measurements captured the effect of time-varying pressure gradient fields derived in the analytical solutions. This is tested by using small reservoirs at both ends of the channel which allowed a time-varying pressure gradient to develop with a time scale on the order of the transient EOF. Results showed that under these common conditions, the effect of the pressure build up in the reservoirs on the temporal development of the transient startup EOF in the channels cannot be neglected. The measurements also captured the analytical predictions for channel walls made of different materials (i.e., zeta potentials). This was tested in channels that had three PDMS and one quartz wall, resulting in a flow with an asymmetric velocity profile due to variations in the zeta potential between the walls. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

The interstellar line spectra of zeta Ophiuchi and zeta Persei and their relation to the short wavelength microwave background radiation. Ph.D. Thesis - N. Y. Univ.

NASA Technical Reports Server (NTRS)

Bortolot, V. J., Jr.

1972-01-01

Thirty-one high dispersion Coude spectrograms of zeta Ophiuchi and seven of zeta Persei were numerically synthesized to produce high resolution, low noise spectra in the interval 3650 A to 4350 that yield data on atomic and molecular absorption in well-defined regions of the interstellar medium. The detection threshold is improved by as much as a factor 5 over single plates. Several interstellar lines were discovered in the zeta Oph - 15km/sec cloud and the zeta Per + 13 km/sec cloud.

Estimation of Nanodiamond Surface Charge Density from Zeta Potential and Molecular Dynamics Simulations.

PubMed

Ge, Zhenpeng; Wang, Yi

2017-04-20

Molecular dynamics simulations of nanoparticles (NPs) are increasingly used to study their interactions with various biological macromolecules. Such simulations generally require detailed knowledge of the surface composition of the NP under investigation. Even for some well-characterized nanoparticles, however, this knowledge is not always available. An example is nanodiamond, a nanoscale diamond particle with surface dominated by oxygen-containing functional groups. In this work, we explore using the harmonic restraint method developed by Venable et al., to estimate the surface charge density (σ) of nanodiamonds. Based on the Gouy-Chapman theory, we convert the experimentally determined zeta potential of a nanodiamond to an effective charge density (σ eff ), and then use the latter to estimate σ via molecular dynamics simulations. Through scanning a series of nanodiamond models, we show that the above method provides a straightforward protocol to determine the surface charge density of relatively large (> ∼100 nm) NPs. Overall, our results suggest that despite certain limitation, the above protocol can be readily employed to guide the model construction for MD simulations, which is particularly useful when only limited experimental information on the NP surface composition is available to a modeler.

Novel Method for Finding [zeta](2[rho]) from a Product of Sines

ERIC Educational Resources Information Center

Osler, Thomas J.

2006-01-01

Euler gave a simple method for showing that [zeta](2)=1/1[superscript 2] + 1/2[superscript 2] + 1/3[superscript 2] + ... = [pi][superscript 2]/6. He generalized his method so as to find [zeta](4), [zeta](6), [zeta](8),.... His computations became increasingly more complex as the arguments increased. In this note we show a different generalization…

A nontoxic, photostable and high signal-to-noise ratio mitochondrial probe with mitochondrial membrane potential and viscosity detectivity

NASA Astrophysics Data System (ADS)

Chen, Yanan; Qi, Jianguo; Huang, Jing; Zhou, Xiaomin; Niu, Linqiang; Yan, Zhijie; Wang, Jianhong

2018-01-01

Herein, we reported a yellow emission probe 1-methyl-4-(6-morpholino-1, 3-dioxo-1H-benzo[de]isoquinolin-2(3H)-yl) pyridin-1-ium iodide which could specifically stain mitochondria in living immortalized and normal cells. In comparison to the common mitochondria tracker (Mitotracker Deep Red, MTDR), this probe was nontoxic, photostable and ultrahigh signal-to-noise ratio, which could real-time monitor mitochondria for a long time. Moreover, this probe also showed high sensitivity towards mitochondrial membrane potential and intramitochondrial viscosity change. Consequently, this probe was used for imaging mitochondria, detecting changes in mitochondrial membrane potential and intramitochondrial viscosity in physiological and pathological processes.

Reducing blood viscosity with magnetic fields

NASA Astrophysics Data System (ADS)

Tao, R.; Huang, K.

2011-07-01

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.

Activation-induced proteolysis of cytoplasmic domain of zeta in T cell receptors and Fc receptors.

PubMed

Taupin, J L; Anderson, P

1994-12-01

The CD3-T cell receptor (TCR) complex on T cells and the Fc gamma receptor type III (Fc gamma RIII)-zeta-gamma complex on natural killer cells are functionally analogous activation receptors that associate with a family of disulfide-linked dimers composed of the related subunits zeta and gamma. Immunochemical analysis of receptor complexes separated on two-dimensional diagonal gels allowed the identification of a previously uncharacterized zeta-p14 heterodimer. zeta-p14 is a component of both CD3-TCR and Fc gamma RIII-zeta-gamma. Peptide mapping analysis shows that p14 is structurally related to zeta, suggesting that it is either: (i) derived from zeta proteolytically or (ii) the product of an alternatively spliced mRNA. The observation that COS cells transformed with a cDNA encoding zeta express zeta-p14 supports the former possibility. The expression of CD3-TCR complexes including zeta-p14 increases following activation with phorbol 12-myristate 13-acetate or concanavalin A, suggesting that proteolysis of zeta may contribute to receptor modulation or desensitization.

Predicting the influence of liposomal lipid composition on liposome size, zeta potential and liposome-induced dendritic cell maturation using a design of experiments approach.

PubMed

Soema, Peter C; Willems, Geert-Jan; Jiskoot, Wim; Amorij, Jean-Pierre; Kersten, Gideon F

2015-08-01

In this study, the effect of liposomal lipid composition on the physicochemical characteristics and adjuvanticity of liposomes was investigated. Using a design of experiments (DoE) approach, peptide-containing liposomes containing various lipids (EPC, DOPE, DOTAP and DC-Chol) and peptide concentrations were formulated. Liposome size and zeta potential were determined for each formulation. Moreover, the adjuvanticity of the liposomes was assessed in an in vitro dendritic cell (DC) model, by quantifying the expression of DC maturation markers CD40, CD80, CD83 and CD86. The acquired data of these liposome characteristics were successfully fitted with regression models, and response contour plots were generated for each response factor. These models were applied to predict a lipid composition that resulted in a liposome with a target zeta potential. Subsequently, the expression of the DC maturation factors for this lipid composition was predicted and tested in vitro; the acquired maturation responses corresponded well with the predicted ones. These results show that a DoE approach can be used to screen various lipids and lipid compositions, and to predict their impact on liposome size, charge and adjuvanticity. Using such an approach may accelerate the formulation development of liposomal vaccine adjuvants. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

Shear viscosity coefficient of liquid lanthanides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Patel, H. P., E-mail: patel.harshal2@gmail.com; Thakor, P. B., E-mail: pbthakore@rediffmail.com; Prajapati, A. V., E-mail: anand0prajapati@gmail.com

2015-05-15

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.

Shear viscosity coefficient of liquid lanthanides

NASA Astrophysics Data System (ADS)

Patel, H. P.; Sonvane, Y. A.; Thakor, P. B.; Prajapati, A. V.

2015-05-01

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.

Synthesis of the RGO/Al2O3 core-shell nanocomposite flakes and characterization of their unique electrostatic properties using zeta potential measurements

NASA Astrophysics Data System (ADS)

Jastrzębska, A. M.; Karcz, J.; Letmanowski, R.; Zabost, D.; Ciecierska, E.; Zdunek, J.; Karwowska, E.; Siekierski, M.; Olszyna, A.; Kunicki, A.

2016-01-01

The aim of this study was to describe the influence of the modification of electrostatic properties of RGO/Al2O3 core-shell nanocomposite flakes. The amount of crystalline form of aluminum oxide was very small. It existed mostly in amorphous phase in the form of covalently bonded to GO surface. The morphological, structural and physicochemical investigations results showed that spherical Al2O3 nanoparticles (ca. 41 nm) in gamma phase completely covered the surface of curly-shaped RGO flakes and acted as a spreader between individual flakes. The high BET specific surface area of the analyzed composite (119.71 m2/g) together with very low open porosity (0.479 cm3/g) indicated that RGO/Al2O3 nanocomposite flakes showed low tendency to agglomeration. The zeta potential curves obtained for RGO/Al2O3 core-shell nanocomposite flakes were differing from curves obtained for GO and Al2O3 suspensions in distilled water and neutral environment. The specific electrostatic properties of the core-shell system of RGO/Al2O3 flakes had an influence on its surface charge (zeta potential) which was measured by applying an external electric field. The FTIR and Raman investigations results also confirmed that the Cdbnd O species were not taking part in the surface amphoteric reactions resulting in the formation of electrostatic surface charge.

Shear Viscosity Coefficient of 5d Liquid Transition Metals

NASA Astrophysics Data System (ADS)

Thakor, P. B.; Sonvane, Y. A.; Gajjar, P. N.; Jani, A. R.

2011-07-01

In the present paper we have calculated shear viscosity coefficient (η) of 5 d liquid transition metals. To calculate effective pair potential ν(r) and pair distribution function g(r) we have used our own newly constructed model potential and Percus- Yevick hard sphere (PYHS) structure factor S(q) respectively. We have also investigated the effect of different correction function like Hartree (H), Taylor (T) and Sarkar et al. (S) on shear viscosity coefficient (η). Our newly constructed model potential successfully explains the shear viscosity coefficient (η) of 5 d liquid transition metals.

Viscosity of meson matter

NASA Astrophysics Data System (ADS)

Dobado, Antonio; Llanes-Estrada, Felipe J.

2004-06-01

We report a calculation of the shear viscosity in a relativistic multicomponent meson gas as a function of temperature and chemical potentials. We approximately solve the Uehling-Uhlenbeck transport equation of kinetic theory, appropriate for a boson gas, with relativistic kinematics. Since at low temperatures the gas can be taken as mostly composed of pions, with a fraction of kaons and etas, we explore the region where binary elastic collisions with at least one pion are the dominant scattering processes. Our input meson scattering phase shifts are fits to the experimental data obtained from chiral perturbation theory and the inverse amplitude method. Our results take the correct nonrelativistic limit (viscosity proportional to the square root of the temperature), show a viscosity of the order of the cube of the pion mass up to temperatures somewhat below that mass, and then a large increase due to kaons and etas. Our approximation may break down at even higher temperatures, where the viscosity follows a temperature power law with an exponent near 3.

Inference of viscosity jump at 670 km depth and lower mantle viscosity structure from GIA observations

NASA Astrophysics Data System (ADS)

Nakada, Masao; Okuno, Jun'ichi; Irie, Yoshiya

2018-03-01

A viscosity model with an exponential profile described by temperature (T) and pressure (P) distributions and constant activation energy (E_{{{um}}}^{{*}} for the upper mantle and E_{{{lm}}}^* for the lower mantle) and volume (V_{{{um}}}^{{*}} and V_{{{lm}}}^*) is employed in inferring the viscosity structure of the Earth's mantle from observations of glacial isostatic adjustment (GIA). We first construct standard viscosity models with an average upper-mantle viscosity ({\\bar{η }_{{{um}}}}) of 2 × 1020 Pa s, a typical value for the oceanic upper-mantle viscosity, satisfying the observationally derived three GIA-related observables, GIA-induced rate of change of the degree-two zonal harmonic of the geopotential, {\\dot{J}_2}, and differential relative sea level (RSL) changes for the Last Glacial Maximum sea levels at Barbados and Bonaparte Gulf in Australia and for RSL changes at 6 kyr BP for Karumba and Halifax Bay in Australia. Standard viscosity models inferred from three GIA-related observables are characterized by a viscosity of ˜1023 Pa s in the deep mantle for an assumed viscosity at 670 km depth, ηlm(670), of (1 - 50) × 1021 Pa s. Postglacial RSL changes at Southport, Bermuda and Everglades in the intermediate region of the North American ice sheet, largely dependent on its gross melting history, have a crucial potential for inference of a viscosity jump at 670 km depth. The analyses of these RSL changes based on the viscosity models with {\\bar{η }_{{{um}}}} ≥ 2 × 1020 Pa s and lower-mantle viscosity structures for the standard models yield permissible {\\bar{η }_{{{um}}}} and ηlm (670) values, although there is a trade-off between the viscosity and ice history models. Our preferred {\\bar{η }_{{{um}}}} and ηlm (670) values are ˜(7 - 9) × 1020 and ˜1022 Pa s, respectively, and the {\\bar{η }_{{{um}}}} is higher than that for the typical value of oceanic upper mantle, which may reflect a moderate laterally heterogeneous upper

Impaired viscosity of gastric secretion and its mucin content as potential contributing factors to the development of chronic constipation.

PubMed

Castro-Combs, Juan; Garcia, Cesar J; Majewski, Marek; Wallner, Grzegorz; Sarosiek, Jerzy

2014-11-01

The alimentary tract mucosa continuously releases mucus-rich secretion. Mucin, the major component of mucus, determines its viscosity and provides lubrication for the luminal content of indigestible food particles. To measure mucin secretion rate and its viscosity in patients with chronic constipation (CC) and in asymptomatic volunteers. Nineteen patients with symptoms of CC and 19 controls were included in the study. Mucin secretion and viscosity were assessed in aspirated gastric juice in basal conditions and after stimulation with pentagastrin (1 h each). Mucin content was tested by PAS methodology. Viscosity was measured using cone/plate digital viscometer. Mucin secretion rates in basal and stimulated conditions in controls were 65 and 42 % higher than in patients with CC (P < 0.05 and P < 0.001, respectively). Basal viscosity in controls was 48 % higher than in CC (P < 0.05) at the lowest and 55 % higher (P < 0.05) at the middle velocities. Viscosity in pentagastrin-stimulated conditions in controls was 71 % higher than in CC (P < 0.01) at the lowest and 35 % higher (P < 0.05) at the middle velocities. (1) The significantly lower rate of soluble mucin secretion in patients with CC than in normal volunteers may reflect impairment in mucin-related lubrication. (2) Significantly lower viscosity of gastric secretion in patients with CC may result from the lower rate of mucin secretion and may also diminish lubrication within the alimentary tract. (3) This may potentially set the stage for the development of symptoms related to chronic constipation and open a new therapeutic avenue for this patient population.

Mixtures of latex particles and the surfactant of opposite charge used as interface stabilizers--influence of particle contact angle, zeta potential, flocculation and shear energy.

PubMed

Deleurence, Rémi; Parneix, Caroline; Monteux, Cécile

2014-09-28

We investigate the stabilization of air-water interfaces by mixtures of negatively charged latex particles (sulfate polystyrene) and cationic surfactants (alkyl trimethylammonium bromides). First we report results concerning the binding of surfactant molecules to the latex particles. As the surfactant concentration increases, the charge of the particles reverses, from negative to positive, because CnTAB first binds electrostatically to the latex particles and then through hydrophobic interaction with the monolayer already adsorbed on the particles as well as directly with the hydrophobic surface of the latex. Over a large range of surfactant concentrations around the charge inversion, a strong flocculation is observed and 100 μm large aggregates form in the suspension. Unlike previous studies published on mixtures of inorganic particles with oppositely charged surfactants, we show that we can vary the sign of the zeta potential of the particles without changing the contact angle of the particles over a large range of surfactant concentrations. Indeed, the latex particles that we study are more hydrophobic than inorganic particles, hence adding moderate concentrations of the surfactant results in a weak variation of the contact angle while the charge of the particles can be reversed. This enables decoupling of the effect of zeta potential and contact angle on the interfacial properties of the mixtures. Our study shows that the contact angle and the charge of the particles are not sufficient parameters to control the foam properties, and the key-parameters are the flocculation state and the shear energy applied to produce the foam. Indeed, flocculated samples, whatever the sign of the zeta potential, enable production of a stable armour at the interface. The large aggregates do not adsorb spontaneously at the interface because of their large size, however when a large shear energy is used to produce the foam very stable foam is obtained, where particles are trapped

The use of zeta potential as a tool to study phase transitions in binary phosphatidylcholines mixtures.

PubMed

Sierra, M B; Pedroni, V I; Buffo, F E; Disalvo, E A; Morini, M A

2016-06-01

Temperature dependence of the zeta potential (ZP) is proposed as a tool to analyze the thermotropic behavior of unilamellar liposomes prepared from binary mixtures of phosphatidylcholines in the absence or presence of ions in aqueous suspensions. Since the lipid phase transition influences the surface potential of the liposome reflecting a sharp change in the ZP during the transition, it is proposed as a screening method for transition temperatures in complex systems, given its high sensitivity and small amount of sample required, that is, 70% less than that required in the use of conventional calorimeters. The sensitivity is also reflected in the pre-transition detection in the presence of ions. Plots of phase boundaries for these mixed-lipid vesicles were constructed by plotting the delimiting temperatures of both main phase transition and pre-transition vs. the lipid composition of the vesicle. Differential scanning calorimetry (DSC) studies, although subject to uncertainties in interpretation due to broad bands in lipid mixtures, allowed the validation of the temperature dependence of the ZP method for determining the phase transition and pre-transition temperatures. The system chosen was dipalmitoylphosphatidylcholine/dimyristoyl phosphatidylcholine (DMPC/DPPC), the most common combination in biological membranes. This work may be considered as a starting point for further research into more complex lipid mixtures with functional biological importance. Copyright © 2016 Elsevier B.V. All rights reserved.

A gene variation of 14-3-3 zeta isoform in rat hippocampus.

PubMed

Murakami, K; Situ, S Y; Eshete, F

1996-11-14

A variant form of 14-3-3 zeta was isolated from the rat hippocampal cDNA library. The cloned cDNA is 1687 bp in length and it contains an entire ORF (nt = 63-797) with 245 amino acids that is characteristic to 14-3-3 zeta subtype. By comparing with reported sequences of 14-3-3 zeta, we found three nucleotide substitutions within the coding sequence in our clone; C<-->T transition at nt = 325 and G<-->C transversions at nt = 387 and 388. Both are missense mutations, leading ACG (Thr) to ATG (Met) and CGT (Arg) to GCT (Ala) conversions at residue 88 and 109, respectively. Our results show that at least three different genetic variants of 14-3-3 zeta are present in rat species which results in protein variations. Such mutation in the amino acid sequence is an important indication of the diverse functions of this protein and may also contribute to the recent contradictory observations regarding the role of the 14-3-3 zeta subtype.

Surface functionalisation with viscosity-sensitive BODIPY molecular rotor

NASA Astrophysics Data System (ADS)

Vyšniauskas, Aurimas; Lopez-Duarte, Ismael; Thompson, Alex J.; Bull, James A.; Kuimova, Marina K.

2018-07-01

Surface functionalisation with viscosity sensitive dyes termed ‘molecular rotors’ can potentially open up new opportunities in sensing, for example for non-invasive biological viscosity imaging, in studying the effect of shear stress on lipid membranes and in cells, and in imaging contacts between surfaces upon applied pressure. We have functionalised microscope slides with BODIPY-based molecular rotor capable of viscosity sensing via its fluorescence lifetime. We have optimised functionalisation conditions and prepared the slides with the BODIPY rotor attached directly to the surface of glass slides and through polymer linkers of 5 kDa and 40 kDa in mass. The slides were characterised for their sensitivity to viscosity, and used to measure viscosity of supported lipid bilayers during photooxidation, and of giant unilamellar vesicles lying on the surface of the slide. We conclude that our functionalised slides show promise for a variety of viscosity sensing applications.

Zeta Potential Measurements on Three Clays from Turkey and Effects of Clays on Coal Flotation

PubMed

Hussain; Dem&idot;rc&idot;; özbayoğlu

1996-12-25

There is a growing trend of characterizing coal and coal wastes in order to study the effect of clays present in them during coal washing. Coarse wastes from the Zonguldak Coal Washery, Turkey, were characterized and found to contain kaolinite, illite, and chlorite. These three clays, obtained in almost pure form from various locations in Turkey, have been subjected to X-ray diffraction (XRD) analysis to assess their purity and zeta potential measurements in order to evaluate their properties in terms of their surface charge and point of zero charge (pzc) values. It was found from XRD data that these clays were almost pure and their electrokinetic potential should therefore be representative of their colloidal behavior. All three clay minerals were negatively charged over the range from pH 2.5 to 11. Chlorite and illite have pzc at pH 3 and pH 2.5, respectively, whereas kaolinite has no pzc. The effect of these clays in Zonguldak coal, wastes, and black waters on coal flotation was studied by floating artificial mixtures of Zonguldak clean coal (4.5% ash) and individual clay. The flotation tests on coal/individual clay revealed that each clay influences coal flotation differently according to its type and amount. Illite had the worst effect on coal floated, followed by chlorite and kaolinite. The loss of yield in coal was found to be 18% for kaolinite, 20% for chlorite, and 28% for illite, indicating the worst effect of illite and least for kaolinite during coal flotation.

An accurate estimation method of kinematic viscosity for standard viscosity liquids

NASA Astrophysics Data System (ADS)

Kurano, Y.; Kobayashi, H.; Yoshida, K.; Imai, H.

1992-07-01

Deming's method of least squares is introduced to make an accurate kinematic viscosity estimation for a series of 13 standard-viscosity liquids at any desired temperature. The empirical ASTM kinematic viscosity-temperature equation is represented in the form loglog( v+c)=a-b log T, where v (in mm2. s-1) is the kinematic viscosity at temperature T (in K), a and b are the constants for a given liquid, and c has a variable value. In the present application, however, c is assumed to have a constant value for each standard-viscosity liquid, as do a and b in the ASTM equation. This assumption has since been verified experimentally for all standard-viscosity liquids. The kinematic viscosities for the 13 standard-viscosity liquids have been measured with a high accuracy in the temperature range of 20 40°C using a series of the NRLM capillary master viscometers with an automatic flow time detection system. The deviations between measured and estimated kinematic viscosities were less than ±0.04% for the 10 standard-viscosity liquids JS2.5 to JS2000 and ±0.11% for the 3 standard-viscosity liquids JS15H to JS200H, respectively. From the above investigation, it was revealed that the uncertainty in the present estimation method is less than one-third that in the usual ASTM method.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khvorostukhin, A. S.; Joint Institute for Nuclear Research, 141980 Dubna; Institute of Applied Physics, Moldova Academy of Science, MD-2028 Kishineu

Shear {eta} and bulk {zeta} viscosities are calculated in a quasiparticle model within a relaxation-time approximation for pure gluon matter. Below T{sub c}, the confined sector is described within a quasiparticle glueball model. The constructed equation of state reproduces the first-order phase transition for the glue matter. It is shown that with this equation of state, it is possible to describe the temperature dependence of the shear viscosity to entropy ratio {eta}/s and the bulk viscosity to entropy ratio {zeta}/s in reasonable agreement with available lattice data, but absolute values of the {zeta}/s ratio underestimate the upper limits of thismore » ratio in the lattice measurements typically by an order of magnitude.« less

pH Effects on solubility, zeta potential, and correlation between antibacterial activity and molecular weight of chitosan.

PubMed

Chang, Shun-Hsien; Lin, Hong-Ting Victor; Wu, Guan-James; Tsai, Guo Jane

2015-12-10

Six chitosans with molecular weights (MWs) of 300, 156, 72.1, 29.2, 7.1, and 3.3 kDa were prepared by cellulase degradation of chitosan (300 kDa) and ultrafiltration techniques. We examined the correlation between activity against Escherichia coli and Staphylococcus aureus and chitosan MW, and provided the underlying explanation. In acidic pH conditions, the chitosan activity increased with increasing MW, irrespective of the temperature and bacteria tested. However, at neutral pH, chitosan activity increased as the MW decreased, and little activity was observed for chitosans with MW >29.2 kDa. At pH 5.0 and 6.0, chitosans exhibited good water solubility and zeta potential (ZP) decreased with the MW, whereas the solubility and ZP of the chitosans decreased with increasing MW at pH 7.0. Particularly, low solubility and negative ZP values were determined for chitosans with MW >29.2 kDa, which may explain the loss of their antibacterial activity at pH 7.0. Copyright © 2015 Elsevier Ltd. All rights reserved.

Chromospheric Structure and Wind Acceleration in Zeta Aur Stars

NASA Technical Reports Server (NTRS)

Bennett, Philip D.

2001-01-01

This NASA grant supported an analysis of the variability of the wind of the supergiant primary star (K4 Ib) in the eclipsing binary Zeta Aurigae (Zeta Aur). In the ultraviolet, the main-sequence companion star (B5 V) dominates the observed flux, and therefore serves as a convenient probe of the cool supergiant's wind. This study utilized the extensive set of (100+) ultraviolet spectroscopic observations obtained with the International Ultraviolet Explorer (IUE) satellite over its operational lifetime of 1978-1995. Although the resolution of IUE is limited (about 25 km/s), it is adequate to resolve variability in the wind features in Zeta Aur's ultraviolet spectrum, which are blueshifted 70 km/s from line center. Our analysis used the tau-v technique of Cardelli and Savage, which makes full use of the available line profile information. We find that the wind column densities vary by up to an order of magnitude over time. These results are being written up for submission to the Astrophysical Journal as the third paper of a series on the chromosphere and wind of Zeta Aurigae. The first two papers report on the construction of mean chromosphere and wind models respectively, based on HST/GHRS observations and funded by STScI. The third paper - this research - reports on variability of the Zeta Aur wind as determined from our analysis of the long IUE time series. This paper will be completed within the next three months; the delay in publication was to allow the completion of Papers 1 and 2, which logically precede the present work. Therefore, an additional no-cost extension was requested in order to ensure budgeted funds remain available for publication of this work. Unfortunately, this request was denied, and so I am forced to write this final report before publication of Paper 3. Regardless, this paper will be submitted for publication within the next three months.

Group entropies, correlation laws, and zeta functions.

PubMed

Tempesta, Piergiulio

2011-08-01

The notion of group entropy is proposed. It enables the unification and generaliztion of many different definitions of entropy known in the literature, such as those of Boltzmann-Gibbs, Tsallis, Abe, and Kaniadakis. Other entropic functionals are introduced, related to nontrivial correlation laws characterizing universality classes of systems out of equilibrium when the dynamics is weakly chaotic. The associated thermostatistics are discussed. The mathematical structure underlying our construction is that of formal group theory, which provides the general structure of the correlations among particles and dictates the associated entropic functionals. As an example of application, the role of group entropies in information theory is illustrated and generalizations of the Kullback-Leibler divergence are proposed. A new connection between statistical mechanics and zeta functions is established. In particular, Tsallis entropy is related to the classical Riemann zeta function.

Shock wave viscosity measurements

NASA Astrophysics Data System (ADS)

Celliers, Peter

2013-06-01

Several decades ago a method was proposed and demonstrated to measure the viscosity of fluids at high pressure by observing the oscillatory damping of sinusoidal perturbations on a shock front. A detailed mathematical analysis of the technique carried out subsequently by Miller and Ahrens revealed its potential, as well as a deep level of complexity in the analysis. We revisit the ideas behind this technique in the context of a recent experimental development: two-dimensional imaging velocimetry. The new technique allows one to capture a broad spectrum of perturbations down to few micron scale-lengths imposed on a shock front from an initial perturbation. The detailed evolution of the perturbation spectrum is sensitive to the viscosity in the fluid behind the shock front. Initial experiments are aimed at examining the viscosity of shock compressed SiO2 just above the shock melting transition. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Studying red blood cell agglutination by measuring electrical and mechanical properties with a double optical tweezers

NASA Astrophysics Data System (ADS)

Fontes, Adriana; Fernandes, Heloise P.; de Thomaz, André A.; Barbosa, Luiz C.; Barjas-Castro, Maria L.; Cesar, Carlos L.

2007-07-01

The red blood cell (RBC) viscoelastic membrane contains proteins and glycolproteins embedded in, or attached, to a fluid lipid bilayer and are negatively charged, which creates a repulsive electric (zeta) potential between the cells and prevents their aggregation in the blood stream. The basis of the immunohematologic tests is the interaction between antigens and antibodies that causes hemagglutination. The identification of antibodies and antigens is of fundamental importance for the transfusional routine. This agglutination is induced by decreasing the zeta-potential through the introduction of artificial potential substances. This report proposes the use of the optical tweezers to measure the membrane viscosity, the cell adhesion, the zeta-potential and the size of the double layer of charges (CLC) formed around the cell in an electrolytic solution. The adhesion was quantified by slowly displacing two RBCs apart until the disagglutination. The CLC was measured using the force on the bead attached to a single RBC in response to an applied voltage. The zeta-potential was obtained by measuring the terminal velocity after releasing the RBC from the optical trap at the last applied voltage. For the membrane viscosity experiment, we trapped a bead attached to RBCs and measured the force to slide one RBC over the other as a function of the relative velocity. After we tested the methodology, we performed measurements using antibody and potential substances. We observed that this experiment can provide information about cell agglutination that helps to improve the tests usually performed in blood banks. We also believe that this methodology can be applied for measurements of zeta-potentials in other kind of samples.

Communication: Simple liquids' high-density viscosity

NASA Astrophysics Data System (ADS)

Costigliola, Lorenzo; Pedersen, Ulf R.; Heyes, David M.; Schrøder, Thomas B.; Dyre, Jeppe C.

2018-02-01

This paper argues that the viscosity of simple fluids at densities above that of the triple point is a specific function of temperature relative to the freezing temperature at the density in question. The proposed viscosity expression, which is arrived at in part by reference to the isomorph theory of systems with hidden scale invariance, describes computer simulations of the Lennard-Jones system as well as argon and methane experimental data and simulation results for an effective-pair-potential model of liquid sodium.

Rotationally excited HD toward Zeta Ophiuchi

NASA Technical Reports Server (NTRS)

Wright, E. L.; Morton, D. C.

1979-01-01

Copernicus satellite measurements of HD in J-double prime = 1 and J-double prime = 0 toward Zeta Oph are reported. The ratio of the number densities of HD in the J = 0 and J = 1 states is determined to be 0.15 + or - 0.02 at the 1-sigma level. A value of approximately 24 x 10 to the -17th erg/cu cm per A at 1000 A is obtained for the UV energy density at the Zeta Oph cloud, and the mechanisms for excitation of HD are examined. A tight upper limit is derived for the abundance of HCl, which has been predicted to be present due to the interaction of ionized chlorine with neutral hydrogen. A calculation is performed which indicates that the cloud is 28 pc from the star. It is shown that the two-component cloud model of Black and Dalgarno (1977) with densities of 500 and 2500 H nuclei per cu cm for the outer regions and core, respectively, is in excellent agreement with the observations.

Dynamic interaction between 14-3-3zeta and bax during TNF-α-induced apoptosis in living cells

NASA Astrophysics Data System (ADS)

Gao, Xuejuan; Xing, Da; Chen, Tongsheng

2006-09-01

Bax, a proapoptotic member of the Bcl-2 family, localizes largely in the cytoplasm but redistributes to mitochondria and undergoes oligomerization to induce the release of apoptogenic factors such as cytochrome c in response to apoptotic stimuli. Cytoplasmic protein 14-3-3zeta binds to Bax and, upon apoptotic stimulation, releases Bax by a caspase-independent mechanism. However, the direct interaction of the cytoplasmic 14-3-3zeta and Bax in living cells has not been observed. In present study, to monitor the dynamic interaction between 14-3-3zeta and Bax in living cells in real time during apoptosis induced by tumor necrosis factor (TNF-α), DsRed-14-3-3zeta plasmid is constructed. By cotransfecting DsRed- 14-3-3zeta and GFP-Bax plasmids into human lung adenocarcinoma cells (ASTC-a-1), we observe the dynamic interaction between Bax and 14-3-3zeta using fluorescence resonance energy transfer (FRET) technique on laser scanning confocal microscope. The results show that 14-3-3zeta remains in the cytoplasm but GFP-Bax translocates to mitochondria completely after TNF-α stimulation. These results reveal that 14-3-3zeta binds directly to Bax in healthy cells, and that 14-3-3zeta negatively regulates Bax translocation to mitochondria during TNF-α-induced apoptosis.

Shear viscosity in an anisotropic unitary Fermi gas

NASA Astrophysics Data System (ADS)

Samanta, Rickmoy; Sharma, Rishi; Trivedi, Sandip P.

2017-11-01

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.

Three proposed B-associations in the vicinity of zeta puppis

NASA Technical Reports Server (NTRS)

Upton, E. K. L.

1971-01-01

There appear to be three loose B associations in the general vicinity of zeta Puppis, all at distances of approximately 300 to 400 parsecs from the sun. Their diameters, perpendicular to the line of sight, are 20 to 50 parsecs, and their separations are of similar size. All three are situated in bright areas of the Gum nebula. The proposed associations A and C lie in the two brightest parts of the nebula. The three associations are not all of the same age. Association C is about 50 million years old, whereas A and B are decidedly younger. The ages of A and B cannot be determined from the present data, as their color-magnitude diagrams show no clear turnoff from the main sequence. Association A may be young enough to qualify as the birthplace of zeta Puppis. There is no other identifiable association in which zeta Puppis can have originated, unless its age is substantially greater than the 3 million years assumed.

Can Eccentric Debris Disks Be Long-lived? A First Numerical Investigation and Application to Zeta(exp 2) Reticuli

NASA Technical Reports Server (NTRS)

Faramaz, V.; Beust, H.; Thebault, P.; Augereau, J.-C.; Bonsor, A.; delBurgo, C.; Ertel, S.; Marshall, J. P.; Milli, J.; Montesinos, B.;

Elucidation of the mechanisms of action of Bacteriophage K/nano-emulsion formulations against S. aureus via measurement of particle size and zeta potential.

PubMed

Esteban, Patricia Perez; Jenkins, A Toby A; Arnot, Tom C

2016-03-01

In earlier work we have demonstrated the effect that nano-emulsions have on bacterial growth, and most importantly the enhanced bacteriophage infectivity against Staphylococcus aureus in planktonic culture when phage are carried in nano-emulsions. However, the mechanisms of enhancement of the bacteriophage killing effect are not specifically understood. This work focuses on the investigation of the possible interactions between emulsion droplets and bacterial cells, between emulsion droplets and bacteriophages, and finally interactions between all three components: nano-emulsion droplets, bacteria, and bacteriophages. The first approach consists of simple calculations to determine the spatial distribution of the components, based on measurements of particle size. It was found that nano-emulsion droplets are much more numerous than bacteria or bacteriophage, and due to their size and surface area they must be covering the surface of both cells and bacteriophage particles. Stabilisation of bacteriophages due to electrostatic forces and interaction with nano-emulsion droplets is suspected, since bacteriophages may be protected against inactivation due to 'charge shielding'. Zeta potential was measured for the individual components in the system, and for all of them combined. It was concluded that the presence of nano-emulsions could be reducing electrostatic repulsion between bacterial cells and bacteriophage, both of which are very negatively 'charged'. Moreover, nano-emulsions lead to more favourable interaction between bacteriophages and bacteria, enhancing the anti-microbial or killing effect. These findings are relevant since the physicochemical properties of nano-emulsions (i.e. particle size distribution and zeta potential) are key in determining the efficacy of the formulation against infection in the context of responsive burn wound dressings-which is the main target for this work. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

Electroosmotic flow in a rectangular channel with variable wall zeta-potential: comparison of numerical simulation with asymptotic theory.

PubMed

Datta, Subhra; Ghosal, Sandip; Patankar, Neelesh A

2006-02-01

Electroosmotic flow in a straight micro-channel of rectangular cross-section is computed numerically for several situations where the wall zeta-potential is not constant but has a specified spatial variation. The results of the computation are compared with an earlier published asymptotic theory based on the lubrication approximation: the assumption that any axial variations take place on a long length scale compared to a characteristic channel width. The computational results are found to be in excellent agreement with the theory even when the scale of axial variations is comparable to the channel width. In the opposite limit when the wavelength of fluctuations is much shorter than the channel width, the lubrication theory fails to describe the solution either qualitatively or quantitatively. In this short wave limit the solution is well described by Ajdari's theory for electroosmotic flow between infinite parallel plates (Ajdari, A., Phys. Rev. E 1996, 53, 4996-5005.) The infinitely thin electric double layer limit is assumed in the theory as well as in the simulation.

Observations of H II regions around Zeta OPH and other O-B stars

NASA Astrophysics Data System (ADS)

Shestakova, L. I.; Kutirev, A. S.; Ataev, A. Sh.

1988-01-01

A Fabry-Perot spectrometer was used to measure the emission intensities in H-beta near Zeta Oph, Alpha Vir, Alpha Cam, and HD 188209. The spectrometer sensitivity is 0.2 rayleighs, the intensity measurement accuracy is 20 percent. Ionization zone boundaries are determined for Zeta Oph and Alpha Vir; the angular diameters of both regions are about 15 deg. The contour of the H II region near Zeta Oph on the level of the double background in the southwest does not close; instead, it expands again and incorporates the region associated with the B-association II Sco.

Relaxation-based viscosity mapping for magnetic particle imaging.

PubMed

Utkur, M; Muslu, Y; Saritas, E U

2017-05-07

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.

Relaxation-based viscosity mapping for magnetic particle imaging

NASA Astrophysics Data System (ADS)

Utkur, M.; Muslu, Y.; Saritas, E. U.

2017-05-01

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.

Relating zeta functions of discrete and quantum graphs

NASA Astrophysics Data System (ADS)

Harrison, Jonathan; Weyand, Tracy

2018-02-01

We write the spectral zeta function of the Laplace operator on an equilateral metric graph in terms of the spectral zeta function of the normalized Laplace operator on the corresponding discrete graph. To do this, we apply a relation between the spectrum of the Laplacian on a discrete graph and that of the Laplacian on an equilateral metric graph. As a by-product, we determine how the multiplicity of eigenvalues of the quantum graph, that are also in the spectrum of the graph with Dirichlet conditions at the vertices, depends on the graph geometry. Finally we apply the result to calculate the vacuum energy and spectral determinant of a complete bipartite graph and compare our results with those for a star graph, a graph in which all vertices are connected to a central vertex by a single edge.

Zeta Pegasi: An SPB Variable Star

NASA Technical Reports Server (NTRS)

Goebel, John H.

2007-01-01

Broadband photometric observations of the bright star Zeta Pegasi are presented that display brightness variability of 488.2 +/- 6.6 micromag (ppm) range with a period of 22.952 +/- 0.804 hr (f approx. equals 1.04566 c/d). The variation is monosinusoidal, so the star is recommended for membership in the class of small-amplitude Slowly Pulsating B-Stars (SPB) variables oscillating in a non-radial g-mode.

Nonequilibrium viscosity of glass

NASA Astrophysics Data System (ADS)

Mauro, John C.; Allan, Douglas C.; Potuzak, Marcel

2009-09-01

Since glass is a nonequilibrium material, its properties depend on both composition and thermal history. While most prior studies have focused on equilibrium liquid viscosity, an accurate description of nonequilibrium viscosity is essential for understanding the low temperature dynamics of glass. Departure from equilibrium occurs as a glass-forming system is cooled through the glass transition range. The glass transition involves a continuous breakdown of ergodicity as the system gradually becomes trapped in a subset of the available configurational phase space. At very low temperatures a glass is perfectly nonergodic (or “isostructural”), and the viscosity is described well by an Arrhenius form. However, the behavior of viscosity during the glass transition range itself is not yet understood. In this paper, we address the problem of glass viscosity using the enthalpy landscape model of Mauro and Loucks [Phys. Rev. B 76, 174202 (2007)] for selenium, an elemental glass former. To study a wide range of thermal histories, we compute nonequilibrium viscosity with cooling rates from 10-12 to 1012K/s . Based on these detailed landscape calculations, we propose a simplified phenomenological model capturing the essential physics of glass viscosity. The phenomenological model incorporates an ergodicity parameter that accounts for the continuous breakdown of ergodicity at the glass transition. We show a direct relationship between the nonequilibrium viscosity parameters and the fragility of the supercooled liquid. The nonequilibrium viscosity model is validated against experimental measurements of Corning EAGLE XG™ glass. The measurements are performed using a specially designed beam-bending apparatus capable of accurate nonequilibrium viscosity measurements up to 1016Pas . Using a common set of parameters, the phenomenological model provides an accurate description of EAGLE XG™ viscosity over the full range of measured temperatures and fictive temperatures.

Reference Correlation for the Viscosity of Carbon Dioxide

NASA Astrophysics Data System (ADS)

Laesecke, Arno; Muzny, Chris D.

2017-03-01

A comprehensive database of experimental and computed data for the viscosity of carbon dioxide (CO2) was compiled and a new reference correlation was developed. Literature results based on an ab initio potential energy surface were the foundation of the correlation of the viscosity in the limit of zero density in the temperature range from 100 to 2000 K. Guided symbolic regression was employed to obtain a new functional form that extrapolates correctly to 0 and to 10 000 K. Coordinated measurements at low density made it possible to implement the temperature dependence of the Rainwater-Friend theory in the linear-in-density viscosity term. The residual viscosity could be formulated with a scaling term ργ/T, the significance of which was confirmed by symbolic regression. The final viscosity correlation covers temperatures from 100 to 2000 K for gaseous CO2 and from 220 to 700 K with pressures along the melting line up to 8000 MPa for compressed and supercritical liquid states. The data representation is more accurate than with the previous correlations, and the covered pressure and temperature range is significantly extended. The critical enhancement of the viscosity of CO2 is included in the new correlation.

Computational strategies for the Riemann zeta function

NASA Astrophysics Data System (ADS)

Borwein, Jonathan M.; Bradley, David M.; Crandall, Richard E.

2000-09-01

We provide a compendium of evaluation methods for the Riemann zeta function, presenting formulae ranging from historical attempts to recently found convergent series to curious oddities old and new. We concentrate primarily on practical computational issues, such issues depending on the domain of the argument, the desired speed of computation, and the incidence of what we call "value recycling".

Intrinsic Viscosity of Dendrimers via Equilibrium Molecular Dynamics

NASA Astrophysics Data System (ADS)

Drew, Phil; Adolf, David

2004-03-01

Equilibrium molecular dynamics simulations of dendrimers in dilute solution have been performed using dl-poly. Analysis of the system stress tensor via the Green-Kubo formula produces the viscosity of the dendrimer solution which, when coupled with that of a solvent only system leads to the intrinsic viscosity of the dendrimer solute. Particular attention has been paid to error analysis as the auto-correlation of the stress tensor exhibits a long time tail, potentially leading to large uncertainties in the solution, and hence intrinsic, viscosities. In order to counter this effect and provide reliable statistical averaging, simulations have been run spanning very many times the longest system relaxation. Comparison is made to previous studies, using different techniques, which suggest a peak in the intrinsic viscosity of dendrimers at around generation four. Results are also presented from investigations in to the individual contributions to the system stress tensor from the solvent and the solute.

Imaging aerosol viscosity

NASA Astrophysics Data System (ADS)

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

2017-04-01

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

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

PubMed Central

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

2016-01-01

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

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

PubMed

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

2016-08-31

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).

The Structural Evolution of Milky-Way-Like Star-Forming Galaxies zeta is approximately 1.3

NASA Technical Reports Server (NTRS)

Patel, Shannon G.; Fumagalli, Mattia; Franx, Marun; VanDokkum, Pieter G.; VanDerWel, Arjen; Leja, Joel; Labbe, Ivo; Brammr, Gabriel; Whitaker, Katherine E.; Skelton, Rosalind E.;

Superparamagnetic nanoparticle-based viscosity test

NASA Astrophysics Data System (ADS)

Wu, Kai; Liu, Jinming; Wang, Yi; Ye, Clark; Feng, Yinglong; Wang, Jian-Ping

2015-08-01

Hyperviscosity syndrome is triggered by high blood viscosity in the human body. This syndrome can result in retinopathy, vertigo, coma, and other unanticipated complications. Serum viscosity is one of the important factors affecting whole blood viscosity, which is regarded as an indicator of general health. In this letter, we propose and demonstrate a Brownian relaxation-based mixing frequency method to test human serum viscosity. This method uses excitatory and detection coils and Brownian relaxation-dominated superparamagnetic nanoparticles, which are sensitive to variables of the liquid environment such as viscosity and temperature. We collect the harmonic signals produced by magnetic nanoparticles and estimate the viscosity of unknown solutions by comparison to the calibration curves. An in vitro human serum viscosity test is performed in less than 1.5 min.

Viscosity of confined two-dimensional Yukawa liquids: A nonequilibrium method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Landmann, S.; Kählert, H.; Thomsen, H.

2015-09-15

We present a nonequilibrium method that allows one to determine the viscosity of two-dimensional dust clusters in an isotropic confinement. By applying a tangential external force to the outer parts of the cluster (e.g., with lasers), a sheared velocity profile is created. The decay of the angular velocity towards the center of the confinement potential is determined by a balance between internal (viscosity) and external friction (neutral gas damping). The viscosity can then be calculated from a fit of the measured velocity profile to a solution of the Navier-Stokes equation. Langevin dynamics simulations are used to demonstrate the feasibility ofmore » the method. We find good agreement of the measured viscosity with previous results for macroscopic Yukawa plasmas.« less

Electrokinetic motion of a spherical micro particle at an oil-water interface in microchannel.

PubMed

Wang, Chengfa; Li, Mengqi; Song, Yongxin; Pan, Xinxiang; Li, Dongqing

2018-03-01

The electrokinetic motion of a negatively charged spherical particle at an oil-water interface in a microchannel is numerically investigated and analyzed in this paper. A three-dimensional (3D) transient numerical model is developed to simulate the particle electrokinetic motion. The channel wall, the surface of the particle and the oil-water interface are all considered negatively charged. The effects of the direct current (DC) electric field, the zeta potentials of the particle-water interface and the oil-water interface, and the dynamic viscosity ratio of oil to water on the velocity of the particle are studied in this paper. In addition, the influences of the particle size are also discussed. The simulation results show that the micro-particle with a small value of negative zeta potential moves in the same direction of the external electric field. However, if the zeta potential value of the particle-water interface is large enough, the moving direction of the particle is opposite to that of the electric field. The velocity of the particle at the interface increases with the increase in the electric field strength and the particle size, but decreases with the increase in the dynamic viscosity ratio of oil to water, and the absolute value of the negative zeta potentials of both the particle-water interface and the oil-water interface. This work is the first numerical study of the electrokinetic motion of a charged particle at an oil-water interface in a microchannel. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

PubMed

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

2015-03-01

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.

Viscosity measurements of crystallizing andesite from Tungurahua volcano (Ecuador)

PubMed Central

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

2015-01-01

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

Reference Correlation for the Viscosity of Carbon Dioxide1

PubMed Central

Laesecke, Arno; Muzny, Chris D.

2017-01-01

A comprehensive database of experimental and computed data for the viscosity of carbon dioxide (CO2) was compiled and a new reference correlation was developed. Literature results based on an ab initio potential energy surface were the foundation of the correlation of the viscosity in the limit of zero density in the temperature range from 100 K to 2000 K. Guided symbolic regression was employed to obtain a new functional form that extrapolates correctly to T → 0 K and to 10 000 K. Coordinated measurements at low density made it possible to implement the temperature dependence of the Rainwater-Friend theory in the linear-in-density viscosity term. The residual viscosity could be formulated with a scaling term ργ/T the significance of which was confirmed by symbolic regression. The final viscosity correlation covers temperatures from 100 K to 2000 K for gaseous CO2, and from 220 K to 700 K with pressures along the melting line up to 8000 MPa for compressed and supercritical liquid states. The data representation is more accurate than with the previous correlations, and the covered pressure and temperature range is significantly extended. The critical enhancement of the viscosity of CO2 is included in the new correlation. PMID:28736460

Effect of Viscosity on the Crystallization of Undercooled Liquids

NASA Technical Reports Server (NTRS)

2003-01-01

There have been numerous studies of glasses indicating that low-gravity processing enhances glass formation. NASA PI s are investigating the effect of low-g processing on the nucleation and crystal growth rates. Dr. Ethridge is investigating a potential mechanism for glass crystallization involving shear thinning of liquids in 1-g. For shear thinning liquids, low-g (low convection) processing will enhance glass formation. The study of the viscosity of glass forming substances at low shear rates is important to understand these new crystallization mechanisms. The temperature dependence of the viscosity of undercooled liquids is also very important for NASA s containerless processing studies. In general, the viscosity of undercooled liquids is not known, yet knowledge of viscosity is required for crystallization calculations. Many researchers have used the Turnbull equation in error. Subsequent nucleation and crystallization calculations can be in error by many orders of magnitude. This demonstrates the requirement for better methods for interpolating and extrapolating the viscosity of undercooled liquids. This is also true for undercooled water. Since amorphous water ice is the predominant form of water in the universe, astrophysicists have modeled the crystallization of amorphous water ice with viscosity relations that may be in error by five orders-of-magnitude.

Highly branched polyethylenes as lubricant viscosity and friction modifiers

DOE PAGES

Robinson, Joshua W.; Zhou, Yan; Qu, Jun; ...

2016-10-08

A series of highly branched polyethylene (BPE) were prepared and evaluated in a Group I base oil as potential viscosity and friction modifiers. The 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 with respect to viscosity index and friction reduction. In conclusion, this study provides scientific insights into polymer design for future lubricant development activities.

Computing the Viscosity of Supercooled Liquids: Markov Network Model

PubMed Central

Li, Ju; Kushima, Akihiro; Eapen, Jacob; Lin, Xi; Qian, Xiaofeng; Mauro, John C.; Diep, Phong; Yip, Sidney

2011-01-01

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 107 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. PMID:21464988

Effect of the adsorption of lithium and borate species on the zeta potential of particles of cobalt ferrite, nickel ferrite, and magnetite.

PubMed

Barale, M; Lefèvre, G; Carrette, F; Catalette, H; Fédoroff, M; Cote, G

2008-12-01

Zetametric measurements on suspensions of oxide particles (cobalt ferrite, nickel ferrite, and magnetite) representative of corrosion products from primary circuits of pressurized water reactors were performed at 25 and 70 degrees C in the presence of lithium and borate species. No effect of lithium ions was observed. Borate species cause a decrease of the isoelectric point (IEP), attributed to the sorption of borate as a negative complex MOB(OH)3(-). A predictive model based on thermodynamic calculations (2-pK and diffuse layer models) of the surface acidity constants from the data of acid-base titrations combined with an empirical relationship between the surface potential Psi 0 and the zeta potential determined by zetametry was developed. A whole set of parameters valid at 25 degrees C, in a range of ionic strength between 10(-4) and 10(-2) molL(-1) and in a range of pH between 4 and 8, was determined for this model. Increase of temperature to 70 degrees C in the presence of borate results in a decrease of IEP for cobalt ferrite and an increase of the IEP for nickel ferrite.

LETTER TO THE EDITOR: Fractal diffusion coefficient from dynamical zeta functions

NASA Astrophysics Data System (ADS)

Cristadoro, Giampaolo

2006-03-01

Dynamical zeta functions provide a powerful method to analyse low-dimensional dynamical systems when the underlying symbolic dynamics is under control. On the other hand, even simple one-dimensional maps can show an intricate structure of the grammar rules that may lead to a non-smooth dependence of global observables on parameters changes. A paradigmatic example is the fractal diffusion coefficient arising in a simple piecewise linear one-dimensional map of the real line. Using the Baladi-Ruelle generalization of the Milnor-Thurnston kneading determinant, we provide the exact dynamical zeta function for such a map and compute the diffusion coefficient from its smallest zero.

Spectroscopic studies on di-pophyrin rotor as micro-viscosity sensor

NASA Astrophysics Data System (ADS)

Doan, H.; Raut, S.; Kimbal, J.; Gryczynski, Z.; Dzyuba, S.; Balaz, M.

2015-03-01

In typical biological systems the fluid compartment makes up more than 70% percent of the system weight. A variety of mass and signal transportation as well as intermolecular interactions are often governed by viscosity. It is important to be able to measure/estimate viscosity and detect the changes in viscosity upon various stimulations. Understanding the influence of changes in viscosity is crucial and development of the molecular systems that sensitive to micro-viscosity is a goal of many researches. Molecular rotors have been considered the potential target since they present enhanced sensitivity to local viscosity that can strongly restrict molecular rotation. To understand the mechanics of rotor interaction with the environment we have been studied conjugated pophyrin-dimer rotor (DP) that emit in the near IR. Our goal is to investigate the photo physical properties such as absorption, transition moment orientation, emission and excitation, polarization anisotropy and fluorescence lifetime in various mediums of different viscosities from ethanol to poly vinyl alcohol (PVA) matrices. The results imply the influences of the medium's viscosity on the two distinct confirmations: planar and twisted conformations of DP. Linear dichroism from polarized absorption in PVA matrices shows various orientations of transition moments. Excitation anisotropy shows similar transition splitting between two conformations. Time resolved intensity decay at two different observations confirms the two different emission states and furthermore the communication between the two states in the form of energy transfer upon excitation.

Steady Shear Viscosities of Two Hard Sphere Colloidal Dispersions

NASA Astrophysics Data System (ADS)

Cheng, Zhengdong; Chaikin, Paul M.; Phan, See-Eng; Russel, William B.; Zhu, Jixiang

1996-03-01

Though hard spheres have the simplest inter-particle potential, the many body hydrodynamic interactions are complex and the rheological properties of dispersions are not fully understood in the concentrated regime. We studied two model systems: colloidal poly-(Methyl Methacrylate) spheres with a grafted layer of poly-(12-hydroxy stearic acid) (PMMA/PHSA) and spherical Silica particles (PST-5, Nissan Chemical Industries, Ltd, Tokyo, Japan). Steady shear viscosities were measured by a Zimm viscometer. The high shear relative viscosity of the dispersions compares well with other hard sphere systems, but the low shear relative viscosity of PMMA/PHSA dispersions is η / η 0 = 50 at φ = 0.5 , higher than η / η 0 = 22 for other hard sphere systems, consistent with recently published data (Phys. Rev. Lett. 75(1995)958). Bare Silica spheres are used to clarify the effect of the grafted layer. With the silica spheres, volume fraction can be determined independent of intrinsic viscosity measurements; also, higher concentrated dispersions can be made.

Models for viscosity and shear localization in bubble-rich magmas

NASA Astrophysics Data System (ADS)

Vona, Alessandro; Ryan, Amy G.; Russell, James K.; Romano, Claudia

2016-09-01

Bubble content influences magma rheology and, thus, styles of volcanic eruption. Increasing magma vesicularity affects the bulk viscosity of the bubble-melt suspension and has the potential to promote non-Newtonian behavior in the form of shear localization or brittle failure. Here, we present a series of high temperature uniaxial deformation experiments designed to investigate the effect of bubbles on the magma bulk viscosity. The starting materials are cores of natural rhyolitic obsidian synthesized to have variable vesicularity (ϕ = 0- 66%). The foamed cores were deformed isothermally (T = 750 °C) at atmospheric conditions using a high-temperature uniaxial press under constant displacement rates (strain rates between 0.5- 1 ×10-4 s-1) and to total strains of 10-40%. The viscosity of the bubble-free melt (η0) was measured by micropenetration and parallel plate methods to establish a baseline for experiments on the vesicle rich cores. At the experimental conditions, rising vesicle content produces a marked decrease in bulk viscosity that is best described by a two-parameter empirical equation: log10 ⁡ηBulk =log10 ⁡η0 - 1.47[ ϕ / (1 - ϕ) ] 0.48. Our parameterization of the bubble-melt rheology is combined with Maxwell relaxation theory to map the potential onset of non-Newtonian behavior (shear localization) in magmas as a function of melt viscosity, vesicularity, and strain rate. For low degrees of strain (i.e. as in our study), the rheological properties of vesicular magmas under different flow types (pure vs. simple shear) are indistinguishable. For high strain or strain rates where simple and pure shear viscosity values may diverge, our model represents a maximum boundary condition. Vesicular magmas can behave as non-Newtonian fluids at lower strain rates than unvesiculated melts, thereby, promoting shear localization and (explosive or non-explosive) magma fragmentation. The extent of shear localization in magma influences outgassing efficiency

Line identifications in the ultraviolet spectra of Tau Herculis, B5 IV, and Zeta Draconis, B6 III

NASA Technical Reports Server (NTRS)

Underhill, A. B.; Adelman, S. J.

1976-01-01

Tables of the lines found on two tracings each of the ultraviolet spectrum of Tau Her, B5 IV, and Zeta Dra, B6 III, made by the Copernicus satellite and possible identifications are given. The ranges 1025-1451A for Tau Her and 1035 to 1425A for Zeta Dra are covered by the U2 spectrometer at a resolution of 0.2A; the ranges 2028 to 2959A for Tau Her and 2000 to 3000A for Zeta Dra are covered by the V2 spectrometer at a resolution of 0.4A. The observed density of lines in the U2 region is 1.1 lines/A for Tau Her and 1.7 lines/A for Zeta Dra. In the V2 region it is 0.8 lines/A for Tau Her and 0.9 lines/A for Zeta Dra.

Viscosity and Solvation

ERIC Educational Resources Information Center

Robertson, C. T.

1973-01-01

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)

Temperature-viscosity models reassessed.

PubMed

Peleg, Micha

2017-05-04

The temperature effect on viscosity of liquid and semi-liquid foods has been traditionally described by the Arrhenius equation, a few other mathematical models, and more recently by the WLF and VTF (or VFT) equations. The essence of the Arrhenius equation is that the viscosity is proportional to the absolute temperature's reciprocal and governed by a single parameter, namely, the energy of activation. However, if the absolute temperature in K in the Arrhenius equation is replaced by T + b where both T and the adjustable b are in °C, the result is a two-parameter model, which has superior fit to experimental viscosity-temperature data. This modified version of the Arrhenius equation is also mathematically equal to the WLF and VTF equations, which are known to be equal to each other. Thus, despite their dissimilar appearances all three equations are essentially the same model, and when used to fit experimental temperature-viscosity data render exactly the same very high regression coefficient. It is shown that three new hybrid two-parameter mathematical models, whose formulation bears little resemblance to any of the conventional models, can also have excellent fit with r 2 ∼ 1. This is demonstrated by comparing the various models' regression coefficients to published viscosity-temperature relationships of 40% sucrose solution, soybean oil, and 70°Bx pear juice concentrate at different temperature ranges. Also compared are reconstructed temperature-viscosity curves using parameters calculated directly from 2 or 3 data points and fitted curves obtained by nonlinear regression using a larger number of experimental viscosity measurements.

Zeta Function Regularization in Casimir Effect Calculations and J. S. DOWKER's Contribution

NASA Astrophysics Data System (ADS)

Elizalde, Emilio

2012-06-01

A summary of relevant contributions, ordered in time, to the subject of operator zeta functions and their application to physical issues is provided. The description ends with the seminal contributions of Stephen Hawking and Stuart Dowker and collaborators, considered by many authors as the actual starting point of the introduction of zeta function regularization methods in theoretical physics, in particular, for quantum vacuum fluctuation and Casimir effect calculations. After recalling a number of the strengths of this powerful and elegant method, some of its limitations are discussed. Finally, recent results of the so-called operator regularization procedure are presented.

Zeta Function Regularization in Casimir Effect Calculations and J. S. Dowker's Contribution

NASA Astrophysics Data System (ADS)

Elizalde, Emilio

2012-07-01

A summary of relevant contributions, ordered in time, to the subject of operator zeta functions and their application to physical issues is provided. The description ends with the seminal contributions of Stephen Hawking and Stuart Dowker and collaborators, considered by many authors as the actual starting point of the introduction of zeta function regularization methods in theoretical physics, in particular, for quantum vacuum fluctuation and Casimir effect calculations. After recalling a number of the strengths of this powerful and elegant method, some of its limitations are discussed. Finally, recent results of the so called operator regularization procedure are presented.

Dissimilar viscosity induced sample pre-concentration in elecrokinetic nanofluidic channels

NASA Astrophysics Data System (ADS)

Wink, Dean; Shelton, Elijah; Pennathur, Sumita; Storey, Brian

2013-11-01

Nanofluidic analysis systems boast many advantages: portability, small sample handling, short processing times, and potential for integration with mobile electronics. However, such systems face the challenge of detecting increasingly small volumes of sample at low concentrations. In this work, we demonstrate a unique pre-concentration technique in electrokinetic nanofluidic systems based on a viscosity mismatch between two fluids. In nanofluidic electrokinetic systems, finite electric double layers (EDL) lead to non-uniform electric potentials and transverse concentration distributions. Therefore, when the EDL is comparable in size to the channel height, negatively charged ions are repelled from negatively charged walls and preferentially populate the channel centerline. Furthermore, an axial piecewise viscosity distribution induces internal pressure gradients within the channel. These force the ions to move at a different average velocities based on the pressure gradient being favorable or adverse, leading to focusing. To experimentally probe this phenomenon, we electrokinetically inject solutions of borate buffer with and without glycerol (to change the viscosity) and use a fluorescent tracer dye to visualize the flow. We perform the injections in cross-geometry channels of 20 micron, 1 micron, and 250 nanometer depths. We measure fluorescence at 5, 10 and 15 mm distances from junction. Enhancement is characterized by comparing intensities to control measurements for systems with uniform viscosity.

Tunnel determinants from spectral zeta functions. Instanton effects in quantum mechanics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Izquierdo, A. Alonso; Guilarte, J. Mateos

2014-07-23

In this paper we develop an spectral zeta function regularization procedure on the determinants of instanton fluctuation operators that describe the semi-classical order of tunnel effects between degenerate vacua.

Capillary waves with surface viscosity

NASA Astrophysics Data System (ADS)

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

2017-11-01

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.

Evaluation of anti-freeze viscosity modifier for potential external tank applications

NASA Technical Reports Server (NTRS)

Lynn, R. O. L.

1981-01-01

Viscosity modifiers and gelling agents were evaluated in combination with ethylene glycol and dimethyl sulfoxide water eutectics. Pectin and agarose are found to gel these eutectics effectively in low concentration, but the anti-freeze protection afforded by these compositions is found to be marginal in simulations of the intended applications. Oxygen vent shutters and vertical metallic surfaces were simulated, with water supplied as a spray, dropwise, and by condensation from the air.

Viscosity of a multichannel one-dimensional Fermi gas

DOE Office of Scientific and Technical Information (OSTI.GOV)

DeGottardi, Wade; Matveev, K. A.

Many one-dimensional systems of experimental interest possess multiple bands arising from shallow confining potentials. In this paper, we study a gas of weakly interacting fermions and show that the bulk viscosity is dramatically altered by the occupation of more than one band. The reasons for this are twofold: a multichannel system is more easily displaced from equilibrium and the associated relaxation processes lead to more rapid equilibration than in the single channel case. We estimate the bulk viscosity in terms of the underlying microscopic interactions. The experimental relevance of this physics is discussed in the context of quantum wires andmore » trapped cold atomic gases.« less

Zeta functions on tori using contour integration

NASA Astrophysics Data System (ADS)

Elizalde, Emilio; Kirsten, Klaus; Robles, Nicolas; Williams, Floyd

2015-12-01

A new, seemingly useful presentation of zeta functions on complex tori is derived by using contour integration. It is shown to agree with the one obtained by using the Chowla-Selberg series formula, for which an alternative proof is thereby given. In addition, a new proof of the functional determinant on the torus results, which does not use the Kronecker first limit formula nor the functional equation of the non-holomorphic Eisenstein series. As a bonus, several identities involving the Dedekind eta function are obtained as well.

Mapping Protein-Protein Interactions of the Resistance-Related Bacterial Zeta Toxin-Epsilon Antitoxin Complex (ε₂ζ₂) with High Affinity Peptide Ligands Using Fluorescence Polarization.

PubMed

Fernández-Bachiller, María Isabel; Brzozowska, Iwona; Odolczyk, Norbert; Zielenkiewicz, Urszula; Zielenkiewicz, Piotr; Rademann, Jörg

2016-07-16

Toxin-antitoxin systems constitute a native survival strategy of pathogenic bacteria and thus are potential targets of antibiotic drugs. Here, we target the Zeta-Epsilon toxin-antitoxin system, which is responsible for the stable maintenance of certain multiresistance plasmids in Gram-positive bacteria. Peptide ligands were designed on the basis of the ε₂ζ₂ complex. Three α helices of Zeta forming the protein-protein interaction (PPI) site were selected and peptides were designed conserving the residues interacting with Epsilon antitoxin while substituting residues binding intramolecularly to other parts of Zeta. Designed peptides were synthesized with an N-terminal fluoresceinyl-carboxy-residue for binding assays and provided active ligands, which were used to define the hot spots of the ε₂ζ₂ complex. Further shortening and modification of the binding peptides provided ligands with affinities <100 nM, allowing us to determine the most relevant PPIs and implement a robust competition binding assay.

Differential interaction and aggregation of 3-repeat and 4-repeat tau isoforms with 14-3-3{zeta} protein

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sadik, Golam; Tanaka, Toshihisa, E-mail: tanaka@psy.med.osaka-u.ac.jp; Kato, Kiyoko

2009-05-22

Tau isoforms, 3-repeat (3R) and 4-repeat tau (4R), are differentially involved in neuronal development and in several tauopathies. 14-3-3 protein binds to tau and 14-3-3/tau association has been found both in the development and in tauopathies. To understand the role of 14-3-3 in the differential regulation of tau isoforms, we have performed studies on the interaction and aggregation of 3R-tau and 4R-tau, either phosphorylated or unphosphorylated, with 14-3-3{zeta}. We show by surface plasmon resonance studies that the interaction between unphosphorylated 3R-tau and 14-3-3{zeta} is {approx}3-folds higher than that between unphosphorylated 4R-tau and 14-3-3{zeta}. Phosphorylation of tau by protein kinase Amore » (PKA) increases the affinity of both 3R- and 4R-tau for 14-3-3{zeta} to a similar level. An in vitro aggregation assay employing both transmission electron microscopy and fluorescence spectroscopy revealed the aggregation of unphosphorylated 4R-tau to be significantly higher than that of unphosphorylated 3R-tau following the induction of 14-3-3{zeta}. The filaments formed from 3R- and 4R-tau were almost similar in morphology. In contrast, the aggregation of both 3R- and 4R-tau was reduced to a similar low level after phosphorylation with PKA. Taken together, these results suggest that 14-3-3{zeta} exhibits a similar role for tau isoforms after PKA-phosphorylation, but a differential role for unphosphorylated tau. The significant aggregation of 4R-tau by 14-3-3{zeta} suggests that 14-3-3 may act as an inducer in the generation of 4R-tau-predominant neurofibrillary tangles in tauopathies.« less

Carbon and nitrogen abundances in the supergiants HD 93840 and zeta Per

NASA Technical Reports Server (NTRS)

Massa, Derck; Altner, Bruce; Wynne, David; Lamers, H. J. G. L. M.

1990-01-01

The BN supergiant HD 93840 is shown to have the same temperature and surface gravity as the normal Bi Ib zeta Per. Differential abundance analysis of their C 4 and N 5 wind line profiles are found. The results are independent of the usual model atmosphere analyses and, therefore, a valuable check on them. Ratios for the C and N surface abundances in HD 93840 compared to Per of 1:10 and 4.6:1 are found respectively. By introducing a simple model for the compositions of both atmospheres the fraction of material in each atmosphere which has undergone CNO processing, more than 90 percent for HD 93840 and less than about 15 percent for zeta Per, is derived.

In vitro phosphorylation of insulin receptor substrate 1 by protein kinase C-zeta: functional analysis and identification of novel phosphorylation sites.

PubMed

Sommerfeld, Mark R; Metzger, Sabine; Stosik, Magdalene; Tennagels, Norbert; Eckel, Jürgen

2004-05-18

Protein kinase C-zeta (PKC-zeta) participates both in downstream insulin signaling and in the negative feedback control of insulin action. Here we used an in vitro approach to identify PKC-zeta phosphorylation sites within insulin receptor substrate 1 (IRS-1) and to characterize the functional implications. A recombinant IRS-1 fragment (rIRS-1(449)(-)(664)) containing major tyrosine motifs for interaction with phosphatidylinositol (PI) 3-kinase strongly associated to the p85alpha subunit of PI 3-kinase after Tyr phosphorylation by the insulin receptor. Phosphorylation of rIRS-1(449)(-)(664) by PKC-zeta induced a prominent inhibition of this process with a mixture of classical PKC isoforms being less effective. Both PKC-zeta and the classical isoforms phosphorylated rIRS-1(449)(-)(664) on Ser(612). However, modification of this residue did not reduce the affinity of p85alpha binding to pTyr-containing peptides (amino acids 605-615 of rat IRS-1), as determined by surface plasmon resonance. rIRS-1(449)(-)(664) was then phosphorylated by PKC-zeta using [(32)P]ATP and subjected to tryptic phosphopeptide mapping based on two-dimensional HPLC coupled to mass spectrometry. Ser(498) and Ser(570) were identified as novel phosphoserine sites targeted by PKC-zeta. Both sites were additionally confirmed by phosphopeptide mapping of the corresponding Ser --> Ala mutants of rIRS-1(449)(-)(664). Ser(570) was specifically targeted by PKC-zeta, as shown by immunoblotting with a phosphospecific antiserum against Ser(570) of IRS-1. Binding of p85alpha to the S570A mutant was less susceptible to inhibition by PKC-zeta, when compared to the S612A mutant. In conclusion, our in vitro data demonstrate a strong inhibitory action of PKC-zeta at the level of IRS-1/PI 3-kinase interaction involving multiple serine phosphorylation sites. Whereas Ser(612) appears not to participate in the negative control of insulin signaling, Ser(570) may at least partly contribute to this process.

Viscosity measuring using microcantilevers

DOEpatents

Oden, Patrick Ian

2001-01-01

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.

Scientific Objectives of the Critical Viscosity Experiment

NASA Technical Reports Server (NTRS)

Berg, R. F.; Moldover, M. R.

1993-01-01

In microgravity, the Critical Viscosity Experiment will measure the viscosity of xenon 15 times closer to the critical point than is possible on earth. The results are expected to include the first direct observation of the predicted power-law divergence of viscosity in a pure fluid and they will test calculations of the value of the exponent associated with the divergence. The results, when combined with Zeno's decay-rate data, will strengthen the test of mode coupling theory. Without microgravity viscosity data, the Zeno test will require an extrapolation of existing 1-g viscosity data by as much as factor of 100 in reduced temperature. By necessity, the extrapolation would use an incompletely verified theory of viscosity crossover. With the microgravity viscosity data, the reliance on crossover models will be negligible allowing a more reliable extrapolation. During the past year, new theoretical calculations for the viscosity exponent finally achieved consistency with the best experimental data for pure fluids. This report gives the justification for the proposed microgravity Critical Viscosity Experiment in this new context. This report also combines for the first time the best available light scattering data with our recent viscosity data to demonstrate the current status of tests of mode coupling theory.

Catalytic properties of an expressed and purified higher plant type zeta-carotene desaturase from Capsicum annuum.

PubMed

Breitenbach, J; Kuntz, M; Takaichi, S; Sandmann, G

1999-10-01

The zeta-carotene desaturase from Capsicum annuum (EC 1.14.99.-) was expressed in Escherichia coli, purified and characterized biochemically. The enzyme acts as a monomer with lipophilic quinones as cofactors. Km values for the substrate zeta-carotene or the intermediate neurosporene in the two-step desaturation reaction are almost identical. Product analysis showed that different lycopene isomers are formed, including substantial amounts of the all-trans form, together with 7,7',9,9'-tetracis prolycopene via the corresponding neurosporene isomers. The application of different geometric isomers as substrates revealed that the zeta-carotene desaturase has no preference for certain isomers and that the nature of the isomers formed during catalysis depends strictly on the isomeric composition of the substrate.

Asymptotic analysis on a pseudo-Hermitian Riemann-zeta Hamiltonian

NASA Astrophysics Data System (ADS)

Bender, Carl M.; Brody, Dorje C.

2018-04-01

The differential-equation eigenvalue problem associated with a recently-introduced Hamiltonian, whose eigenvalues correspond to the zeros of the Riemann zeta function, is analyzed using Fourier and WKB analysis. The Fourier analysis leads to a challenging open problem concerning the formulation of the eigenvalue problem in the momentum space. The WKB analysis gives the exact asymptotic behavior of the eigenfunction.

Compositional dependence of lower crustal viscosity

NASA Astrophysics Data System (ADS)

Shinevar, William J.; Behn, Mark D.; Hirth, Greg

2015-10-01

We calculate the viscosity structure of the lower continental crust as a function of its bulk composition using multiphase mixing theory. We use the Gibbs free-energy minimization routine Perple_X to calculate mineral assemblages for different crustal compositions under pressure and temperature conditions appropriate for the lower continental crust. The effective aggregate viscosities are then calculated using a rheologic mixing model and flow laws for the major crust-forming minerals. We investigate the viscosity of two lower crustal compositions: (i) basaltic (53 wt % SiO2) and (ii) andesitic (64 wt % SiO2). The andesitic model predicts aggregate viscosities similar to feldspar and approximately 1 order of magnitude greater than that of wet quartz. The viscosity range calculated for the andesitic crustal composition (particularly when hydrous phases are stable) is most similar to independent estimates of lower crust viscosity in actively deforming regions based on postglacial isostatic rebound, postseismic relaxation, and paleolake shoreline deflection.

One-, two- and three-phase viscosity treatments for basaltic lava flows

PubMed Central

Harris, Andrew J. L.; Allen, John S.

2009-01-01

Lava flows comprise three-phase mixtures of melt, crystals, and bubbles. While existing one-phase treatments allow melt phase viscosity to be assessed on the basis of composition, water content, and/or temperature, two-phase treatments constrain the effects of crystallinity or vesicularity on mixture viscosity. However, three-phase treatments, allowing for the effects of coexisting crystallinity and vesicularity, are not well understood. We investigate existing one- and two-phase treatments using lava flow case studies from Mauna Loa (Hawaii) and Mount Etna (Italy) and compare these with a three-phase treatment that has not been applied previously to basaltic mixtures. At Etna, melt viscosities of 425 ± 30 Pa s are expected for well-degassed (0.1 w. % H2O), and 135 ± 10 Pa s for less well-degassed (0.4 wt % H2O), melt at 1080°C. Application of a three-phase model yields mixture viscosities (45% crystals, 25–35% vesicles) in the range 5600–12,500 Pa s. This compares with a measured value for Etnean lava of 9400 ± 1500 Pa s. At Mauna Loa, the three-phase treatment provides a fit with the full range of field measured viscosities, giving three-phase mixture viscosities, upon eruption, of 110–140 Pa s (5% crystals, no bubble effect due to sheared vesicles) to 850–1400 Pa s (25–30% crystals, 40–60% spherical vesicles). The ability of the three-phase treatment to characterize the full range of melt-crystal-bubble mixture viscosities in both settings indicates the potential of this method in characterizing basaltic lava mixture viscosity. PMID:21691456

Recombinant Human DNase I Reduces the Viscosity of Cystic Fibrosis Sputum

NASA Astrophysics Data System (ADS)

Shak, Steven; Capon, Daniel J.; Hellmiss, Renate; Marsters, Scot A.; Baker, Carrie L.

1990-12-01

Respiratory distress and progressive lung destruction in cystic fibrosis can be attributed to bacterial persistence and the accumulation of viscous purulent secretions in the airways. More than 30 yr ago it was suggested that the large amounts of DNA in purulent secretions contribute to its viscosity and that bovine pancreatic DNase I could reduce the viscosity. To evaluate the potential clinical utility of recombinant human DNase I (rhDNase) in the treatment of cystic fibrosis, we have cloned, sequenced, and expressed rhDNase. Catalytic amounts of rhDNase greatly reduce the viscosity of purulent cystic fibrosis sputum, transforming it within minutes from a nonflowing viscous gel to a flowing liquid. The reduction in viscosity is associated with a decrease in size of DNA in the sputum. Inhalation of a rhDNase aerosol may be a simple direct approach that will help individuals with cystic fibrosis and other patients with pneumonia or bronchitis to clear their airways of purulent secretions.

Recombinant human DNase I reduces the viscosity of cystic fibrosis sputum.

PubMed

Shak, S; Capon, D J; Hellmiss, R; Marsters, S A; Baker, C L

1990-12-01

Respiratory distress and progressive lung destruction in cystic fibrosis can be attributed to bacterial persistence and the accumulation of viscous purulent secretions in the airways. More than 30 yr ago it was suggested that the large amounts of DNA in purulent secretions contribute to its viscosity and that bovine pancreatic DNase I could reduce the viscosity. To evaluate the potential clinical utility of recombinant human DNase I (rhDNase) in the treatment of cystic fibrosis, we have cloned, sequenced, and expressed rhDNase. Catalytic amounts of rhDNase greatly reduce the viscosity of purulent cystic fibrosis sputum, transforming it within minutes from a nonflowing viscous gel to a flowing liquid. The reduction in viscosity is associated with a decrease in size of DNA in the sputum. Inhalation of a rhDNase aerosol may be a simple direct approach that will help individuals with cystic fibrosis and other patients with pneumonia or bronchitis to clear their airways of purulent secretions.

Viscosity of the earth's core.

NASA Technical Reports Server (NTRS)

Gans, R. F.

1972-01-01

Calculation of the viscosity of the core at the boundary of the inner and outer core. It is assumed that this boundary is a melting transition and the viscosity limits of the Andrade (1934,1952) hypothesis (3.7 to 18.5 cp) are adopted. The corresponding kinematic viscosities are such that the precessional system explored by Malkus (1968) would be unstable. Whether it would be sufficiently unstable to overcome a severely subadiabatic temperature gradient cannot be determined.

Fuzzy-PI-based centralised control of semi-isolated FP-SEPIC/ZETA BDC in a PV/battery hybrid system

NASA Astrophysics Data System (ADS)

Mahendran, Venmathi; Ramabadran, Ramaprabha

2016-11-01

Multiport converters with centralised controller have been most commonly used in stand-alone photovoltaic (PV)/battery hybrid system to supply the load smoothly without any disturbances. This study presents the performance analysis of four-port SEPIC/ZETA bidirectional converter (FP-SEPIC/ZETA BDC) using various types of centralised control schemes like Fuzzy tuned proportional integral controller (Fuzzy-PI), fuzzy logic controller (FLC) and conventional proportional integral (PI) controller. The proposed FP-SEPIC/ZETA BDC with various control strategy is derived for simultaneous power management of a PV source using distributed maximum power point tracking (DMPPT) algorithm, a rechargeable battery, and a load by means of centralised controller. The steady state and the dynamic response of the FP-SEPIC/ZETA BDC are analysed using three different types of controllers under line and load regulation. The Fuzzy-PI-based control scheme improves the dynamic response of the system when compared with the FLC and the conventional PI controller. The power balance between the ports is achieved by pseudorandom carrier modulation scheme. The response of the FP-SEPIC/ZETA BDC is also validated experimentally using hardware prototype model of 500 W system. The effectiveness of the control strategy is validated using simulation and experimental results.

Viscosities of aqueous blended amines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hsu, C.H.; Li, M.H.

1997-07-01

Solutions of alkanolamines are an industrially important class of compounds used in the natural gas, oil refineries, petroleum chemical plants, and synthetic ammonia industries for the removal of acidic components like CO{sub 2} and H{sub 2}S from gas streams. The viscosities of aqueous mixtures of diethanolamine (DEA) + N-methyldiethanolamine (MDEA), DEA + 2-amino-2-methyl-1-propanol (AMP), and monoethanolamine (MEA) + 2-piperidineethanol (2-PE) were measured from 30 C to 80 C. A Redlich-Kister equation for the viscosity deviation was applied to represent the viscosity. On the basis of the available viscosity data for five ternary systems, MEA + MDEA + H{sub 2}O, MEAmore » + AMP + H{sub 2}O, DEA + MDEA + H{sub 2}O, DEA + AMP + H{sub 2}O, and MEA + 2-PE + H{sub 2}O, a generalized set of binary parameters were determined. For the viscosity calculation of the systems tested, the overall average absolute percent deviation is about 1.0% for a total of 499 data points.« less

Revisiting the assessment of semen viscosity and its relationship to leucocytospermia.

PubMed

Flint, M; du Plessis, S S; Menkveld, R

2014-10-01

With infertility challenges posing an obstacle to many couples, the extension of variables to assess male fertility is an important line of research. At the Reproductive Biology Unit where the study was undertaken, a considerable proportion of male patient's seeking fertility assessment presented with hyperviscous semen samples and elevated concentrations of leucocytes. Despite viscosity being included as part of a routine spermiogram, it raises a considerable amount of concern as it is assessed semiquantitatively. The study was undertaken to evaluate the quantification of semen viscosity in centipoise (cP) and to investigate whether a correlation exists between hyperviscosity and leucocytospermia. A total of 200 semen samples were assessed from a sample cohort of two population groups: 162 male patients undergoing fertility assessment and 38 volunteer donors. Semen viscosity was determined by measuring the filling time of a capillary-loaded Leja chamber and quantifying the viscosity in cP. Leucocytes were identified histochemically with a leucocyte peroxidase test. The viscosity when quantified in cP was significantly higher in the peroxidase positive sample group (9.01 ± 0.49 vs. 7.39 ± 0.23 cP; P < 0.005). The introduction of a more accurate method of quantifying viscosity may possibly help to identify, diagnose and treat patients suffering from leucocytospermia to ultimately enhance their fertility potential. © 2013 Blackwell Verlag GmbH.

Ultrasonication effect on thermophysical properties of Al2O3 nanofluids

NASA Astrophysics Data System (ADS)

Shah, Janki; Ranjan, Mukesh; Gupta, Sanjeev K.; Sonvane, Yogesh

2018-04-01

In this work, we studied the thermal conductivity and viscosity of alumina nanofluids for their excellent thermophysical properties. Here we considered the bath sonication time effects on thermal conductivity, viscosity and zeta potential of alumina nanofluid with different concentration (0.2, 0.3, 0.4, 0.5 Vol.%). We observed that the thermal conductivity of the nanofluids increased nonlinearly with an increased sonication time/energy as well as viscosity decreased. An enhancement of the thermal conductivity and viscosity at higher particle concentration is also observed. The results indicate that thermal properties of Al2O3 nanofluid enhances as the sonication time increases and prove Al2O3 nanofluid is one of the best thermostable heat transfer fluids compared to conventional cooling fluids.

Cell surface groups of two picocyanobacteria strains studied by zeta potential investigations, potentiometric titration, and infrared spectroscopy.

PubMed

Dittrich, Maria; Sibler, Sabine

2005-06-15

In order to clarify the role of picocyanobacteria in aquatic biogeochemical processes (e.g., calcite precipitation), cell surface properties need to be investigated. An experimental study of the cell surface characteristics of two Synechococcus-type unicellular autotrophic picocyanobacterial strains was carried out. One strain was isolated from Lake Plon and contained phycocyanin, the other strain came from Lago Maggiore and was rich in phycoerythrin. Potentiometric titrations were conducted to determine the different types of sites present on the bacteria cell walls. Infrared spectroscopy allowed characterization of the various functional groups (RNH(2), RCOOH, ROH, RPO(2)) and investigations of zeta potential provided insight into the isoelectrical points of the strains. Titrations reveal three distinct sites on the bacterial surfaces of phycocyanin- and phycoerythrin-rich strains with pK values of 4.8+/-0.3/5.0+/-0.2, 6.6+/-0.2/6.7+/-0.4, and 8.8+/-0.1/8.7+/-0.2, corresponding to carboxyl, phosphate, and amine groups with surface densities of 2.6+/-0.4/7.4+/-1.6 x 10(-4), 1.9+/-0.5/4.4+/-0.8 x 10(-4), and 2.5+/-0.4/4.8+/-0.7 x 10(-4) mol/g of dry bacteria. The deprotonation constants are similar to those of bacterial strains and site densities are also within an order of magnitude of other strains. The phycoerythrin-rich strain had a higher number of binding sites than the phycocyanin-rich strain. The results showed that picocyanobacteria may adsorb either calcium cations or carbonate anions and therefore strongly influence the biogeochemical cycling of calcite in pelagic systems.

p62 modulates Akt activity via association with PKC{zeta} in neuronal survival and differentiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Joung, Insil; Kim, Hak Jae; Kwon, Yunhee Kim

2005-08-26

p62 is a ubiquitously expressed phosphoprotein that interacts with a number of signaling molecules and a major component of neurofibrillary tangles in the brain of Alzheimer's disease patients. It has been implicated in important cellular functions such as cell proliferation and anti-apoptotic pathways. In this study, we have addressed the potential role of p62 during neuronal differentiation and survival using HiB5, a rat neuronal progenitor cell. We generated a recombinant adenovirus encoding T7-epitope tagged p62 to reliably transfer p62 cDNA into the neuronal cells. The results show that an overexpression of p62 led not only to neuronal differentiation, but alsomore » to decreased cell death induced by serum withdrawal in HiB5 cells. In this process p62-dependent Akt phosphorylation occurred via the release of Akt from PKC{zeta} by association of p62 and PKC{zeta}, which is known as a negative regulator of Akt activation. These findings indicate that p62 facilitates cell survival through novel signaling cascades that result in Akt activation. Furthermore, we found that p62 expression was induced during neuronal differentiation. Taken together, the data suggest p62 is a regulator of neuronal cell survival and differentiation.« less

Mononuclear Pd(II) complex as a new therapeutic agent: Synthesis, characterization, biological activity, spectral and DNA binding approaches

NASA Astrophysics Data System (ADS)

Saeidifar, Maryam; Mirzaei, Hamidreza; Ahmadi Nasab, Navid; Mansouri-Torshizi, Hassan

2017-11-01

The binding ability between a new water-soluble palladium(II) complex [Pd(bpy)(bez-dtc)]Cl (where bpy is 2,2‧-bipyridine and bez-dtc is benzyl dithiocarbamate), as an antitumor agent, and calf thymus DNA was evaluated using various physicochemical methods, such as UV-Vis absorption, Competitive fluorescence studies, viscosity measurement, zeta potential and circular dichroism (CD) spectroscopy. The Pd(II) complex was synthesized and characterized using elemental analysis, molar conductivity measurements, FT-IR, 1H NMR, 13C NMR and electronic spectra studies. The anticancer activity against HeLa cell lines demonstrated lower cytotoxicity than cisplatin. The binding constants and the thermodynamic parameters were determined at different temperatures (300 K, 310 K and 320 K) and shown that the complex can bind to DNA via electrostatic forces. Furthermore, this result was confirmed by the viscosity and zeta potential measurements. The CD spectral results demonstrated that the binding of Pd(II) complex to DNA induced conformational changes in DNA. We hope that these results will provide a basis for further studies and practical clinical use of anticancer drugs.

Optical fiber-based fluorescent viscosity sensor

NASA Astrophysics Data System (ADS)

Haidekker, Mark A.; Akers, Walter J.; Fischer, Derek; Theodorakis, Emmanuel A.

2006-09-01

Molecular rotors are a unique group of viscosity-sensitive fluorescent probes. Several recent studies have shown their applicability as nonmechanical fluid viscosity sensors, particularly in biofluids containing proteins. To date, molecular rotors have had to be dissolved in the fluid for the measurement to be taken. We now show that molecular rotors may be covalently bound to a fiber-optic tip without loss of viscosity sensitivity. The optical fiber itself may be used as a light guide for emission light (external illumination of the tip) as well as for both emission and excitation light. Covalently bound molecular rotors exhibit a viscosity-dependent intensity increase similar to molecular rotors in solution. An optical fiber-based fluorescent viscosity sensor may be used in real-time measurement applications ranging from biomedical applications to the food industry.

Optical fiber-based fluorescent viscosity sensor.

PubMed

Haidekker, Mark A; Akers, Walter J; Fischer, Derek; Theodorakis, Emmanuel A

2006-09-01

Molecular rotors are a unique group of viscosity-sensitive fluorescent probes. Several recent studies have shown their applicability as nonmechanical fluid viscosity sensors, particularly in biofluids containing proteins. To date, molecular rotors have had to be dissolved in the fluid for the measurement to be taken. We now show that molecular rotors may be covalently bound to a fiber-optic tip without loss of viscosity sensitivity. The optical fiber itself may be used as a light guide for emission light (external illumination of the tip) as well as for both emission and excitation light. Covalently bound molecular rotors exhibit a viscosity-dependent intensity increase similar to molecular rotors in solution. An optical fiber-based fluorescent viscosity sensor may be used in real-time measurement applications ranging from biomedical applications to the food industry.

Estimated Viscosities and Thermal Conductivities of Gases at High Temperatures

NASA Technical Reports Server (NTRS)

Svehla, Roger A.

1962-01-01

Viscosities and thermal conductivities, suitable for heat-transfer calculations, were estimated for about 200 gases in the ground state from 100 to 5000 K and 1-atmosphere pressure. Free radicals were included, but excited states and ions were not. Calculations for the transport coefficients were based upon the Lennard-Jones (12-6) potential for all gases. This potential was selected because: (1) It is one of the most realistic models available and (2) intermolecular force constants can be estimated from physical properties or by other techniques when experimental data are not available; such methods for estimating force constants are not as readily available for other potentials. When experimental viscosity data were available, they were used to obtain the force constants; otherwise the constants were estimated. These constants were then used to calculate both the viscosities and thermal conductivities tabulated in this report. For thermal conductivities of polyatomic gases an Eucken-type correction was made to correct for exchange between internal and translational energies. Though this correction may be rather poor at low temperatures, it becomes more satisfactory with increasing temperature. It was not possible to obtain force constants from experimental thermal conductivity data except for the inert atoms, because most conductivity data are available at low temperatures only (200 to 400 K), the temperature range where the Eucken correction is probably most in error. However, if the same set of force constants is used for both viscosity and thermal conductivity, there is a large degree of cancellation of error when these properties are used in heat-transfer equations such as the Dittus-Boelter equation. It is therefore concluded that the properties tabulated in this report are suitable for heat-transfer calculations of gaseous systems.

In-silico prediction of concentration-dependent viscosity curves for monoclonal antibody solutions

PubMed Central

Tomar, Dheeraj S.; Li, Li; Broulidakis, Matthew P.; Luksha, Nicholas G.; Burns, Christopher T.; Singh, Satish K.; Kumar, Sandeep

2017-01-01

ABSTRACT Early stage developability assessments of monoclonal antibody (mAb) candidates can help reduce risks and costs associated with their product development. Forecasting viscosity of highly concentrated mAb solutions is an important aspect of such developability assessments. Reliable predictions of concentration-dependent viscosity behaviors for mAb solutions in platform formulations can help screen or optimize drug candidates for flexible manufacturing and drug delivery options. Here, we present a computational method to predict concentration-dependent viscosity curves for mAbs solely from their sequence—structural attributes. This method was developed using experimental data on 16 different mAbs whose concentration-dependent viscosity curves were experimentally obtained under standardized conditions. Each concentration-dependent viscosity curve was fitted with a straight line, via logarithmic manipulations, and the values for intercept and slope were obtained. Intercept, which relates to antibody diffusivity, was found to be nearly constant. In contrast, slope, the rate of increase in solution viscosity with solute concentration, varied significantly across different mAbs, demonstrating the importance of intermolecular interactions toward viscosity. Next, several molecular descriptors for electrostatic and hydrophobic properties of the 16 mAbs derived using their full-length homology models were examined for potential correlations with the slope. An equation consisting of hydrophobic surface area of full-length antibody and charges on VH, VL, and hinge regions was found to be capable of predicting the concentration-dependent viscosity curves of the antibody solutions. Availability of this computational tool may facilitate material-free high-throughput screening of antibody candidates during early stages of drug discovery and development. PMID:28125318

In-silico prediction of concentration-dependent viscosity curves for monoclonal antibody solutions.

PubMed

Tomar, Dheeraj S; Li, Li; Broulidakis, Matthew P; Luksha, Nicholas G; Burns, Christopher T; Singh, Satish K; Kumar, Sandeep

2017-04-01

Early stage developability assessments of monoclonal antibody (mAb) candidates can help reduce risks and costs associated with their product development. Forecasting viscosity of highly concentrated mAb solutions is an important aspect of such developability assessments. Reliable predictions of concentration-dependent viscosity behaviors for mAb solutions in platform formulations can help screen or optimize drug candidates for flexible manufacturing and drug delivery options. Here, we present a computational method to predict concentration-dependent viscosity curves for mAbs solely from their sequence-structural attributes. This method was developed using experimental data on 16 different mAbs whose concentration-dependent viscosity curves were experimentally obtained under standardized conditions. Each concentration-dependent viscosity curve was fitted with a straight line, via logarithmic manipulations, and the values for intercept and slope were obtained. Intercept, which relates to antibody diffusivity, was found to be nearly constant. In contrast, slope, the rate of increase in solution viscosity with solute concentration, varied significantly across different mAbs, demonstrating the importance of intermolecular interactions toward viscosity. Next, several molecular descriptors for electrostatic and hydrophobic properties of the 16 mAbs derived using their full-length homology models were examined for potential correlations with the slope. An equation consisting of hydrophobic surface area of full-length antibody and charges on V H , V L , and hinge regions was found to be capable of predicting the concentration-dependent viscosity curves of the antibody solutions. Availability of this computational tool may facilitate material-free high-throughput screening of antibody candidates during early stages of drug discovery and development.

Considerations of viscosity in the preliminaries to mammalian fertilisation.

PubMed

Hunter, Ronald H F; Coy, P; Gadea, J; Rath, D

2011-03-01

Migration of spermatozoa in the female genital tract will be strongly influenced by the viscosity of the fluids encountered, yet little systematic analysis has been given to such a consideration. This essay reviews the series of milieux confronting a fertilising sperm during its progression to the oviduct ampulla. Two groups are discussed, first those in which ejaculation is into the vagina, second those in which semen enters the uterus during a protracted mating. Viscous glycoprotein secretions that accumulate in the oviduct isthmus of both groups before ovulation are highlighted, as is the environment generated in the ampulla by the post-ovulatory suspension of oocyte(s), cumulus cells and spermatozoa; follicular and peritoneal fluids may also be present. The viscosity of all female tract fluids responds to cyclical variations in temperature, and these exist within the oviduct near the time of ovulation. Gradations in viscosity influence the pattern and strength of sperm flagellar activity and the rate of forward movement. Measurements of sperm motility are currently made in a physiological medium of constant viscosity and temperature, thereby overlooking changes in the female genital tract. A more sophisticated approach might reveal an adequate fertilising potential in a proportion of putatively poor semen samples.

GRANULATION IN THE PHOTOSPHERE OF {zeta} CYGNI

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gray, David F., E-mail: dfgray@uwo.ca

2012-05-15

A series of 35 high-resolution spectra are used to measure the third-signature plot of the G8 III star, {zeta} Cygni, which shows convective velocities only 8% larger than the Sun. Bisector mapping yields a flux deficit, a measure of granulation contrast, typical of other giants. The observations also give radial velocities with errors {approx}30 m s{sup -1} and allow the orbit to be refined. Velocity excursions relative to the smooth orbital motion, possibly from the granulation, have values exceeding 200 m s{sup -1}. Temperature variations were looked for using line-depth ratios, but none were found.

Conditions of viscosity measurement for detecting irradiated peppers

NASA Astrophysics Data System (ADS)

Hayashi, Toru; Todoriki, Setsuko; Okadome, Hiroshi; Kohyama, Kaoru

1995-04-01

Viscosity of gelatinized suspensions of black and white peppers decreased depending upon dose. The viscosity was influenced by gelatinization and viscosity measurement conditions. The difference between unirradiated pepper and an irradiated one was larger at a higher pH and temperature for gelatinization. A viscosity parameter normalized with the starch content of pepper sample and the viscosity of a 5% suspension of corn starch could get rid of the influence of the conditions for viscosity measurement such as a type of viscometer, shear rate and temperature.

The spectral energy distribution of Zeta Puppis and HD 50896

NASA Technical Reports Server (NTRS)

Holm, A. V.; Cassinelli, J. P.

1977-01-01

The ultraviolet spectral energy distribution of the O5f star Zeta Pup and the WN5 star HD 50896 are derived from OAO-2 observations with the calibration of Bless, Code, and Fairchild (1976). An estimate of the interstellar reddening (0.12 magnitude) of the Wolf-Rayet star is determined from the size of the characteristic interstellar extinction bump at 4.6 inverse microns. After correction for extinction, both stars show a flat energy distribution in the ultraviolet. The distribution of HD 50896 from 1100 A to 2 microns is in good agreement with results of extended model atmospheres, but some uncertainty remains because of the interstellar-extinction correction. The absolute energy distribution of Zeta Pup is fitted by a 42,000-K plane-parallel model if the model's flux is adjusted for the effects of electron scattering in the stellar wind and for UV line blanketing that was determined empirically from high-resolution Copernicus satellite observations. To achieve this fit, it is necessary to push both the spectroscopically determined temperature and the ultraviolet calibration to the limits of their probable errors.

Organization of the human [zeta]-crystallin/quinone reductase gene (CRYZ)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gonzalez, P.; Rao, P.V.; Zigler, J.S. Jr.

1994-05-15

[zeta]-Crystallin is a protein highly expressed in the lens of guinea pigs and camels, where it comprises about 10% of the total soluble protein. It has recently been characterized as a novel quinone oxidoreductase present in a variety of mammalian tissues. The authors report here the isolation and characterization of the human [zeta]-crystallin gene (CRYZ) and its processed pseudogene. The functional gene is composed of nine exons and spans about 20 kb. The 5[prime]-flanking region of the gene is rich in G and C (58%) and lacks TATA and CAAT boxes. Previous analysis of the guinea pig gene revealed themore » presence of two different promoters, one responsible for the high lens-specific expression and the other for expression at the enzymatic level in numerous tissues. Comparative analysis with the guinea pig gene shows that a region of [approximately]2.5 kb that includes the promoter responsible for the high expression in the lens in guinea pig is not present in the human gene. 34 refs., 6 figs., 1 tab.« less

Molecular basis of length polymorphism in the human zeta-globin gene complex.

PubMed Central

Goodbourn, S E; Higgs, D R; Clegg, J B; Weatherall, D J

1983-01-01

The length polymorphism between the human zeta-globin gene and its pseudogene is caused by an allele-specific variation in the copy number of a tandemly repeating 36-base-pair sequence. This sequence is related to a tandemly repeated 14-base-pair sequence in the 5' flanking region of the human insulin gene, which is known to cause length polymorphism, and to a repetitive sequence in intervening sequence (IVS) 1 of the pseudo-zeta-globin gene. Evidence is presented that the latter is also of variable length, probably because of differences in the copy number of the tandem repeat. The homology between the three length polymorphisms may be an indication of the presence of a more widespread group of related sequences in the human genome, which might be useful for generalized linkage studies. PMID:6308667

Averages of ratios of the Riemann zeta-function and correlations of divisor sums

NASA Astrophysics Data System (ADS)

Conrey, Brian; Keating, Jonathan P.

2017-10-01

Nonlinearity has published articles containing a significant number-theoretic component since the journal was first established. We examine one thread, concerning the statistics of the zeros of the Riemann zeta function. We extend this by establishing a connection between the ratios conjecture for the Riemann zeta-function and a conjecture concerning correlations of convolutions of Möbius and divisor functions. Specifically, we prove that the ratios conjecture and an arithmetic correlations conjecture imply the same result. This provides new support for the ratios conjecture, which previously had been motivated by analogy with formulae in random matrix theory and by a heuristic recipe. Our main theorem generalises a recent calculation pertaining to the special case of two-over-two ratios.

Viscosity of high-temperature iodine

NASA Technical Reports Server (NTRS)

Kang, Steve H.; Kunc, Joseph A.

1991-01-01

The viscosity coefficient of iodine in the temperature range 500 - 3000 K is calculated. Because of the low dissociation energy of the I2 molecules, the dissociation degree of the gas increases quickly with temperature, and I + I2 and I + I collisions must be taken into account in calculation of viscosity at temperatures greater than 1000 deg. Several possible channels for atom-atom interaction are considered, and the resulting collision integrals are averaged over all the important channels. It is also shown that the rigid-sphere model is inaccurate in predictions of the viscosity.

Effects of viscosity on sperm motility studied with optical tweezers

NASA Astrophysics Data System (ADS)

Hyun, Nicholas; Chandsawangbhuwana, Charlie; Zhu, Qingyuan; Shi, Linda Z.; Yang-Wong, Collin; Berns, Michael W.

2012-02-01

The purpose of this study is to analyze human sperm motility and energetics in media with different viscosities. Multiple experiments were performed to collect motility parameters using customized computer tracking software that measures the curvilinear velocity (VCL) and the minimum laser power (Pesc) necessary to hold an individual sperm in an optical trap. The Pesc was measured by using a 1064 nm Nd:YVO4 continuous wave laser that optically traps motile sperm at a power of 450 mW in the focused trap spot. The VCL was measured frame by frame before trapping. In order to study sperm energetics under different viscous conditions sperm were labeled with the fluorescent dye DiOC6(3) to measure membrane potentials of mitochondria in the sperm midpiece. Fluorescence intensity was measured before and during trapping. The results demonstrate a decrease in VCL but an increase in Pesc with increasing viscosity. Fluorescent intensity is the same regardless of the viscosity level indicating no change in sperm energetics. The results suggest that, under the conditions tested, viscosity physically affects the mechanical properties of sperm motility rather than the chemical pathways associated with energetics.

Viscosity of two-dimensional strongly coupled dusty plasma modified by a perpendicular magnetic field

NASA Astrophysics Data System (ADS)

Feng, Yan; Lin, Wei; Murillo, M. S.

2017-11-01

Transport properties of two-dimensional (2D) strongly coupled dusty plasmas have been investigated in detail, but never for viscosity with a strong perpendicular magnetic field; here, we examine this scenario using Langevin dynamics simulations of 2D liquids with a binary Yukawa interparticle interaction. The shear viscosity η of 2D liquid dusty plasma is estimated from the simulation data using the Green-Kubo relation, which is the integration of the shear stress autocorrelation function. It is found that, when a perpendicular magnetic field is applied, the shear viscosity of 2D liquid dusty plasma is modified substantially. When the magnetic field is increased, its viscosity increases at low temperatures, while at high temperatures its viscosity diminishes. It is determined that these different variational trends of η arise from the different behaviors of the kinetic and potential parts of the shear stress under external magnetic fields.

Comparison and experimental validation of two potential resonant viscosity sensors in the kilohertz range

NASA Astrophysics Data System (ADS)

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

2013-08-01

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.

High mobility group box-1 is phosphorylated by protein kinase C zeta and secreted in colon cancer cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Hanna; Park, Minhee; Shin, Nara

2012-07-27

Highlights: Black-Right-Pointing-Pointer Specific enzyme for HMGB1 phosphorylation and its secretion is proposed. Black-Right-Pointing-Pointer Inhibition of PKC-{zeta} leads to significant reduction of the secreted HMGB1. Black-Right-Pointing-Pointer Phosphorylation of specific site of HMGB1 redirects its secretion in cancer cells. Black-Right-Pointing-Pointer Activation of PKC-{zeta} in cancers explains the enhanced HMGB1 secretion. -- Abstract: High mobility group box-1 (HMGB1), a nuclear protein, is overexpressed and secreted in cancer cells. Phosphorylation on two different nuclear localization signal regions are known to be important for the nuclear-to-cytoplasmic transport and secretion of HMGB1. However, little is known about the biochemical mechanism of HMGB1 modifications and its subsequentmore » secretion from cancer cells. To identify the specific enzyme and important sites for HMGB1 phosphorylation, we screened the protein kinase C (PKC) family in a colon cancer cell line (HCT116) for HMGB1 binding by pull-down experiments using a 3XFLAG-HMGB1 construct. Strong interactions between atypical PKCs (PKC-{zeta}, {lambda}, and {iota}) and cytoplasmic HMGB1 were observed in HCT116 cells. We further identified the most critical PKC isotype that regulates HMGB1 secretion is PKC-{zeta} by using PKC inhibitors and siRNA experiments. The serine residues at S39, S53 and S181 of HMGB1 were related to enhancing HMGB1 secretion. We also demonstrated overexpression and activation of PKC-{zeta} in colon cancer tissues. Our findings suggest that PKC-{zeta} is involved in the phosphorylation of HMGB1, and the phosphorylation of specific serine residues in the nuclear localization signal regions is related to enhanced HMGB1 secretion in colon cancer cells.« less

The preparation, surface structure, zeta potential, surface charge density and photocatalytic activity of TiO2 nanostructures of different shapes

NASA Astrophysics Data System (ADS)

Grover, Inderpreet Singh; Singh, Satnam; Pal, Bonamali

2013-09-01

Titania based nanocatalysts such as sodium titanates of different morphology having superior surface properties are getting wide importance in photocatalysis research. Despite having sodium (Na) contents and its high temperature synthesis (that generally deteriorate the photoreactivity), these Na-titanates often exhibit better photoactivity than P25-TiO2 catalyst. Hence, this work demonstrated the influence of crystal structure, BET surface area, surface charge, zeta potential (ζ) and metal loading on the photocatalytic activity of as-prepared sodium titanate nanotube (TNT) and titania nanorod (TNR). Straw like hollow orthorhombic-TNT (Na2Ti2O5·H2O) particles (W = 9-12 nm and L = 82-115 nm) and rice like pure anatase-TNR particles (W = 8-13 nm and L = 81-134 nm) are obtained by the hydrothermal treatment of P25-TiO2 with NaOH, which in fact, altered the net surface charge of TNT and TNR particles. The observed ζ = -2.82 (P25-TiO2), -13.5 (TNT) and -22.5 mV (TNR) are significantly altered by the Ag and Cu deposition. It has been found here that TNT displayed best photocatalytic activity for the imidacloprid insecticide (C9H10ClN5O2) degradation to CO2 formation under UV irradiation because of its largest surface area 176 m2 g-1 among the catalysts studied.

Density-functional theory of spherical electric double layers and zeta potentials of colloidal particles in restricted-primitive-model electrolyte solutions.

PubMed

Yu, Yang-Xin; Wu, Jianzhong; Gao, Guang-Hua

2004-04-15

A density-functional theory is proposed to describe the density profiles of small ions around an isolated colloidal particle in the framework of the restricted primitive model where the small ions have uniform size and the solvent is represented by a dielectric continuum. The excess Helmholtz energy functional is derived from a modified fundamental measure theory for the hard-sphere repulsion and a quadratic functional Taylor expansion for the electrostatic interactions. The theoretical predictions are in good agreement with the results from Monte Carlo simulations and from previous investigations using integral-equation theory for the ionic density profiles and the zeta potentials of spherical particles at a variety of solution conditions. Like the integral-equation approaches, the density-functional theory is able to capture the oscillatory density profiles of small ions and the charge inversion (overcharging) phenomena for particles with elevated charge density. In particular, our density-functional theory predicts the formation of a second counterion layer near the surface of highly charged spherical particle. Conversely, the nonlinear Poisson-Boltzmann theory and its variations are unable to represent the oscillatory behavior of small ion distributions and charge inversion. Finally, our density-functional theory predicts charge inversion even in a 1:1 electrolyte solution as long as the salt concentration is sufficiently high. (c) 2004 American Institute of Physics.

14-3-3 sigma and 14-3-3 zeta plays an opposite role in cell growth inhibition mediated by transforming growth factor-beta 1.

PubMed

Hong, Hye-Young; Jeon, Woo-Kwang; Bae, Eun-Jin; Kim, Shin-Tae; Lee, Ho-Jae; Kim, Seong-Jin; Kim, Byung-Chul

2010-03-01

The expression of 14-3-3 proteins is dysregulated in various types of cancer. This study was undertaken to investigate the effects of 14-3-3 zeta and 14-3-3 sigma on cell growth inhibition mediated by transforming growth factor-beta 1 (TGF-beta1). Mouse mammary epithelial cells (Eph4) that are transformed with oncogenic c-H-Ras (EpRas) and no longer sensitive to TGF-beta1-mediated growth inhibition displayed increased expression of 14-3-3 zeta and decreased expression of 14-3-3 sigma compared with parental Eph4 cells. Using small interfering RNA-mediated knockdown and overexpression of 14-3-3 sigma or 14-3-3 zeta, we showed that 14-3-3 sigma is required for TGF-beta1-mediated growth inhibition whereas 14-3-3 zeta negatively modulates this growth inhibitory response. Notably, overexpression of 14-3-3 zeta increased the level of Smad3 protein that is phosphorylated at linker regions and cannot mediate the TGF-beta1 growth inhibitory response. Consistent with this finding, mutation of the 14-3-3 zeta phosphorylation sites in Smad3 markedly reduced the 14-3-3 zeta-mediated inhibition of TGF-beta1-induced p15 promoter-reporter activity and cell cycle arrest, suggesting that these residues are critical targets of 14-3-3 zeta in the suppression of TGF-beta1-mediated growth. Taken together, our findings indicate that dysregulation of 14-3-3 sigma or 14-3-3 zeta contributes to TGF-beta1 resistance in cancer cells.

Comparative evaluation of aqueous humor viscosity.

PubMed

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

2015-01-01

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 < 0.0001). The aqueous humor viscosity of the raptor, dog, cat, and horse can be successfully determined using a dynamic shear rheometer. © 2014 American College of Veterinary Ophthalmologists.

Mesoscopic model for the viscosities of nematic liquid crystals.

PubMed

Chrzanowska, A; Kröger, M; Sellers, S

1999-10-01

Based on the definition of the mesoscopic concept by Blenk et al. [Physica A 174, 119 (1991); J. Noneq. Therm. 16, 67 (1991); Mol. Cryst. Liq. Cryst. 204, 133 (1991)] an approach to calculate the Leslie viscosity coefficients for nematic liquid crystals is presented. The approach rests upon the mesoscopic stress tensor, whose structure is assumed similar to the macroscopic Leslie viscous stress. The proposed form is also the main dissipation part of the mesoscopic Navier-Stokes equation. On the basis of the correspondence between microscopic and mesoscopic scales a mean-field mesoscopic potential is introduced. It allows us to obtain the stress tensor angular velocity of the free rotating molecules with the help of the orientational Fokker-Planck equation. The macroscopic stress tensor is calculated as an average of the mesoscopic counterpart. Appropriate relations among mesoscopic viscosities have been found. The mesoscopic analysis results are shown to be consistent with the diffusional model of Kuzuu-Doi and Osipov-Terentjev with the exception of the shear viscosity alpha(4). In the nematic phase alpha(4) is shown to have two contributions: isotropic and nematic. There exists an indication that the influence of the isotropic part is dominant over the nematic part. The so-called microscopic stress tensor used in the microscopic theories is shown to be the mean-field potential-dependent representation of the mesoscopic stress tensor. In the limiting case of total alignment the Leslie coefficients are estimated for the diffusional and mesoscopic models. They are compared to the results of the affine transformation model of the perfectly ordered systems. This comparison shows disagreement concerning the rotational viscosity, whereas the coefficients characteristic for the symmetric part of the viscous stress tensor remain the same. The difference is caused by the hindered diffusion in the affine model case.

Toxicity and Metabolism of Zeta-Cypermethrin in Field-Collected and Laboratory Strains of the Neotropical Predator Chrysoperla externa Hagen (Neuroptera: Chrysopidae).

PubMed

Haramboure, M; Smagghe, G; Niu, J; Christiaens, O; Spanoghe, P; Alzogaray, R A

2017-06-01

Resistance to pesticides has been studied in several insect pests, but information on the natural enemies of pests-including the Neotropical predator Chrysoperla externa Hagen (Neuroptera: Chrysopidae), a major biological control agent in South America-is lacking. We report here a comparative study between a field-collected strain of C. externa subjected to monthly sprayings of pyrethroids and neonicotinoids and a laboratory strain without exposure to pesticides. The tolerance of both strains against zeta-cypermethrin was similar, and addition of the synergist piperonyl butoxide increased the toxicity by 30% in both strains. Gas-chromatography analyses and mixed-function-oxidase measurements indicated similar values in both strains and also confirmed the key role of oxidative metabolism in this species. Because C. externa has maintained a tolerance to zeta-cypermethrin without previous pesticide exposure, this species could potentially be mass-reared and released in fields in the presence of pesticide pressure.

Comparison the clinical outcomes and complications of high-viscosity versus low-viscosity in osteoporotic vertebral compression fractures.

PubMed

Guo, Zhao; Wang, Wei; Gao, Wen-Shan; Gao, Fei; Wang, Hui; Ding, Wen-Yuan

2017-12-01

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.

Comparison the clinical outcomes and complications of high-viscosity versus low-viscosity in osteoporotic vertebral compression fractures

PubMed Central

Guo, Zhao; Wang, Wei; Gao, Wen-shan; Gao, Fei; Wang, Hui; Ding, Wen-Yuan

2017-01-01

Abstract 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. PMID:29310386

The ng_ζ1 toxin of the gonococcal epsilon/zeta toxin/antitoxin system drains precursors for cell wall synthesis.

PubMed

Rocker, Andrea; Peschke, Madeleine; Kittilä, Tiia; Sakson, Roman; Brieke, Clara; Meinhart, Anton

2018-04-27

Bacterial toxin-antitoxin complexes are emerging as key players modulating bacterial physiology as activation of toxins induces stasis or programmed cell death by interference with vital cellular processes. Zeta toxins, which are prevalent in many bacterial genomes, were shown to interfere with cell wall formation by perturbing peptidoglycan synthesis in Gram-positive bacteria. Here, we characterize the epsilon/zeta toxin-antitoxin (TA) homologue from the Gram-negative pathogen Neisseria gonorrhoeae termed ng_ɛ1 / ng_ζ1. Contrary to previously studied streptococcal epsilon/zeta TA systems, ng_ɛ1 has an epsilon-unrelated fold and ng_ζ1 displays broader substrate specificity and phosphorylates multiple UDP-activated sugars that are precursors of peptidoglycan and lipopolysaccharide synthesis. Moreover, the phosphorylation site is different from the streptococcal zeta toxins, resulting in a different interference with cell wall synthesis. This difference most likely reflects adaptation to the individual cell wall composition of Gram-negative and Gram-positive organisms but also the distinct involvement of cell wall components in virulence.

Viscosity dictates metabolic activity of Vibrio ruber

PubMed Central

Borić, Maja; Danevčič, Tjaša; Stopar, David

2012-01-01

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

Hydrodynamic Electron Flow and Hall Viscosity

NASA Astrophysics Data System (ADS)

Scaffidi, Thomas; Nandi, Nabhanila; Schmidt, Burkhard; Mackenzie, Andrew P.; Moore, Joel E.

2017-06-01

In metallic samples of small enough size and sufficiently strong momentum-conserving scattering, the viscosity of the electron gas can become the dominant process governing transport. In this regime, momentum is a long-lived quantity whose evolution is described by an emergent hydrodynamical theory. Furthermore, breaking time-reversal symmetry leads to the appearance of an odd component to the viscosity called the Hall viscosity, which has attracted considerable attention recently due to its quantized nature in gapped systems but still eludes experimental confirmation. Based on microscopic calculations, we discuss how to measure the effects of both the even and odd components of the viscosity using hydrodynamic electronic transport in mesoscopic samples under applied magnetic fields.

Hydrodynamic Electron Flow and Hall Viscosity.

PubMed

Scaffidi, Thomas; Nandi, Nabhanila; Schmidt, Burkhard; Mackenzie, Andrew P; Moore, Joel E

2017-06-02

In metallic samples of small enough size and sufficiently strong momentum-conserving scattering, the viscosity of the electron gas can become the dominant process governing transport. In this regime, momentum is a long-lived quantity whose evolution is described by an emergent hydrodynamical theory. Furthermore, breaking time-reversal symmetry leads to the appearance of an odd component to the viscosity called the Hall viscosity, which has attracted considerable attention recently due to its quantized nature in gapped systems but still eludes experimental confirmation. Based on microscopic calculations, we discuss how to measure the effects of both the even and odd components of the viscosity using hydrodynamic electronic transport in mesoscopic samples under applied magnetic fields.

Viscosity of particle laden films

NASA Astrophysics Data System (ADS)

Timounay, Yousra; Rouyer, Florence

2017-06-01

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.

High-Temperature Viscosity Of Commercial Glasses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hrma, Pavel R; See, Clem A; Lam, Oanh P

2005-01-01

Viscosity was measured for six types of commercial glasses: low-expansion-borosilicate glasses, E glasses, fiberglass wool glasses, TV panel glasses, container glasses, and float glasses. Viscosity data were obtained with rotating spindle viscometers within the temperature range between 900°C and 1550°C; the viscosity varied from 1 Pa∙s to 750 Pa∙s. Arrhenius coefficients were calculated for individual glasses and linear models were applied to relate them to the mass fractions of 11 major components (SiO2, CaO, Na2O, Al2O3, B2O3, BaO, SrO, K2O, MgO, PbO, and ZrO2) and 12 minor components (Fe2O3, ZnO, Li2O, TiO2, CeO2, F, Sb2O3, Cr2O3, As2O3, MnO2, SO3, andmore » Co3O4). The models are recommended for glasses containing 42 to 84 mass% SiO2 to estimate viscosities or temperatures at a constant viscosity for melts within both the temperature range from 1100°C to 1550°C and viscosity range from 10 to 400 Pas.« less

Local zeta factors and geometries under Spec Z

NASA Astrophysics Data System (ADS)

Manin, Yu I.

2016-08-01

The first part of this note shows that the odd-period polynomial of each Hecke cusp eigenform for the full modular group produces via the Rodriguez-Villegas transform ([1]) a polynomial satisfying the functional equation of zeta type and having non-trivial zeros only in the middle line of its critical strip. The second part discusses the Chebyshev lambda-structure of the polynomial ring as Borger's descent data to \\mathbf{F}_1 and suggests its role in a possible relation of the Γ\\mathbf{R}-factor to 'real geometry over \\mathbf{F}_1' (cf. [2]).

Mantle viscosity structure constrained by joint inversions of seismic velocities and density

NASA Astrophysics Data System (ADS)

Rudolph, M. L.; Moulik, P.; Lekic, V.

2017-12-01

The viscosity structure of Earth's deep mantle affects the thermal evolution of Earth, the ascent of mantle upwellings, sinking of subducted oceanic lithosphere, and the mixing of compositional heterogeneities in the mantle. Modeling the long-wavelength dynamic geoid allows us to constrain the radial viscosity profile of the mantle. Typically, in inversions for the mantle viscosity structure, wavespeed variations are mapped into density variations using a constant- or depth-dependent scaling factor. Here, we use a newly developed joint model of anisotropic Vs, Vp, density and transition zone topographies to generate a suite of solutions for the mantle viscosity structure directly from the seismologically constrained density structure. The density structure used to drive our forward models includes contributions from both thermal and compositional variations, including important contributions from compositionally dense material in the Large Low Velocity Provinces at the base of the mantle. These compositional variations have been neglected in the forward models used in most previous inversions and have the potential to significantly affect large-scale flow and thus the inferred viscosity structure. We use a transdimensional, hierarchical, Bayesian approach to solve the inverse problem, and our solutions for viscosity structure include an increase in viscosity below the base of the transition zone, in the shallow lower mantle. Using geoid dynamic response functions and an analysis of the correlation between the observed geoid and mantle structure, we demonstrate the underlying reason for this inference. Finally, we present a new family of solutions in which the data uncertainty is accounted for using covariance matrices associated with the mantle structure models.

Whole-blood viscosity and the insulin-resistance syndrome.

PubMed

Høieggen, A; Fossum, E; Moan, A; Enger, E; Kjeldsen, S E

1998-02-01

In a previous study we found that elevated blood viscosity was linked to the insulin resistance syndrome, and we proposed that high blood viscosity may increase insulin resistance. That study was based on calculated viscosity. To determine whether directly measured whole-blood viscosity was related to the insulin-resistance syndrome in the same way as calculated viscosity had been found to be. Healthy young men were examined with the hyperinsulinemic isoglycemic glucose clamp technique, and we related insulin sensitivity (glucose disposal rate) to other metabolic parameters and to blood viscosity. We established a technique for direct measurement of whole-blood viscosity. There were statistically significant negative correlations between glucose disposal rate and whole-blood viscosity at low and high shear rates (r = -0.41, P = 0.007 for both, n = 42). Whole-blood viscosity was correlated positively (n = 15) to serum triglyceride (r = 0.54, P = 0.04) and total cholesterol (r = 0.52, P = 0.05), and negatively with high-density lipoprotein cholesterol (r = -0.53, P = 0.04) concentrations. Insulin sensitivity index was correlated positively to high-density lipoprotein cholesterol (r = 0.54, P = 0.04) and negatively to serum triglyceride (r = -0.69, P = 0.005) and to total cholesterol (r = -0.81, P = 0.0003) concentrations. The present results demonstrate for the first time that there is a negative relationship between directly measured whole-blood viscosity and insulin sensitivity as a part of the insulin-resistance syndrome. Whole-blood viscosity contributes to the total peripheral resistance, and these results support the hypothesis that insulin resistance has a hemodynamic basis.

The white dwarf companion of the B a 2 star zeta Cap

NASA Technical Reports Server (NTRS)

Boehm-Vitense, E.

1981-01-01

The Ba II star zeta Cap has a white dwarf companion. Its T (sub eff) is determined to be 22000 K, its mass is approximately one solar mass. The importance of this finding for the explanation of abundance peculiarities is discussed.

Zeta Sperm Selection Improves Pregnancy Rate and Alters Sex Ratio in Male Factor Infertility Patients: A Double-Blind, Randomized Clinical Trial

PubMed Central

Nasr Esfahani, Mohammad Hossein; Deemeh, Mohammad Reza; Tavalaee, Marziyeh; Sekhavati, Mohammad Hadi; Gourabi, Hamid

2016-01-01

Background Selection of sperm for intra-cytoplasmic sperm injection (ICSI) is usually considered as the ultimate technique to alleviate male-factor infertility. In routine ICSI, selection is based on morphology and viability which does not necessarily preclude the chance injection of DNA-damaged or apoptotic sperm into the oocyte. Sperm with high negative surface electrical charge, named “Zeta potential”, are mature and more likely to have intact chromatin. In addition, X-bearing spermatozoa carry more negative charge. Therefore, we aimed to compare the clinical outcomes of Zeta procedure with routine sperm selection in infertile men candidate for ICSI. Materials and Methods From a total of 203 ICSI cycles studied, 101 cycles were allocated to density gradient centrifugation (DGC)/Zeta group and the remaining 102 were included in the DGC group in this prospective study. Clinical outcomes were com- pared between the two groups. The ratios of Xand Y bearing sperm were assessed by fluorescence in situ hybridization (FISH) and quantitative polymerase chain reaction (qPCR) methods in 17 independent semen samples. Results In the present double-blind randomized clinical trial, a significant increase in top quality embryos and pregnancy rate were observed in DGC/Zeta group compared to DGC group. Moreover, sex ratio (XY/XX) at birth significantly was lower in the DGC/Zeta group compared to DGC group despite similar ratio of X/Y bearings sper- matozoa following Zeta selection. Conclusion Zeta method not only improves the percentage of top embryo quality and pregnancy outcome but also alters the sex ratio compared to the conventional DGC method, despite no significant change in the ratio of Xand Ybearing sperm population (Registration number: IRCT201108047223N1). PMID:27441060

Mapping microbubble viscosity using fluorescence lifetime imaging of molecular rotors

PubMed Central

Hosny, Neveen A.; Mohamedi, Graciela; Rademeyer, Paul; Owen, Joshua; Wu, Yilei; Tang, Meng-Xing; Eckersley, Robert J.; Stride, Eleanor; Kuimova, Marina K.

2013-01-01

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

Viscosity Measurement for Tellurium Melt

NASA Technical Reports Server (NTRS)

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

2006-01-01

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.

Critical Viscosity of Xenon investigators

NASA Technical Reports Server (NTRS)

2001-01-01

Dr. Dr. Robert F. Berg (right), principal investigator and Dr. Micheal R. Moldover (left), co-investigator, for the Critical Viscosity of Xenon (CVX/CVX-2) experiment. They are with the National Institutes of Standards and Technology, Gaithersburg, MD. The Critical Viscosity of Xenon Experiment (CVX-2) on the STS-107 Research 1 mission in 2002 will measure the viscous behavior of xenon, a heavy inert gas used in flash lamps and ion rocket engines, at its critical point. Although it does not easily combine with other chemicals, its viscosity at the critical point can be used as a model for a range of chemicals.

Fluid Merging Viscosity Measurement (FMVM)

NASA Technical Reports Server (NTRS)

2004-01-01

Astronaut Mike Fincke places droplets of honey onto the strings for the Fluid Merging Viscosity Measurement (FMVM) investigation onboard the International Space Station (ISS). The FMVM experiment measures the time it takes for two individual highly viscous fluid droplets to coalesce or merge into one droplet. Different fluids and droplet size combinations were tested in the series of experiments. By using the microgravity environment, researchers can measure the viscosity or 'thickness' of fluids without the influence of containers and gravity using this new technique. Understanding viscosity could help scientists understand industrially important materials such as paints, emulsions, polymer melts and even foams used to produce pharmaceutical, food, and cosmetic products.

Density and viscosity of lipids under pressure

USDA-ARS?s Scientific Manuscript database

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...

Cancer resistance, carcinogenesis and ground substance viscosity.

PubMed

Stone, O J

1986-05-01

Tumor host resistance and promotion are multiple complex simultaneous phenomena. This paper relates only to the effect of ground substance viscosity on tumor host interaction. Tar, anthralin, ultraviolet light, x-ray and arsenic have been widely used to treat inflammatory skin disorders such as psoriasis. They are also well known carcinogens. It is proposed that both the anti-inflammatory effect and part of the carcinogenic effect could occur by decreasing ground substance viscosity and suppressing fibroblasts. Streptococcal infections, chloroquine and pyridoxine deficiency increase inflammatory skin disorders and are known to be beneficial to tumor resistance. It is proposed that both effects could occur because of their effect of increasing ground substance viscosity and, at least with streptococcal infections, by stimulating fibroblasts. Within certain limits, vitamin C has a stimulant effect on fibroblast and ground substance viscosity. Beta carotene is active in stimulating wound healing. Localized edema of the dermal papillae precedes granulocytic inflammation in disorders like psoriasis. Anything that decreases ground substance viscosity will prevent dilution of tissue fluids by decreasing localized edema and thus decrease formation of some mediators of inflammation. Anything that increases ground substance and its viscosity will promote local dilution of tissue fluid. Increasing dilution of tissue fluids promotes the formation of some mediators of inflammation. Tumors commonly secrete hyaluronidase. It is proposed that substances that decrease ground substance viscosity (hyaluronidase-like activity) encourage tumors and substances that increase ground substance viscosity (anti-hyaluronidase-like effect) increase resistance to tumors.

A Study of Oil Viscosity Mental Model

NASA Astrophysics Data System (ADS)

Albaiti; Liliasari; Sumarna, Omay; Abdulkadir Martoprawiro, Muhamad

2017-02-01

There is no study regarding on how to learn viscosity of the liquid (e.g. oil) by interconnecting macroscopic, sub-microscopic and symbolic levels. Therefore, the purpose of this research was to study the mental model of the oil viscosity. Intermolecular attractive force of oil constituent on the sub-microscopic level is depicted in the form of mental models. In this research, the viscosity data for some types of oil was measured by using Hoppler method. Viscosity of mineral oil SAE 20W-50, mineral oil SAE 15W-40 and synthetic oil SAE 10W-40 were 1.75, 1.31, and 1.03 Pa s, and the densities of these oils were 908.64, 885.04, and 877.02 kg/m3, respectively. The results showed that the greater density of the mineral oil that is assumed to be composed of linear chains of hydrocarbons, the longer the chain of hydrocarbon linear. Consequently, there are stronger the London force and greater the oil viscosity. The density and viscosity of synthetic oil are lower than that of both mineral oils. Synthetic oil structurally forms polymers with large branching. This structure affects a lower synthetic oil viscosity. This study contributes to construct a mental model of pre-service chemistry teachers.

Viscosity of Xenon Examined in Microgravity

NASA Technical Reports Server (NTRS)

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

1999-01-01

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.

Viscosity Control Experiment Feasibility Study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morris, Heidi E.; Bradley, Paul Andrew

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 modifymore » 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.« less

DWPF STARTUP FRIT VISCOSITY MEASUREMENT ROUND ROBIN RESULTS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Crum, Jarrod V.; Edwards, Tommy B.; Russell, Renee L.

2012-07-31

A viscosity standard is needed to replace the National Institute of Standards and Technology (NIST) glasses currently being used to calibrate viscosity measurement equipment. The current NIST glasses are either unavailable or less than ideal for calibrating equipment to measure the viscosity of high-level waste glasses. This report documents the results of a viscosity round robin study conducted on the Defense Waste Processing Facility (DWPF) startup frit. DWPF startup frit was selected because its viscosity-temperature relationship is similar to most DWPF and Hanford high-level waste glass compositions. The glass underwent grinding and blending to homogenize the large (100 lb) batch.more » Portions of the batch were supplied to the laboratories (named A through H) for viscosity measurements following a specified temperature schedule with a temperature range of 1150 C to 950 C and with an option to measure viscosity at lower temperatures if their equipment was capable of measuring at the higher viscosities. Results were used to fit the Vogel-Tamman-Fulcher and Arrhenius equations to viscosity as a function of temperature for the entire temperature range of 460 C through 1250 C as well as the limited temperature interval of approximately 950 C through 1250 C. The standard errors for confidence and prediction were determined for the fitted models.« less

Hydrodynamic Electron Flow and Hall Viscosity

NASA Astrophysics Data System (ADS)

Scaffidi, Thomas; Moll, Philip; Kushwaha, Pallavi; Nandi, Nabhanila; Schmidt, Burkhard; MacKenzie, Andrew; Moore, Joel

In metallic samples of small enough size and sufficiently strong electron-electron scattering, the viscosity of the electron gas can become the dominant process governing transport. In this regime, momentum is a long-lived quantity whose evolution is described by an emergent hydrodynamical theory for which bounds on diffusion were conjectured based on an holographic correspondence. Furthermore, breaking time-reversal symmetry can lead to the appearance of an odd component to the viscosity called the Hall viscosity which has attracted a lot of attention recently due to its quantized nature in gapped systems but still eludes experimental confirmation. Based on microscopic calculations, we discuss how to measure the effects of both the even and odd components of the viscosity using hydrodynamic electronic transport in mesoscopic samples under applied magnetic fields. Gordon and Betty Moore Foundation.

Measuring electrical and mechanical properties of red blood cells with a double optical tweezers

NASA Astrophysics Data System (ADS)

Fontes, Adriana; Fernandes, Heloise P.; Barjas-Castro, Maria L.; de Thomaz, André A.; Pozzo, Liliana d. Y.; Barbosa, Luiz C.; Cesar, Carlos L.

2006-08-01

The fluid lipid bilayer viscoelastic membrane of red blood cells (RBC) contains antigen glycolproteins and proteins which can interact with antibodies to cause cell agglutination. This is the basis of most of the immunohematologic tests in blood banks and the identification of the antibodies against the erythrocyte antigens is of fundamental importance for transfusional routines. The negative charges of the RBCs creates a repulsive electric (zeta) potential between the cells and prevents their aggregation in the blood stream. The first counterions cloud strongly binded moving together with the RBC is called the compact layer. This report proposes the use of a double optical tweezers for a new procedure for measuring: (1) the apparent membrane viscosity, (2) the cell adhesion, (3) the zeta potential and (4) the compact layer's size of the charges formed around the cell in the electrolytic solution. To measure the membrane viscosity we trapped silica beads strongly attached to agglutinated RBCs and measured the force to slide one RBC over the other as a function of the relative velocity. The RBC adhesion was measured by slowly displacing two RBCs apart until the disagglutination happens. The compact layer's size was measured using the force on the silica bead attached to a single RBC in response to an applied voltage and the zeta potential was obtained by measuring the terminal velocity after releasing the RBC from the optical trap at the last applied voltage. We believe that the methodology here proposed can improve the methods of diagnosis in blood banks.

A comparative study of high-viscosity cement percutaneous vertebroplasty vs. low-viscosity cement percutaneous kyphoplasty for treatment of osteoporotic vertebral compression fractures.

PubMed

Sun, Kai; Liu, Yang; Peng, Hao; Tan, Jun-Feng; Zhang, Mi; Zheng, Xian-Nian; Chen, Fang-Zhou; Li, Ming-Hui

2016-06-01

The clinical effects of two different methods-high-viscosity cement percutaneous vertebroplasty (PVP) and low-viscosity cement percutaneous kyphoplasty (PKP) in the treatment of osteoporotic vertebral compression fractures (OVCFs) were investigated. From June 2010 to August 2013, 98 cases of OVCFs were included in our study. Forty-six patients underwent high-viscosity PVP and 52 patients underwent low-viscosity PKP. The occurrence of cement leakage was observed. Pain relief and functional activity were evaluated using the Visual Analog Scale (VAS) and Oswestry Disability Index (ODI), respectively. Restoration of the vertebral body height and angle of kyphosis were assessed by comparing preoperative and postoperative measurements of the anterior heights, middle heights and the kyphotic angle of the fractured vertebra. Nine out of the 54 vertebra bodies and 11 out of the 60 vertebra bodies were observed to have cement leakage in the high-viscosity PVP and low-viscosity PKP groups, respectively. The rate of cement leakage, correction of anterior vertebral height and kyphotic angles showed no significant differences between the two groups (P>0.05). Low-viscosity PKP had significant advantage in terms of the restoration of middle vertebral height as compared with the high-viscosity PVP (P<0.05). Both groups showed significant improvements in pain relief and functional capacity status after surgery (P<0.05). It was concluded that high-viscosity PVP and low-viscosity PKP have similar clinical effects in terms of the rate of cement leakage, restoration of the anterior vertebral body height, changes of kyphotic angles, functional activity, and pain relief. Low-viscosity PKP is better than high-viscosity PVP in restoring the height of the middle vertebra.

Preparation and characterization of methacrylate hydrogels for zeta potential control

NASA Technical Reports Server (NTRS)

Gregonis, D. E.; Ma, S. M.; Vanwagenen, R.; Andrade, J. D.

1976-01-01

A technique based on the measurement of streaming potentials has been developed to evaluate the effects of hydrophilic coatings on electroosmotic flow. The apparatus and procedure are described as well as some results concerning the electrokinetic potential of glass capillaries as a function of ionic strength, pH, and temperature. The effect that turbulence and entrance flow conditions have on accurate streaming potential measurements is discussed. Various silane adhesion promoters exhibited only a slight decrease in streaming potential. A coating utilizing a glycidoxy silane base upon which methylcellulose is applied affords a six-fold decrease over uncoated tubes. Hydrophilic methacrylate gels show similar streaming potential behavior, independent of the water content of the gel. By introduction of positive or negative groups into the hydrophilic methacrylate gels, a range of streaming potential values are obtained having absolute positive or negative signs.

Development of Viscosity Model for Petroleum Industry Applications

NASA Astrophysics Data System (ADS)

Motahhari, Hamed reza

Heavy oil and bitumen are challenging to produce and process due to their very high viscosity, but their viscosity can be reduced either by heating or dilution with a solvent. Given the key role of viscosity, an accurate viscosity model suitable for use with reservoir and process simulators is essential. While there are several viscosity models for natural gases and conventional oils, a compositional model applicable to heavy petroleum and diluents is lacking. The objective of this thesis is to develop a general compositional viscosity model that is applicable to natural gas mixtures, conventional crudes oils, heavy petroleum fluids, and their mixtures with solvents and other crudes. The recently developed Expanded Fluid (EF) viscosity correlation was selected as a suitable compositional viscosity model for petroleum applications. The correlation relates the viscosity of the fluid to its density over a broad range of pressures and temperatures. The other inputs are pressure and the dilute gas viscosity. Each fluid is characterized for the correlation by a set of fluid-specific parameters which are tuned to fit data. First, the applicability of the EF correlation was extended to asymmetric mixtures and liquid mixtures containing dissolved gas components. A new set of mass-fraction based mixing rules was developed to calculate the fluid-specific parameters for mixtures. The EF correlation with the new set of mixing rules predicted the viscosity of over 100 mixtures of hydrocarbon compounds and carbon dioxide with overall average absolute relative deviations (AARD) of less than 10% either with measured densities or densities estimated by Advanced Peng-Robinson equation of state (APR EoS). To improve the viscosity predictions with APR EoS-estimated densities, general correlations were developed for non-zero viscosity binary interaction parameters. The EF correlation was extended to non-hydrocarbon compounds typically encountered in natural gas industry. It was

Role of shear stress in nitric oxide-dependent modulation of renal angiotensin II vasoconstriction.

PubMed

Endlich, K; Muller, C; Barthelmebs, M; Helwig, J J

1999-08-01

1. Renal vasoconstriction in response to angiotensin II (ANGII) is known to be modulated by nitric oxide (NO). Since shear stress stimulates the release of a variety of vasoactive compounds from endothelial cells, we studied the impact of shear stress on the haemodynamic effect of ANGII in isolated perfused kidneys of rats under control conditions and during NO synthase inhibition with L-NAME (100 microM). 2. Kidneys were perfused in the presence of cyclo-oxygenase inhibitor (10 microM indomethacin) with Tyrode's solution of relative viscosity zeta=1 (low viscosity perfusate, LVP) or, in order to augment shear stress, with Tyrode's solution containing 7% Ficoll 70 of relative viscosity zeta=2 (high viscosity perfusate, HVP). 3. Vascular conductance was 3.5+/-0.4 fold larger in HVP as compared with LVP kidneys, associated with an augmentation of overall wall shear stress by 37+/-5%. During NO inhibition, vascular conductance was only 2.5+/-0.2 fold elevated in HVP vs LVP kidneys, demonstrating shear stress-induced vasodilatation by NO and non-NO/non-prostanoid compound(s). 4. ANGII (10 - 100 pM) constricted the vasculature in LVP kidneys, but was without effect in HVP kidneys. During NO inhibition, in contrast, ANGII vasoconstriction was potentiated in HVP as compared with LVP kidneys. 5. The potentiation of ANGII vasoconstriction during NO inhibition has been shown to be mediated by endothelium-derived P450 metabolites and to be sensitive to AT2 receptor blockade in our earlier studies. Accordingly, in HVP kidneys, increasing concentrations of the AT2 receptor antagonist PD123319 (5 and 500 nM) gradually abolished the potentiation of ANGII vasoconstriction during NO inhibition, but did not affect vasoconstriction in response to ANGII in LVP kidneys. 6. Our results demonstrate, that augmentation of shear stress by increasing perfusate viscosity induces vasodilatation in the rat kidney, which is partially mediated by NO. Elevated levels of shear stress attenuate

NVP melt/magma viscosity: insight on Mercury lava flows

NASA Astrophysics Data System (ADS)

Rossi, Stefano; Morgavi, Daniele; Namur, Olivier; Vetere, Francesco; Perugini, Diego; Mancinelli, Paolo; Pauselli, Cristina

2016-04-01

). The change of melt viscosity induced by crystallization of a NVP composition was measured in the temperature ranges from 1463 to 1229 °C. Results showed an increase in effective viscosity from 4.3 Pa s to 1090 Pa s as the crystal content increased from 0 vol% to ca. 25 vol.%. The crystallization processes in the nominally dry NVP began at 1308 °C. Interestingly, melts viscosity changes from 4 to 16 Pa s as temperature varies from 1463 to 1327 °C. The extreme Mercurian lava fluidity experimentally measured has revealed the potentiality of NVP lavas to cover huge areas as shown by satellite data. Keywords: Viscosity, Concentric cylinders, NVP, Mercury.

Viscosity effects in wind wave generation

NASA Astrophysics Data System (ADS)

Paquier, A.; Moisy, F.; Rabaud, M.

2016-12-01

We investigate experimentally the influence of the liquid viscosity on the problem of the generation of waves by a turbulent wind at the surface of a liquid, extending the results of Paquier et al. [A. Paquier et al., Phys. Fluids 27, 122103 (2015), 10.1063/1.4936395] over nearly three decades of viscosity. The surface deformations are measured with micrometer accuracy using the free-surface synthetic schlieren method. We recover the two regimes of surface deformations previously identified: the wrinkle regime at small wind velocity, resulting from the viscous imprint on the liquid surface of the turbulent fluctuations in the boundary layer, and the regular wave regime at large wind velocity. Below the wave threshold, we find that the characteristic amplitude of the wrinkles scales as ν-1 /2u*3 /2 over nearly the whole range of viscosities, whereas their size is essentially unchanged. We propose a simple model for this scaling, which compares well with the data. We show that the critical friction velocity u* for the onset of regular waves slowly increases with viscosity as ν0.2. Whereas the transition between wrinkles and waves is smooth at low viscosity, including for water, it becomes rather abrupt at high viscosity. A third wave regime is found at ν >(100 -200 ) ×10-6m2s-1 , characterized by a slow, nearly periodic emission of large-amplitude isolated fluid bumps.

On small values of the Riemann zeta-function at Gram points

DOE Office of Scientific and Technical Information (OSTI.GOV)

Korolev, M A

In this paper, we prove the existence of a large set of Gram points t{sub n} such that the values ζ(0.5+it{sub n}) are 'anomalously' close to zero. A lower bound for the negative 'discrete' moment of the Riemann zeta-function on the critical line is also given. Bibliography: 13 titles.

Viscosity as related to dietary fiber: a review.

PubMed

Dikeman, Cheryl L; Fahey, George C

2006-01-01

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.

Investigation of Preparation and Mechanisms of a Dispersed Particle Gel Formed from a Polymer Gel at Room Temperature

PubMed Central

Zhao, Guang; Dai, Caili; Zhao, Mingwei; You, Qing; Chen, Ang

2013-01-01

A dispersed particle gel (DPG) was successfully prepared from a polymer gel at room temperature. The polymer gel system, morphology, viscosity changes, size distribution, and zeta potential of DPG particles were investigated. The results showed that zirconium gel systems with different strengths can be cross-linked within 2.5 h at low temperature. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM) results showed that the particles were polygonal particles with nano-size distribution. According to the viscosity changes, the whole preparation process can be divided into two major stages: the bulk gel cross-linking reaction period and the DPG particle preparation period. A polymer gel with a 3-dimensional network was formed in the bulk gel cross-linking reaction period whereas shearing force and frictional force were the main driving forces for the preparation of DPG particles, and thus affected the morphology of DPG particles. High shearing force and frictional force reduced the particle size distribution, and then decreased the zeta potential (absolute value). The whole preparation process could be completed within 3 h at room temperature. It could be an efficient and energy-saving technology for preparation of DPG particles. PMID:24324817

Duloxetine loaded-microemulsion system to improve behavioral activities by upregulating serotonin and norepinephrine in brain for the treatment of depression.

PubMed

Sindhu, Pardeep; Kumar, Shobhit; Iqbal, Babar; Ali, Javed; Baboota, Sanjula

2018-04-01

Duloxetine is a well-known antidepressant molecule which is used in the treatment of depression but due to poor solubility it suffers with the drawback of low oral bioavailability. The objective of present work was to formulate and characterize duloxetine loaded microemulsion to enhance the oral bioavailability. Prepared microemulsion was studied for droplet size, zeta potential, refractive index, polydispersity index (PDI), percentage transmittance, viscosity and in vitro release study. Optimized microemulsion (D1) showed spherical droplets with mean diameter of 35.40 ± 3.11 nm, PDI of 0.170 and zeta potential values of -25.8 mV. Formulation showed good transmittance (greater than 99%), viscosity (0.205 Pa s) and refractive index (1.43 ± 0.01). Increased duloxetine release was obtained with microemulsion in comparison to drug suspension. Behavioral tests like mobility test, tail suspension test and forced swimming test performed in depressed and treated rats with duloxetine microemulsion significantly improved the behavioral activities in comparison to duloxetine suspension. Pharmacokinetic studies showed that microemulsion exhibited 1.8 times increment in bioavailability in comparison to duloxetine suspension. Copyright © 2018 Elsevier Ltd. All rights reserved.

IUE observations of the atmospheric eclipsing binary system Zeta Aurigae

NASA Technical Reports Server (NTRS)

Champman, R. D.

1980-01-01

IUE observations of the eclipsing binary system Zeta Aurigae made prior to and during the eclipse of the relatively small B8 V star by the cool supergiant star (spectral type K2 II) are reported. Spectral lines produced by the absorption of B star radiation in the atmosphere of the K star during eclipse can be used as a probe of the extended K star atmosphere, due to the negligible cool star continuum in the 1200-3200 A region. Spectra taken prior to eclipse are found to be similar to those of the single B8 V star 64 Ori, with the exception of very strong multi-component absorption lines of Si II, Si IV, C IV and the Mg resonance doublet with strong P Cygni profiles, indicating a double shell. Absorption lines including those corresponding to Al II, Al III, Cr II, Mn II, Fe II, Ni II and Ca II are observed to increase in strength and number as the eclipse progresses, with high-ionization-potential lines formed far from the K star, possibly in a shock wave, and low-ionization potential lines, formed in cool plasma, probably a cool wind, nearer to the K star. Finally, an emission-line spectra with lines corresponding to those previously observed in absorption is noted at the time the B-star continuum had disappeared.

Electron treatment of wood pulp for the viscose process

NASA Astrophysics Data System (ADS)

Stepanik, T. M.; Ewing, D. E.; Whitehouse, R.

2000-03-01

Electron processing is currently being evaluated by several viscose producers for integration into their process. The viscose industry converts dissolving wood pulp into products such as staple fibre, filament, cord, film, packaging, and non-edible sausage casings. These materials are used in the clothing, drapery, hygiene, automobile, food, and packaging industries. Viscose producers are facing increasingly high production costs and stringent environmental regulations that have forced some plants to close. Electron treatment of wood pulp can significantly reduce the amounts of chemicals used for producing viscose and the production of hazardous pollutants. Acsion Industries has worked with companies worldwide to demonstrate the benefits of using electron treated pulp for producing viscose (rayon). This paper describes the viscose process, the benefits of using electron treatment in the viscose process, and Acsion's efforts in developing this technology.

Molecular basis of high viscosity in concentrated antibody solutions: Strategies for high concentration drug product development.

PubMed

Tomar, Dheeraj S; Kumar, Sandeep; Singh, Satish K; Goswami, Sumit; Li, Li

2016-01-01

Effective translation of breakthrough discoveries into innovative products in the clinic requires proactive mitigation or elimination of several drug development challenges. These challenges can vary depending upon the type of drug molecule. In the case of therapeutic antibody candidates, a commonly encountered challenge is high viscosity of the concentrated antibody solutions. Concentration-dependent viscosity behaviors of mAbs and other biologic entities may depend on pairwise and higher-order intermolecular interactions, non-native aggregation, and concentration-dependent fluctuations of various antibody regions. This article reviews our current understanding of molecular origins of viscosity behaviors of antibody solutions. We discuss general strategies and guidelines to select low viscosity candidates or optimize lead candidates for lower viscosity at early drug discovery stages. Moreover, strategies for formulation optimization and excipient design are also presented for candidates already in advanced product development stages. Potential future directions for research in this field are also explored.

Rheology and tribology of lubricants with polymeric viscosity modifiers

NASA Astrophysics Data System (ADS)

Babak, LotfizadehDehkordi

Elastohydrodynamic lubrication (EHL) theory has been used to model the lubrication state of antifriction machine elements, where initial viscosity and pressure viscosity coefficients are essential parameters in film thickness modeling. Since the pressures of lubricants in the contact zone can be very high, it is important to know the rheological properties of lubricants in these pressure and temperature regimes. The characteristics of viscosity behavior as a function of pressure are also essential for a universal definition of the pressure viscosity coefficient in order to estimate film thickness in an EHL regime. In this study, viscosities and pressure-viscosity coefficients of ten commercial engine and gear oils and seventeen laboratory-produced oil/polymer viscosity modifiers (VM) additives are measured up to 1.3 GPa at 40, 75 and 100 °C. For the first time, a sharp increase in the viscosity and piezoviscous factor is observed in both mineral-based and synthetic-based oils with different VMs. Analysis of the experimental results indicates that sharp increase in viscosity observed in these experiments are believed to arise from physical changes in the VMs, that is liquid-solid phase transition. Evidence is offered that polymer properties such as molecular weight, concentration and structure influence the onset of the phase transitions. A modified Yasutomi model, which normally describes the pressure dependence of the viscosity of lubricants very well, fails to predict the viscosity of the specimens above the onset of sharp increase in viscosity. A design of experiment (DOE) analysis using Design-Expert software indicates that pressure and temperature are the most critical parameters in the viscosity variation. Tribological tests demonstrate that wear in the contact, zone occurs at temperatures and stresses that coincides with the VM phase transitions in both commercial and laboratory synthesized oil/VMs. Tribological results also indicate that the onset of the

Diskoseismology: Probing accretion disks. II - G-modes, gravitational radiation reaction, and viscosity

NASA Technical Reports Server (NTRS)

Nowak, Michael A.; Wagoner, Robert V.

1992-01-01

A scalar potential is used to derive a single partial differential equation governing the oscillation of a disk. The eigenfunctions and eigenfrequencies of a variety of disk models are found to fall into two main classes which are analogous to the p-modes and g-modes in the sun. Specifically, the eigenfunctions and eigenfrequencies of isothermal disks are computed, and the way in which these results can be generalized to other disk models is indicated. The (assumed) relatively small rates of growth or damping of the modes due to various mechanisms, in particular gravitational radiation reaction and parameterized models of viscosity are also computed. It is found that for certain parameters the p-modes are unstable to gravitational radiation reaction (CFS instability), while both the p-modes and g-modes are unstable to viscosity unless highly anisotropic viscosity models are considered.

A comparison of high viscosity bone cement and low viscosity bone cement vertebroplasty for severe osteoporotic vertebral compression fractures.

PubMed

Zhang, Liang; Wang, Jingcheng; Feng, Xinmin; Tao, Yuping; Yang, Jiandong; Wang, Yongxiang; Zhang, Shengfei; Cai, Jun; Huang, Jijun

2015-02-01

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.

Variation of the apparent viscosity of thickened drinks.

PubMed

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

2011-01-01

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

Viscosity of Common Seed and Vegetable Oils

NASA Astrophysics Data System (ADS)

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

1997-02-01

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.

Quartz resonator fluid density and viscosity monitor

DOEpatents

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

1998-01-01

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.

Ab initio intermolecular potential energy surface for the CO2—N2 system and related thermophysical properties

NASA Astrophysics Data System (ADS)

Crusius, Johann-Philipp; Hellmann, Robert; Castro-Palacio, Juan Carlos; Vesovic, Velisa

2018-06-01

A four-dimensional potential energy surface (PES) for the interaction between a rigid carbon dioxide molecule and a rigid nitrogen molecule was constructed based on quantum-chemical ab initio calculations up to the coupled-cluster level with single, double, and perturbative triple excitations. Interaction energies for a total of 1893 points on the PES were calculated using the counterpoise-corrected supermolecular approach and basis sets of up to quintuple-zeta quality with bond functions. The interaction energies were extrapolated to the complete basis set limit, and an analytical site-site potential function with seven sites for carbon dioxide and five sites for nitrogen was fitted to the interaction energies. The CO2—N2 cross second virial coefficient as well as the dilute gas shear viscosity, thermal conductivity, and binary diffusion coefficient of CO2—N2 mixtures were calculated for temperatures up to 2000 K to validate the PES and to provide reliable reference values for these important properties. The calculated values are in very good agreement with the best experimental data.

Viscosity and compressibility of diacylglycerol under high pressure

NASA Astrophysics Data System (ADS)

Malanowski, Aleksander; Rostocki, A. J.; Kiełczyński, P.; Szalewski, M.; Balcerzak, A.; Kościesza, R.; Tarakowski, R.; Ptasznik, S.; Siegoczyński, R. M.

2013-03-01

The influence of high pressure on viscosity and compressibility of diacylglycerol (DAG) oil has been presented in this paper. The investigated DAG oil was composed of 82% of DAGs and 18% TAGs (triacylglycerols). The dynamic viscosity of DAG was investigated as a function of the pressure up to 400 MPa. The viscosity was measured by means of the surface acoustic wave method, where the acoustic waveguides were used as sensing elements. As the pressure was rising, the larger ultrasonic wave attenuation was observed, whereas amplitude decreased with the liquid viscosity augmentation. Measured changes of physical properties were most significant in the pressure range near the phase transition. Deeper understanding of DAG viscosity and compressibility changes versus pressure could shed more light on thermodynamic properties of edible oils.

Viscotaxis: Microswimmer Navigation in Viscosity Gradients

NASA Astrophysics Data System (ADS)

Liebchen, Benno; Monderkamp, Paul; ten Hagen, Borge; Löwen, Hartmut

2018-05-01

The survival of many microorganisms, like Leptospira or Spiroplasma bacteria, can depend on their ability to navigate towards regions of favorable viscosity. While this ability, called viscotaxis, has been observed in several bacterial experiments, the underlying mechanism remains unclear. We provide a framework to study viscotaxis of biological or synthetic self-propelled swimmers in slowly varying viscosity fields and show that suitable body shapes create viscotaxis based on a systematic asymmetry of viscous forces acting on a microswimmer. Our results shed new light on viscotaxis in Spiroplasma and Leptospira and suggest that dynamic body shape changes exhibited by both types of microorganisms may have an unrecognized functionality: to prevent them from drifting to low viscosity regions where they swim poorly. The present theory classifies microswimmers regarding their ability to show viscotaxis and can be used to design synthetic viscotactic swimmers, e.g., for delivering drugs to a target region distinguished by viscosity.

Non-invasive fluid density and viscosity measurement

DOEpatents

Sinha, Dipen N [Los Alamos, NM

2012-05-01

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.

Effects of nonuniform viscosity on ciliary locomotion

NASA Astrophysics Data System (ADS)

Shoele, Kourosh; Eastham, Patrick S.

2018-04-01

The effect of nonuniform viscosity on the swimming velocity of a free swimmer at zero Reynolds number is examined. Using the generalized reciprocal relation for Stokes flow with nonuniform viscosity, we formulate the locomotion problem in a fluid medium with spatially varying viscosity. Assuming the limit of small variation in the viscosity of the fluid as a result of nonuniform distribution of nutrients around a swimmer, we derive a perturbation model to calculate the changes in the swimming performance of a spherical swimmer as a result of position-dependent viscosity. The swimmer is chosen to be a spherical squirmer with a steady tangential motion on its surface modeling ciliary motion. The nutrient concentration around the body is described by an advection-diffusion equation. The roles of the surface stroke pattern, the specific relationship between the nutrient and viscosity, and the Péclet number of the nutrient in the locomotion velocity of the squirmer are investigated. Our results show that for a pure treadmill stroke, the velocity change is maximum at the limit of zero Péclet number and monotonically decreases toward zero at very high Péclet number. When higher surface stroke modes are present, larger modification in swimming velocity is captured at high Péclet number where two mechanisms of thinning the nutrient boundary layer and appearance of new stagnation points along the surface of squirmer are found to be the primary reasons behind the swimming velocity modifications. It is observed that the presence of nonuniform viscosity allows for optimal swimming speed to be achieved with stroke combinations other than pure treadmill.

Estimating the Kinematic Viscosity of Petroleum Fractions

NASA Astrophysics Data System (ADS)

AlMulla, Hessa A.; Albahri, Tareq A.

2017-04-01

Kinematic viscosity correlation has been developed for liquid petroleum fractions at 37.78°C and 98.89°C (100 and 210°F) standard temperatures using a large variety of experimental data. The only required inputs are the specific gravity and the average boiling point temperature. The accuracy of the correlation was compared with several other correlations available in the literature. The proposed correlations proved to be more accurate in predicting the viscosity at 37.78°C and 98.89°C with average absolute deviations of 0.39 and 0.72 mm2/s, respectively. Another objective was to develop a relation for the variation of viscosity with temperature to predict the viscosity of petroleum fraction at a certain temperature from the knowledge of the viscosity for the same liquid at two other temperatures. The newly developed correlation represents a wide array of temperatures from 20°C to 150°C and viscosities from 0.14 mm2/s to 343.64 mm2/s. The results have been validated with experimental data consisting of 9558 data points, yielding an overall deviation of 0.248 mm2/s and R2 of 0.998. In addition, new formulas were developed to interconvert the viscosity of petroleum fractions from one unit of measure to another based on finding the best fit for a set of experimental data from the literature with R2 as high as 1.0 for many cases. Detailed analysis showed good agreement between the predicted values and the experimental data.

Decorrelation-based viscosity measurement using phase-sensitive optical coherence tomography (Conference Presentation)

NASA Astrophysics Data System (ADS)

Blackburn, Brecken J.; Gu, Shi; Jenkins, Michael W.; Rollins, Andrew M.

2017-02-01

A robust method to measure viscosity of microquantities of biological samples, such as blood and mucus, could lead to a better understanding and diagnosis of diseases. Microsamples have presented persistent challenges to conventional rheology, which requires bulk quantities of a sample. Alternatively, fluid viscosity can be probed by monitoring microscale motion of particles. Here, we present a decorrelation-based method using M-mode phase-sensitive optical coherence tomography (OCT) to measure particle Brownian motion. This is similar to previous methods using laser speckle decorrelation but with sensitivity to nanometer-scale displacement. This allows for the measurement of decorrelation in less than 1 millisecond and significantly decreases sensitivity to bulk motion, thereby potentially enabling in vivo and in situ applications. From first principles, an analytical method is established using M-mode images obtained from a 47 kHz spectral-domain OCT system. A g(1) first-order autocorrelation is calculated from windows containing several pixels over a time frame of 200-1000 microseconds. Total imaging time is 500 milliseconds for averaging purposes. The autocorrelation coefficient over this short time frame decreases linearly and at a rate proportional to the diffusion constant of the particles, allowing viscosity to be calculated. In verification experiments using phantoms of microbeads in 200 µL glycerol-water mixtures, this method showed insensitivity to 2 mm/s lateral bulk motion and accurate viscosity measurements over a depth of 400 µm. In addition, the method measured a significant decrease of the apparent diffusion constant of soft tissue after formalin fixation, suggesting potential applications in mapping tissue stiffness.

Molecular basis of high viscosity in concentrated antibody solutions: Strategies for high concentration drug product development

PubMed Central

Tomar, Dheeraj S.; Kumar, Sandeep; Singh, Satish K.; Goswami, Sumit; Li, Li

2016-01-01

ABSTRACT Effective translation of breakthrough discoveries into innovative products in the clinic requires proactive mitigation or elimination of several drug development challenges. These challenges can vary depending upon the type of drug molecule. In the case of therapeutic antibody candidates, a commonly encountered challenge is high viscosity of the concentrated antibody solutions. Concentration-dependent viscosity behaviors of mAbs and other biologic entities may depend on pairwise and higher-order intermolecular interactions, non-native aggregation, and concentration-dependent fluctuations of various antibody regions. This article reviews our current understanding of molecular origins of viscosity behaviors of antibody solutions. We discuss general strategies and guidelines to select low viscosity candidates or optimize lead candidates for lower viscosity at early drug discovery stages. Moreover, strategies for formulation optimization and excipient design are also presented for candidates already in advanced product development stages. Potential future directions for research in this field are also explored. PMID:26736022

Can a grain size-dependent viscosity help yielding realistic seismic velocities of LLSVPs?

NASA Astrophysics Data System (ADS)

Schierjott, J.; Cheng, K. W.; Rozel, A.; Tackley, P. J.

2017-12-01

Seismic studies show two antipodal regions of low shear velocity at the core-mantle boundary (CMB), one beneath the Pacific and one beneath Africa. These regions, called Large Low Shear Velocity Provinces (LLSVPs), are thought to be thermally and chemically distinct and thus have a different density and viscosity. Whereas there is some general consensus about the density of the LLSVPs the viscosity is still a very debated topic. So far, in numerical studies the viscosity is treated as either depth- and/or temperature- dependent but the potential grain size- dependence of the viscosity is neglected most of the time. In this study we use a self-consistent convection model which includes a grain size- dependent rheology based on the approach by Rozel et al. (2011) and Rozel (2012). Further, we consider a primordial layer and a time-dependent basalt production at the surface to dynamically form the present-day chemical heterogeneities, similar to earlier studies, e.g by Nakagawa & Tackley (2014). With this model we perform a parameter study which includes different densities and viscosities of the imposed primordial layer. We detect possible thermochemical piles based on different criterions, compute their average effective viscosity, density, rheology and grain size and investigate which detecting criterion yields the most realistic results. Our preliminary results show that a higher density and/or viscosity of the piles is needed to keep them at the core-mantle boundary (CMB). Relatively to the ambient mantle grain size is high in the piles but due to the temperature at the CMB the viscosity is not remarkably different than the one of ordinary plumes. We observe that grain size is lower if the density of the LLSVP is lower than the one of our MORB material. In that case the average temperature of the LLSVP is also reduced. Interestingly, changing the reference viscosity is responsible for a change in the average viscosity of the LLSVP but not for a different average

The micromechanics model analysis of the viscosity regulation of ultra-high strength concrete with low viscosity

NASA Astrophysics Data System (ADS)

Zhu, M.; Wang, F. G.; Wang, F. Z.; Liu, Y. P.

2017-02-01

The plastic viscosity of mortar and concrete with different binder content, sand ratio, water-binder ratio, microbead dosage and different class and dosage of fly ash were tested and calculated according tomicromechanics model proposed by A. Ghanbari and B.L. Karihaloo, The correlations between these parameters and fresh concrete workability were also investigated, which showed i. high consistence with the objective reality. When binder content, microbead dosage, fly ash dosage or the water-binder ratio was increased or sand ratio was reduced, the fresh concrete viscosity would decrease correspondingly. However their effects were not that same. The relationships between T50 a, V-funnel and inverted slump time with fresh concrete viscosity were established, respectively.

Viscosity Meaurement Technique for Metal Fuels

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ban, Heng; Kennedy, Rory

2015-02-09

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, themore » 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.« less

Radio and submillimetre observations of wind structure in zeta Puppis

NASA Astrophysics Data System (ADS)

Blomme, R.; van de Steene, G. C.; Prinja, R. K.; Runacres, M. C.; Clark, J. S.

2003-09-01

We present radio and submillimetre observations of the O4I(n)f star zeta Pup, and discuss structure in the outer region of its wind ( ~ 10-100 R_*). The properties of bremsstrahlung, the dominant emission process at these wavelengths, make it sensitive to structure and allow us to study how the amount of structure changes in the wind by comparing the fluxes at different wavelengths. Possible forms of structure at these distances include Corotating Interaction Regions (CIRs), stochastic clumping, a disk or a polar enhancement. As the CIRs are azimuthally asymmetric, they should result in variability at submillimetre or radio wavelengths. To look for this variability, we acquired 3.6 and 6 cm observations with the Australia Telescope Compact Array (ATCA), covering about two rotational periods of the star. We supplemented these with archive observations from the NRAO Very Large Array (VLA), which cover a much longer time scale. We did not find variability at more than the +/-20% level. The long integration time does allow an accurate determination of the fluxes at 3.6 and 6 cm. Converting these fluxes into a mass loss rate, we find dot {M} = 3.5 x 10-6 Msun/yr. This value confirms the significant discrepancy with the mass loss rate derived from the Hα profile, making zeta Pup an exception to the usually good agreement between the Hα and radio mass loss rates. To study the run of structure as a function of distance, we supplemented the ATCA data by observing zeta Pup at 850 mu m with the James Clerk Maxwell Telescope (JCMT) and at 20 cm with the VLA. A smooth wind model shows that the millimetre fluxes are too high compared to the radio fluxes. While recombination of helium in the outer wind cannot be discounted as an explanation, the wealth of evidence for structure strongly suggests this as the explanation for the discrepancy. Model calculations show that the structure needs to be present in the inner ~ 70 R_* of the wind, but that it decays significantly, or maybe

Bulk viscosity of molecular fluids

NASA Astrophysics Data System (ADS)

Jaeger, Frederike; Matar, Omar K.; Müller, Erich A.

2018-05-01

The bulk viscosity of molecular models of gases and liquids is determined by molecular simulations as a combination of a dilute gas contribution, arising due to the relaxation of internal degrees of freedom, and a configurational contribution, due to the presence of intermolecular interactions. The dilute gas contribution is evaluated using experimental data for the relaxation times of vibrational and rotational degrees of freedom. The configurational part is calculated using Green-Kubo relations for the fluctuations of the pressure tensor obtained from equilibrium microcanonical molecular dynamics simulations. As a benchmark, the Lennard-Jones fluid is studied. Both atomistic and coarse-grained force fields for water, CO2, and n-decane are considered and tested for their accuracy, and where possible, compared to experimental data. The dilute gas contribution to the bulk viscosity is seen to be significant only in the cases when intramolecular relaxation times are in the μs range, and for low vibrational wave numbers (<1000 cm-1); This explains the abnormally high values of bulk viscosity reported for CO2. In all other cases studied, the dilute gas contribution is negligible and the configurational contribution dominates the overall behavior. In particular, the configurational term is responsible for the enhancement of the bulk viscosity near the critical point.

Imaging tumor microscopic viscosity in vivo using molecular rotors

PubMed Central

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

2017-01-01

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

Highly Branched Polyethylenes as Lubricant Viscosity and Friction Modifiers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Robinson, Joshua W.; Zhou, Yan; Qu, Jun

2016-10-08

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.

Geometry of torn boudin-An indicator of relative viscosity

NASA Astrophysics Data System (ADS)

Samanta, Susanta Kumar; Basu Majumder, Debojyoti; Sarkar, Goutam

2017-11-01

The present study determines the role of viscosity on the development of rectangular torn boudin and its various types, defined by the curvature of their exterior and face margins. Numerical modeling was performed with the help of Finite Element Method considering Maxwell visco-elastic materials in commercial code ANSYS. Seven different viscosities were used and interchanged among the boudin, inter-boudin and matrix materials to understand the effect of viscosity ratios, specifically of relative viscosity of inter-boudin material. Results show that the viscosity of inter-boudin material has significant control on the shape of torn boudins apart from the viscosity ratio of boudin to matrix material. Bone-shaped boudin develops only when the inter-boudin is more competent than boudin and it becomes more prominent when matrix is also competent than boudin, but incompetent than inter-boudin. When boudins are stiffer than inter-boudin, barrel-shaped and fish-head boudins with concave faces develop. Exterior or face margins remain almost straight when boudin is relatively rigid compared to its surrounding matrix materials, or when there is no or very little viscosity contrast between boudin and inter-boudin material even in case of large boudin-matrix viscosity contrast. Therefore, the relative viscosity among the boudin, inter-boudin and matrix materials can be estimated qualitatively by studying the shape of boudin in the field.

Inference of mantle viscosity for depth resolutions of GIA observations

NASA Astrophysics Data System (ADS)

Nakada, Masao; Okuno, Jun'ichi

2016-11-01

Inference of the mantle viscosity from observations for glacial isostatic adjustment (GIA) process has usually been conducted through the analyses based on the simple three-layer viscosity model characterized by lithospheric thickness, upper- and lower-mantle viscosities. Here, we examine the viscosity structures for the simple three-layer viscosity model and also for the two-layer lower-mantle viscosity model defined by viscosities of η670,D (670-D km depth) and ηD,2891 (D-2891 km depth) with D-values of 1191, 1691 and 2191 km. The upper-mantle rheological parameters for the two-layer lower-mantle viscosity model are the same as those for the simple three-layer one. For the simple three-layer viscosity model, rate of change of degree-two zonal harmonics of geopotential due to GIA process (GIA-induced J˙2) of -(6.0-6.5) × 10-11 yr-1 provides two permissible viscosity solutions for the lower mantle, (7-20) × 1021 and (5-9) × 1022 Pa s, and the analyses with observational constraints of the J˙2 and Last Glacial Maximum (LGM) sea levels at Barbados and Bonaparte Gulf indicate (5-9) × 1022 Pa s for the lower mantle. However, the analyses for the J˙2 based on the two-layer lower-mantle viscosity model only require a viscosity layer higher than (5-10) × 1021 Pa s for a depth above the core-mantle boundary (CMB), in which the value of (5-10) × 1021 Pa s corresponds to the solution of (7-20) × 1021 Pa s for the simple three-layer one. Moreover, the analyses with the J˙2 and LGM sea level constraints for the two-layer lower-mantle viscosity model indicate two viscosity solutions: η670,1191 > 3 × 1021 and η1191,2891 ˜ (5-10) × 1022 Pa s, and η670,1691 > 1022 and η1691,2891 ˜ (5-10) × 1022 Pa s. The inferred upper-mantle viscosity for such solutions is (1-4) × 1020 Pa s similar to the estimate for the simple three-layer viscosity model. That is, these analyses require a high viscosity layer of (5-10) × 1022 Pa s at least in the deep mantle, and suggest

Quantitative characterization of the viscosity of a microemulsion

NASA Technical Reports Server (NTRS)

Berg, Robert F.; Moldover, Michael R.; Huang, John S.

1987-01-01

The viscosity of the three-component microemulsion water/decane/AOT has been measured as a function of temperature and droplet volume fraction. At temperatures well below the phase-separation temperature the viscosity is described by treating the droplets as hard spheres suspended in decane. Upon approaching the two-phase region from low temperature, there is a large (as much as a factor of four) smooth increase of the viscosity which may be related to the percolation-like transition observed in the electrical conductivity. This increase in viscosity is not completely consistent with either a naive electroviscous model or a simple clustering model. The divergence of the viscosity near the critical point (39 C) is superimposed upon the smooth increase. The magnitude and temperature dependence of the critical divergence are similar to that seen near the critical points of binary liquid mixtures.

Boundary Conditions for the Maintenance of Memory by PKM[zeta] in Neocortex

ERIC Educational Resources Information Center

Shema, Reul; Hazvi, Shoshi; Sacktor, Todd C.; Dudai, Yadin

2009-01-01

We report here that ZIP, a selective inhibitor of the atypical protein kinase C isoform PKM[zeta], abolishes very long-term conditioned taste aversion (CTA) associations in the insular cortex of the behaving rat, at least 3 mo after encoding. The effect of ZIP is not replicated by a general serine/threonine protein kinase inhibitor that is…

Crustal Viscosity Structure Estimated from Multi-Phase Mixing Theory

NASA Astrophysics Data System (ADS)

Shinevar, W. J.; Behn, M. D.; Hirth, G.

2014-12-01

Estimates of lower crustal viscosity are typically constrained by analyses of isostatic rebound, post seismic creep, and laboratory-derived flow laws for crustal rocks and minerals. Here we follow a new approach for calculating the viscosity structure of the lower continental crust. We use Perple_X to calculate mineral assemblages for different crustal compositions. Effective viscosity is then calculated using the rheologic mixing model of Huet et al. (2014) incorporating flow laws for each mineral phase. Calculations are performed along geotherms appropriate for the Basin and Range, Tibetan Plateau, Colorado Plateau, and the San Andreas Fault. To assess the role of crustal composition on viscosity, we examined two compositional gradients extending from an upper crust with ~67 wt% SiO2 to a lower crust that is either: (i) basaltic with ~53 wt% SiO2 (Rudnick and Gao, 2003), or (ii) andesitic with ~64% SiO2 (Hacker et al., 2011). In all cases, the middle continental crust has a viscosity that is 2-3 orders of magnitude greater than that inferred for wet quartz, a common proxy for mid-crustal viscosities. An andesitic lower crust results in viscosities of 1020-1021 Pa-s and 1021-1022 Pa-s for hotter and colder crustal geotherms, respectively. A mafic lower crust predicts viscosities that are an order of magnitude higher for the same geotherm. In all cases, the viscosity calculated from the mixing model decreases less with depth compared to single-phase estimates. Lastly, for anhydrous conditions in which alpha quartz is stable, we find that there is a strong correlation between Vp/Vs and bulk viscosity; in contrast, little to no correlation exists for hydrous conditions.

Self-similarity criteria in anisotropic flows with viscosity stratification

NASA Astrophysics Data System (ADS)

Danaila, L.; Voivenel, L.; Varea, E.

2017-02-01

Variable-viscosity flows exhibit a faster trend towards a fully developed turbulent state since fluctuations are produced at a larger amount. A legitimate expectation is that self-similarity to be tenable earlier than in classical, single-viscosity flows. The question which begs to be answered is: which are the self-similarity criteria for variable-viscosity, density-matched, flows? The similarity assumption, i.e., all scales evolve in a similar fashion in space/time, is applied to the transport equation for one- and two-point statistics of anisotropic, variable-viscosity flows. It is shown that the similarity assumption is valid for regions of the flow where viscosity (mean values and the fluctuations root-mean-square) is uniform. In regions where viscosity gradients are important, such as the sheared region and jet boundaries, similarity is not tenable. Our claims are applicable to any decaying flow, isotropic or anisotropic. Support is provided by experimental data obtained in the near field region of a jet issuing into a more viscous environment. The viscosity ratio is 3.5.

The role of viscosity in TATB hot spot ignition

NASA Astrophysics Data System (ADS)

Fried, Laurence E.; Zepeda-Ruis, Luis; Howard, W. Michael; Najjar, Fady; Reaugh, John E.

2012-03-01

The role of dissipative effects, such as viscosity, in the ignition of high explosive pores is investigated using a coupled chemical, thermal, and hydrodynamic model. Chemical reactions are tracked with the Cheetah thermochemical code coupled to the ALE3D hydrodynamic code. We perform molecular dynamics simulations to determine the viscosity of liquid TATB. We also analyze shock wave experiments to obtain an estimate for the shock viscosity of TATB. Using the lower bound liquid-like viscosities, we find that the pore collapse is hydrodynamic in nature. Using the upper bound viscosity from shock wave experiments, we find that the pore collapse is closest to the viscous limit.

Measurement of the dynamic viscosity of hybrid engine oil -Cuo-MWCNT nanofluid, development of a practical viscosity correlation and utilizing the artificial neural network

NASA Astrophysics Data System (ADS)

Aghaei, Alireza; Khorasanizadeh, Hossein; Sheikhzadeh, Ghanbar Ali

2018-01-01

The main objectives of this study have been measurement of the dynamic viscosity of CuO-MWCNTs/SAE 5w-50 hybrid nanofluid, utilization of artificial neural networks (ANN) and development of a new viscosity model. The new nanofluid has been prepared by a two-stage procedure with volume fractions of 0.05, 0.1, 0.25, 0.5, 0.75 and 1%. Then, utilizing a Brookfield viscometer, its dynamic viscosity has been measured for temperatures of 5, 15, 25, 35, 45, 55 °C. The experimental results demonstrate that the viscosity increases by increasing the nanoparticles volume fraction and decreases by increasing temperature. Based on the experimental data the maximum and minimum nanofluid viscosity enhancements, when the volume fraction increases from 0.05 to 1, are 35.52% and 12.92% for constant temperatures of 55 and 15 °C, respectively. The higher viscosity of oil engine in higher temperatures is an advantage, thus this result is important. The measured nanofluid viscosity magnitudes in various shear rates show that this hybrid nanofluid is Newtonian. An ANN model has been employed to predict the viscosity of the CuO-MWCNTs/SAE 5w-50 hybrid nanofluid and the results showed that the ANN can estimate the viscosity efficiently and accurately. Eventually, for viscosity estimation a new temperature and volume fraction based third-degree polynomial empirical model has been developed. The comparison shows that this model is in good agreement with the experimental data.

Temperature-viscosity relationships of selected asphalt cements.

DOT National Transportation Integrated Search

1970-06-01

To gain information on the appropriate temperature to obtain a given desirable viscosity for the various asphalt cements commonly used in Oregon, viscosities were determined at three or more temperatures near the mixing temperature. From the values d...

Seismic Constraints on the Mantle Viscosity Structure beneath Antarctica

NASA Astrophysics Data System (ADS)

Wiens, Douglas; Heeszel, David; Aster, Richard; Nyblade, Andrew; Wilson, Terry

2015-04-01

Lateral variations in upper mantle viscosity structure can have first order effects on glacial isostatic adjustment. These variations are expected to be particularly large for the Antarctic continent because of the stark geological contrast between ancient cratonic and recent tectonically active terrains in East and West Antarctica, respectively. A large misfit between observed and predicted GPS rates for West Antarctica probably results in part from the use of a laterally uniform viscosity structure. Although not linked by a simple relationship, mantle seismic velocities can provide important constraints on mantle viscosity structure, as they are both largely controlled by temperature and water content. Recent higher resolution seismic models for the Antarctic mantle, derived from data acquired by new seismic stations deployed in the AGAP/GAMSEIS and ANET/POLENET projects, offer the opportunity to use the seismic velocity structure to place new constraints on the viscosity of the Antarctic upper mantle. We use an Antarctic shear wave velocity model derived from array analysis of Rayleigh wave phase velocities [Heeszel et al, in prep] and examine a variety of methodologies for relating seismic, thermal and rheological parameters to compute a suite of viscosity models for the Antarctic mantle. A wide variety of viscosity structures can be derived using various assumptions, but they share several robust common elements. There is a viscosity contrast of at least two orders of magnitude between East and West Antarctica at depths of 80-250 km, reflecting the boundary between cold cratonic lithosphere in East Antarctica and warm upper mantle in West Antarctica. The region beneath the Ellsworth-Whitmore Mtns and extending to the Pensacola Mtns. shows intermediate viscosity between the extremes of East and West Antarctica. There are also significant variations between different parts of West Antarctica, with the lowest viscosity occurring beneath the Marie Byrd Land (MBL

The Role of Viscosity in TATB Hot Spot Ignition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fried, L E; Zepeda-Ruis, L; Howard, W M

2011-08-02

The role of dissipative effects, such as viscosity, in the ignition of high explosive pores is investigated using a coupled chemical, thermal, and hydrodynamic model. Chemical reactions are tracked with the Cheetah thermochemical code coupled to the ALE3D hydrodynamic code. We perform molecular dynamics simulations to determine the viscosity of liquid TATB. We also analyze shock wave experiments to obtain an estimate for the shock viscosity of TATB. Using the lower bound liquid-like viscosities, we find that the pore collapse is hydrodynamic in nature. Using the upper bound viscosity from shock wave experiments, we find that the pore collapse ismore » closest to the viscous limit.« less

Effects of fluid viscosity on a moving sonoluminescing bubble.

PubMed

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

2011-08-01

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.

Quantitative photoacoustic elasticity and viscosity imaging for cirrhosis detection

NASA Astrophysics Data System (ADS)

Wang, Qian; Shi, Yujiao; Yang, Fen; Yang, Sihua

2018-05-01

Elasticity and viscosity assessments are essential for understanding and characterizing the physiological and pathological states of tissue. In this work, by establishing a photoacoustic (PA) shear wave model, an approach for quantitative PA elasticity imaging based on measurement of the rise time of the thermoelastic displacement was developed. Thus, using an existing PA viscoelasticity imaging method that features a phase delay measurement, quantitative PA elasticity imaging and viscosity imaging can be obtained in a simultaneous manner. The method was tested and validated by imaging viscoelastic agar phantoms prepared at different agar concentrations, and the imaging data were in good agreement with rheometry results. Ex vivo experiments on liver pathological models demonstrated the capability for cirrhosis detection, and the results were consistent with the corresponding histological results. This method expands the scope of conventional PA imaging and has potential to become an important alternative imaging modality.

An Arrhenius-type viscosity function to model sintering using the Skorohod Olevsky viscous sintering model within a finite element code.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ewsuk, Kevin Gregory; Arguello, Jose Guadalupe, Jr.; Reiterer, Markus W.

2006-02-01

The ease and ability to predict sintering shrinkage and densification with the Skorohod-Olevsky viscous sintering (SOVS) model within a finite-element (FE) code have been improved with the use of an Arrhenius-type viscosity function. The need for a better viscosity function was identified by evaluating SOVS model predictions made using a previously published polynomial viscosity function. Predictions made using the original, polynomial viscosity function do not accurately reflect experimentally observed sintering behavior. To more easily and better predict sintering behavior using FE simulations, a thermally activated viscosity function based on creep theory was used with the SOVS model. In comparison withmore » the polynomial viscosity function, SOVS model predictions made using the Arrhenius-type viscosity function are more representative of experimentally observed viscosity and sintering behavior. Additionally, the effects of changes in heating rate on densification can easily be predicted with the Arrhenius-type viscosity function. Another attribute of the Arrhenius-type viscosity function is that it provides the potential to link different sintering models. For example, the apparent activation energy, Q, for densification used in the construction of the master sintering curve for a low-temperature cofire ceramic dielectric has been used as the apparent activation energy for material flow in the Arrhenius-type viscosity function to predict heating rate-dependent sintering behavior using the SOVS model.« less

The Larger the Viscosity, the Higher the Bounce

NASA Astrophysics Data System (ADS)

Stern, Menachem; Klein Schaarsberg, Martin; Peters, Ivo; Dodge, Kevin; Zhang, Wendy; Jaeger, Heinrich

A low-viscosity liquid drop can bounce upon impact onto a solid. A high-viscosity drop typically just flattens, i.e., it splats. Surprisingly, our experiments with a droplet made of densely packed glass beads in silicone oil display the opposite behavior: the low-viscosity oil suspension drop splats. The high-viscosity oil suspension bounces. Increasing solvent viscosity increases the rebound energy. To gain insight into the underlying mechanism, we model the suspension as densely packed elastic spheres experiencing viscous lubrication drag between neighbors. The model reproduces the observed trends. Plots of elastic compression and drag experienced by the particles show that rebounds are made possible by (1) a fraction of the impact energy being stored during initial contact via elastic compression, (2) a rapid broadening of local lubrication drag interactions at the initial impact site into a spatially uniform upward force throughout the drop. Including finite wall drag due to the presence of ambient air into the numerical model diminishes and eventually cuts off the rebound.

Effect of viscosity on droplet-droplet collisional interaction

NASA Astrophysics Data System (ADS)

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

2017-06-01

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.

Viscosity of a concentrated suspension of rigid monosized particles

NASA Astrophysics Data System (ADS)

Brouwers, H. J. H.

2010-05-01

This paper addresses the relative viscosity of concentrated suspensions loaded with unimodal hard particles. So far, exact equations have only been put forward in the dilute limit, e.g., by Einstein [A. Einstein, Ann. Phys. 19, 289 (1906) (in German); Ann. Phys. 34, 591 (1911) (in German)] for spheres. For larger concentrations, a number of phenomenological models for the relative viscosity was presented, which depend on particle concentration only. Here, an original and exact closed form expression is derived based on geometrical considerations that predicts the viscosity of a concentrated suspension of monosized particles. This master curve for the suspension viscosity is governed by the relative viscosity-concentration gradient in the dilute limit (for spheres the Einstein limit) and by random close packing of the unimodal particles in the concentrated limit. The analytical expression of the relative viscosity is thoroughly compared with experiments and simulations reported in the literature, concerning both dilute and concentrated suspensions of spheres, and good agreement is found.

Up to 50-fold increase in urine viscosity with iso-osmolar contrast media in the rat.

PubMed

Seeliger, Erdmann; Becker, Klaus; Ladwig, Mechthild; Wronski, Thomas; Persson, Pontus B; Flemming, Bert

2010-08-01

To compare changes in urinary viscosity in the renal tubules following administration of a high-viscosity iso-osmolar contrast agent (iodixanol) to that observed following administration of a less viscous, higher osmolar contrast agent (iopromide) in anesthetized rats. A total of 43 rats were studied. Experiments were approved by the Berlin, Germany, animal protection administration. A viscometer was developed to measure viscosity in minute samples (7 microL). Urine was collected, viscosity was measured (at 37 degrees C), and glomerular filtration rate (GFR) was determined by means of creatinine clearance. Boluses of 1.5 mL of iodixanol (320 mg iodine per milliliter, iso-osmolar to plasma, high viscosity) or iopromide (370 mg iodine per milliliter, higher osmolality and lower viscosity than iodixanol) were injected into the thoracic aorta. There were five groups (seven rats per group). Groups 1 (iodixanol) and 2 (iopromide) had free access to water prior to the experiment; groups 3 (iodixanol) and 4 (iopromide) received an additional infusion of isotonic saline (4 mL/kg/h). Group 5 was treated as group 1 but received only 0.75 mL of iodixanol. The observation period was 100 minutes. Statistical comparisons were made by means of nonparametric procedures (Friedman test, Kruskal-Wallis test). Iodixanol increased urine viscosity from 0.69 to 36.7 mm(2)/sec; thus, urine became threefold more viscous than native iodixanol solution. The increase in urine viscosity after injection of iopromide was from 0.73 to 2.3 mm(2)/sec. While GFR was not significantly affected by iopromide, GFR transiently decreased by 50% after administration of iodixanol. Iopromide had a diuretic effect twofold greater than that of iodixanol. Saline infusion blunted the viscosity rise and transient decline in GFR caused by iodixanol, as did reducing the iodixanol dose by 50%. Contrast media, in particular iodixanol, increase urine viscosity (which is equal to tubular fluid viscosity in the

Effect of contact angle, zeta potential and particles size on the in vitro studies of Al2O3 and SiO2 nanoparticles.

PubMed

Karunakaran, Gopalu; Suriyaprabha, Rangaraj; Rajendran, Venkatachalam; Kannan, Narayanasamy

2015-02-01

Currently, nanometal oxides find their role in different biological applications such as tissue engineering, implant and bone replacement materials. Owing to the increased use of nanoparticles, it is necessary to understand their release and toxicity in the biological system. In this regard, three independent studies such as in vitro cytotoxicity, antioxidant activity and biocompatibility of nano- and micrometal oxide particles such as alumina (Al2O3) and silica (SiO2) are evaluated. It is evident from cell viability study that nanoAl2O3 and SiO2 particles are less toxic when compared with microAl2O3 and SiO2 to NIH 3T3 cell lines up to 200 µg/ml. Antioxidant properties of micro- and nanoAl2O3 in terms of radical scavenging percentage for micro- and nanoAl2O3 are 59.1% and 72.1%, respectively, at 100 mg. Similarly, the radical scavenging percentage of nano- and bulk SiO2 are 81.0% and 67.2%, respectively. The present study reveals that the cellular behaviour, interaction and biocompatibility of metal oxides differ with dose, particle size, contact angle and zeta potential. The present study opens up a new strategy to analyse in vitro nanotoxicity.

Effect of Bulk Viscosity on the Oscillating Screen Viscometer

NASA Technical Reports Server (NTRS)

Berg, Robert F.; Moldover, Michael R.

1993-01-01

Close to the critical temperature, the bulk viscosity of the xenon sample will exceed the shear viscosity by more than a factor of a billion. Nevertheless, the viscometer's low operating frequency ensures that the only significant force on the oscillating screen will be due to the shear viscosity.

Negative viscosity can enhance learning of inertial dynamics.

PubMed

Huang, Felix C; Patton, James L; Mussa-Ivaldi, Ferdinando A

2009-06-01

We investigated how learning of inertial load manipulation is influenced by movement amplification with negative viscosity. Using a force-feedback device, subjects trained on anisotropic loads (5 orientations) with free movements in one of three conditions (inertia only, negative viscosity only, or combined), prior to common evaluation conditions (prescribed circular pattern with inertia only). Training with Combined-Load resulted in lower error (6.89±3.25%) compared to Inertia-Only (8.40±4.32%) and Viscosity-Only (8.17±4.13%) according to radial deviation analysis (% of trial mean radius). Combined-Load and Inertia-Only groups exhibited similar unexpected no-load trials (8.38±4.31% versus 8.91±4.70% of trial mean radius), which suggests comparable low-impedance strategies. These findings are remarkable since negative viscosity, only available during training, evidently enhanced learning when combined with inertia. Modeling analysis suggests that a feedforward after-effect of negative viscosity cannot predict such performance gains. Instead, results from Combined-Load training are consistent with greater feedforward inertia compensation along with a small increase in impedance control. The capability of the nervous system to generalize learning from negative viscosity suggests an intriguing new method for enhancing sensorimotor adaptation.

Viscosity studies of water based magnetite nanofluids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anu, K.; Hemalatha, J.

2016-05-23

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.

High-resolution ultraviolet observations of interstellar lines toward Zeta Persei observed with the balloon-borne ultraviolet stellar spectrometer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Snow, T.P.; Lamers, H.J.G.L.M.; Joseph, C.L.

1987-10-01

The balloon-borne ultraviolet stellar spectrometer payload has been used to obtain high-resolution data on interstellar absorption lines toward Zeta Per. The only lines clearly present in the 2150-2450 region were several Fe II features, which show double structure. The two velocity components were sufficiently well separated that it was possible to construct separate curves of growth to derive the Fe II column densities for the individual components. These column densities and the component velocity separation were then used to compute a realistic two-component curve of growth for the line of sight to Zeta Per, which was then used to reanalyzemore » existing ultraviolet data from Copernicus. The results were generally similar to an earlier two-component analysis of the Copernicus data, with the important exception that the silicon depletion increased from near zero to about 1 dex. This makes the Zeta Per depletion pattern quite similar to those derived for other reddened lines of sight, supporting the viewpoint that the general diffuse interstellar medium has a nearly constant pattern of depletions. 31 references.« less

Motion of fluids with very little viscosity

NASA Technical Reports Server (NTRS)

Prandtl, L

1928-01-01

I have set myself the task to investigate systematically the laws of motion of a fluid whose viscosity is assumed to be very small. The viscosity is supposed to be so small that it can be disregarded wherever there are no great velocity differences nor accumulative effects.

Spiders Tune Glue Viscosity to Maximize Adhesion.

PubMed

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

2015-11-24

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.

Reducing the Viscosity of Blood by Pulsed Magnetic Field

NASA Astrophysics Data System (ADS)

Tao, R.; Huang, K.

2010-03-01

Blood viscosity is a major player in heart disease. When blood is viscous, in addition to a high blood pressure required for the blood circulation, blood vessel walls are also easy to be damaged. While this issue is very important, currently the only method to reduce the blood viscosity is to take medicine, such as aspirin. Here we report our new finding that the blood viscosity can be reduced by pulsed magnetic field. Blood is a suspension of red blood cells (erythrocytes), white blood cells (leukocytes) and platelets in plasma, a complex solution of gases, salts, proteins, carbohydrates, and lipids. The base liquid, plasma, has low viscosity. The effective viscosity of whole blood increases mainly due to the red blood cells, which have a volume fraction about 40% or above. Red blood cells contain iron and are sensitive to magnetic field. Therefore, when we apply a strong magnetic field, the red cells make their diameters align in the field direction to form short chains. This change in rheology reduces the effective viscosity as high as 20-30%. While this reduction is not permanent, it lasts for several hours and repeatable. The reduction rate can be controlled by selecting suitable magnetic field and duration of field application to make blood viscosity within the normal range.

Challenges in Determining Intrinsic Viscosity Under Low Ionic Strength Solution Conditions.

PubMed

Pindrus, Mariya A; Shire, Steven J; Yadav, Sandeep; Kalonia, Devendra S

2017-04-01

To determine the intrinsic viscosity of several monoclonal antibodies (mAbs) under varying pH and ionic strength solution conditions. An online viscosity detector attached to HPLC (Viscotek®) was used to determine the intrinsic viscosity of mAbs. The Ross and Minton equation was used for viscosity prediction at high protein concentrations. Bulk viscosity was determined by a Cambridge viscometer. At 15 mM ionic strength, intrinsic viscosity of the mAbs determined by the single-point approach varied from 5.6 to 6.4 mL/g with changes in pH. High ionic strength did not significantly alter intrinsic viscosity, while a significant increase (up to 24.0 mL/g) was observed near zero mM. No difference in bulk viscosity of mAb3 was observed around pH 6 as a function of ionic strength. Data analysis revealed that near zero mM ionic strength limitations of the single-point technique result in erroneously high intrinsic viscosity. Intrinsic viscosity is a valuable tool that can be used to model baseline viscosity at higher protein concentrations. However, it is not predictive of solution non-ideality at higher protein concentrations. Furthermore, breakdown of numerous assumptions limits the applicability of experimental techniques near zero mM ionic strength conditions. For molecules and conditions studied, the single-point approach produced reliable intrinsic viscosity results at 15 mM. However, this approach must be used with caution near zero mM ionic strength. Data analysis can be used to reveal whether determined intrinsic viscosity is reliable or erroneously high.

Results of the Fluid Merging Viscosity Measurement International Space Station Experiment

NASA Technical Reports Server (NTRS)

Ethridge, Edwin C.; Kaukler, William; Antar, Basil

2009-01-01

The purpose of FMVM is to measure the rate of coalescence of two highly viscous liquid drops and correlate the results with the liquid viscosity and surface tension. The experiment takes advantage of the low gravitational free floating conditions in space to permit the unconstrained coalescence of two nearly spherical drops. The merging of the drops is accomplished by deploying them from a syringe and suspending them on Nomex threads followed by the astronaut s manipulation of one of the drops toward a stationary droplet till contact is achieved. Coalescence and merging occurs due to shape relaxation and reduction of surface energy, being resisted by the viscous drag within the liquid. Experiments were conducted onboard the International Space Station in July of 2004 and subsequently in May of 2005. The coalescence was recorded on video and down-linked near real-time. When the coefficient of surface tension for the liquid is known, the increase in contact radius can be used to determine the coefficient of viscosity for that liquid. The viscosity is determined by fitting the experimental speed to theoretically calculated contact radius speed for the same experimental parameters. Recent fluid dynamical numerical simulations of the coalescence process will be presented. The results are important for a better understanding of the coalescence process. The experiment is also relevant to liquid phase sintering, free form in-situ fabrication, and as a potential new method for measuring the viscosity of viscous glass formers at low shear rates.

HST-WFC3 Near-Infrared Spectroscopy of Quenched Galaxies at zeta approx 1.5 from the WISP Survey: Stellar Populations Properties

NASA Technical Reports Server (NTRS)

Bedregal, A. G.; Scarlata, C.; Henry, A. L.; Atek, H.; Rafelski, M.; Teplitz, H. I.; Dominguez, A.; Siana, B.; Colbert, J. W.; Malkan, M.;

Detecting cell lysis using viscosity monitoring in E. coli fermentation to prevent product loss

PubMed Central

Newton, Joseph M.; Schofield, Desmond; Vlahopoulou, Joanna

2016-01-01

Monitoring the physical or chemical properties of cell broths to infer cell status is often challenging due to the complex nature of the broth. Key factors indicative of cell status include cell density, cell viability, product leakage, and DNA release to the fermentation broth. The rapid and accurate prediction of cell status for hosts with intracellular protein products can minimise product loss due to leakage at the onset of cell lysis in fermentation. This article reports the rheological examination of an industrially relevant E. coli fermentation producing antibody fragments (Fab'). Viscosity monitoring showed an increase in viscosity during the exponential phase in relation to the cell density increase, a relatively flat profile in the stationary phase, followed by a rapid increase which correlated well with product loss, DNA release and loss of cell viability. This phenomenon was observed over several fermentations that a 25% increase in broth viscosity (using induction‐point viscosity as a reference) indicated 10% product loss. Our results suggest that viscosity can accurately detect cell lysis and product leakage in postinduction cell cultures, and can identify cell lysis earlier than several other common fermentation monitoring techniques. This work demonstrates the utility of rapidly monitoring the physical properties of fermentation broths, and that viscosity monitoring has the potential to be a tool for process development to determine the optimal harvest time and minimise product loss. © 2016 The Authors. Biotechnology Progress published by Wiley Periodicals, Inc. on behalf of American Institute of Chemical Engineers, 32:1069–1076, 2016 PMID:27111912

Hydrodynamic simulations of accretion flows with time-varying viscosity

NASA Astrophysics Data System (ADS)

Roy, Abhishek; Chakrabarti, Sandip K.

2017-12-01

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 ∼ rε), but the exponent (ε) 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.

Viscosity Relaxation in Molten HgZnTe

NASA Technical Reports Server (NTRS)

Su, Ching-Hua; Lehoczky, S. L.; Kim, Yeong Woo; Baird, James K.; Whitaker, Ann F. (Technical Monitor)

2001-01-01

Rotating cup measurements of the viscosity of the pseudo-binary melt, HgZnTe have shown that the isothermal liquid with zinc mole fraction 0.16 requires tens of hours of equilibration time before a steady viscous state can be achieved. Over this relaxation period, the viscosity at 790 C increases by a factor of two, while the viscosity at 810 C increases by 40%. Noting that the Group VI elements tend to polymerize when molten, we suggest that the viscosity of the melt is enhanced by the slow formation of Te atom chains. To explain the build-up of linear Te n-mers, we propose a scheme, which contains formation reactions with second order kinetics that increase the molecular weight, and decomposition reactions with first order kinetics that inactivate the chains. The resulting rate equations can be solved for the time dependence of each molecular weight fraction. Using these molecular weight fractions, we calculate the time dependence of the average molecular weight. Using the standard semi-empirical relation between polymer average molecular weight and viscosity, we then calculate the viscosity relaxation curve. By curve fitting, we find that the data imply that the rate constant for n-mer formation is much smaller than the rate constant for n-mer deactivation, suggesting that Te atoms only weakly polymerize in molten HgZnTe. The steady state toward which the melt relaxes occurs as the rate of formation of an n-mer becomes exactly balanced by the sum of the rate for its deactivation and the rate for its polymerization to form an (n+1)-mer.

Photoinduced aging and viscosity evolution in Se-rich Ge-Se glasses

NASA Astrophysics Data System (ADS)

Gueguen, Yann; King, Ellyn A.; Keryvin, Vincent; Sangleboeuf, Jean-Christophe; Rouxel, Tanguy; Bureau, Bruno; Lucas, Pierre

2013-08-01

We propose here to investigate the non-equilibrium viscosity of Ge-Se glasses under and after light irradiation. Ge10Se90 and Ge20Se80 fibers have been aged in the dark and under ambient light, over months. During aging, both the relaxation of enthalpy and the viscosity have been investigated. The viscosity was measured by shear relaxation-recovery tests allowing the measurement of non-equilibrium viscosity. When Ge10Se90 glass fibers are aged under irradiation, a relatively fast fictive temperature decrease is observed. Concomitantly, during aging under irradiation, the non-equilibrium viscosity increases and reaches an equilibrium after two months of aging. This viscosity increase is also observed in Ge20Se80 fibers. Nevertheless, this equilibrium viscosity is far below the viscosity expected at the configurational equilibrium. As soon as the irradiation ceases, the viscosity increases almost instantaneously by about one order of magnitude. Then, if the fibers are kept in the dark, their viscosity slowly increases over months. The analysis of the shear relaxation functions shows that the aging is thermorheologically simple. On the other side, there is no simple relaxation between the shear relaxation functions measured under irradiation and those measured in the dark. These results clearly suggest that a very specific photoinduced aging process occurs under irradiation. This aging is due to photorelaxation. Nevertheless, the viscosity changes are not solely correlated to photoaging and photorelaxation. A scenario is proposed to explain all the observed viscosity evolutions under and after irradiation, on the basis of photoinduced transient defects.

Drag reduction by a linear viscosity profile.

PubMed

De Angelis, Elisabetta; Casciola, Carlo M; L'vov, Victor S; Pomyalov, Anna; Procaccia, Itamar; Tiberkevich, Vasil

2004-11-01

Drag reduction by polymers in turbulent flows raises an apparent contradiction: the stretching of the polymers must increase the viscosity, so why is the drag reduced? A recent theory proposed that drag reduction, in agreement with experiments, is consistent with the effective viscosity growing linearly with the distance from the wall. With this self-consistent solution the reduction in the Reynolds stress overwhelms the increase in viscous drag. In this Rapid Communication we show, using direct numerical simulations, that a linear viscosity profile indeed reduces the drag in agreement with the theory and in close correspondence with direct simulations of the FENE-P model at the same flow conditions.

Rapid viscosity measurements of powdered thermosetting resins

NASA Technical Reports Server (NTRS)

Price, H. L.; Burks, H. D.; Dalal, S. K.

1978-01-01

A rapid and inexpensive method of obtaining processing-related data on powdered thermosetting resins has been investigated. The method involved viscosity measurements obtained with a small specimen (less than 100 mg) parallel plate plastometer. A data acquisition and reduction system was developed which provided a value of viscosity and strain rate about 12-13 second intervals during a test. The effects of specimen compaction pressure and reduction of adhesion between specimen and parallel plates were examined. The plastometer was used to measure some processing-related viscosity changes of an addition polyimide resin, including changes caused by pre-test heat treatment, test temperature, and strain rate.

Ras Diffusion Is Sensitive to Plasma Membrane Viscosity

PubMed Central

Goodwin, J. Shawn; Drake, Kimberly R.; Remmert, Catha L.; Kenworthy, Anne K.

2005-01-01

The cell surface contains a variety of barriers and obstacles that slow the lateral diffusion of glycosylphosphatidylinositol (GPI)-anchored and transmembrane proteins below the theoretical limit imposed by membrane viscosity. How the diffusion of proteins residing exclusively on the inner leaflet of the plasma membrane is regulated has been largely unexplored. We show here that the diffusion of the small GTPase Ras is sensitive to the viscosity of the plasma membrane. Using confocal fluorescence recovery after photobleaching, we examined the diffusion of green fluorescent protein (GFP)-tagged HRas, NRas, and KRas in COS-7 cells loaded with or depleted of cholesterol, a well-known modulator of membrane bilayer viscosity. In cells loaded with excess cholesterol, the diffusional mobilities of GFP-HRas, GFP-NRas, and GFP-KRas were significantly reduced, paralleling the behavior of the viscosity-sensitive lipid probes DiIC16 and DiIC18. However, the effects of cholesterol depletion on protein and lipid diffusion in cell membranes were highly dependent on the depletion method used. Cholesterol depletion with methyl-β-cyclodextrin slowed Ras diffusion by a viscosity-independent mechanism, whereas overnight cholesterol depletion slightly increased both protein and lipid diffusion. The ability of Ras to sense membrane viscosity may represent a general feature of proteins residing on the cytoplasmic face of the plasma membrane. PMID:15923235

Viscosity of fiber preloads affects food intake in adolescents.

PubMed

Vuksan, V; Panahi, S; Lyon, M; Rogovik, A L; Jenkins, A L; Leiter, L A

2009-09-01

Dietary fiber that develops viscosity in the gastrointestinal tract is capable of addressing various aspects of food intake control. The aim of this study was to assess subsequent food intake and appetite in relation to the level of viscosity following three liquid preloads each containing 5 g of either a high (novel viscous polysaccharide; NVP), medium (glucomannan; GLM), or low (cellulose; CE) viscosity fiber. In this double-blind, randomized, controlled and crossover trial, 31 healthy weight adolescents (25 F:6 M; age 16.1+/-0.6 years; BMI 22.2+/-3.7 kg/m(2)) consumed one of the three preloads 90 min prior to an ad libitum pizza meal. Preloads were identical in taste, appearance, nutrient content and quantity of fiber, but different in their viscosities (10, 410, and 700 poise for CE, GLM, and NVP, respectively). Pizza intake was significantly lower (p=0.008) after consumption of the high-viscosity NVP (278+/-111 g) compared to the medium-viscosity GLM (313+/-123 g) and low-viscosity CE (316+/-138 g) preloads, with no difference between the GLM and CE preloads. Appetite scores, physical symptoms and 24-h intake did not differ among treatment groups. A highly viscous NVP preload leads to reduced subsequent food intake, in terms of both gram weight and calories, in healthy weight adolescents. This study provides preliminary evidence of an independent contribution of viscosity on food intake and may form a basis for further studies on factors influencing food intake in adolescents.

A nearly water-saturated mantle transition zone inferred from mineral viscosity.

PubMed

Fei, Hongzhan; Yamazaki, Daisuke; Sakurai, Moe; Miyajima, Nobuyoshi; Ohfuji, Hiroaki; Katsura, Tomoo; Yamamoto, Takafumi

2017-06-01

An open question for solid-earth scientists is the amount of water in Earth's interior. The uppermost mantle and lower mantle contain little water because their dominant minerals, olivine and bridgmanite, have limited water storage capacity. In contrast, the mantle transition zone (MTZ) at a depth of 410 to 660 km is considered to be a potential water reservoir because its dominant minerals, wadsleyite and ringwoodite, can contain large amounts of water [up to 3 weight % (wt %)]. However, the actual amount of water in the MTZ is unknown. Given that water incorporated into mantle minerals can lower their viscosity, we evaluate the water content of the MTZ by measuring dislocation mobility, a property that is inversely proportional to viscosity, as a function of temperature and water content in ringwoodite and bridgmanite. We find that dislocation mobility in bridgmanite is faster by two orders of magnitude than in anhydrous ringwoodite but 1.5 orders of magnitude slower than in water-saturated ringwoodite. To fit the observed mantle viscosity profiles, ringwoodite in the MTZ should contain 1 to 2 wt % water. The MTZ should thus be nearly water-saturated globally.

Effects of Metal Ions on Viscosity of Aqueous Sodium Carboxylmethylcellulose Solution and Development of Dropping Ball Method on Viscosity

ERIC Educational Resources Information Center

Set, Seng; Ford, David; Kita, Masakazu

2015-01-01

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…

Viscosity Measurement Using Drop Coalescence in Microgravity

NASA Technical Reports Server (NTRS)

Antar, Basil N.; Ethridge, Edwin C.; Maxwell, Daniel; Curreri, Peter A. (Technical Monitor)

2002-01-01

We present in here validation studies of a new method for application in microgravity environment which measures the viscosity of highly viscous undercooled liquids using drop coalescence. The method has the advantage of avoiding heterogeneous nucleation at container walls caused by crystallization of undercooled liquids during processing. Homogeneous nucleation can also be avoided due to the rapidity of the measurement using this method. The technique relies on measurements from experiments conducted in near zero gravity environment as well as highly accurate analytical formulation for the coalescence process. The viscosity of the liquid is determined by allowing the computed free surface shape relaxation time to be adjusted in response to the measured free surface velocity for two coalescing drops. Results are presented from two sets of validation experiments for the method which were conducted on board aircraft flying parabolic trajectories. In these tests the viscosity of a highly viscous liquid, namely glycerin, was determined at different temperatures using the drop coalescence method described in here. The experiments measured the free surface velocity of two glycerin drops coalescing under the action of surface tension alone in low gravity environment using high speed photography. The liquid viscosity was determined by adjusting the computed free surface velocity values to the measured experimental data. The results of these experiments were found to agree reasonably well with the known viscosity for the test liquid used.

Development of ocular viscosity characterization method.

PubMed

Shu-Hao Lu; Guo-Zhen Chen; Leung, Stanley Y Y; Lam, David C C

2016-08-01

Glaucoma is the second leading cause for blindness. Irreversible and progressive optic nerve damage results when the intraocular pressure (IOP) exceeds 21 mmHg. The elevated IOP is attributed to blocked fluid drainage from the eye. Methods to measure the IOP are widely available, but methods to measure the viscous response to blocked drainage has yet been developed. An indentation method to characterize the ocular flow is developed in this study. Analysis of the load-relaxation data from indentation tests on drainage-controlled porcine eyes showed that the blocked drainage is correlated with increases in ocular viscosity. Successful correlation of the ocular viscosity with drainage suggests that ocular viscosity maybe further developed as a new diagnostic parameter for assessment of normal tension glaucoma where nerve damage occurs without noticeable IOP elevation; and as a diagnostic parameter complimentary to conventional IOP in conventional diagnosis.

Nucleoplasmic viscosity of living cells investigated by fluorescence correlation spectroscopy

NASA Astrophysics Data System (ADS)

Liang, Lifang; Xing, Da; Chen, Tongshen; Pei, Yihui

2007-11-01

Fluorescence correlation spectroscopy (FCS) is a new kind of real-time, high-speed and single-molecule technique. It is used to detect the kinetic characteristics of fluorescent dye such as diffusion coefficient in the aqueous solution. Combined with confocal microscope optics, it has been now widely applied in cell biological research. Through a time correlation analysis of spontaneous intensity fluctuations, this technique with EGFP as a probe is capable of determining viscosity of fluids according to Stokes-Einstein equation. Nucleoplasmic viscosity is an important physical parameter to quantify the rheological characteristics of the nucleoplasm. Investigation on nucleoplasmic viscosity plays an important role in further understanding intranuclear environment. In this paper, FCS is introduced to noninvasively investigate nucleoplasmic viscosity of living cells. The results show that nucleoplasmic viscosity of lung adenocarcinoma (ASTC-a-1) cells is 2.55+/-0.61 cP and nucleoplasmic viscosity is larger than cytoplasmic viscosity at 37 °C (pH 7.4). In addition, significant changes in nucleoplasmic viscosity are detected by FCS when cells are exposed to hyper or hypotonic medium. Our study suggests that FCS can be used to detect the kinetic characteristics of biomolecules in living cells and thus helps to investigate the dynamic changes of the microenvironment in the cell.

Maintenance of reference standards in the field of viscosity

NASA Astrophysics Data System (ADS)

Moşulică, E. A.; Cîrneanu, I.; Constantin, N.; Rucai, V.

2018-01-01

Participation in the work of comparison in the field of viscosity, within the program conducted under the jurisdiction of ASTM (American Society for Testing and Materials), D-2 Committee, Subcommittee "Flow Properties," Newtonian Fluids) was necessary to ensure traceability of measuring unit of kinematic viscosity. Results of the comparison of the specialized participating laboratories on 4 continents, has proved annual capability of INM in the transmission unit of kinematic viscosity. Cannon Position Company in the US organizes co-operation program in the field of kinematic viscosity ASTM D 02.07. The company distributes standard substances Cannon viscosity participating laboratories and consolidate the results of the measurements. Physical-chemical laboratory has fully accepted the proposed schedule of the company Cannon. Final report of the comparison showed that in the year 2015 a number of 25 laboratories and institutes of metrology attented to the program.

Effect of Oils on Kinematic Viscosity of R134a

NASA Astrophysics Data System (ADS)

Sato, Tomoaki; Takaishi, Yoshinori; Oguchi, Kosei

The kinematic viscosity defined as a ratio of viscosity to density is one of the key properties in producing technically important dimensionless numbers such as Prandtl and Reynolds numbers. We measured both viscosity and density of R134a/POE and R134a/PAG mixtures at saturation in the range of relatively low oilconcentrations. The density measurements for oil-concentrations up to 50 mass% were conducted with a densimeter making use of glass buoys within overall uncertainty of ±1.0%, and the viscosity measurements for oil-concentrations up to 16 mass% were carried out with an oscillating-cup viscometer making use of polarizer with overall uncertainty less than ±3.5%. The kinematic viscosities obtained from the experimental viscosity and density data are presented for both R134a/POE and R134a/PAG mixtures in the range of temperatures from 278 K to 288 K for oil-concentrations up to 15 mass%. The oil-concentration dependence of the kinematic viscosity for both mixtures is also reported.

Quetol 651: Not just a low viscosity resin.

PubMed

Ellis, E Ann

2016-01-01

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.

Photoinduced aging and viscosity evolution in Se-rich Ge-Se glasses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gueguen, Yann; Sangleboeuf, Jean-Christophe; Rouxel, Tanguy

We propose here to investigate the non-equilibrium viscosity of Ge-Se glasses under and after light irradiation. Ge{sub 10}Se{sub 90} and Ge{sub 20}Se{sub 80} fibers have been aged in the dark and under ambient light, over months. During aging, both the relaxation of enthalpy and the viscosity have been investigated. The viscosity was measured by shear relaxation-recovery tests allowing the measurement of non-equilibrium viscosity. When Ge{sub 10}Se{sub 90} glass fibers are aged under irradiation, a relatively fast fictive temperature decrease is observed. Concomitantly, during aging under irradiation, the non-equilibrium viscosity increases and reaches an equilibrium after two months of aging. Thismore » viscosity increase is also observed in Ge{sub 20}Se{sub 80} fibers. Nevertheless, this equilibrium viscosity is far below the viscosity expected at the configurational equilibrium. As soon as the irradiation ceases, the viscosity increases almost instantaneously by about one order of magnitude. Then, if the fibers are kept in the dark, their viscosity slowly increases over months. The analysis of the shear relaxation functions shows that the aging is thermorheologically simple. On the other side, there is no simple relaxation between the shear relaxation functions measured under irradiation and those measured in the dark. These results clearly suggest that a very specific photoinduced aging process occurs under irradiation. This aging is due to photorelaxation. Nevertheless, the viscosity changes are not solely correlated to photoaging and photorelaxation. A scenario is proposed to explain all the observed viscosity evolutions under and after irradiation, on the basis of photoinduced transient defects.« less

Subduction zone evolution and low viscosity wedges and channels

NASA Astrophysics Data System (ADS)

Manea, Vlad; Gurnis, Michael

2007-12-01

Dehydration of subducting lithosphere likely transports fluid into the mantle wedge where the viscosity is decreased. Such a decrease in viscosity could form a low viscosity wedge (LVW) or a low viscosity channel (LVC) on top of the subducting slab. Using numerical models, we investigate the influence of low viscosity wedges and channels on subduction zone structure. Slab dip changes substantially with the viscosity reduction within the LVWs and LVCs. For models with or without trench rollback, overthickening of slabs is greatly reduced by LVWs or LVCs. Two divergent evolutionary pathways have been found depending on the maximum depth extent of the LVW and wedge viscosity. Assuming a viscosity contrast of 0.1 with background asthenosphere, models with a LVW that extends down to 400 km depth show a steeply dipping slab, while models with an LVW that extends to much shallower depth, such as 200 km, can produce slabs that are flat lying beneath the overriding plate. There is a narrow range of mantle viscosities that produces flat slabs (5 to10 × 10 19 Pa s) and the slab flattening process is enhanced by trench rollback. Slab can be decoupled from the overriding plate with a LVC if the thickness is at least a few 10 s of km, the viscosity reduction is at least a factor of two and the depth extent of the LVC is several hundred km. These models have important implications for the geochemical and spatial evolution of volcanic arcs and the state of stress within the overriding plate. The models explain the poor correlation between traditional geodynamic controls, subducting plate age and convergence rates, on slab dip. We predict that when volcanic arcs change their distance from the trench, they could be preceded by changes in arc chemistry. We predict that there could be a larger volatile input into the wedge when arcs migrate toward the trench and visa-versa. The transition of a subduction zone into the flat-lying regime could be preceded by changes in the volatile

Lattice Boltzmann simulations of immiscible displacement process with large viscosity ratios

NASA Astrophysics Data System (ADS)

Rao, Parthib; Schaefer, Laura

2017-11-01

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.

Plasma viscosity increase with progression of peripheral arterial atherosclerotic disease.

PubMed

Poredos, P; Zizek, B

1996-03-01

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

Understanding the Viscosity of Liquids used in Infant Dysphagia Management

PubMed Central

Frazier, Jackie; Chestnut, Amanda; Jackson, Arwen; Barbon, Carly E. A.; Steele, Catriona M.; Pickler, Laura

2016-01-01

When assessing swallowing in infants, it is critical to have confidence that the liquids presented during the swallow study closely replicate the viscosity of liquids in the infant's typical diet. However, we lack research on rheological properties of frequently used infant formulas or breastmilk, and various forms of barium contrast media used in swallow studies. The aim of the current study was to provide objective viscosity measurements for typical infant liquid diet options and barium contrast media. A TA-Instruments AR2000 Advanced Rheometer was used to measure the viscosity, five standard infant formulas, three barium products and two breastmilk samples. Additionally, this study measured the viscosity of infant formulas and breastmilk when mixed with powdered barium contrast in a 20% weight-to-volume (w/v) concentration. Study findings determined that standard infant formulas and the two breastmilk samples had low viscosities, at the lower end of the National Dysphagia Diet (NDD) thin liquid range. Two specialty formulas tested had much thicker viscosities, close to the NDD nectar-thick liquid range lower boundary. The study showed differences in viscosity between two 60% w/v barium products (Liquid E-Z-Paque® and E-Z-Paque® powder); the powdered product had a much lower viscosity, despite identical barium concentration. When E-Z-Paque® powdered barium was mixed in a 20% w/v concentration using water, standard infant formulas or breastmilk, the resulting viscosities were at the lower end of the NDD thin range, and only slightly thicker than the non-barium comparator liquids. When E-Z-Paque® powdered barium was mixed in a 20% w/v concentration with the two thicker specialty formulas (Enfamil AR 20kcal and 24 kcal), unexpected alterations in their original viscosity occurred. These findings highlight the clinical importance of objective measures of viscosity as well as objective data on how infant formulas or breastmilk may change in consistency when mixed

Understanding the Viscosity of Liquids used in Infant Dysphagia Management.

PubMed

Frazier, Jacqueline; Chestnut, Amanda H; Jackson, Arwen; Barbon, Carly E A; Steele, Catriona M; Pickler, Laura

2016-10-01

When assessing swallowing in infants, it is critical to have confidence that the liquids presented during the swallow study closely replicate the viscosity of liquids in the infant's typical diet. However, we lack research on rheological properties of frequently used infant formulas or breastmilk, and various forms of barium contrast media used in swallow studies. The aim of the current study was to provide objective viscosity measurements for typical infant liquid diet options and barium contrast media. A TA-Instruments AR2000 Advanced Rheometer was used to measure the viscosity of five standard infant formulas, three barium products, and two breastmilk samples. Additionally, this study measured the viscosity of infant formulas and breastmilk when mixed with powdered barium contrast in a 20 % weight-to-volume (w/v) concentration. The study findings determined that standard infant formulas and the two breastmilk samples had low viscosities, at the lower end of the National Dysphagia Diet (NDD) thin liquid range. Two specialty formulas tested had much thicker viscosities, close to the lower boundary of the NDD nectar-thick liquid range. The study showed differences in viscosity between 60 % w/v barium products (Liquid E-Z-Paque(®) and E-Z-Paque(®) powder); the powdered product had a much lower viscosity, despite identical barium concentration. When E-Z-Paque(®) powdered barium was mixed in a 20 % w/v concentration using water, standard infant formulas, or breastmilk, the resulting viscosities were at the lower end of the NDD thin range and only slightly thicker than the non-barium comparator liquids. When E-Z-Paque(®) powdered barium was mixed in a 20 % w/v concentration with the two thicker specialty formulas (Enfamil AR 20 and 24 kcal), unexpected alterations in their original viscosity occurred. These findings highlight the clinical importance of objective measures of viscosity as well as objective data on how infant formulas or breastmilk may change in

Influence of interfacial viscosity on the dielectrophoresis of drops

NASA Astrophysics Data System (ADS)

Mandal, Shubhadeep; Chakraborty, Suman

2017-05-01

The dielectrophoresis of a Newtonian uncharged drop in the presence of an axisymmetric nonuniform DC electric field is studied analytically. The present study is focused on the effects of interfacial viscosities on the dielectrophoretic motion and shape deformation of an isolated suspended drop. The interfacial viscosities generate surface-excess viscous stress which is modeled as a two-dimensional Newtonian fluid which obeys the Boussinesq-Scriven constitutive law with constant values of interfacial tension, interfacial shear, and dilatational viscosities. In the regime of small drop deformation, we have obtained analytical solution for the drop velocity and deformed shape by neglecting surface charge convection and fluid inertia. Our study demonstrates that the drop velocity is independent of the interfacial shear viscosity, while the interfacial dilatational viscosity strongly affects the drop velocity. The interfacial viscous effects always retard the dielectrophoretic motion of a perfectly conducting/dielectric drop. Notably, the interfacial viscous effects can retard or augment the dielectrophoretic motion of a leaky dielectric drop depending on the electrohydrodynamic properties. The shape deformation of a leaky dielectric drop is found to decrease (or increase) due to interfacial shear (or dilatational) viscosity.

14-3-3 zeta is a molecular target in guggulsterone induced apoptosis in head and neck cancer cells.

PubMed

Macha, Muzafar A; Matta, Ajay; Chauhan, Ss; Siu, Kw Michael; Ralhan, Ranju

2010-11-30

The five-year survival rates for head and neck squamous cell carcinoma (HNSCC) patients are less than 50%, and the prognosis has not improved, despite advancements in standard multi-modality therapies. Hence major emphasis is being laid on identification of novel molecular targets and development of multi-targeted therapies. 14-3-3 zeta, a multifunctional phospho-serine/phospho-threonine binding protein, is emerging as an effector of pro-survival signaling by binding to several proteins involved in apoptosis (Bad, FKHRL1 and ASK1) and may serve as an appropriate target for head and neck cancer therapy. Herein, we determined effect of guggulsterone (GS), a farnesoid X receptor antagonist, on 14-3-3 zeta associated molecular pathways for abrogation of apoptosis in head and neck cancer cells. Head and neck cancer cells were treated with guggulsterone (GS). Effect of GS-treatment was evaluated using cell viability (MTT) assay and apoptosis was verified by annexin V, DNA fragmentation and M30 CytoDeath antibody assay. Mechanism of GS-induced apoptosis was determined by western blotting and co-IP assays using specific antibodies. Using in vitro models of head and neck cancer, we showed 14-3-3 zeta as a key player regulating apoptosis in GS treated SCC4 cells. Treatment with GS releases BAD from the inhibitory action of 14-3-3 zeta in proliferating HNSCC cells by activating protein phosphatase 2A (PP2A). These events initiate the intrinsic mitochondrial pathway of apoptosis, as revealed by increased levels of cytochrome c in cytoplasmic extracts of GS-treated SCC4 cells. In addition, GS treatment significantly reduced the expression of anti-apoptotic proteins, Bcl-2, xIAP, Mcl1, survivin, cyclin D1 and c-myc, thus committing cells to apoptosis. These events were followed by activation of caspase 9, caspase 8 and caspase 3 leading to cleavage of its downstream target, poly-ADP-ribose phosphate (PARP). GS targets 14-3-3 zeta associated cellular pathways for reducing

Hot accretion flow with anisotropic viscosity

NASA Astrophysics Data System (ADS)

Wu, Mao-Chun; Bu, De-Fu; Gan, Zhao-Ming; Yuan, Ye-Fei

2017-12-01

In extremely low accretion rate systems, the ion mean-free path can be much larger than the gyroradius. Therefore, gas pressure is anisotropic with respect to magnetic field lines. The effects of pressure anisotropy can be modeled by an anisotropic viscosity with respect to magnetic field lines. Angular momentum can be transferred by anisotropic viscosity. In this paper, we investigate hot accretion flow with anisotropic viscosity. We consider the case that anisotropic viscous stress is much larger than Maxwell stress. We find that the flow is convectively unstable. We also find that the mass inflow rate decreases towards a black hole. Wind is very weak; its mass flux is 10-15% of the mass inflow rate. The inward decrease of inflow rate is mainly due to convective motions. This result may be useful to understand the accretion flow in the Galactic Center Sgr A* and M 87 galaxy.

High-Resolution Lithosphere Viscosity and Dynamics Revealed by Magnetotelluric Imaging

NASA Astrophysics Data System (ADS)

Liu, L.; Hasterok, D. P.

2016-12-01

An accurate viscosity structure is critical to truthfully modeling continental lithosphere dynamics, especially at spatial scales of <200 km where active tectonic deformation and volcanism occur. However, the effective viscosity structure of the lithosphere remains a key challenge in geodynamics due to the intimate involvement of viscosity with time and its dependence on many 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.

Stimulation of Mucin, Mucus, and Viscosity during Lubiprostone in Patients with Chronic Constipation may Potentially Lead to Increase of Lubrication.

PubMed

Majewski, Marek; Sarosiek, Irene; Wallner, Grzegorz; Edlavitch, Stanley A; Sarosiek, Jerzy

2014-12-18

basal conditions and increased by 25% (210.0 vs. 167.6 ml/h) (P=0.024) during stimulation with pentagastrin. The rate of gastric mucus secretion during therapy with lubiprostone was 91% higher (257.3 vs. 135 mg/h) (P=0.001) in basal conditions and 28% higher (348.1 vs. 270.8 mg/h) (NS) in stimulated conditions, although the latter was not statistically significant. The rate of gastric mucin secretion during lubiprostone therapy was 85% higher (98.4 vs. 65.5 mg/h) (P=0.011) in basal conditions and 38% (98.3 vs. 71.7 mg/h) (NS) higher in stimulated conditions. In basal conditions, the viscosity of gastric secretion during administration of lubiprostone increased by 240% at the lowest (P<0.001) and by 106% at the highest shear rate (P<0.001). In stimulated conditions, it increased by 226% (P<0.01) at the lowest shear rate and by 67% (P<0.01) at the highest shear rate. The significantly higher content of gastric mucus and mucin during therapy in basal conditions with lubiprostone in patients with CC suggests and supports the potentially leading role of lubiprostone and ClC-2 stimulation in their secretion. This increased stimulation results in profoundly increased viscosity, which in turn facilitates and/or accelerates the transit and evacuation of non-digestible food components. Although increases in mucus and mucin were observed in stimulated conditions, neither increase was statistically significant. Based on this experiment, we hypothesize that, in CC patients, the significantly increased rate of mucus and its major component, mucin secretion, during lubiprostone administration may partially explain its clinical effectiveness and also have additional clinically important effects. We propose that since the increased mucus production enhances the protective quality of the mucosal barrier, it also boosts its potential to withstand luminal aggressive components such as acid/pepsin duet, Helicobacter pylori and/or nonsteroidal anti-inflammatory drugs/aspirin, or a

Stimulation of Mucin, Mucus, and Viscosity during Lubiprostone in Patients with Chronic Constipation may Potentially Lead to Increase of Lubrication

PubMed Central

Majewski, Marek; Sarosiek, Irene; Wallner, Grzegorz; Edlavitch, Stanley A; Sarosiek, Jerzy

2014-01-01

. 57.5 ml/h) (P<0.001) in basal conditions and increased by 25% (210.0 vs. 167.6 ml/h) (P=0.024) during stimulation with pentagastrin. The rate of gastric mucus secretion during therapy with lubiprostone was 91% higher (257.3 vs. 135 mg/h) (P=0.001) in basal conditions and 28% higher (348.1 vs. 270.8 mg/h) (NS) in stimulated conditions, although the latter was not statistically significant. The rate of gastric mucin secretion during lubiprostone therapy was 85% higher (98.4 vs. 65.5 mg/h) (P=0.011) in basal conditions and 38% (98.3 vs. 71.7 mg/h) (NS) higher in stimulated conditions. In basal conditions, the viscosity of gastric secretion during administration of lubiprostone increased by 240% at the lowest (P<0.001) and by 106% at the highest shear rate (P<0.001). In stimulated conditions, it increased by 226% (P<0.01) at the lowest shear rate and by 67% (P<0.01) at the highest shear rate. Conclusions: The significantly higher content of gastric mucus and mucin during therapy in basal conditions with lubiprostone in patients with CC suggests and supports the potentially leading role of lubiprostone and ClC-2 stimulation in their secretion. This increased stimulation results in profoundly increased viscosity, which in turn facilitates and/or accelerates the transit and evacuation of non-digestible food components. Although increases in mucus and mucin were observed in stimulated conditions, neither increase was statistically significant. Based on this experiment, we hypothesize that, in CC patients, the significantly increased rate of mucus and its major component, mucin secretion, during lubiprostone administration may partially explain its clinical effectiveness and also have additional clinically important effects. We propose that since the increased mucus production enhances the protective quality of the mucosal barrier, it also boosts its potential to withstand luminal aggressive components such as acid/pepsin duet, Helicobacter pylori and

Transport properties of N2 gas at cryogenic temperatures. [computation of viscosity and thermal conductivity

NASA Technical Reports Server (NTRS)

Pearson, W. E.

1974-01-01

The viscosity and thermal conductivity of nitrogen gas for the temperature range 5 K - 135 K have been computed from the second Chapman-Enskog approximation. Quantum effects, which become appreciable at the lower temperatures, are included by utilizing collision integrals based on quantum theory. A Lennard-Jones (12-6) potential was assumed. The computations yield viscosities about 20 percent lower than those predicted for the high end of this temperature range by the method of corresponding states, but the agreement is excellent when the computed values are compared with existing experimental data.

Preparation and characterization of potato starch-thymol dispersion and film as potential antioxidant and antibacterial materials.

PubMed

Davoodi, Mina; Kavoosi, Gholamreza; Shakeri, Raheleh

2017-11-01

The antioxidant/antimicrobial capacity and physical properties of potato starch dispersions enriched with polysorbate-thymol micelle were investigated. Results showed that potato starch have radical scavenging and antibacterial activities only in the presence of polysorbate-thymol but with lower level than polysorbate-thymol alone. The decrease in the antioxidant and antibacterial activities may be attributed to the encapsulation of thymol in the starch chain. Polysorbate-thymol caused a decrease in the particle size and viscosity and an increase in the zeta potential of the starch dispersions. Futhermore, polysorbate-thymol leads to a decrease in the tensile strength, rigidity and swelling, and an increase in the flexibility, solubility and water vapour permeability of the starch films. Atomic force microscopy revealed polysorbate-thymol micelles in the film matrix enclosed by polysaccharide crystal. Scanning electron microscope analysis indicated that polysorbate-thymol caused a coarse film microstructure with the distributed crack in the film matrix. Based on the results, the antioxidant and antibacterial activities of the starch-polysorbate-thymol make starch film suitable for food packaging and preservation. Copyright © 2017 Elsevier B.V. All rights reserved.

Detecting cell lysis using viscosity monitoring in E. coli fermentation to prevent product loss.

PubMed

Newton, Joseph M; Schofield, Desmond; Vlahopoulou, Joanna; Zhou, Yuhong

2016-07-08

Monitoring the physical or chemical properties of cell broths to infer cell status is often challenging due to the complex nature of the broth. Key factors indicative of cell status include cell density, cell viability, product leakage, and DNA release to the fermentation broth. The rapid and accurate prediction of cell status for hosts with intracellular protein products can minimise product loss due to leakage at the onset of cell lysis in fermentation. This article reports the rheological examination of an industrially relevant E. coli fermentation producing antibody fragments (Fab'). Viscosity monitoring showed an increase in viscosity during the exponential phase in relation to the cell density increase, a relatively flat profile in the stationary phase, followed by a rapid increase which correlated well with product loss, DNA release and loss of cell viability. This phenomenon was observed over several fermentations that a 25% increase in broth viscosity (using induction-point viscosity as a reference) indicated 10% product loss. Our results suggest that viscosity can accurately detect cell lysis and product leakage in postinduction cell cultures, and can identify cell lysis earlier than several other common fermentation monitoring techniques. This work demonstrates the utility of rapidly monitoring the physical properties of fermentation broths, and that viscosity monitoring has the potential to be a tool for process development to determine the optimal harvest time and minimise product loss. © 2016 The Authors. Biotechnology Progress published by Wiley Periodicals, Inc. on behalf of American Institute of Chemical Engineers, 32:1069-1076, 2016. © 2016 The Authors. Biotechnology Progress published by Wiley Periodicals, Inc. on behalf of American Institute of Chemical Engineers.

Phenomenological constraints on the bulk viscosity of QCD

NASA Astrophysics Data System (ADS)

Paquet, Jean-François; Shen, Chun; Denicol, Gabriel; Jeon, Sangyong; Gale, Charles

2017-11-01

While small at very high temperature, the bulk viscosity of Quantum Chromodynamics is expected to grow in the confinement region. Although its precise magnitude and temperature-dependence in the cross-over region is not fully understood, recent theoretical and phenomenological studies provided evidence that the bulk viscosity can be sufficiently large to have measurable consequences on the evolution of the quark-gluon plasma. In this work, a Bayesian statistical analysis is used to establish probabilistic constraints on the temperature-dependence of bulk viscosity using hadronic measurements from RHIC and LHC.

Shear viscosities of photons in strongly coupled plasmas

DOE PAGES

Yang, Di-Lun; Müller, Berndt

2016-07-18

We investigate the shear viscosity of thermalized photons in the quark gluon plasma (QGP) at weak coupling and N=4 super Yang–Mills plasma (SYMP) at both strong and weak couplings. We find that the shear viscosity due to the photon–parton scattering up to the leading order of electromagnetic coupling is suppressed when the coupling of the QGP/SYMP is increased, which stems from the blue-shift of the thermal-photon spectrum at strong coupling. In addition, the shear viscosity rapidly increases near the deconfinement transition in a phenomenological model analogous to the QGP.

Methods of Viscosity Measurements in Sealed Ampoules

NASA Technical Reports Server (NTRS)

Mazuruk, Konstantin

1999-01-01

Viscosity of semiconductor and metallic melts is usually measured by oscillating cup method. This method utilizes the melts contained in vacuum sealed silica ampoules, thus the problems related to volatility, contamination, and high temperature and pressure can be alleviated. In a typical design, the time required for a single measurement is of the order of one hour. In order to reduce this time to a minute range, a high resolution (0.05 arc.sec) angular detection system is implemented in our design of the viscometer. Furthermore, an electromagnet generating a rotational magnetic field (RMF) is incorporated into the apparatus. This magnetic field can be used to remotely and non intrusively measure the electrical conductivity of the melt. It can also be used to induce a well controlled rotational flow in the system. The transient behavior of this flow can potentially yield the viscosity of the fluid. Based on RMF implementation, two novel viscometry methods are proposed in this work: a) the transient torque method, b) the resonance method. A unified theoretical approach to the three methods (oscillating cup, transient torque, and resonance) is presented along with the initial test results of the constructed apparatus. Advantages of each of the method are discussed.

Mapping Protein–Protein Interactions of the Resistance-Related Bacterial Zeta Toxin–Epsilon Antitoxin Complex (ε2ζ2) with High Affinity Peptide Ligands Using Fluorescence Polarization

PubMed Central

Fernández-Bachiller, María Isabel; Brzozowska, Iwona; Odolczyk, Norbert; Zielenkiewicz, Urszula; Zielenkiewicz, Piotr; Rademann, Jörg

2016-01-01

Toxin–antitoxin systems constitute a native survival strategy of pathogenic bacteria and thus are potential targets of antibiotic drugs. Here, we target the Zeta–Epsilon toxin–antitoxin system, which is responsible for the stable maintenance of certain multiresistance plasmids in Gram-positive bacteria. Peptide ligands were designed on the basis of the ε2ζ2 complex. Three α helices of Zeta forming the protein–protein interaction (PPI) site were selected and peptides were designed conserving the residues interacting with Epsilon antitoxin while substituting residues binding intramolecularly to other parts of Zeta. Designed peptides were synthesized with an N-terminal fluoresceinyl-carboxy-residue for binding assays and provided active ligands, which were used to define the hot spots of the ε2ζ2 complex. Further shortening and modification of the binding peptides provided ligands with affinities <100 nM, allowing us to determine the most relevant PPIs and implement a robust competition binding assay. PMID:27438853

The viscosity of magmatic silicate liquids: A model for calculation

NASA Technical Reports Server (NTRS)

Bottinga, Y.; Weill, D. F.

1971-01-01

A simple model has been designed to allow reasonably accurate calculations of viscosity as a function of temperature and composition. The problem of predicting viscosities of anhydrous silicate liquids has been investigated since such viscosity numbers are applicable to many extrusive melts and to nearly dry magmatic liquids in general. The fluidizing action of water dissolved in silicate melts is well recognized and it is now possible to predict the effect of water content on viscosity in a semiquantitative way. Water was not incorporated directly into the model. Viscosities of anhydrous compositions were calculated, and, where necessary, the effect of added water and estimated. The model can be easily modified to incorporate the effect of water whenever sufficient additional data are accumulated.

Fluorescence lifetime imaging of optically levitated aerosol: a technique to quantitatively map the viscosity of suspended aerosol particles.

PubMed

Fitzgerald, C; Hosny, N A; Tong, H; Seville, P C; Gallimore, P J; Davidson, N M; Athanasiadis, A; Botchway, S W; Ward, A D; Kalberer, M; Kuimova, M K; Pope, F D

2016-08-21

We describe a technique to measure the viscosity of stably levitated single micron-sized aerosol particles. Particle levitation allows the aerosol phase to be probed in the absence of potentially artefact-causing surfaces. To achieve this feat, we combined two laser based techniques: optical trapping for aerosol particle levitation, using a counter-propagating laser beam configuration, and fluorescent lifetime imaging microscopy (FLIM) of molecular rotors for the measurement of viscosity within the particle. Unlike other techniques used to measure aerosol particle viscosity, this allows for the non-destructive probing of viscosity of aerosol particles without interference from surfaces. The well-described viscosity of sucrose aerosol, under a range of relative humidity conditions, is used to validate the technique. Furthermore we investigate a pharmaceutically-relevant mixture of sodium chloride and salbutamol sulphate under humidities representative of in vivo drug inhalation. Finally, we provide a methodology for incorporating molecular rotors into already levitated particles, thereby making the FLIM/optical trapping technique applicable to real world aerosol systems, such as atmospheric aerosols and those generated by pharmaceutical inhalers.

Textured-surface quartz resonator fluid density and viscosity monitor

DOEpatents

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

1998-08-25

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.

Zeta potential response of human erythrocyte membranes to the modulators of Gardos channel activity under low rate β-radiation.

PubMed

Zhirnov, V V; Iakovenko, I N; Voitsitskiy, V M; Khyzhnyak, S V; Zubrikova-Chugainova, O G; Gorobetz, V A

2015-12-01

Study of human erythrocyte DP response under modification by activators and blockers of the functional state of Ca2+-dependent K+ channels under low rate β-radiation. Erythrocytes were isolated from the donor blood. The zeta potential was computed from the value of the cell electrophoretic mobility. The investigated drugs preliminary introduced in cellular suspensions, and then aliquote of 90Sr(NO3)2 solution to get the final activity concentration of 44,4kBq⋅l-1. The radioisotope radiation of 90Sr/90Y (RR, 15 μGy⋅h-1) increases an absolute value of erythrocyte membranes DP (DPab), and its action is reversible. It specifies the effect is mediated by non-ionizing part of the RR. Dibutyril-cAMP dose-independent increases DPab of erythrocyte membranes in the concentration range of 1-100 мкМ, but RR does not amplify this effect. Anaprilin increases dose-independent DPab in concentrations 10 and 100 μМ. The effect of maximal concentration of anaprilin (100 μМ) decreases by RR. Clotrimazol increases DPab of erythrocyte membranes in the concentration range of 0,1-10 μМ relatively control, while its maximal concentration - decreases, and the minimal level does not reliably influence on this index The action of сlotrimazol on DP in concentrations of 10-100 μМ is abolished by RR, and is not changed in the range of 0,1-1,0 μМ. Nitrendipine raises DPab of erythrocyte membranes in all of range of concentrations, and RR amplifies the effect of the drug. 1. There is a threshold of the biological action on cells for the ionizing component of radioisotope radiation determined by efficiency of operation their antioxidant system.2. At dose rates below a threshold, the action of ionizing radiation is mediated by its non-ionizing component, and is reversible, and therefore is determined only in the field of radiation. V. V. Zhirnov, I. N. Iakovenko, V.M. Voitsitskiy, S. V. Khyzhnyak, О. G. Zubrikova-Chugainova, V.A. Gorobetz.

Peristalsis of nonconstant viscosity Jeffrey fluid with nanoparticles

NASA Astrophysics Data System (ADS)

Alvi, N.; Latif, T.; Hussain, Q.; Asghar, S.

Mixed convective peristaltic activity of variable viscosity nanofluids is addressed. Unlike the conventional consideration of constant viscosity; the viscosity is taken as temperature dependent. Constitutive relations for linear viscoelastic Jeffrey fluid are employed and uniform magnetic field is applied in the transverse direction. For nanofluids, the formulation is completed in presence of Brownian motion, thermophoresis, viscous dissipation and Joule heating. Consideration of temperature dependence of viscosity is not a choice but the realistic requirement of the wall temperature and the heat generated due to the viscous dissipation. Well established large wavelength and small Reynolds number approximations are invoked. Non-linear coupled system is analytically solved for the convergent series solutions identifying the interval of convergence explicitly. A comparative study between analytical and numerical solution is made for certainty. Influence of the parameters undertaken for the description of the problem is pointed out and its physics explained.

Viscosity of alumina nanoparticles dispersed in car engine coolant

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kole, Madhusree; Dey, T.K.

The present paper, describes our experimental results on the viscosity of the nanofluid prepared by dispersing alumina nanoparticles (<50 nm) in commercial car coolant. The nanofluid prepared with calculated amount of oleic acid (surfactant) was tested to be stable for more than 80 days. The viscosity of the nanofluids is measured both as a function of alumina volume fraction and temperature between 10 and 50 C. While the pure base fluid display Newtonian behavior over the measured temperature, it transforms to a non-Newtonian fluid with addition of a small amount of alumina nanoparticles. Our results show that viscosity of themore » nanofluid increases with increasing nanoparticle concentration and decreases with increase in temperature. Most of the frequently used classical models severely under predict the measured viscosity. Volume fraction dependence of the nanofluid viscosity, however, is predicted fairly well on the basis of a recently reported theoretical model for nanofluids that takes into account the effect of Brownian motion of nanoparticles in the nanofluid. The temperature dependence of the viscosity of engine coolant based alumina nanofluids obeys the empirical correlation of the type: log ({mu}{sub nf}) = A exp(BT), proposed earlier by Namburu et al. (author)« less

Local viscosity distribution in bifurcating microfluidic blood flows

NASA Astrophysics Data System (ADS)

Kaliviotis, E.; Sherwood, J. M.; Balabani, S.

2018-03-01

The red blood cell (RBC) aggregation phenomenon is majorly responsible for the non-Newtonian nature of blood, influencing the blood flow characteristics in the microvasculature. Of considerable interest is the behaviour of the fluid at the bifurcating regions. In vitro experiments, using microchannels, have shown that RBC aggregation, at certain flow conditions, affects the bluntness and skewness of the velocity profile, the local RBC concentration, and the cell-depleted layer at the channel walls. In addition, the developed RBC aggregates appear unevenly distributed in the outlets of these channels depending on their spatial distribution in the feeding branch, and on the flow conditions in the outlet branches. In the present work, constitutive equations of blood viscosity, from earlier work of the authors, are applied to flows in a T-type bifurcating microchannel to examine the local viscosity characteristics. Viscosity maps are derived for various flow distributions in the outlet branches of the channel, and the location of maximum viscosity magnitude is obtained. The viscosity does not appear significantly elevated in the branches of lower flow rate as would be expected on the basis of the low shear therein, and the maximum magnitude appears in the vicinity of the junction, and towards the side of the outlet branch with the higher flow rate. The study demonstrates that in the branches of lower flow rate, the local viscosity is also low, helping us to explain why the effects of physiological red blood cell aggregation have no adverse effects in terms of in vivo vascular resistance.

Plasma viscosity with mass transport in spherical inertial confinement fusion implosion simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vold, E. L.; Molvig, K.; Joglekar, A. S.

2015-11-15

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 Lagrangian 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 andmore » 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 reduces the need for artificial viscosity to maintain numerical stability in the Lagrangian formulation and also modifies the flux-limiting needed for electron thermal conduction.« less

Measurement of the microscopic viscosities of microfluids with a dynamic optical tweezers system

NASA Astrophysics Data System (ADS)

Zhang, Yuquan; Wu, Xiaojing; Wang, Yijia; Zhu, Siwei; Gao, Bruce Z.; Yuan, X.-C.

2014-06-01

Viscosity coefficients of microfluids—Newtonian and non-Newtonian—were explored through the rotational motion of a particle trapped by optical tweezers in a microflute. Unlike conventional methods based on viscometers, our microfluidic system employs samples of less than 30 μl to complete a measurement. Viscosity coefficients of ethanol and fetal bovine serum, as typical examples of Newtonian and non-Newtonian fluids, were obtained experimentally, and found to be in excellent agreement with theoretical predictions. Additionally, a practical application to a DNA solution with incremental ethidium bromide content was employed and the results are consistent with clinical data, indicating that our system provides a potentially important complementary tool for use in such biological and medical applications.

Design of Oil Viscosity Sensor Based on Plastic Optical Fiber

NASA Astrophysics Data System (ADS)

Yunus, Muhammad; Arifin, A.

2018-03-01

A research of plastic optical fiber based sensors have been studied for measurement of oil viscosity. This sensor was made with straight configuration, U configuration, and gamma configuration have two types, there are optical fiber sensor with cladding and without cladding. Viscosity sensor was made, dipped into an oil sample with a concentration of viscosity percentage about 270 mPa.s - 350 mPa.s. The light from the LED propagated into the optical fiber, then it was received by the photodetector converted to output power. When plastic optical fiber dipped into an oil sample, viscosity of oil affect increase of refractive index on optical fiber resulting in a bigger loss of power so the light intensity will be smaller, consequences the measured output power will be smaller. Sensitivity and resolution viscosity sensor without cladding peel showed the best result rather than viscosity sensor with cladding peel. The best result in the measurement showed in gamma configuration with 3 cm length of cladding peel and the diameter of bending 0,25 cm is the range 103,090 nWatt, sensitivity 1,289 nWatt/mPa.s, and resolution 0,776 mPa.s. This method is effectively and efficiently used as an oil viscosity sensor with high sensitivity and resolution.

Heat flux viscosity in collisional magnetized plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, C., E-mail: cliu@pppl.gov; Fox, W.; Bhattacharjee, A.

2015-05-15

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 themore » 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.« less

The viscosity of pāhoehoe lava: In situ syn-eruptive measurements from Kilauea, Hawaii

NASA Astrophysics Data System (ADS)

Chevrel, Magdalena Oryaëlle; Harris, Andrew J. L.; James, Mike R.; Calabrò, Laura; Gurioli, Lucia; Pinkerton, Harry

2018-07-01

Viscosity is one of the most important physical properties controlling lava flow dynamics. Usually, viscosity is measured in the laboratory where key parameters can be controlled but can never reproduce the natural environment and original state of the lava in terms of crystal and bubble contents, dissolved volatiles, and oxygen fugacity. The most promising approach for quantifying the rheology of molten lava in its natural state is therefore to carry out direct field measurements by inserting a viscometer into the lava while it is flowing. Such in-situ syn-eruptive viscosity measurements are notoriously difficult to perform due to the lack of appropriate instrumentation and the difficulty of working on or near an active lava flow. In the field, rotational viscometer measurements are of particular value as they have the potential to measure the properties of the flow interior rather than an integration of the viscosity of the viscoelastic crust + flow interior. To our knowledge only one field rotational viscometer is available, but logistical constraints have meant that it has not been used for 20 yr. Here, we describe new viscosity measurements made using the refurbished version of this custom-built rotational viscometer, as performed on active pāhoehoe lobes from the 61G lava flow of Kilauea's Pu'u 'Ō'ō eruption in 2016. We successfully measured a viscosity of ∼380 Pa s at strain-rates between 1.6 and 5 s-1 and at 1144 °C. Additionally, synchronous lava sampling allowed us to provide detailed textural and chemical characterization of quenched samples. Application of current physico-chemical models based on this characterization (16 ± 4 vol.% crystals; 50 ± 6 vol.% vesicles), gave viscosity estimates that were approximately compatible with the measured values, highlighting the sensitivity of model-based viscosity estimates on the effect of deformable bubbles. Our measurements also agree on the range of viscosities in comparison to previous field

Measurement and correlation of jet fuel viscosities at low temperatures

NASA Technical Reports Server (NTRS)

Schruben, D. L.

1985-01-01

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.

Effect of viscosity on tear drainage and ocular residence time.

PubMed

Zhu, Heng; Chauhan, Anuj

2008-08-01

An increase in residence time of dry eye medications including artificial tears will likely enhance therapeutic benefits. The drainage rates and the residence time of eye drops depend on the viscosity of the instilled fluids. However, a quantitative understanding of the dependence of drainage rates and the residence time on viscosity is lacking. The current study aims to develop a mathematical model for the drainage of Newtonian fluids and also for power-law non-Newtonian fluids of different viscosities. This study is an extension of our previous study on the mathematical model of tear drainage. The tear drainage model is modified to describe the drainage of Newtonian fluids with viscosities higher than the tear viscosity and power-law non-Newtonian fluids with rheological parameters obtained from fitting experimental data in literature. The drainage rate through canaliculi was derived from the modified drainage model and was incorporated into a tear mass balance to calculate the transients of total solute quantity in ocular fluids and the bioavailability of instilled drugs. For Newtonian fluids, increasing the viscosity does not affect the drainage rate unless the viscosity exceeds a critical value of about 4.4 cp. The viscosity has a maximum impact on drainage rate around a value of about 100 cp. The trends are similar for shear thinning power law fluids. The transients of total solute quantity, and the residence time agrees at least qualitatively with experimental studies. A mathematical model has been developed for the drainage of Newtonian fluids and power-law fluids through canaliculi. The model can quantitatively explain different experimental observations on the effect of viscosity on the residence of instilled fluids on the ocular surface. The current study is helpful for understanding the mechanism of fluid drainage from the ocular surface and for improving the design of dry eye treatments.

Diffusion coefficient and shear viscosity of rigid water models.

PubMed

Tazi, Sami; Boţan, Alexandru; Salanne, Mathieu; Marry, Virginie; Turq, Pierre; Rotenberg, Benjamin

2012-07-18

We report the diffusion coefficient and viscosity of popular rigid water models: two non-polarizable ones (SPC/E with three sites, and TIP4P/2005 with four sites) and a polarizable one (Dang-Chang, four sites). We exploit the dependence of the diffusion coefficient on the system size (Yeh and Hummer 2004 J. Phys. Chem. B 108 15873) to obtain the size-independent value. This also provides an estimate of the viscosity of all water models, which we compare to the Green-Kubo result. In all cases, a good agreement is found. The TIP4P/2005 model is in better agreement with the experimental data for both diffusion and viscosity. The SPC/E and Dang-Chang models overestimate the diffusion coefficient and underestimate the viscosity.

Viscosity-dependent diffusion of fluorescent particles using fluorescence correlation spectroscopy.

PubMed

Jung, Chanbae; Lee, Jaeran; Kang, Manil; Kim, Sok Won

2014-11-01

Fluorescent particles show the variety characteristics by the interaction with other particles and solvent. In order to investigate the relationship between the dynamic properties of fluorescent particles and solvent viscosity, particle diffusion in various solvents was evaluated using a fluorescence correlation spectroscopy. Upon analyzing the correlation functions of AF-647, Q-dot, and beads with different viscosity values, the diffusion time of all particles was observed to increase with increasing solvent viscosity, and the ratio of diffusion time to solvent viscosity, τ D /η, showed a linear dependence on particle size. The particle diffusion coefficients calculated from the diffusion time decreased with increasing solvent viscosity. Further, the hydrodynamic radii of AF-647, Q-dot, and beads were 0.98 ± 0.1 nm, 64.8 ± 3.23 nm, and 89.8 ± 4.91 nm, respectively, revealing a linear dependence on τ D /η, which suggests that the hydrodynamic radius of a particle strongly depends on both the physical size of the particle and solvent viscosity.

An interstellar cloud density from Copernicus observations of CO in the spectrum of Zeta Ophiuchi

NASA Technical Reports Server (NTRS)

Smith, A. M.; Stecher, T. P.; Krishna Swamy, K. S.

1978-01-01

Interstellar CO absorption bands in Copernicus spectra of Zeta Oph have been studied. Absorption profiles, computed under the assumption that excitation is due to collisions with H2 molecules and interaction with the 3-K background radiation field, were fitted to the reduced data of nine bands. When a gas kinetic temperature of 56 K is assumed, the best-fit condition implies a hydrogen-nucleus density of 120 per cu cm, a CO column density of 1.2 by 10 to the 15th power per sq cm, and a radial-velocity dispersion of 0.9 km/s. The relevance of these results to existing ideas concerning the Zeta Oph interstellar clouds is discussed. It is suggested that the strongest interstellar component is not circumstellar in origin but is instead part of a supernova remnant. Simple calculations are made to establish the plausibility of the supernova-remnant identification. This suggestion is also supported by Heiles's (1976) 21-cm pictures.

Relating Fresh Concrete Viscosity Measurements from Different Rheometers

PubMed Central

Ferraris, Chiara F.; Martys, Nicos S.

2003-01-01

Concrete rheological properties need to be properly measured and predicted in order to characterize the workability of fresh concrete, including special concretes such as self-consolidating concrete (SCC). It was shown by a round-robin test held in 2000 [1,2] that different rheometer designs gave different values of viscosity for the same concrete. While empirical correlation between different rheometers was possible, for a procedure that is supposed to “scientifically” improve on the empirical slump tests, this situation is unsatisfactory. To remedy this situation, a new interpretation of the data was developed. In this paper, it is shown that all instruments tested could be directly and quantitatively compared in terms of relative plastic viscosity instead of the plastic viscosity alone. This should eventually allow the measurements from various rheometer designs to be directly calibrated against known standards of plastic viscosity, putting concrete rheometry and concrete workability on a sounder materials science basis. PMID:27413607

Interstellar detection of the intersystem line Si II lambda 2335 toward zeta Ophiuchi

NASA Technical Reports Server (NTRS)

Cardelli, Jason A.; Sofia, Ulysses J.; Savage, Blair D.; Keenan, Francis P.; Dufton, Philip L.

1994-01-01

We report on the detection of the weak intersystem transistion of Si II lambda 2335 A in the sight line toward zeta Oph using the Ech-B mode (3.5 km/s resolution) of the Goddard High Resolution Spectrograph. The high-quality spectrum is characterized by an empirically measured signal-to-noise of 450, in excellent agreement with that expected from photon-statistics. The measured equivalent width of the Si II line is W(sub lambda) = 0.48 +/- 0.12 mA. Using the new experimental f-value of Calamai, Smith, and Bergeson, we find a Si II column density of 2.34 (+/- 0.58) x 10(exp 15) atoms/sq cm and (Si/H)(sub zeta Oph) = 1.78 (+/- 0.44) x 10(exp -6) for the principal absorbing component(s) at v(sub sun) approx. = -15 km/s. Analysis of the Si II lambda 1808 absorption over the same velocity range using the new experimental f-value of Bergeson & Lawler yields a column density (corrected for saturation) that is consistent within the weak line errors and confirms the relative accuracies of these new f-values. Furthermore, these results indicate that accurate abundances can now be derived for Si II, particularly from the weak Si II lambda 2335 A since it is free of saturation effects. For the zeta Oph v(sub sun) approx. = -15 km/s component(s), we find that greater than 95% of the available cosmic abundance (i.e. the 1989 meteoritic abundances of Anders & Grevesse) of Mg, Fe, and Si is 'missing' from the gas phase and is presumably locked up in the dust. These elements are present in the dust grains in ratios of Fe/Si approximately equals 0.9 and Mg/Si approximately equals 1.1, consistent with the ratio of their cosmic abundances. These ratios are in sharp contrast to more diffuse clouds like those seen toward the high-latitude halo star HD 93521 where in the dust Fe/Si approximately equals 1.8 and Mg/Si approximately equals 2.1.

HD 93521, zeta Ophiuchi, and the effects of rapid rotation on the atmospheres and winds of 09.5 V stars

NASA Technical Reports Server (NTRS)

Massa, Derck

1995-01-01

Both low- and high-resolution IUE spectra of the rapidly rotating 09.5 V stars HD 93521 and zeta Oph are used to develop a coherent picture of the effects of rapid rotation on the atmospheres and winds of late, main-sequence O stars. The observational consequences are by far the strongest on HD 93521, most likely because it is being viewed nearly equator-on. In particular, it is shown that HD 93521 (1) a much smaller UV optical flux ratio than expected, (2) UV photospheric lines indicative of a BO supergiant, (3) an abnormally strong N v wind doublet, and (4) wind profiles suggesting that its wind has latitudinally dependent properties. Because HD 93521 has a larger observed v sin i than zeta Oph and yet its H-alpha emission is no stronger than in zeta Oph, it is speculated that zeta Oph actually rotates as fast or faster than HD 93521, but has a smaller sin i. Because zeta Oph is significantly reddened, nothing can be determined about its intrinsic UV energy distribution. However, it is shown that its UV photospheric lines are a bit peculiar and that its C IV and N V wind doublets are abnormally strong and have unusual profiles. The C IV profile agrees with models of a rotationally distorted wind similar to the one in HD 93521, except viewed at an angle i approximately 60 deg-80 deg. The spectral peculiarities of both stars are attributed to the combined effects of gravity darkening of their atmospheres and rotational distortion of their winds. The differences between their spectra are interpreted as the result of being viewed at different inclination angles. Because of the gravity darkening, atmospheric analyses of either star based on single temperature and surface gravity model atmospheres are probably unreliable. Finally, I describe how different effects conspire to make the spectroscopic signatures of gravity darkening so pronounced at 09.5 V.

A viscosity sensitive fluorescent dye for real-time monitoring of mitochondria transport in neurons.

PubMed

Baek, Yeonju; Park, Sang Jun; Zhou, Xin; Kim, Gyungmi; Kim, Hwan Myung; Yoon, Juyoung

2016-12-15

We present here a viscosity sensitive fluorescent dye, namely thiophene dihemicyanine (TDHC), that enables the specific staining of mitochondria. In comparison to the common mitochondria tracker (Mitotracker Deep Red, MTDR), this dye demonstrated its unique ability for robust staining of mitochondria with high photostability and ultrahigh signal-to-noise ratio (SNR). Moreover, TDHC also showed high sensitivity towards mitochondria membrane potential (ΔΨm) and intramitochondria viscosity change. Consequently, this dye was utilized in real-time monitoring of mitochondria transport in primary cortical neurons. Finally, the Two-Photon Microscopy (TPM) imaging ability of TDHC was also demonstrated. Copyright © 2016 Elsevier B.V. All rights reserved.

Impact of Viscosity on Filling the Injection Mould Cavity

NASA Astrophysics Data System (ADS)

Satin, Lukáš; Bílik, Jozef

2016-09-01

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.

Polyfunctional dispersants for controlling viscosity of phyllosilicates

DOEpatents

Chaiko, David J.

2006-07-25

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.

Diffusion, Viscosity and Crystal Growth in Microgravity

NASA Technical Reports Server (NTRS)

Myerson, Allan S.

1996-01-01

The diffusivity of TriGlycine Sulfate (TGS), Potassium Dihydrogen Phosphate (KDP), Ammonium Dihydrogen Phosphate (ADF) and other compounds of interest to microgravity crystal growth, in supersaturated solutions as a function of solution concentration, 'age' and 'history was studied experimentally. The factors that affect the growth of crystals from water solutions in microgravity have been examined. Three non-linear optical materials have been studied, potassium dihydrogen phosphate (KDP), ammonium dihydrogen phosphate (ADP) and triglycine sulfate (TGC). The diffusion coefficient and viscosity of supersaturated water solutions were measured. Also theoretical model of diffusivity and viscosity in a metastable state, model of crystal growth from solution including non-linear time dependent diffusivity and viscosity effect and computer simulation of the crystal growth process which allows simulation of the microgravity crystal growth were developed.

The reality of artificial viscosity

DOE PAGES

Margolin, L. G.

2018-02-24

Artificial viscosity is used in the computer simulation of high Reynolds number flows and is one of the oldest numerical artifices. In this work, I will describe the origin and the interpretation of artificial viscosity as a physical phenomenon. The basis of this interpretation is the finite scale theory, which describes the evolution of integral averages of the fluid solution over finite (length) scales. I will outline the derivation of finite scale Navier–Stokes equations and highlight the particular properties of the equations that depend on the finite scales. Those properties include enslavement, inviscid dissipation, and a law concerning the partitionmore » of total flux of conserved quantities into advective and diffusive components.« less

The reality of artificial viscosity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Margolin, L. G.

Artificial viscosity is used in the computer simulation of high Reynolds number flows and is one of the oldest numerical artifices. In this work, I will describe the origin and the interpretation of artificial viscosity as a physical phenomenon. The basis of this interpretation is the finite scale theory, which describes the evolution of integral averages of the fluid solution over finite (length) scales. I will outline the derivation of finite scale Navier–Stokes equations and highlight the particular properties of the equations that depend on the finite scales. Those properties include enslavement, inviscid dissipation, and a law concerning the partitionmore » of total flux of conserved quantities into advective and diffusive components.« less

Dairy-Based Emulsions: Viscosity Affects Fat Difference Thresholds and Sweetness Perception.

PubMed

Zahn, Susann; Hoppert, Karin; Ullrich, Franziska; Rohm, Harald

2013-11-27

In complex emulsions, viscosity or viscosity-associated sensory attributes such as creaminess are important for quality assessment and product differentiation. Two sets of emulsions with fat or locust bean gum content being varied at seven levels were developed; the two emulsions at each level had similar apparent viscosity. Additionally, sugar concentration was kept constant either with respect to total emulsion, or with respect to the aqueous phase. Series of two-alternative forced choice tests were performed with one constant stimulus, and just noticeable differences were calculated using probability regression. The results show that, when viscosity was not compensated, it was easy for the subjects to (a) distinguish emulsions with different fat content when the fat content was addressed in the question, and to (b) distinguish emulsions with different fat or locust bean gum content when creaminess was addressed. For the latter descriptor, it is of minor importance whether viscosity is altered by fat content or a thickener. Weber fractions that were calculated for viscosity were approximately 0.20. The quantitative effects of viscosity on sweetness, however, depend on how product rheology was modified.

Live Cell Imaging of Viscosity in 3D Tumour Cell Models.

PubMed

Shirmanova, Marina V; Shimolina, Lubov' E; Lukina, Maria M; Zagaynova, Elena V; Kuimova, Marina K

2017-01-01

Abnormal levels of viscosity in tissues and cells are known to be associated with disease and malfunction. While methods to measure bulk macroscopic viscosity of bio-tissues are well developed, imaging viscosity at the microscopic scale remains a challenge, especially in vivo. Molecular rotors are small synthetic viscosity-sensitive fluorophores in which fluorescence parameters are strongly correlated to the microviscosity of their immediate environment. Hence, molecular rotors represent a promising instrument for mapping of viscosity in living cells and tissues at the microscopic level. Quantitative measurements of viscosity can be achieved by recording time-resolved fluorescence decays of molecular rotor using fluorescence lifetime imaging microscopy (FLIM), which is also suitable for dynamic viscosity mapping, both in cellulo and in vivo. Among tools of experimental oncology, 3D tumour cultures, or spheroids, are considered a more adequate in vitro model compared to a cellular monolayer, and represent a less labour-intensive and more unified approach compared to animal tumour models. This chapter describes a methodology for microviscosity imaging in tumour spheroids using BODIPY-based molecular rotors and two photon-excited FLIM.

Analyte preconcentration in nanofluidic channels with nonuniform zeta potential

NASA Astrophysics Data System (ADS)

Eden, A.; McCallum, C.; Storey, B. D.; Pennathur, S.; Meinhart, C. D.

2017-12-01

It is well known that charged analytes in the presence of nonuniform electric fields concentrate at locations where the relevant driving forces balance, and a wide range of ionic stacking and focusing methods are commonly employed to leverage these physical mechanisms in order to improve signal levels in biosensing applications. In particular, nanofluidic channels with spatially varying conductivity distributions have been shown to provide increased preconcentration of charged analytes due to the existence of a finite electric double layer (EDL), in which electrostatic attraction and repulsion from charged surfaces produce nonuniform transverse ion distributions. In this work, we use numerical simulations to show that one can achieve greater levels of sample accumulation by using field-effect control via wall-embedded electrodes to tailor the surface potential heterogeneity in a nanochannel with overlapped EDLs. In addition to previously demonstrated stacking and focusing mechanisms, we find that the coupling between two-dimensional ion distributions and the axial electric field under overlapped EDL conditions can generate an ion concentration polarization interface in the middle of the channel. Under an applied electric field, this interface can be used to concentrate sample ions between two stationary regions of different surface potential and charge density. Our numerical model uses the Poisson-Nernst-Planck system of equations coupled with the Stokes equation to demonstrate the phenomenon, and we discuss in detail the driving forces behind the predicted sample enhancement. The numerical velocity and salt concentration profiles exhibit good agreement with analytical results from a simplified one-dimensional area-averaged model for several limiting cases, and we show predicted amplification ratios of up to 105.

Apparatus and method for measuring viscosity

DOEpatents

Murphy, R.J. Jr.

1986-02-25

The present invention is directed to an apparatus and method for measuring the viscosity of a fluid. This apparatus and method is particularly useful for the measurement of the viscosity of a liquid in a harsh environment characterized by high temperature and the presence of corrosive or deleterious gases and vapors which adversely affect conventional ball or roller bearings. The apparatus and method of the present invention employ one or more flexural or torsional bearings to suspend a bob capable of limited angular motion within a rotatable sleeve suspended from a stationary frame. 7 figs.

Apparatus and method for measuring viscosity

DOEpatents

Murphy, Jr., Robert J.

1986-01-01

The present invention is directed to an apparatus and method for measuring the viscosity of a fluid. This apparatus and method is particularly useful for the measurement of the viscosity of a liquid in a harsh environment characterized by high temperature and the presence of corrosive or deleterious gases and vapors which adversely affect conventional ball or roller bearings. The apparatus and method of the present invention employ one or more flexural or torsional bearings to suspend a bob capable of limited angular motion within a rotatable sleeve suspended from a stationary frame.

Radiating gravitational collapse with shear viscosity

NASA Astrophysics Data System (ADS)

Chan, R.

2000-08-01

A model is proposed of a collapsing radiating star consisting of an isotropic fluid with shear viscosity undergoing radial heat flow with outgoing radiation. The pressure of the star, at the beginning of the collapse, is isotropic but owing to the presence of the shear viscosity the pressure becomes more and more anisotropic. The behaviour of the density, pressure, mass, luminosity and the effective adiabatic index is analysed. Our work is compared to the case of a collapsing shearing fluid of a previous model, for a star with 6Msolar.

Hall viscosity and electromagnetic response of electrons in graphene

NASA Astrophysics Data System (ADS)

Sherafati, Mohammad; Principi, Alessandro; Vignale, Giovanni

The Hall viscosity is a dissipationless component of the viscosity tensor of an electron liquid with broken time- reversal symmetry, such as a two-dimensional electron gas (2DEG) in the quantum Hall state. Similar to the Hall conductivity, the Hall viscosity is an anomalous transport coefficient; however, while the former is connected with the current response, the latter stems from the stress response to a geometric deformation. For a Galilean-invariant system such as 2DEG, the current density is indeed the generator of the geometric deformation: therefore a connection between the Hall connectivity and viscosity is expected and by now well established. In the case of graphene, a non-Galilean-invariant system, the existence of such a connection is far from obvious, as the current operator is essentially different from the momentum operator. In this talk, I will first present our results of the geometric Hall viscosity of electrons in single-layer graphene. Then, from the expansion of the nonlocal Hall conductivity for small wave vectors, I demonstrate that, in spite of the lack of Galilean invariance, an effective mass can be defined such that the relationship between the Hall conductivity and the viscosity retains the form it has in Galilean-invariant systems, not only for a large number of occupied Landau levels, but also, with very high accuracy, for the undoped system.

Evaluation of Lama glama semen viscosity with a cone-plate rotational viscometer.

PubMed

Casaretto, C; Martínez Sarrasague, M; Giuliano, S; Rubin de Celis, E; Gambarotta, M; Carretero, I; Miragaya, M

2012-05-01

Llama semen is highly viscous. This characteristic is usually evaluated subjectively by measuring the thread formed when carefully pippeting a sample of semen. The aims of this study were (i) to objectively determine and analyse llama semen viscosity, (ii) to compare semen viscosity between ejaculates of the same male as well as between different males, (iii) to study the correlation between viscosity and other semen characteristics and (iv) to evaluate the effect of collagenase on semen viscosity. Semen viscosity was evaluated using a cone-plate Brookfield rotational viscometer. A non Newtonian, pseudoplastic behaviour was observed in the 45 semen samples evaluated. Rheological parameters were determined obtaining the following results (mean ± SD): apparent viscosity at 11.5 s(-1): 46.71 ± 26.8 cpoise and at 115 s(-1): 12.61 ± 4.1 cpoise; structural viscosity (K) (dyne s cm(-2)): 2.18 ± 1.4 and coefficient of consistency (n): 0.45 ± 0.1. Statistical differences were found between different ejaculates of the same male for structural viscosity and apparent viscosity at 11.5 s(-1) (P < 0.01). Correlation was found only between coefficient of consistency (n) and sperm concentration (P < 0.01). Significant differences for coefficient of consistency (n) and viscosity at 115 s(-1) were found between samples incubated with and without collagenase (P < 0.05). © 2011 Blackwell Verlag GmbH.

Torque Transient of Magnetically Drive Flow for Viscosity Measurement

NASA Technical Reports Server (NTRS)

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

2004-01-01

Viscosity is a good indicator of structural changes for complex liquids, such as semiconductor melts with chain or ring structures. This paper discusses the theoretical and experimental results of the transient torque technique for non-intrusive viscosity measurement. Such a technique is essential for the high temperature viscosity measurement of high pressure and toxic semiconductor melts. In this paper, our previous work on oscillating cup technique was expanded to the transient process of a magnetically driven melt flow in a damped oscillation system. Based on the analytical solution for the fluid flow and cup oscillation, a semi-empirical model was established to extract the fluid viscosity. The analytical and experimental results indicated that such a technique has the advantage of short measurement time and straight forward data analysis procedures

Two-state protein model with water interactions: Influence of temperature on the intrinsic viscosity of myoglobin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bakk, Audun

2001-06-01

We describe a single-domain protein as a two-state system with water interactions. Around the unfolded apolar parts of the protein we incorporate the hydration effect by introducing hydrogen bonds between the water molecules in order to mimic the {open_quotes}icelike{close_quotes} shell structure. Intrinsic viscosity, proportional to the effective hydrodynamic volume, for sperm whale metmyoglobin is assigned from experimental data in the folded and in the denaturated state. By weighing statistically the two states against the degree of folding, we express the total intrinsic viscosity. The temperature dependence of the intrinsic viscosity, for different chemical potentials, is in good correspondence with experimentalmore » data [P. L. Privalov , J. Mol. Biol. >190, 487 (1986)]. Cold and warm unfolding, common to small globular proteins, is also a result of the model.« less

The performance of bioinspired valveless piezoelectric micropump with respect to viscosity change.

PubMed

Lee, Seung Chul; Hur, Sunghoon; Kang, Dooho; Kim, Bo Heum; Lee, Sang Joon

2016-04-29

This study investigated the effect of the serial connection of two pumping chambers on transport of liquid with increased viscosity. A serially connected valveless piezoelectric micropump was fabricated inspired by the liquid-feeding strategy of a female mosquito drinking liquid with a wide range of viscosities, from nectar to blood. The performance of the micropump was investigated by varying the viscosity of working liquid. Results showed that the optimal phase difference between the two chambers was 180° out-of-phase for all viscosity conditions. The two chambers operating at 180° out-of-phase exhibited higher pumping performance compared with the sum of each single chamber solely actuated, when viscosity increased. The flow patterns in the micropump showed that the rectification efficiency improved with the increase in viscosity. Results indicated that the serially connected valveless piezoelectric micropump is more robust to the increase of viscosity than a single-chamber piezoelectric micropump. This study would be helpful in the design of microfluidic devices for transporting liquids with a wide range of viscosities.

THE EFFECT OF ANISOTROPIC VISCOSITY ON COLD FRONTS IN GALAXY CLUSTERS

DOE Office of Scientific and Technical Information (OSTI.GOV)

ZuHone, J. A.; Markevitch, M.; Kunz, M. W.

2015-01-10

Cold fronts—contact discontinuities in the intracluster medium (ICM) of galaxy clusters—should be disrupted by Kelvin-Helmholtz (K-H) instabilities due to the associated shear velocity. However, many observed cold fronts appear stable. This opens the possibility of placing constraints on microphysical mechanisms that stabilize them, such as the ICM viscosity and/or magnetic fields. We performed exploratory high-resolution simulations of cold fronts arising from subsonic gas sloshing in cluster cores using the grid-based Athena MHD code, comparing the effects of isotropic Spitzer and anisotropic Braginskii viscosity (expected in a magnetized plasma). Magnetized simulations with full Braginskii viscosity or isotropic Spitzer viscosity reduced bymore » a factor f ∼ 0.1 are both in qualitative agreement with observations in terms of suppressing K-H instabilities. The rms velocity of turbulence within the sloshing region is only modestly reduced by Braginskii viscosity. We also performed unmagnetized simulations with and without viscosity and find that magnetic fields have a substantial effect on the appearance of the cold fronts, even if the initial field is weak and the viscosity is the same. This suggests that determining the dominant suppression mechanism of a given cold front from X-ray observations (e.g., viscosity or magnetic fields) by comparison with simulations is not straightforward. Finally, we performed simulations including anisotropic thermal conduction, and find that including Braginskii viscosity in these simulations does not significantly affect the evolution of cold fronts; they are rapidly smeared out by thermal conduction, as in the inviscid case.« less

Preliminary X-ray crystallographic analysis of glutathione transferase zeta 1 (GSTZ1a-1a)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boone, Christopher D.; Zhong, Guo; Smeltz, Marci

2014-01-21

Crystals of glutathione transferase zeta 1 were grown and shown to diffract X-rays to 3.1 Å resolution. They belonged to space group P1, with unit-cell parameters a = 42.0, b = 49.6, c = 54.6 Å, α = 82.9, β = 69.9, γ = 73.4°.

Concomitant degradation of bisphenol A during ultrasonication and Fenton oxidation and production of biofertilizer from wastewater sludge.

PubMed

Mohapatra, D P; Brar, S K; Tyagi, R D; Surampalli, R Y

2011-09-01

Degradation of bisphenol A (BPA), an endocrine disruptor, from wastewater sludge (WWS) has attracted great interest recently. In the present study, the effects of different pre-treatment methods, including ultrasonication (US), Fenton's oxidation (FO) and ferro-sonication (FS) was assessed in terms of increase in solubilization of WWS and simultaneous degradation of BPA. Among US, FO and FS pre-treatment, higher suspended solids (SS), volatile suspended solids (VSS), chemical oxygen demand (COD) and soluble organic carbon (SOC) solubilization (39.7%, 51.2%, 64.5% and 17.6%, respectively) was observed during a ferro-sonication pre-treatment process carried out for 180 min, resulting in higher degradation of BPA (82.7%). In addition, the effect of rheological parameters (viscosity and particle size) and zeta potential on the degradation of BPA in raw and different pre-treated sludges were also investigated. The results showed that a decrease in viscosity and particle size and an increase in zeta potential resulted in higher degradation of BPA. BPA degradation by laccases produced by Sinorhizobium meliloti in raw and pre-treated sludge was also determined. Higher activity of laccases (207.9 U L(-1)) was observed in ferro-sonicated pre-treated sludge (180 min ultrasonic time), resulting in higher removal of BPA (0.083 μg g(-1)), suggesting concomitant biological degradation of BPA. Copyright © 2011 Elsevier B.V. All rights reserved.

Effect of organized assemblies. Part 4. Formulation of highly concentrated coal-water slurry using a natural surfactant

DOE Office of Scientific and Technical Information (OSTI.GOV)

Debadutta Das; Sagarika Panigrahi; Pramila K. Misra

2008-05-15

Coal-water slurry has received considerable research nowadays due to its ability in substituting energy sources. The present work reports the formulation of highly concentrated coal-water slurry using a natural occurring surface active compound, saponin, extracted from the fruits of plant Sapindous laurifolia. The isolation of saponin from the plant and its surface activity has been discussed. The rheological characteristics of coal-water slurry have been investigated as a function of coal loading, ash content of coal, pH, temperature, and amount of saponin. The viscosity of the slurry and zeta potential are substantially decreased with concomitant shift of the isoelectric point ofmore » coal on adsorption of saponin to it. In the presence of 0.8% of saponin, coal-water slurry containing 64% weight fraction of coal could be achieved. The slurry is stable for a period of as long as 1 month in contrast to 4-5 h in the case of bare coal-water slurry. The results confirm the use of saponin as a suitable additive for coal-water slurry similar to the commercially available additive such as sodium dodecyl sulfate. Basing on the effect of pH on the zeta potential and viscosity of slurry, a suitable mechanism for saponin-coal interaction and orientation of saponin at the coal-water interface has been proposed. 47 refs., 12 figs., 5 tabs.« less

Flares, Magnetic Reconnections and Accretion Disk Viscosity

NASA Astrophysics Data System (ADS)

Welsh, William

2001-07-01

Accretion disks are invoked to explain a host of astrophysical phenomena, from protostellar objects to AGN. And yet the mechanism allowing accretion disks to operate are completely unknown. This proposal seeks to observe the ``smoking gun'' signature of magnetically-driven viscosity in accretion disks. Magnetically-induced viscosity is a plausible and generally accepted hypothesis {for esthetic reasons}, but it is completely untested. Determining the cause of accretion disk viscosity is of major significance to all accretion-disk powered systems {e.g. CVs, X-ray binaries, AGN and protostellar disks}. These data will also firmly establish the importance of magnetic fields in accretion disks. Because of its known flaring properites, we will observe the accretion disk in EM Cyg simulataneously with STIS/FUV and CHANDRA. The simultaneous X-rays are absolutely necessary for the unambiguous detection of accretion disk magnetic reconnection flares.

Influence of Functional Groups on the Viscosity of Organic Aerosol.

PubMed

Rothfuss, Nicholas E; Petters, Markus D

2017-01-03

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 (ONO 2 ) > carbonyl (CO) ≈ ester (COO) > methylene (CH 2 ). 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.

Study on improving viscosity of polymer solution based on complex reaction

NASA Astrophysics Data System (ADS)

Sun, G.; Li, D.; Zhang, D.; Xu, T. H.

2018-05-01

The current status of polymer flooding Technology on high salinity oil reservoir is not ideal. A method for increasing the viscosity of polymer solutions is urgently needed. This paper systematically studied the effect of ions with different mass concentrations on the viscosity of polymer solutions. Based on the theory of complex reaction, a countermeasure of increasing viscosity of polymer solution under conditions of high salinity reservoir was proposed. The results show that Ca2+ and Mg2+ have greater influence on the solution viscosity than K+ and Na+. When the concentration of divalent ions increases from 0 mg/L to 80 mg/L, the viscosity of the polymer solution decreases from 210 mPa·s to 38.6 mPa·s. The viscosity of the polymer solution prepared from the sewage treated with the Na2C2O4 increased by 25.3%. Atomic force microscopy test results show that Na2C2O4 can effectively shield the divalent metal ions, so that the polymer molecules in the solution stretch more, thereby increasing the solution viscosity. Atomic force microscopy test results show that Na2C2O4 can effectively shield the divalent metal ions, so that the polymer molecules in the solution stretch more, thereby increasing the solution viscosity.

A study on the dependence of nuclear viscosity on temperature

NASA Astrophysics Data System (ADS)

Vardaci, E.; Di Nitto, A.; Nadtochy, P. N.; La Rana, G.; Cinausero, M.; Prete, G.; Gelli, N.; Ashaduzzaman, M.; Davide, F.; Pulcini, A.; Quero, D.; Kozulin, E. M.; Knyazheva, G. N.; Itkis, I. M.

2018-05-01

Nuclear viscosity is an irreplaceable ingredient of nuclear fission collective dynamical models. It drives the exchange of energy between the collective variables and the thermal bath of single particle degrees of freedom. Its dependence on the shape and temperature is a matter of controversy. By using systems of intermediate fissility we have demonstrated in a recent study that the viscosity parameters is larger for compact shapes, and decreases for larger deformations of the fissioning system, at variance with the conclusions of the statistical model modified to include empirically viscosity and time scales. In this contribution we propose an experimental scenario to highlight the possible dependence of the viscosity from the temperature.

Viscosity of thickened fluids that relate to the Australian National Standards.

PubMed

Karsten Hadde, Enrico; Ann Yvette Cichero, Julie; Michael Nicholson, Timothy

2016-08-01

In 2007, Australia published standardized terminology and definitions for three levels of thickened fluids used in the management of dysphagia. This study examined the thickness of the current Australian National Fluid Standards rheologically (i.e. viscosity, yield stress) and correlated these results with the "fork test", as described in the national standards. Clinicians who prescribe or work with thickened liquids and laypersons were recruited to categorize 15 different thickened fluids of known viscosities using the fork test. The mean apparent viscosity and the yield stress for each fluid category were calculated. Clear responses were obtained by both clinicians and laypersons for very thin fluids (< 90 mPa.s) and very thick fluids (> 1150 mPa.s), but large variations of responses were seen for intermediate viscosities. Measures of viscosity and yield stress were important in allocating liquids to different categories. Three bands of fluid viscosity with distinct intermediate band gaps and associated yield stress measures were clearly identifiable and are proposed as objective complements to the Australian National Standards. The "fork test" provides rudimentary information about both viscosity and yield stress, but is an inexact measure of both variables.

Mucin and phospholipids determine viscosity of gallbladder bile in patients with gallstones

PubMed Central

Jüngst, Dieter; Niemeyer, Anna; Müller, Iris; Zündt, Benedikta; Meyer, Günther; Wilhelmi, Martin; del Pozo, Reginald

2001-01-01

AIM: An increased viscosity of gallbladder bile has been considered an important factor in the pathogenesis of gallstone disease. Besides lipids and proteins, mucin has been suggested to affect the viscosity of bile. To further clarify these issues we compared mucin, protein and the lipid componEnts of hepatic and gallbladder bile and its viscosity in patients with gallstones. METHODS: Viscosity of bile (mPa.s) was measured using rotation viscosimetry in regard to the non Newtonian property of bile at low shear rates. RESULTS: Biliary viscosity was markedly higher in gallbladder bile of patients with cholesterol (5.00 ± 0.60 mPa.s, mean ± SEM, n = 28) and mixed stones (3.50 ± 0.68 mPa.s; n = 8) compared to hepatic bile (0.92 ± 0.06 mPa.s, n = 6). A positive correlation between mucin and viscosity was found in gallbladder biles (r = 0. 65; P < 0.001) but not in hepatic biles. The addition of physiologic and supraphysiologic amounts of mucin to gallbladder bile resulted in a dose dependent non linear increase of its viscosity. A positive correlation was determined between phospholipid concentration and viscosity (r = 0.34, P < 0.005) in gallbladder biles. However, no correlation was found between total protein or the other lipid concentrations and viscosity in both gallbladder and hepatic biles. CONCLUSION: The viscosity of gallbladder bile is markedly higher than that of hepatic bile in patients with gallstones. The concentration of mucin is the major determinant of biliary viscosity and may contribute by this mechanism to the role of mucin in the pathogenesis of gallstones. PMID:11819761

The role of bulk viscosity on the decay of compressible, homogeneous, isotropic turbulence

NASA Astrophysics Data System (ADS)

Johnsen, Eric; Pan, Shaowu

2016-11-01

The practice of neglecting bulk viscosity in studies of compressible turbulence is widespread. While exact for monatomic gases and unlikely to strongly affect the dynamics of fluids whose bulk-to-shear viscosity ratio is small and/or of weakly compressible turbulence, this assumption is not justifiable for compressible, turbulent flows of gases whose bulk viscosity is orders of magnitude larger than their shear viscosities (e.g., CO2). To understand the mechanisms by which bulk viscosity and the associated phenomena affect compressible turbulence, we conduct DNS of freely decaying compressible, homogeneous, isotropic turbulence for ratios of bulk-to-shear viscosity ranging from 0-1000. Our simulations demonstrate that bulk viscosity increases the decay rate of turbulent kinetic energy; while enstrophy exhibits little sensitivity to bulk viscosity, dilatation is reduced by an order of magnitude within the two eddy turnover time. Via a Helmholtz decomposition of the flow, we determined that bulk viscosity damps the dilatational velocity and reduces dilatational-solenoidal exchanges, as well as pressure-dilatation coupling. In short, bulk viscosity renders compressible turbulence incompressible by reducing energy transfer between translational and internal modes.

Calculated viscosity-distance dependence for some actively flowing lavas

NASA Technical Reports Server (NTRS)

Pieri, David

1987-01-01

The importance of viscosity as a gauge of the various energy and momentum dissipation regimes of lava flows has been realized for a long time. Nevertheless, despite its central role in lava dynamics and kinematics, it remains among the most difficult of flow physical properties to measure in situ during an eruption. Attempts at reconstructing the actual emplacement viscosities of lava flows from their solidified topographic form are difficult. Where data are available on the position of an advancing flow front as a function of time, it is possible to calculate the effective viscosity of the front as a function of distance from the vent, under the assumptions of a steady state regime. As an application and test of an equation given, relevant parameters from five recent flows on Mauna Loa and Kilauea were utilized to infer the dynamic structure of their aggregate flow front viscosity as they advanced, up to cessation. The observed form of the viscosity-distance relation for the five active Hawaiian flows examined appears to be exponential, with a rapid increase just before the flows stopped as one would expect.

Development of viscosity sensor with long period fiber grating technology

NASA Astrophysics Data System (ADS)

Lin, Jyh-Dong; Wang, Jian-Neng; Chen, Shih-Huang; Wang, Juei-Mao

2009-03-01

In this paper, we describe the development of a viscosity sensing system using a simple and low-cost long-period fiber grating (LPFG) sensor. The LPFG sensor was extremely sensitive to the refractive index of the medium surrounding the cladding surface of the sensing grating, thus allowing it to be used as an ambient index sensor or chemical concentration indicator. Viscosity can be simply defined as resistance to flow of a liquid. We have measured asphalt binder, 100-190000 centistokes, in comparison with optical sensing results. The system sensing asphalt binders exhibited increase trend in the resonance wavelength shift when the refractive index of the medium changed. The prototype sensor consisted of a LPFG sensing component and a cone-shaped reservoir where gravitational force can cause asphalt binders flow through the capillary. Thus the measured time for a constant volume of asphalt binders can be converted into either absolute or kinematic viscosity. In addition, a rotational viscometer and a dynamic shear rheometer were also used to evaluate the viscosity of this liquid, the ratio between the applied shear stress and rate of shear, as well as the viscoelastic property including complex shear modulus and phase angle. The measured time could be converted into viscosity of asphalt binder based on calculation. This simple LPFG viscosity sensing system is hopefully expected to benefit the viscosity measurement for the field of civil, mechanical and aerospace engineering.

Damping of drop oscillations by surfactants and surface viscosity

NASA Technical Reports Server (NTRS)

Rush, Brian M.; Nadim, Ali

1999-01-01

An energy equation is derived for the general case of a viscous drop suspended in a viscous medium with surfactants contaminating the interface. It contains terms that clearly identify dissipation contributions from the viscous effects in the bulk fluids, surface shear and dilatational viscosity effects at the interface, and surfactant transport. An efficient boundary integral method is developed which incorporates the effects of a constant surface dilatational viscosity in simulations of an oscillating two-dimensional inviscid drop. Surface dilatational viscosity is shown to have a significant damping effect on the otherwise undamped inviscid oscillations.

Fabrication of hydroxyapatite ceramics with controlled pore characteristics by slip casting.

PubMed

Yao, Xiumin; Tan, Shouhong; Jiang, Dongliang

2005-02-01

Porous hydroxyapatite (HAp) ceramics with controlled pore characteristics were fabricated using slip casting method by mixing PMMA with HAp powder. The optimum conditions of HAp slip for slip casting was achieved by employing various experimental techniques, zeta potential and sedimentation, as a function of pH of the slips in the pH range of 4-12. HAp suspensions displayed an absolute maximum in zeta potential values and a minimum in sedimentation height at pH 11.5. The optimal amount of dispersant for the HAp suspensions was found at 1.0 wt% according to the viscosity of 25 vol% HAp slurry. The rheological behaviour of HAp slurry displays a shear-thinning behavior without thixotropy, which is needed in slip casting processing. The pore characteristics of sintered porous hydroxyapatite bioceramics can be controlled by added PMMA particle size and volume. The obtained ceramics exhibit higher strength than those obtained by dry pressing.

Anomalous intrinsic viscosity of octadecylamine-functionalised carbon nanotubes in suspension.

PubMed

Donovan, K J; Scott, K

2013-06-28

Single walled carbon nanotubes, SWCNTs, are used as a model cylinder of nanoscopic dimensions for testing rheological theories of how addition of cylindrical particles affects the viscosity of a suspension of such particles. Using the rate of growth of the accompanying induced linear dichroism following application of an applied electric field, the dynamics of carbon nanotube alignment is studied in suspensions of octadecylamine functionalised single walled carbon nanotubes, ODA-SWCNTs, in 1,2 dichloroethane. From such measurements the viscosity of the suspension is measured as the concentration of the suspension is varied. While working within the dilute limit the viscosity is found to increase linearly with concentration and the intrinsic viscosity of the suspension is found to be 8000. This anomalously high intrinsic viscosity is compared with the predictions of various models for a rigid cylinder and found to be incompatible with any of the current models. Some suggestions are made as to the way this ODA-SWCNT result may be eventually accommodated within other models.

Integrated Solvent Design for CO 2 Capture and Viscosity Tuning

DOE PAGES

Cantu, David C.; Malhotra, Deepika; Koech, Phillip K.; ...

2017-08-18

We present novel design strategies for reduced viscosity single-component, water-lean CO 2 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 CO 2 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 ofmore » the equilibrium toward a non-charged (acid) form that further reduces the viscosity. Here, 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.« less

Experimental understanding of the viscosity reduction ability of TLCPs with different PEs

NASA Astrophysics Data System (ADS)

Tang, Youhong; Zuo, Min; Gao, Ping

2014-08-01

In this study, two thermotropic liquid crystalline polyesters (TLCPs) synthesized by polycondensation of p-hydroxybenzoic acid /hydroquinone/ poly dicarboxylic acid were used as viscosity reduction agents for polyethylene (PE). The TLCPs had different thermal, rheological and other physical properties that were quantitatively characterized. The two TLCPs were blended with high density PE (HDPE) and high molecular mass PE (HMMPE) by simple twin screw extrusion under the same weight ratio of 1.0 wt% and were each rheologically characterized at 190°C. The TLCPs acted as processing modifiers for the PEs and the bulk viscosity of the blends decreased dramatically. However, the viscosity reduction ability was not identical: one TLCP had obviously higher viscosity reduction ability on the HDPE, with a maximum viscosity reduction ratio of 68.1%, whereas the other TLCP had higher viscosity reduction ability on the HMMPE, with a maximum viscosity reduction ratio of 98.7%. Proposed explanations for these differences are evaluated.

Viscosity Difference Measurements for Normal and Para Liquid Hydrogen Mixtures

NASA Technical Reports Server (NTRS)

Webeler, R.; Bedard, F.

1961-01-01

The absence of experimental data in the literature concerning a viscosity difference for normal and equilibrium liquid hydrogen may be attributed to the limited reproducibility of "oscillating disk" measurements in a liquid-hydrogen environment. Indeed, there is disagreement over the viscosity values for equilibrium liquid hydrogen even without proton spin considerations. Measurements presented here represent the first application of the piezoelectric alpha quartz torsional oscillator technique to liquid-hydrogen viscosity measurements.

Viscosity of carbonate-rich melts under different oxygen fugacity conditions

NASA Astrophysics Data System (ADS)

Di Genova, Danilo; Hess, Kai-Uwe; Cimarelli, Corrado; Dingwell, Donald B.

2015-04-01

Viscosity is a fundamental property of many materials and its changes affects the fluid dynamics of natural system as well as industrial processes. The mobility of carbonatitic melts, which are carbonate-rich and very fluid melts, has attracted renewed interest in both earth science and industry. In fact, these melts are considered the main transport agent of carbon from the mantle to the crust and may be intimately linked to the generation of kimberlites. At the same time lithium, potassium and sodium carbonate are used as electrolytes in molten carbonate fuel cells which operate at high temperatures (~650° C) for the production of electricity without CO2 emissions. Accurate measurement of the transport property (i.e. viscosity) of carbonatitic melts is a priority in order to understand the carbonatite mobility and reaction rates. Additionally, obtaining accurate viscosity measurements of such low viscosity melts is however an experimental challenge due to volatility, very low torques and chemical melt instability in the viscometer. To overcome these limitations we have customized a Modular Compact Rheometer (MCR 502 from Anton Paar) ad hoc equipped with 2 narrow gap concentric-cylinder geometries of steel and Pt-Au. The rheometer is characterized by an air-bearing-supported synchronous motor with torque ranging between 0.01 μNm and 230 mNm (resolution of 0.1 nNm), achieving very low viscosity measurements in the order of mPa s, temperatures up to 1000° C and shear rates ranging between 1 and 100 sec-1. These experimental conditions well match the temperature-viscosity-shear rate window relevant for carbonate melts. Here we present the calibration of the rheometer and the results of a rheological characterization study on a series of very low viscous synthetic and natural carbonatitic melts at different oxygen fugacity (air and CO2 saturated atmosphere). Viscosity measurements on carbonate melts have been performed in the temperature range between ~650 and 1000

Shear Viscosity of Aluminium under Shock Compression

NASA Astrophysics Data System (ADS)

Liu, Fu-Sheng; Yang, Mei-Xia; Liu, Qi-Wen; Chen, Jun-Xiang; Jing, Fu-Qian

2005-03-01

Based on the Newtonian viscous fluid model and the analytic perturbation theory of Miller and Ahrens for the oscillatory damping of a sinusoidal shock front, a flyer-impact technique is developed to investigate the effective viscosity of shocked aluminium. The shear viscosity coefficient is determined to be about 5000 poises at 42 GPa with strain rate of 1.27×106 s-1, which is a reasonable estimation compared with the results of other measurement methods.

The effect of artificial bulk viscosity in simulations of forced compressible turbulence

DOE Office of Scientific and Technical Information (OSTI.GOV)

Campos, A.; Morgan, B.

The use of an artificial bulk viscosity for shock stabilization is a common approach employed in turbulence simulations with high-order numerics. The effect of the artificial bulk viscosity is analyzed in the context of large eddy simulations by using as a test case simulations of linearly-forced compressible homogeneous turbulence (Petersen and Livescu, 2010 [12]). This case is unique in that it allows for the specification of a priori target values for total dissipation and ratio of solenoidal to dilatational dissipation. A comparison between these target values and the true predicted levels of dissipation is thus used to investigate the performancemore » of the artificial bulk viscosity. Results show that the artificial bulk viscosity is effective at achieving stable solutions, but also leads to large values of artificial dissipation that outweigh the physical dissipation caused by fluid viscosity. An alternate approach, which employs the artificial thermal conductivity only, shows that the dissipation of dilatational modes is entirely due to the fluid viscosity. However, this method leads to unwanted Gibbs oscillations around the shocklets. The use of shock sensors that further localize the artificial bulk viscosity did not reduce the amount of artificial dissipation introduced by the artificial bulk viscosity. Finally, an improved forcing function that explicitly accounts for the role of the artificial bulk viscosity in the budget of turbulent kinetic energy was explored.« less

The effect of artificial bulk viscosity in simulations of forced compressible turbulence

DOE PAGES

Campos, A.; Morgan, B.

2018-05-17

The use of an artificial bulk viscosity for shock stabilization is a common approach employed in turbulence simulations with high-order numerics. The effect of the artificial bulk viscosity is analyzed in the context of large eddy simulations by using as a test case simulations of linearly-forced compressible homogeneous turbulence (Petersen and Livescu, 2010 [12]). This case is unique in that it allows for the specification of a priori target values for total dissipation and ratio of solenoidal to dilatational dissipation. A comparison between these target values and the true predicted levels of dissipation is thus used to investigate the performancemore » of the artificial bulk viscosity. Results show that the artificial bulk viscosity is effective at achieving stable solutions, but also leads to large values of artificial dissipation that outweigh the physical dissipation caused by fluid viscosity. An alternate approach, which employs the artificial thermal conductivity only, shows that the dissipation of dilatational modes is entirely due to the fluid viscosity. However, this method leads to unwanted Gibbs oscillations around the shocklets. The use of shock sensors that further localize the artificial bulk viscosity did not reduce the amount of artificial dissipation introduced by the artificial bulk viscosity. Finally, an improved forcing function that explicitly accounts for the role of the artificial bulk viscosity in the budget of turbulent kinetic energy was explored.« less

Viscosity Measurements and Correlation of the Squalane + CO2 Mixture

NASA Astrophysics Data System (ADS)

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

2007-02-01

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.

Shear viscosity for dense plasmas by equilibrium molecular dynamics in asymmetric Yukawa ionic mixtures

NASA Astrophysics Data System (ADS)

Haxhimali, Tomorr; Rudd, Robert E.; Cabot, William H.; Graziani, Frank R.

2015-11-01

We present molecular dynamics (MD) calculations of shear viscosity for asymmetric mixed plasma for thermodynamic conditions relevant to astrophysical and inertial confinement fusion plasmas. Specifically, we consider mixtures of deuterium and argon at temperatures of 100-500 eV and a number density of 1025 ions/cc. The motion of 30 000-120 000 ions is simulated in which the ions interact via the Yukawa (screened Coulomb) potential. The electric field of the electrons is included in this effective interaction; the electrons are not simulated explicitly. Shear viscosity is calculated using the Green-Kubo approach with an integral of the shear stress autocorrelation function, a quantity calculated in the equilibrium MD simulations. We systematically study different mixtures through a series of simulations with increasing fraction of the minority high-Z element (Ar) in the D-Ar plasma mixture. In the more weakly coupled plasmas, at 500 eV and low Ar fractions, results from MD compare very well with Chapman-Enskog kinetic results. In the more strongly coupled plasmas, the kinetic theory does not agree well with the MD results. We develop a simple model that interpolates between classical kinetic theories at weak coupling and the Murillo Yukawa viscosity model at higher coupling. This hybrid kinetics-MD viscosity model agrees well with the MD results over the conditions simulated, ranging from moderately weakly coupled to moderately strongly coupled asymmetric plasma mixtures.

Biodegradation of asphalt by Garciaella petrolearia TERIG02 for viscosity reduction of heavy oil.

PubMed

Lavania, Meeta; Cheema, Simrita; Sarma, Priyangshu Manab; Mandal, Ajoy Kumar; Lal, Banwari

2012-02-01

Petroleum hydrocarbon is an important energy resource, but it is difficult to exploit due to the presence of dominated heavy constituents such as asphaltenes. In this study, viscosity reduction of Jodhpur heavy oil (2,637 cP at 50°C) has been carried out by the biodegradation of asphalt using a bacterial strain TERIG02. TERIG02 was isolated from sea buried oil pipeline known as Mumbai Uran trunk line (MUT) located on western coast of India and identified as Garciaella petrolearia by 16S rRNA full gene sequencing. TERIG02 showed 42% viscosity reduction when asphalt along with molasses was used as a sole carbon source compared to only asphalt (37%). The viscosity reduction by asphaltene degradation has been structurally characterized by Fourier transform infrared spectroscopy (FTIR). This strain also shows an additional preference to degrade toxic asphalt and aromatics compounds first unlike the other known strains. All these characteristics makes TERIG02 a potential candidate for enhanced oil recovery and a solution to degrading toxic aromatic compounds.

Green-Kubo relation for viscosity tested using experimental data for a two-dimensional dusty plasma

NASA Astrophysics Data System (ADS)

Feng, Yan; Goree, J.; Liu, Bin; Cohen, E. G. D.

2011-10-01

The theoretical Green-Kubo relation for viscosity is tested using experimentally obtained data. In a dusty plasma experiment, micron-sized dust particles are introduced into a partially ionized argon plasma, where they become negatively charged. They are electrically levitated to form a single-layer Wigner crystal, which is subsequently melted using laser heating. In the liquid phase, these dust particles experience interparticle electric repulsion, laser heating, and friction from the ambient neutral argon gas, and they can be considered to be in a nonequilibrium steady state. Direct measurements of the positions and velocities of individual dust particles are then used to obtain a time series for an off-diagonal element of the stress tensor and its time autocorrelation function. This calculation also requires the interparticle potential, which was not measured experimentally but was obtained using a Debye-Hückel-type model with experimentally determined parameters. Integrating the autocorrelation function over time yields the viscosity for shearing motion among dust particles. The viscosity so obtained is found to agree with results from a previous experiment using a hydrodynamical Navier-Stokes equation. This comparison serves as a test of the Green-Kubo relation for viscosity. Our result is also compared to the predictions of several simulations.

Viscosity Measurement using Drop Coalescence in Microgravity

NASA Technical Reports Server (NTRS)

Antar, Basil N.; Ethridge, Edwin; Maxwell, Daniel

1999-01-01

We present in here details of a new method, using drop coalescence, for application in microgravity environment for determining the viscosity of highly viscous undercooled liquids. The method has the advantage of eliminating heterogeneous nucleation at container walls caused by crystallization of undercooled liquids during processing. Also, due to the rapidity of the measurement, homogeneous nucleation would be avoided. The technique relies on both a highly accurate solution to the Navier-Stokes equations as well as on data gathered from experiments conducted in near zero gravity environment. The liquid viscosity is determined by allowing the computed free surface shape relaxation time to be adjusted in response to the measured free surface velocity of two coalescing drops. Results are presented from two validation experiments of the method which were conducted recently on board the NASA KC-135 aircraft. In these tests the viscosity of a highly viscous liquid, such as glycerine at different temperatures, was determined to reasonable accuracy using the liquid coalescence method. The experiments measured the free surface velocity of two glycerine drops coalescing under the action of surface tension alone in low gravity environment using high speed photography. The free surface velocity was then compared with the computed values obtained from different viscosity values. The results of these experiments were found to agree reasonably well with the calculated values.

Titin Based Viscosity in Ventricular Physiology: An Integrative Investigation of PEVK-Actin Interactions

PubMed Central

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

2011-01-01

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

The influence of tongue strength on oral viscosity discrimination acuity.

PubMed

Steele, Catriona M

2018-06-01

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.

Semiclassical theory of Hall viscosity

NASA Astrophysics Data System (ADS)

Biswas, Rudro

2014-03-01

Hall viscosity is an intriguing stress response in quantum Hall systems and is predicted to be observable via the conductivity in an inhomogeneous electric field. This has been studied extensively using a range of techniques, such as adiabatic transport, effective field theories, and Kubo formulae. All of these are, however, agnostic as to the distinction between strongly correlated quantum Hall states and non-interacting ones, where the effect arises due to the fundamental non-commuting nature of velocities and orbit positions in a magnetic field. In this talk I shall develop the semiclassical theory of quantized cyclotron orbits drifting in an applied inhomogeneous electric field and use it to provide a clear physical picture of how single particle properties in a magnetic field contribute to the Hall viscosity-dependence of the conductivity.

Geometry-dependent viscosity reduction in sheared active fluids

NASA Astrophysics Data System (ADS)

Słomka, Jonasz; Dunkel, Jörn

2017-04-01

We investigate flow pattern formation and viscosity reduction mechanisms in active fluids by studying a generalized Navier-Stokes model that captures the experimentally observed bulk vortex dynamics in microbial suspensions. We present exact analytical solutions including stress-free vortex lattices and introduce a computational framework that allows the efficient treatment of higher-order shear boundary conditions. Large-scale parameter scans identify the conditions for spontaneous flow symmetry breaking, geometry-dependent viscosity reduction, and negative-viscosity states amenable to energy harvesting in confined suspensions. The theory uses only generic assumptions about the symmetries and long-wavelength structure of active stress tensors, suggesting that inviscid phases may be achievable in a broad class of nonequilibrium fluids by tuning confinement geometry and pattern scale selection.

Temperature Dependence of the Viscosity of Isotropic Liquids

NASA Astrophysics Data System (ADS)

Jadzyn, J.; Czechowski, G.; Lech, T.

1999-04-01

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.

The effect of ilmenite viscosity on the dynamics and evolution of an overturned lunar cumulate mantle

NASA Astrophysics Data System (ADS)

Zhang, Nan; Dygert, Nick; Liang, Yan; Parmentier, E. M.

2017-07-01

Lunar cumulate mantle overturn and the subsequent upwelling of overturned mantle cumulates provide a potential framework for understanding the first-order thermochemical evolution of the Moon. Upwelling of ilmenite-bearing cumulates (IBCs) after the overturn has a dominant influence on the dynamics and long-term thermal evolution of the lunar mantle. An important parameter determining the stability and convective behavior of the IBC is its viscosity, which was recently constrained through rock deformation experiments. To examine the effect of IBC viscosity on the upwelling of overturned lunar cumulate mantle, here we conduct three-dimensional mantle convection models with an evolving core superposed by an IBC-rich layer, which resulted from mantle overturn after magma ocean solidification. Our modeling shows that a reduction of mantle viscosity by 1 order of magnitude, due to the presence of ilmenite, can dramatically change convective planform and long-term lunar mantle evolution. Our model results suggest a relatively stable partially molten IBC layer that has surrounded the lunar core to the present day.