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

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.

Anomalous electrical conductivity of nanoscale colloidal suspensions.

PubMed

Chakraborty, Suman; Padhy, Sourav

2008-10-28

The electrical conductivity of colloidal suspensions containing nanoscale conducting particles is nontrivially related to the particle volume fraction and the electrical double layer thickness. Classical electrochemical models, however, tend to grossly overpredict the pertinent effective electrical conductivity values, as compared to those obtained under experimental conditions. We attempt to address this discrepancy by appealing to the complex interconnection between the aggregation kinetics of the nanoscale particles and the electrodynamics within the double layer. In particular, we model the consequent alterations in the effective electrophoretic mobility values of the suspension by addressing the fundamentals of agglomeration-deagglomeration mechanisms through the pertinent variations in the effective particulate dimensions, solid fractions, as well as the equivalent suspension viscosity. The consequent alterations in the electrical conductivity values provide a substantially improved prediction of the corresponding experimental findings and explain the apparent anomalous behavior predicted by the classical theoretical postulates.

Viscosity and density of methanol/water mixtures at low temperatures

NASA Technical Reports Server (NTRS)

Austin, J. G.; Kurata, F.; Swift, G. W.

1968-01-01

Viscosity and density are measured at low temperatures for three methanol/water mixtures. Viscosity is determined by a modified falling cylinder method or a calibrated viscometer. Density is determined by the volume of each mixture contained in a calibrated glass cell placed in a constant-temperature bath.

Temperature-Dependent Conformations of Model Viscosity Index Improvers

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

Ramasamy, Uma Shantini; Cosimbescu, Lelia; Martini, Ashlie

2015-05-01

Lubricants are comprised of base oils and additives where additives are chemicals that are deliberately added to the oil to enhance properties and inhibit degradation of the base oils. Viscosity index (VI) improvers are an important class of additives that reduce the decline of fluid viscosity with temperature [1], enabling optimum lubricant performance over a wider range of operating temperatures. These additives are typically high molecular weight polymers, such as, but not limited to, polyisobutylenes, olefin copolymer, and polyalkylmethacrylates, that are added in concentrations of 2-5% (w/w). Appropriate polymers, when dissolved in base oil, expand from a coiled to anmore » uncoiled state with increasing temperature [2]. The ability of VI additives to increase their molar volume and improve the temperature-viscosity dependence of lubricants suggests there is a strong relationship between molecular structure and additive functionality [3]. In this work, we aim to quantify the changes in polymer size with temperature for four polyisobutylene (PIB) based molecular structures at the nano-scale using molecular simulation tools. As expected, the results show that the polymers adopt more conformations at higher temperatures, and there is a clear indication that the expandability of a polymer is strongly influenced by molecular structure.« less

New holographic dark energy model with constant bulk viscosity in modified f(R,T) gravity theory

NASA Astrophysics Data System (ADS)

Srivastava, Milan; Singh, C. P.

2018-06-01

The aim of this paper is to study new holographic dark energy (HDE) model in modified f(R,T) gravity theory within the framework of a flat Friedmann-Robertson-Walker model with bulk viscous matter content. It is thought that the negative pressure caused by the bulk viscosity can play the role of dark energy component, and drive the accelerating expansion of the universe. This is the motive of this paper to observe such phenomena with bulk viscosity. In the specific model f(R,T)=R+λ T, where R is the Ricci scalar, T the trace of the energy-momentum tensor and λ is a constant, we find the solution for non-viscous and viscous new HDE models. We analyze new HDE model with constant bulk viscosity, ζ =ζ 0= const. to explain the present accelerated expansion of the universe. We classify all possible scenarios (deceleration, acceleration and their transition) with possible positive and negative ranges of λ over the constraint on ζ 0 to analyze the evolution of the universe. We obtain the solutions of scale factor and deceleration parameter, and discuss the evolution of the universe. We observe the future finite-time singularities of type I and III at a finite time under certain constraints on λ . We also investigate the statefinder and Om diagnostics of the viscous new HDE model to discriminate with other existing dark energy models. In late time the viscous new HDE model approaches to Λ CDM model. We also discuss the thermodynamics and entropy of the model and find that it satisfies the second law of thermodynamics.

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.

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.

Enhanced Oxidative and Adsorptive Removal of Diclofenac in Heterogeneous Fenton-like Reaction with Sulfide Modified Nanoscale Zerovalent Iron.

PubMed

Su, Yiming; Jassby, David; Song, Shikun; Zhou, Xuefei; Zhao, Hongying; Filip, Jan; Petala, Eleni; Zhang, Yalei

2018-06-05

Sulfidation of nanoscale zerovalent iron (nZVI) has shown some fundamental improvements on reactivity and selectivity toward pollutants in dissolved-oxygen (DO)-stimulated Fenton-like reaction systems (DO/S-nZVI system). However, the pristine microstructure of sulfide-modified nanoscale zerovalent iron (S-nZVI) remains uncovered. In addition, the relationship between pollutant removal and the oxidation of the S-nZVI is largely unknown. The present study confirms that sulfidation not only imparts sulfide and sulfate groups onto the surface of the nanoparticle (both on the oxide shell and on flake-like structures) but also introduces sulfur into the Fe(0) core region. Sulfidation greatly inhibits the four-electron transfer pathway between Fe(0) and oxygen but facilitates the electron transfer from Fe(0) to surface-bound Fe(III) and consecutive single-electron transfer for the generation of H 2 O 2 and hydroxyl radical. In the DO/S-nZVI system, slight sulfidation (S/Fe molar ratio = 0.1) is able to nearly double the oxidative removal efficacy of diclofenac (DCF) (from 17.8 to 34.2%), whereas moderate degree of sulfidation (S/Fe molar ratio = 0.3) significantly enhances both oxidation and adsorption of DCF. Furthermore, on the basis of the oxidation model of S-nZVI, the DCF removal process can be divided into two steps, which are well modeled by parabolic and logarithmic law separately. This study bridges the knowledge gap between pollutant removal and the oxidation process of chemically modified iron-based nanomaterials.

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.

Nanoscale Surface Modifications of Medical Implants for Cartilage Tissue Repair and Regeneration

PubMed Central

Griffin, MF; Szarko, M; Seifailan, A; Butler, PE

2016-01-01

Background: Natural cartilage regeneration is limited after trauma or degenerative processes. Due to the clinical challenge of reconstruction of articular cartilage, research into developing biomaterials to support cartilage regeneration have evolved. The structural architecture of composition of the cartilage extracellular matrix (ECM) is vital in guiding cell adhesion, migration and formation of cartilage. Current technologies have tried to mimic the cell’s nanoscale microenvironment to improve implants to improve cartilage tissue repair. Methods: This review evaluates nanoscale techniques used to modify the implant surface for cartilage regeneration. Results: The surface of biomaterial is a vital parameter to guide cell adhesion and consequently allow for the formation of ECM and allow for tissue repair. By providing nanosized cues on the surface in the form of a nanotopography or nanosized molecules, allows for better control of cell behaviour and regeneration of cartilage. Chemical, physical and lithography techniques have all been explored for modifying the nanoscale surface of implants to promote chondrocyte adhesion and ECM formation. Conclusion: Future studies are needed to further establish the optimal nanoscale modification of implants for cartilage tissue regeneration. PMID:28217208

Nanoscale Resolution 3D Printing with Pin-Modified Electrified Inkjets for Tailorable Nano/Macrohybrid Constructs for Tissue Engineering.

PubMed

Kim, Jeong In; Kim, Cheol Sang

2018-04-18

Cells respond to their microenvironment, which is of a size comparable to that of the cells. The macroscale features of three-dimensional (3D) printing struts typically result in whole cell contact guidance (CCG). In contrast, at the nanoscale, where features are of a size similar to that of receptors of cells, the response of cells is more complex. The cell-nanotopography interaction involves nanoscale adhesion localized structures, which include cell adhesion-related particles that change in response to the clustering of integrin. For this reason, it is necessary to develop a technique for manufacturing tailorable nano/macrohybrid constructs capable of freely controlling the cellular activity. In this study, a hierarchical 3D nano- to microscale hybrid structure was fabricated by combinational processing of 3D printing and electrified inkjet spinning via pin motions. This method overcomes the disadvantages of conventional 3D printing, providing a novel combinatory technique for the fabrication of 3D hybrid constructs with excellent cell proliferation. Through a pin-modified electrified inkjet spinning, we have successfully fabricated customizable nano-/microscale hybrid constructs in a fibrous or mesh form, which can control the cell fate. We have conducted this study of cell-topography interactions from the fabrication approach to accelerate the development of next-generation 3D scaffolds.

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

Modified Thermoresponsive Hyperbranched Polymers for Improved Viscosity and Enhanced Lubricity of Engine Oils

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

Cosimbescu, Lelia; Robinson, Joshua W.; Bays, John Timothy

The manuscript captures the chronological succession of the molecular design progression through multiple architectures and topologies of the polymeric viscosity index improvers and their rheology bench test performance. Tribology testing was also performed on selected analogs and their friction and wear was evaluated. Finally, a top performing polymer was selected for engine testing, scaled-up, and its rheological performance in a complete formulation was assessed. The engine performance of the viscosity index improver was examined against an industry-established baseline.

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.

Determination of Fluid Density and Viscosity by Analyzing Flexural Wave Propagations on the Vibrating Micro-Cantilever

PubMed Central

Kim, Deokman; Hong, Seongkyeol; Park, Junhong

2017-01-01

The determination of fluid density and viscosity using most cantilever-based sensors is based on changes in resonant frequency and peak width. Here, we present a wave propagation analysis using piezoelectrically excited micro-cantilevers under distributed fluid loading. The standing wave shapes of microscale-thickness cantilevers partially immersed in liquids (water, 25% glycerol, and acetone), and nanoscale-thickness microfabricated cantilevers fully immersed in gases (air at three different pressures, carbon dioxide, and nitrogen) were investigated to identify the effects of fluid-structure interactions to thus determine the fluid properties. This measurement method was validated by comparing with the known fluid properties, which agreed well with the measurements. The relative differences for the liquids were less than 4.8% for the densities and 3.1% for the viscosities, and those for the gases were less than 6.7% for the densities and 7.3% for the viscosities, showing better agreements in liquids than in gases. PMID:29077005

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.

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

electrostatic interaction energy, and the van der Waals interaction energy, was clearly the dominant interaction energy for such a system. Hydrophobic interactions lead to the formation of aggregation networks of solids in the suspensions, entrapping a part of the bulk water, whereas hydrophilic interactions result in the formation of hydration layers around carbonaceous solids. Both of these phenomena cause a loss of bulk water from the slurry and increase the effective solid volume fraction, resulting in an increase in slurry viscosity. The water in the bulk of the slurry, responsible for the fluidity of the slurry is called free water. The amount of free water was determined using thermogravimetric analysis and was observed to increase with an increase in the O/C ratio of a carbonaceous solid (up to ˜20%). The free water to total water ratio was observed to be constant for the slurry of a particular carbonaceous solid for various loadings of solids (44 wt.% to 67 wt.%). The increase in the effective solid volume fractions of slurries was determined using viscosity measurements. A relationship between the effective solid volume fraction and the O/C ratio of the carbonaceous solid was developed. This correlation was then incorporated into the existing equation for viscosity prediction (developed based on particle size distribution and solid volume fraction), to account for the surface chemistry of the carbonaceous solid and hence improve the predictive capabilities. This modified equation was validated using three concentrated carbonaceous slurries with different particle size distributions and was observed to significantly improve accuracy of prediction (deviation of predicted results decreased from up to 96% to 25%). The validation was performed with a lignite, bituminous coal and a petcoke-all with low ash yield. Additives modify the surface chemistry of the carbonaceous solids, thereby affecting the interfacial interactions. Through this research, the effects of additives

Inflammatory cytokine response to titanium chemical composition and nanoscale calcium phosphate surface modification.

PubMed

Hamlet, Stephen; Ivanovski, Saso

2011-05-01

Nanoscale surface modification of titanium dental implants with calcium phosphate (CaP) has been shown to achieve superior bone wound healing and osseointegration compared with smooth or microrough titanium surfaces alone. As bone healing has been shown to be influenced by the action of cytokines, this study examined whether changes in cytokine gene expression from RAW 264.7 cells cultured on commercially pure and titanium alloy (Ti-6Al-4V) microrough or nanoscale crystalline CaP-modified surfaces, may influence downstream events in bone wound healing and osseointegration. Whilst no significant difference in the attachment or proliferation of RAW 264.7 cells was observed, the nanoscale CaP-modified surface elicited a gene expression profile with marked down-regulation of a number of pro-inflammatory cytokines and chemokines. Inflammatory cytokine gene expression was further influenced by chemical composition, with lower levels of pro-inflammatory markers noted following exposure of the macrophage-like cells to titanium alloy (Ti-6Al-4V) compared with the commercially pure titanium surface. Down-regulation of pro-inflammatory cytokine gene expression (confirmed at the protein level for TNFα and CCL5), may thus facilitate the enhanced bone wound healing and osseointegration observed clinically with nanoscale calcium phosphate-modified implant surfaces. Copyright © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Transport of Lactate-modified Nanoscale Iron Particles in Porous Media

NASA Astrophysics Data System (ADS)

Reddy, K. R.

2012-12-01

Nanoscale iron particles (NIP) have recently shown to be effective for dehalogenation of recalcitrant organic contaminants such as pentachlorphenol (PCP) and dinitrotoluene (DNT) in the environment. However, effective transport of NIP into the contaminated subsurface zones is crucial for the success of in-situ remediation. Previous studies showed that the transport of NIP in soils is very limited and surface-modification of NIP is required to achieve adequate transport. This paper investigates the transport of NIP and lactate-modified NIP (LMNIP) through four different porous media (sands with different particle size and distribution). A series of laboratory column experiments was conducted to quantify the transport of NIP and LMNIP at two different slurry concentrations of 1 g/L and 4 g/L under two different flow velcoities. NIP used in this study possessed magentic properties, thus a magnetic susceptibility sensor system was used to monitor the changes in magnetic susceptibility (MS) along the length of the column at different times during the experiments. At the end of testing, the distribution of total Fe in the sand column was measured. Results showed a linear correlation between the Fe concentration and MS and it was used to assess the transient transport of NIP and LMNIP in the sand columns. Results showed that LMNIP transported better than bare NIP and higher concentration of 4 g/L LMNIP exhibited unform and greater transport compared to other tested conditions. Transport of NIP increased in the order from fine Ottawa sand > medium field sand > coarse field sand > coarse Ottawa sand. Filtration theory and advective-dispersion equation with reaction were applied to capture the transport response of NIP and LMNIP in the sand columns.

Influence of D-Penicillamine on the Viscosity of Hyaluronic Acid Solutions

NASA Astrophysics Data System (ADS)

Liang, Jing; Krause, Wendy E.; Colby, Ralph H.

2006-03-01

Polyelectrolyte hyaluronic acid (HA, hyaluronan) is an important component in synovial fluid. Its presence results in highly viscoelastic solutions with excellent lubricating and shock-absorbing properties. In comparison to healthy synovial fluid, diseased fluid has a reduced viscosity. In osteoarthritis this reduction in viscosity results from a decline in both the molecular weight and concentration of hyaluronic acid HA. Initial results indicate that D-penicillamine affects the rheology of bovine synovial fluid, a model synovial fluid solution, and its components, including HA. In order to understand how D-penicillamine modifies the viscosity of these solutions, the rheological properties of sodium hyaluronate (NaHA) in phosphate-buffered saline (PBS) with D-penicillamine were studied as function of time, D-penicillamine concentration (0 -- 0.01 M), and storage conditions. Penicillamine has a complex, time dependent effect on the viscosity of NaHA solutions---reducing the zero shear rate viscosity of a 3 mg/mL NaHA in PBS by ca. 40% after 44 days.

Theory of nanoscale friction on chemically modified graphene

NASA Astrophysics Data System (ADS)

Ko, Jae-Hyeon; Kim, Yong-Hyun

2013-03-01

Recently, it is known from FFM experiments that friction force on graphene is significantly increased by chemical modification such as hydrogenation, oxidization, and fluorination, whereas adhesion properties are altered marginally. A novel nanotribological theory on two-dimensional materials is proposed on the basis of experimental results and first-principles density-functional theory (DFT) calculations. The proposed theory indicates that the total lateral stiffness that is the proportional constant of friction force is mostly associated with the out-of-plane bending stiffness of two-dimensional materials. This contrasts to the case of three-dimensional materials, in which the shear strength of materials determines nanoscale friction. We will discuss details of DFT calculations and how to generalize the current theory to three dimensional materials.

Viscosity and diffusivity in melts: from unary to multicomponent systems

NASA Astrophysics Data System (ADS)

Chen, Weimin; Zhang, Lijun; Du, Yong; Huang, Baiyun

2014-05-01

Viscosity and diffusivity, two important transport coefficients, are systematically investigated from unary melt to binary to multicomponent melts in the present work. By coupling with Kaptay's viscosity equation of pure liquid metals and effective radii of diffusion species, the Sutherland equation is modified by taking the size effect into account, and further derived into an Arrhenius formula for the convenient usage. Its reliability for predicting self-diffusivity and impurity diffusivity in unary liquids is then validated by comparing the calculated self-diffusivities and impurity diffusivities in liquid Al- and Fe-based alloys with the experimental and the assessed data. Moreover, the Kozlov model was chosen among various viscosity models as the most reliable one to reproduce the experimental viscosities in binary and multicomponent melts. Based on the reliable viscosities calculated from the Kozlov model, the modified Sutherland equation is utilized to predict the tracer diffusivities in binary and multicomponent melts, and validated in Al-Cu, Al-Ni and Al-Ce-Ni melts. Comprehensive comparisons between the calculated results and the literature data indicate that the experimental tracer diffusivities and the theoretical ones can be well reproduced by the present calculations. In addition, the vacancy-wind factor in binary liquid Al-Ni alloys with the increasing temperature is also discussed. What's more, the calculated inter-diffusivities in liquid Al-Cu, Al-Ni and Al-Ag-Cu alloys are also in excellent agreement with the measured and theoretical data. Comparisons between the simulated concentration profiles and the measured ones in Al-Cu, Al-Ce-Ni and Al-Ag-Cu melts are further used to validate the present calculation method.

Influence of viscosity modifying admixtures on the rheological behavior of cement and mortar pastes

NASA Astrophysics Data System (ADS)

Bouras, R.; Kaci, A.; Chaouche, M.

2012-03-01

The influence of Viscosity-modifying admixtures (VMA) dosage rate on the steady state rheological properties, including the yield stress, fluid consistency index and flow behaviour index, of cementitious materials is considered experimentally. The investigation is undertaken both at cement paste and mortar scales. It is found that the rheological behaviour of the material is in general dependent upon shear-rate interval considered. At sufficiently low shear-rates the materials exhibit shear-thinning. This behaviour is attributed to flow-induced defloculation of the solid particles and VMA polymer disentanglement and alignment. At relatively high shear-rates the pastes becomes shear-thickening, due to repulsive interactions among the solid particles. There is a qualitative difference between the influence of VMA dosage at cement and mortar scales: at cement scale we obtain a monotonic increase of the yield stress, while at mortar scale there exists an optimum VMA dosage for which the yield stress is a minimum. The flow behaviour index exhibit a maximum in the case of cement pastes and monotonically decreases in the case of mortars. On the other hand, the fluid consistency index presents a minimum for both cement pastes and mortars.

Characterization of nanoscale oxide and oxyhydroxide powders using EXAFS spectroscopy

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

Darab, J.G.; Linehan, J.C.; Matson, D.W.

1993-06-01

Extended x-ray absorption fine structure (EXAFS) spectroscopy has been used to determine the structural environment local to iron(HI) and zircorium(IV) cations in respectively, nanoscale iron oxyhydroxide and nanoscale zirconium oxide powders. The iron oxyhydroxide powder, produced by the modified reverse micelle (MRM) technology, was found to have a short-range structure most similar to that of goethite ([alpha]-FeOOH). The short-range structure of the zirconium oxide powder, produced using the rapid thermal decomposition of solutes (RTDS) technology, was found to be a mixture of monoclinic zirconia and cubic zirconia environments.

Characterization of nanoscale oxide and oxyhydroxide powders using EXAFS spectroscopy

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

Darab, J.G.; Linehan, J.C.; Matson, D.W.

1993-06-01

Extended x-ray absorption fine structure (EXAFS) spectroscopy has been used to determine the structural environment local to iron(HI) and zircorium(IV) cations in respectively, nanoscale iron oxyhydroxide and nanoscale zirconium oxide powders. The iron oxyhydroxide powder, produced by the modified reverse micelle (MRM) technology, was found to have a short-range structure most similar to that of goethite ({alpha}-FeOOH). The short-range structure of the zirconium oxide powder, produced using the rapid thermal decomposition of solutes (RTDS) technology, was found to be a mixture of monoclinic zirconia and cubic zirconia environments.

Antimicrobial and osteogenic properties of a hydrophilic-modified nanoscale hydroxyapatite coating on titanium.

PubMed

Murakami, Asuka; Arimoto, Takafumi; Suzuki, Dai; Iwai-Yoshida, Misato; Otsuka, Fukunaga; Shibata, Yo; Igarashi, Takeshi; Kamijo, Ryutaro; Miyazaki, Takashi

2012-04-01

Hydroxyapatite (HA)-coated titanium (Ti) is commonly used for implantable medical devices. This study examined in vitro osteoblast gene expression and antimicrobial activity against early and late colonizers of supra-gingival plaque on nanoscale HA-coated Ti prepared by discharge in a physiological buffered solution. The HA-coated Ti surface showed super-hydrophilicity, whereas the densely sintered HA and Ti surfaces alone showed lower hydrophilicity. The sintered HA and HA-coated Ti surfaces enhanced osteoblast phenotypes in comparison with the bare Ti surface. The HA-coated Ti enabled antimicrobial activity against early colonizers of supra-gingival plaques, namely Streptococcus mitis and Streptococcus gordonii. Such antimicrobial activity may be caused by the surface hydrophilicity, thereby leading to a repulsion force between the HA-coated Ti surface and the bacterial cell membranes. On the contrary, the sintered HA sample was susceptible to infection of microorganisms. Thus, hydrophilic-modified HA-coated Ti may have potential for use in implantable medical devices. From the Clinical Editor: This study establishes that Hydroxyapatite (HA)-coated titanium (Ti) surface of implanted devices may result in an optimal microenvironment to control and prevent infections and may have potential future clinical applications. Copyright © 2012 Elsevier Inc. All rights reserved.

Measurement of viscosity of gaseous mixtures at atmospheric pressure

NASA Technical Reports Server (NTRS)

Singh, J. J.; Mall, G. H.; Chegini, H.

1986-01-01

Coefficients of viscosity of various types of gas mixtures, including simulated natural-gas samples, have been measured at atmospheric pressure and room temperature using a modified capillary tube method. Pressure drops across the straight capillary tube section of a thermal mass flowmeter were measured for small, well-defined, volume flow rates for the test gases and for standard air. In this configuration, the flowmeter provides the volumetric flow rates as well as a well-characterized capillary section for differential pressure measurements across it. The coefficients of viscosity of the test gases were calculated using the reported value of 185.6 micro P for the viscosity of air. The coefficients of viscosity for the test mixtures were also calculated using Wilke's approximation of the Chapman-Enskog (C-E) theory. The experimental and calculated values for binary mixtures are in agreement within the reported accuracy of Wilke's approximation of the C-E theory. However, the agreement for multicomponent mixtures is less satisfactory, possible because of the limitations of Wilkes's approximation of the classical dilute-gas state model.

Revealing the Effects of Nanoscale Membrane Curvature on Lipid Mobility.

PubMed

Kabbani, Abir Maarouf; Woodward, Xinxin; Kelly, Christopher V

2017-10-18

Recent advances in nanoengineering and super-resolution microscopy have enabled new capabilities for creating and observing membrane curvature. However, the effects of curvature on single-lipid diffusion have yet to be revealed. The simulations presented here describe the capabilities of varying experimental methods for revealing the effects of nanoscale curvature on single-molecule mobility. Traditionally, lipid mobility is revealed through fluorescence recovery after photobleaching (FRAP), fluorescence correlation spectroscopy (FCS), and single particle tracking (SPT). However, these techniques vary greatly in their ability to detect the effects of nanoscale curvature on lipid behavior. Traditionally, FRAP and FCS depend on diffraction-limited illumination and detection. A simulation of FRAP shows minimal effects on lipids diffusion due to a 50 nm radius membrane bud. Throughout the stages of the budding process, FRAP detected minimal changes in lipid recovery time due to the curvature versus flat membrane. Simulated FCS demonstrated small effects due to a 50 nm radius membrane bud that was more apparent with curvature-dependent lipid mobility changes. However, SPT achieves a sub-diffraction-limited resolution of membrane budding and lipid mobility through the identification of the single-lipid positions with ≤15 nm spatial and ≤20 ms temporal resolution. By mapping the single-lipid step lengths to locations on the membrane, the effects of membrane topography and curvature could be correlated to the effective membrane viscosity. Single-fluorophore localization techniques, such SPT, can detect membrane curvature and its effects on lipid behavior. These simulations and discussion provide a guideline for optimizing the experimental procedures in revealing the effects of curvature on lipid mobility and effective local membrane viscosity.

Revealing the Effects of Nanoscale Membrane Curvature on Lipid Mobility

PubMed Central

Kabbani, Abir Maarouf; Woodward, Xinxin

2017-01-01

Recent advances in nanoengineering and super-resolution microscopy have enabled new capabilities for creating and observing membrane curvature. However, the effects of curvature on single-lipid diffusion have yet to be revealed. The simulations presented here describe the capabilities of varying experimental methods for revealing the effects of nanoscale curvature on single-molecule mobility. Traditionally, lipid mobility is revealed through fluorescence recovery after photobleaching (FRAP), fluorescence correlation spectroscopy (FCS), and single particle tracking (SPT). However, these techniques vary greatly in their ability to detect the effects of nanoscale curvature on lipid behavior. Traditionally, FRAP and FCS depend on diffraction-limited illumination and detection. A simulation of FRAP shows minimal effects on lipids diffusion due to a 50 nm radius membrane bud. Throughout the stages of the budding process, FRAP detected minimal changes in lipid recovery time due to the curvature versus flat membrane. Simulated FCS demonstrated small effects due to a 50 nm radius membrane bud that was more apparent with curvature-dependent lipid mobility changes. However, SPT achieves a sub-diffraction-limited resolution of membrane budding and lipid mobility through the identification of the single-lipid positions with ≤15 nm spatial and ≤20 ms temporal resolution. By mapping the single-lipid step lengths to locations on the membrane, the effects of membrane topography and curvature could be correlated to the effective membrane viscosity. Single-fluorophore localization techniques, such SPT, can detect membrane curvature and its effects on lipid behavior. These simulations and discussion provide a guideline for optimizing the experimental procedures in revealing the effects of curvature on lipid mobility and effective local membrane viscosity. PMID:29057801

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.

Talin determines the nanoscale architecture of focal adhesions.

PubMed

Liu, Jaron; Wang, Yilin; Goh, Wah Ing; Goh, Honzhen; Baird, Michelle A; Ruehland, Svenja; Teo, Shijia; Bate, Neil; Critchley, David R; Davidson, Michael W; Kanchanawong, Pakorn

2015-09-01

Insight into how molecular machines perform their biological functions depends on knowledge of the spatial organization of the components, their connectivity, geometry, and organizational hierarchy. However, these parameters are difficult to determine in multicomponent assemblies such as integrin-based focal adhesions (FAs). We have previously applied 3D superresolution fluorescence microscopy to probe the spatial organization of major FA components, observing a nanoscale stratification of proteins between integrins and the actin cytoskeleton. Here we combine superresolution imaging techniques with a protein engineering approach to investigate how such nanoscale architecture arises. We demonstrate that talin plays a key structural role in regulating the nanoscale architecture of FAs, akin to a molecular ruler. Talin diagonally spans the FA core, with its N terminus at the membrane and C terminus demarcating the FA/stress fiber interface. In contrast, vinculin is found to be dispensable for specification of FA nanoscale architecture. Recombinant analogs of talin with modified lengths recapitulated its polarized orientation but altered the FA/stress fiber interface in a linear manner, consistent with its modular structure, and implicating the integrin-talin-actin complex as the primary mechanical linkage in FAs. Talin was found to be ∼97 nm in length and oriented at ∼15° relative to the plasma membrane. Our results identify talin as the primary determinant of FA nanoscale organization and suggest how multiple cellular forces may be integrated at adhesion sites.

Reverse micelle synthesis of nanoscale metal containing catalysts

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

Darab, J.G.; Fulton, J.L.; Linehan, J.C.

1993-03-01

The need for morphological control during the synthesis of catalyst precursor powders is generally accepted to be important. In the liquefaction of coal, for example, iron-bearing catalyst precursor particles containing individual crystallites with diameters in the 1-100 nanometer range are believed to achieve good dispersion through out the coal-solvent slurry during liquefaction 2 runs and to undergo chemical transformations to catalytically active iron sulfide phases. The production of the nanoscale powders described here employs the confining spherical microdomains comprising the aqueous phase of a modified reverse micelle (MRM) microemulsion system as nanoscale reaction vessels in which polymerization, electrochemical reduction andmore » precipitation of solvated salts can occur. The goal is to take advantage of the confining nature of micelles to kinetically hinder transformation processes which readily occur in bulk aqueous solution in order to control the morphology and phase of the resulting powder. We have prepared a variety of metal, alloy, and metal- and mixed metal-oxide nanoscale powders from appropriate MRM systems. Examples of nanoscale powders produced include Co, Mo-Co, Ni{sub 3}Fe, Ni, and various oxides and oxyhydroxides of iron. Here, we discuss the preparation and characterization of nickel metal (with a nickel oxide surface layer) and iron oxyhydroxide MRM nanoscale powders. We have used extended x-ray absorption fine structure (EXAFS) spectroscopy to study the chemical polymerization process in situ, x-ray diffraction (XRD), scanning and transmission electron microcroscopies (SEM and TEM), elemental analysis and structural modelling to characterize the nanoscale powders produced. The catalytic activity of these powders is currently being studied.« less

Reverse micelle synthesis of nanoscale metal containing catalysts. [Nickel metal (with a nickel oxide surface layer) and iron oxyhydroxide nanoscale powders

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

Darab, J.G.; Fulton, J.L.; Linehan, J.C.

1993-03-01

The need for morphological control during the synthesis of catalyst precursor powders is generally accepted to be important. In the liquefaction of coal, for example, iron-bearing catalyst precursor particles containing individual crystallites with diameters in the 1-100 nanometer range are believed to achieve good dispersion through out the coal-solvent slurry during liquefaction 2 runs and to undergo chemical transformations to catalytically active iron sulfide phases. The production of the nanoscale powders described here employs the confining spherical microdomains comprising the aqueous phase of a modified reverse micelle (MRM) microemulsion system as nanoscale reaction vessels in which polymerization, electrochemical reduction andmore » precipitation of solvated salts can occur. The goal is to take advantage of the confining nature of micelles to kinetically hinder transformation processes which readily occur in bulk aqueous solution in order to control the morphology and phase of the resulting powder. We have prepared a variety of metal, alloy, and metal- and mixed metal-oxide nanoscale powders from appropriate MRM systems. Examples of nanoscale powders produced include Co, Mo-Co, Ni[sub 3]Fe, Ni, and various oxides and oxyhydroxides of iron. Here, we discuss the preparation and characterization of nickel metal (with a nickel oxide surface layer) and iron oxyhydroxide MRM nanoscale powders. We have used extended x-ray absorption fine structure (EXAFS) spectroscopy to study the chemical polymerization process in situ, x-ray diffraction (XRD), scanning and transmission electron microcroscopies (SEM and TEM), elemental analysis and structural modelling to characterize the nanoscale powders produced. The catalytic activity of these powders is currently being studied.« less

Variable-viscosity thermal hemodynamic slip flow conveying nanoparticles through a permeable-walled composite stenosed artery

NASA Astrophysics Data System (ADS)

Akbar, Noreen Sher; Tripathi, Dharmendra; Bég, O. Anwar

2017-07-01

This paper presents a mathematical model for simulating viscous, incompressible, steady-state blood flow containing copper nanoparticles and coupled heat transfer through a composite stenosed artery with permeable walls. Wall slip hydrodynamic and also thermal buoyancy effects are included. The artery is simulated as an isotropic elastic tube, following Joshi et al. (2009), and a variable viscosity formulation is employed for the flowing blood. The equations governing the transport phenomena are non-dimensionalized and the resulting boundary value problem is solved analytically in the steady state subject to physically appropriate boundary conditions. Numerical computations are conducted to quantify the effects of relevant hemodynamic, thermophysical and nanoscale parameters emerging in the model on velocity and temperature profiles, wall shear stress, impedance resistance and also streamline distributions. The model may be applicable to drug fate transport modeling with nanoparticle agents and also to the optimized design of nanoscale medical devices for diagnosing stenotic diseases in circulatory systems.

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

DOE PAGES

Vold, Erik Lehman; Joglekar, Archis S.; Ortega, Mario I.; ...

2015-11-20

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. In this paper, we have implemented a Lagrangian hydrodynamic code in one-dimensional spherical geometry with plasmaviscosity 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 plasmaviscosity andmore » to determine the impacts of viscosity on temperature histories and neutron yield. It was found that plasmaviscosity has substantial impacts on ICF shock dynamics characterized by shock burn timing, maximum burn temperatures, convergence ratio, and time history of neutron production rates. Finally, plasmaviscosity 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

Viscosity Measurements of SiO2-"FeO"-MgO System in Equilibrium with Metallic Fe

NASA Astrophysics Data System (ADS)

Chen, Mao; Raghunath, Sreekanth; Zhao, Baojun

2014-01-01

The present study delivers the measurements of viscosities in the SiO2-"FeO"-MgO system in equilibrium with metallic Fe. The rotational spindle technique was used for the measurements at the temperature range of 1523 K to 1773 K (1250 °C to 1500 °C). Molybdenum crucibles and spindles were employed in all measurements. The viscosity measurements were carried out at 31 to 47 mol pct SiO2 and up to 18.8 mol pct MgO. Analysis of the quenched sample by Electron probe X-ray microanalysis after the viscosity measurement enables the composition and microstructure of the slag to be directly linked with the viscosity. The replacement of "FeO" by MgO was found to increase viscosity and activation energy of the SiO2-"FeO"-MgO slags. The modified Quasi-chemical Viscosity Model was further optimized in this system based on the current viscosity measurements.

Nanoscale Controls on CO2-water-rock Interactions in Saline Reservoirs

NASA Astrophysics Data System (ADS)

Deyoreo, J.; Depaolo, D. J.

2009-12-01

It is becoming increasingly widely recognized that geologic sequestration of CO2, when combined with economical means of capture, may be one of the most effective approaches to reducing net CO2 emissions to the atmosphere over the next century. Injection of CO2 into saline geologic formations involves forcing a buoyant, low-viscosity fluid into a more dense, higher viscosity fluid. The difference in wetting properties of the two fluids, their partial miscibility, the fact that CO2 and H2O form an acid, and the heterogeneity of geologic formations combine to make the flow and transport details fascinating but difficult to fully characterize and predict. A major question is whether the flow of CO2 into subsurface formations, the efficiency of pore space filling, and the trapping efficiency can be not only predicted but controlled over the decades of injection that might be associated with the life of a power plant. The major technological gaps to controlling and ultimately sequestering subsurface CO2 can be traced to far-from-equilibrum processes that originate at the molecular and nanoscale, but are expressed as complex emergent behavior at larger scales. Essential knowledge gaps involve the effects of nanoscale confinement on material properties, flow and chemical reactions, the effects of nanoparticles, mineral surface dynamics, and microbiota on mineral dissolution/precipitation and fluid flow, and the dynamics of fluid-fluid and fluid-mineral interfaces. To address these scientific and technical challenges, the Energy Frontier Research Center recently established, involving collaboration between LBNL, ORNL, MIT, UC Berkeley, UC Davis and LLNL, will attempt to bring new approaches to the study of nanoscale phenomena in fluid-rock systems to bear on the problem of CO2 behavior in saline formations. The stated goal is to use molecular, nanoscale, and pore-network scale approaches to control flow, dissolution, and precipitation in deep subsurface rock formations to

Intrinsic viscosity and rheological properties of natural and substituted guar gums in seawater.

PubMed

Wang, Shibin; He, Le; Guo, Jianchun; Zhao, Jinzhou; Tang, Hongbiao

2015-05-01

The intrinsic viscosity and rheological properties of guar gum (GG), hydroxypropyl guar (HPG) and carboxymethyl guar (CMG) in seawater and the effects of shear rate, concentration, temperature and pH on these properties were investigated. An intrinsic viscosity-increasing effect was observed with GG and HPG in seawater (SW) compared to deionized water (DW), whereas the intrinsic viscosity of CMG in seawater was much lower than that in DW due to a screening effect that reduced the repulsion between the polymer chains. Regardless of the functional groups, all sample solutions was well characterized by a modified Cross model that exhibited the transition from Newtonian to pseudoplastic in the low shear rate range at the concentrations of interest to industries, and their viscosity increased with the increase in their concentration but decreased with the increase in temperature. In contrast to nonionic GG or HPG, anionic CMG had a slightly decreased viscosity property in SW, exhibiting polyelectrolyte viscosity behavior. The α value in the zero-shear rate viscosity vs. concentration power-law equation for the samples gave the order of CMG>HPG>GG while the SW solution of CMG had the lowest viscous flow activation energy and exhibited a strong pH-dependent viscosity by a different shear rate. Copyright © 2015 Elsevier B.V. All rights reserved.

Viscosity Measurements of "FeO"-SiO2 Slag in Equilibrium with Metallic Fe

NASA Astrophysics Data System (ADS)

Chen, Mao; Raghunath, Sreekanth; Zhao, Baojun

2013-06-01

The current study delivered the measurements of viscosities in the system "FeO"-SiO2 in equilibrium with metallic Fe in the composition range between 15 and 40 wt pct SiO2. The experiments were carried out in the temperature range of 1473 K to 1773 K (1200 °C to 1500 °C) using a rotational spindle technique. An analysis of the quenched sample by electron probe X-ray microanalysis (EPMA) after the viscosity measurement enables the composition and microstructure of the slag to be directly linked with the viscosity. The current results are compared with available literature data. The significant discrepancies of the viscosity measurements in this system have been clarified. The possible reasons affecting the accuracy of the viscosity measurement have been discussed. The activation energies derived from the experimental data have a sharp increase at about 33 wt pct SiO2, which corresponds to the composition of fayalite (Fe2SiO4). The modified quasi-chemical model was constructed in the system "FeO"-SiO2 to describe the current viscosity data.

Multiscale modeling of electroosmotic flow: Effects of discrete ion, enhanced viscosity, and surface friction

NASA Astrophysics Data System (ADS)

Bhadauria, Ravi; Aluru, N. R.

2017-05-01

We propose an isothermal, one-dimensional, electroosmotic flow model for slit-shaped nanochannels. Nanoscale confinement effects are embedded into the transport model by incorporating the spatially varying solvent and ion concentration profiles that correspond to the electrochemical potential of mean force. The local viscosity is dependent on the solvent local density and is modeled using the local average density method. Excess contributions to the local viscosity are included using the Onsager-Fuoss expression that is dependent on the local ionic strength. A Dirichlet-type boundary condition is provided in the form of the slip velocity that is dependent on the macroscopic interfacial friction. This solvent-surface specific interfacial friction is estimated using a dynamical generalized Langevin equation based framework. The electroosmotic flow of Na+ and Cl- as single counterions and NaCl salt solvated in Extended Simple Point Charge (SPC/E) water confined between graphene and silicon slit-shaped nanochannels are considered as examples. The proposed model yields a good quantitative agreement with the solvent velocity profiles obtained from the non-equilibrium molecular dynamics simulations.

On the self-preservation of turbulent jet flows with variable viscosity

NASA Astrophysics Data System (ADS)

Danaila, Luminita; Gauding, Michael; Varea, Emilien; Turbulence; mixing Team

2017-11-01

The concept of self-preservation has played an important role in shaping the understanding of turbulent flows. The assumption of complete self-preservation imposes certain constrains on the dynamics of the flow, allowing to express one-point or two-point statistics by choosing an appropriate unique length scale. Determining this length scale and its scaling is of high relevance for modeling. In this work, we study turbulent jet flows with variable viscosity from the self-preservation perspective. Turbulent flows encountered in engineering and environmental applications are often characterized by fluctuations of viscosity resulting for instance from variations of temperature or species composition. Starting from the transport equation for the moments of the mixture fraction increment, constraints for self-preservation are derived. The analysis is based on direct numerical simulations of turbulent jet flows where the viscosity between host and jet fluid differs. It is shown that fluctuations of viscosity do not affect the decay exponents of the turbulent energy or the dissipation but modify the scaling of two-point statistics in the dissipative range. Moreover, the analysis reveals that complete self-preservation in turbulent flows with variable viscosity cannot be achieved. Financial support from Labex EMC3 and FEDER is gratefully acknowledged.

Characteristics of Chemical and Functional Properties of Modified Cassava Flour (Manihot esculenta) by Autoclaving-Cooling Cycles Method

NASA Astrophysics Data System (ADS)

Cecep Erwan Andriansyah, Raden; Rahman, Taufik; Herminiati, Ainia; Rahman, Nurhaidar; Luthfiyanti, Rohmah

2017-12-01

The modified cassava flour can be made using the method of the autoclaving cooling cycle (AAC). The stability of the warming can be seen from the decreasing value of breakdown viscosity, while the stability of the stirring process can be seen by the decreasing value of setback viscosity. The stages of research include: (1) the making of cassava flour, (2) the making of modified cassava flour by the method of treatment of ACC with a variety of flour concentration and autoclaving time, (3) chemical analysis of the moisture, ash, fat, protein, carbohydrate; The functional properties of the pasting characteristics to the initial temperature of the pasting, peak viscosity, hot paste viscosity, breakdown viscosity, cold paste viscosity and setback viscosity. The result shows that cassava flour modified by treatment of flour concentration 16% and autoclaving time 41 minutes having pasting code and pasting viscosity which is resistant to high temperature. Flour with this character is flour that is expected to maintain the texture of processed products with a paste form that remains stable. Utilization of modified cassava flour by the ACC method can be applied to the pasting product such as noodle and spaghetti, hoping to support for food diversification program to reduce dependence on wheat flour in Indonesia.

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.

Factors affecting the viscosity in high concentration solutions of different monoclonal antibodies.

PubMed

Yadav, Sandeep; Shire, Steven J; Kalonia, Devendra S

2010-12-01

The viscosity profiles of four different IgG(1) molecules were studied as a function of concentration at pH 6.0. At high concentrations, MAb-H and -A showed significantly higher viscosities as compared to MAb-G and -E. Zeta Potential (ξ) measurements showed that all the IgG(1) molecules carried a net positive charge at this pH. MAb-G showed the highest positive zeta potential followed by MAb-E, -H, and -A. A consistent interpretation of the impact of net charge on viscosity for these MAbs is not possible, suggesting that electroviscous effects cannot explain the differences in viscosity. Values of k(D) (dynamic light scattering) indicated that the intermolecular interactions were repulsive for MAb-E and -G; and attractive for MAb-H and -A. Solution storage modulus (G') in high concentration solutions was consistent with attractive intermolecular interactions for MAb-H and -A, and repulsive interactions for MAb-G and -E. Effect of salt addition on solution G' and k(D) indicated that the interactions were primarily electrostatic in nature. The concentration dependent viscosity data were analyzed using a modified Ross and Minton equation. The analysis explicitly differentiates between the effect of molecular shape, size, self-crowding, and electrostatic intermolecular interactions in governing high concentration viscosity behavior. © 2010 Wiley-Liss, Inc. and the American Pharmacists Association

Structural and molecular basis of starch viscosity in hexaploid wheat.

PubMed

Ral, J-P; Cavanagh, C R; Larroque, O; Regina, A; Morell, M K

2008-06-11

Wheat starch is considered to have a low paste viscosity relative to other starches. Consequently, wheat starch is not preferred for many applications as compared to other high paste viscosity starches. Increasing the viscosity of wheat starch is expected to increase the functionality of a range of wheat flour-based products in which the texture is an important aspect of consumer acceptance (e.g., pasta, and instant and yellow alkaline noodles). To understand the molecular basis of starch viscosity, we have undertaken a comprehensive structural and rheological analysis of starches from a genetically diverse set of wheat genotypes, which revealed significant variation in starch traits including starch granule protein content, starch-associated lipid content and composition, phosphate content, and the structures of the amylose and amylopectin fractions. Statistical analysis highlighted the association between amylopectin chains of 18-25 glucose residues and starch pasting properties. Principal component analysis also identified an association between monoesterified phosphate and starch pasting properties in wheat despite the low starch-phosphate level in wheat as compared to tuber starches. We also found a strong negative correlation between the phosphate ester content and the starch content in flour. Previously observed associations between internal starch granule fatty acids and the swelling peak time and pasting temperature have been confirmed. This study has highlighted a range of parameters associated with increased starch viscosity that could be used in prebreeding/breeding programs to modify wheat starch pasting properties.

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).

Addition of simultaneous heat and solute transport and variable fluid viscosity to SEAWAT

USGS Publications Warehouse

Thorne, D.; Langevin, C.D.; Sukop, M.C.

2006-01-01

SEAWAT is a finite-difference computer code designed to simulate coupled variable-density ground water flow and solute transport. This paper describes a new version of SEAWAT that adds the ability to simultaneously model energy and solute transport. This is necessary for simulating the transport of heat and salinity in coastal aquifers for example. This work extends the equation of state for fluid density to vary as a function of temperature and/or solute concentration. The program has also been modified to represent the effects of variable fluid viscosity as a function of temperature and/or concentration. The viscosity mechanism is verified against an analytical solution, and a test of temperature-dependent viscosity is provided. Finally, the classic Henry-Hilleke problem is solved with the new code. ?? 2006 Elsevier Ltd. All rights reserved.

Modelling of wicking and moisture interactions of flax and viscose fibres.

PubMed

Stuart, T; McCall, R D; Sharma, H S S; Lyons, G

2015-06-05

Methods for assessing the wicking properties of individual fibre bundles have been developed from models based on the original Washburn equation (WE) and the modified Washburn equation (MWE), which also accounts for swelling. Both models gave indication of differences in wicking properties of flax and the viscose fibres, though MWE gave additional information that could be interpreted in terms of the physical model. Wicking of the viscose fibres is mainly via inter-fibre capillaries while that of flax is a combination of inter-fibre capillaries and lumen present in some elementary fibres. The degree of swelling and associated rotation of flax fibre in a vapour pressure range of 1-6torr were monitored using an environmental scanning electron microscope (ESEM). Viscose fibre exhibited swelling under the same conditions but did not rotate. The two techniques highlighted different mechanisms of wicking which can be used for monitoring moisture uptake/swelling of treated fibres for fabrication of composites. Copyright © 2015 Elsevier Ltd. All rights reserved.

The Properties of Confined Water and Fluid Flow at the Nanoscale

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

Schwegler, E; Reed, J; Lau, E

This project has been focused on the development of accurate computational tools to study fluids in confined, nanoscale geometries, and the application of these techniques to probe the structural and electronic properties of water confined between hydrophilic and hydrophobic substrates, including the presence of simple ions at the interfaces. In particular, we have used a series of ab-initio molecular dynamics simulations and quantum Monte Carlo calculations to build an understanding of how hydrogen bonding and solvation are modified at the nanoscale. The properties of confined water affect a wide range of scientific and technological problems - including protein folding, cell-membranemore » flow, materials properties in confined media and nanofluidic devices.« less

Lithographically Patterned Nanoscale Electrodeposition of Plasmonic, Bimetallic, Semiconductor, Magnetic, and Polymer Nanoring Arrays

PubMed Central

2015-01-01

Large area arrays of magnetic, semiconducting, and insulating nanorings were created by coupling colloidal lithography with nanoscale electrodeposition. This versatile nanoscale fabrication process allows for the independent tuning of the spacing, diameter, and width of the nanorings with typical values of 1.0 μm, 750 nm, and 100 nm, respectively, and was used to form nanorings from a host of materials: Ni, Co, bimetallic Ni/Au, CdSe, and polydopamine. These nanoring arrays have potential applications in memory storage, optical materials, and biosensing. A modified version of this nanoscale electrodeposition process was also used to create arrays of split gold nanorings. The size of the split nanoring opening was controlled by the angle of photoresist exposure during the fabrication process and could be varied from 50% down to 10% of the ring circumference. The large area (cm2 scale) gold split nanoring array surfaces exhibited strong polarization-dependent plasmonic absorption bands for wavelengths from 1 to 5 μm. Plasmonic nanoscale split ring arrays are potentially useful as tunable dichroic materials throughout the infrared and near-infrared spectral regions. PMID:25553204

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.

Nanoprocess and nanoscale surface functionalization on cathode materials for advanced lithium-ion batteries.

PubMed

Alaboina, Pankaj Kumar; Uddin, Md-Jamal; Cho, Sung-Jin

2017-10-26

Nanotechnology-driven development of cathode materials is an essential part to revolutionize the evolution of the next generation lithium ion batteries. With the progress of nanoprocess and nanoscale surface modification investigations on cathode materials in recent years, the advanced battery technology future seems very promising - Thanks to nanotechnology. In this review, an overview of promising nanoscale surface deposition methods and their significance in surface functionalization on cathodes is extensively summarized. Surface modified cathodes are provided with a protective layer to overcome the electrochemical performance limitations related to side reactions with electrolytes, reduce self-discharge reactions, improve thermal and structural stability, and further enhance the overall battery performance. The review addresses the importance of nanoscale surface modification on battery cathodes and concludes with a comparison of the different nanoprocess techniques discussed to provide a direction in the race to build advanced lithium-ion batteries.

Magnetic sulfide-modified nanoscale zerovalent iron (S-nZVI) for dissolved metal ion removal.

PubMed

Su, Yiming; Adeleye, Adeyemi S; Keller, Arturo A; Huang, Yuxiong; Dai, Chaomeng; Zhou, Xuefei; Zhang, Yalei

2015-05-01

Sulfide-modified nanoscale zerovalent iron (S-nZVI) is attracting a lot of attention due to its ease of production and high reactivity with organic pollutants. However, its structure is still poorly understood and its potential application in heavy metal remediation has not been explored. Herein, the structure of S-nZVI and its cadmium (Cd) removal performance under different aqueous conditions were carefully investigated. Transmission electron microscopy (TEM) with an energy-dispersive X-ray spectroscopy (EDS) analysis suggested that sulfur was incorporated into the zerovalent iron core. Scanning electron microscopy (SEM) with EDS analysis demonstrated that sulfur was also homogeneously distributed within the nanoparticles. When the concentration of Na2S2O4 was increased during synthesis, a flake-like structure (FeSx) increased significantly. S-nZVI had an optimal Cd removal capacity of 85 mg/g, which was >100% higher than for pristine nZVI. Even at pH 5, over 95% removal efficiency was observed, indicating sulfide compounds played a crucial role in metal ion removal and particle chemical stability. Oxygen impaired the structure of S-nZVI but enhanced Cd removal capacity to about 120 mg/g. Particle aging had no negative effect on removal capacity of S-nZVI, and Cd-containing mixtures remained stable in a two months experiment. S-nZVI can efficiently sequester dissolved metal ions from different contaminated water matrices. Copyright © 2015 Elsevier Ltd. All rights reserved.

Idiosyncrasies of volcanic sulfur viscosity and the triggering of unheralded volcanic eruptions

NASA Astrophysics Data System (ADS)

Scolamacchia, Teresa; Cronin, Shane

2016-03-01

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

Online shear viscosity measurement of starchy melts enriched in wheat bran.

PubMed

Robin, Frédéric; Bovet, Nicolas; Pineau, Nicolas; Schuchmann, Heike P; Palzer, Stefan

2011-01-01

Addition of wheat bran to flours modifies their expansion properties after cooking extrusion. This can be attributed to changes in the melt shear viscosity at the die. The effect of wheat bran concentration added to achieve 2 levels of dietary fibers of 12. 6% and 24.4%, and process conditions on the shear viscosity of wheat flour was therefore assessed using an online twin-slit rheometer. The shear viscosity measured at 30 s⁻¹ ranged from 9.5 × 10³ to 53.4 × 10³ Pa s. Regardless of the process conditions and bran concentration, the extruded melts showed a pseudoplastic behavior with a power law index n ranging from 0.05 to 0.27. Increasing the barrel temperature of the extruder from 120 to 180 °C, the water content from 18% to 22% or the screw speed from 400 to 800 rpm significantly decreased the melt shear viscosity at the extruder exit. The addition of bran significantly increased the melt shear viscosity only at the highest bran concentration. The effect was process condition dependant. Mathematical interpretations, based upon observations, of the experimental data were carried out. They can be used to predict the effect of the process conditions on the melt shear viscosity at the die of extruded wheat flour with increasing bran concentration. The viscosity data will be applied in future works to study the expansion properties of extruded wheat flour supplemented with bran. Incorporation of wheat bran, a readily available and low cost by-product, in extruded puffed foods is constrained due to its negative effect on the product texture. Understanding the effect of wheat bran on rheological properties of extruded melts, driving the final product properties, is essential to provide solutions to the food industry and enhance its use. © 2011 Institute of Food Technologists®

Design and characterization of sulfide-modified nanoscale zerovalent iron for cadmium(II) removal from aqueous solutions

NASA Astrophysics Data System (ADS)

Lv, Dan; Zhou, Xiaoxin; Zhou, Jiasheng; Liu, Yuanli; Li, Yizhou; Yang, Kunlun; Lou, Zimo; Baig, Shams Ali; Wu, Donglei; Xu, Xinhua

2018-06-01

Nanoscale zero-valent iron (nZVI) has high removal efficiency and strong reductive ability to organic and inorganic contaminants, but concerns over its stability and dispersity limit its application. In this study, nZVI was modified with sulfide to enhance Cd(II) removal from aqueous solutions. TEM and SEM analyses showed that sulfide-modified nZVI (S-nZVI) had a core-shell structure of nano-sized spherical particles, and BET results proved that sulfide modification doubled the specific surface area from 26.04 to 50.34 m2 g-1 and inhibited the aggregation of nZVI. Mechanism analysis indicated that Cd(II) was immobilized through complexation and precipitation. Cd(II) removal rate on nZVI was only 32% in 2 h, while complete immobilization could be achieved in 15 min on S-nZVI, and S-nZVI with an optimal S/Fe molar ratio of 0.3 offered a cadmium removal capacity of about 150 mg g-1 at pH 7 and 303 K. The process of Cd(II) immobilization on S-nZVI was fitted well with pseudo-second-order kinetic model, and the increase of temperature favored Cd(II) immobilization, suggesting an endothermic process. The presence of Mg2+ and Ca2+ hindered Cd(II) removal while Cu2+ did the opposite, which led to the order as Cu2+ > control > Mg2+ > Ca2+. The removal rate of 20 mg L-1 Cd(II) maintained a high level with the fluctuation of environmental conditions such as pH, ion strength and presence of HA. This study demonstrated that S-nZVI could be a promising adsorbent for Cd(II) immobilization from cadmium-contaminated water.

A nanoscale perspective on the effects of transverse microprestress on drying creep of nanoporous solids

NASA Astrophysics Data System (ADS)

Sinko, Robert; Bažant, Zdeněk P.; Keten, Sinan

2018-01-01

The Pickett effect describes the excess non-additive strain developed during drying of a nanoporous solid material under creep. One explanation for its origins, developed using micromechanical models, is the progressive relaxation of internally developed microprestress. However, these models have not explicitly considered the effects of this microprestress on nanoscale energy barriers that govern the relative motion and displacement between nanopore walls during deformation. Here, we evaluate the nanoscale effects of transverse microprestresses on the drying creep behaviour of a nanoscale slit pore using coarse-grained molecular dynamics. We find that the underlying energy barrier depends exponentially on the transverse microprestress, which is attributed to changes in the effective viscosity and degree of nanoconfinement of molecules in the water interlayer. Specifically, as the transverse microprestress is relaxed (i.e. its magnitude decreases), the activation energy barrier is reduced, thereby leading to an acceleration of the creep behaviour and a stronger Pickett effect. Based on our simulation results, we introduce a new microprestress-dependent energy term into our existing Arrhenius model, which describes the relative displacement of pore walls as a function of the underlying activation energy barriers. Our findings further verify the existing micromechanical theories for the origin of the Pickett effect and establish a quantitative relationship between the transverse microprestress and the intensity of the Pickett effect.

Factors affecting the viscosity of sodium hypochlorite and their effect on irrigant flow.

PubMed

Bukiet, F; Soler, T; Guivarch, M; Camps, J; Tassery, H; Cuisinier, F; Candoni, N

2013-10-01

To assess the influence of concentration, temperature and surfactant addition to a sodium hypochlorite solution on its dynamic viscosity and to calculate the corresponding Reynolds number to determine the corresponding flow regimen. The dynamic viscosity of the irrigant was assessed using a rotational viscometer. Sodium hypochlorite with concentrations ranging from 0.6% to 9.6% was tested at 37 and 22 °C. A wide range of concentrations of three different surfactants was mixed in 2.4% sodium hypochlorite for viscosity measurements. The Reynolds number was calculated under each condition. Data were analysed using two-way anova. There was a significant influence of sodium hypochlorite concentration (P < 0.001) and temperature (P < 0.001) on dynamic viscosity: the latter significantly increased with sodium hypochlorite concentration and decreased with temperature. A significant influence of surfactant concentration on dynamic viscosity (P < 0.001) occurred, especially for high surfactant concentrations: 6.25% for benzalkonium chloride, 15% for Tween 80 and 6.25% for Triton X-100. Reynolds number values calculated for a given flow rate (0.14 mL s(-1)), and root canal diameter (sizes 45 and 70) clearly qualified the irrigant flow regimen as laminar. Dynamic viscosity increased with sodium hypochlorite and surfactant concentration but decreased with temperature. Under clinical conditions, all viscosities measured led to laminar flow. The transition between laminar and turbulent flow may be reached by modifying different parameters at the same time: increasing flow rate and temperature whilst decreasing irrigant viscosity by adding surfactants with a high value of critical micellar concentration. © 2013 International Endodontic Journal. Published by John Wiley & Sons Ltd.

Morphology Formation in PC/ABS Blends during Thermal Processing and the Effect of the Viscosity Ratio of Blend Partners

PubMed Central

Bärwinkel, Stefanie; Seidel, Andreas; Hobeika, Sven; Hufen, Ralf; Mörl, Michaela; Altstädt, Volker

2016-01-01

Morphology formation during compounding, as well as injection molding of blends containing 60 wt % polycarbonate (PC) and 40 wt % polybutadiene rubber-modified styrene-acrylonitrile copolymers (ABS), has been investigated by transmission electron microscopy (TEM). Profiles of the blend morphology have been recorded in injection-molded specimens and significant morphology gradients observed between their skin and core. A <10 µm thick surface layer with strongly dispersed and elongated nano-scale (streak-like) styrene acrylonitrile (SAN) phases and well-dispersed, isolated SAN-grafted polybutadiene rubber particles is followed by a 50–150 µm thick skin layer in which polymer morphology is characterized by lamellar SAN/ABS phases. Thickness of these lamellae increases with the distance from the specimen’s surface. In the core of the specimens the SAN-grafted polybutadiene rubber particles are exclusively present within the SAN phases, which exhibit a much coarser and less oriented, dispersed morphology compared to the skin. The effects of the viscosity of the SAN in the PC/ABS blends on phase morphologies and correlations with fracture mechanics in tensile and impact tests were investigated, including scanning electron microscopy (SEM) assessment of the fracture surfaces. A model explaining the mechanisms of morphology formation during injection molding of PC/ABS blends is discussed. PMID:28773780

Viscosity of SiO2-"FeO"-Al2O3 System in Equilibrium with Metallic Fe

NASA Astrophysics Data System (ADS)

Chen, Mao; Raghunath, Sreekanth; Zhao, Baojun

2013-08-01

The present study delivered the measurements of viscosities in SiO2-"FeO"-Al2O3 system in equilibrium with metallic Fe. The rotational spindle technique was used in the measurements at the temperature range of 1473 K to 1773 K (1200 °C to 1500 °C). Molybdenum crucibles and spindles were employed in all measurements. The Fe saturation condition was maintained by an iron plate placed at the bottom of the crucible. The equilibrium compositions of the slags were measured by EPMA after the viscosity measurements. The effect of up to 20 mol. pct Al2O3 on the viscosity of the SiO2-"FeO" slag was investigated. The "charge compensation effect" of the Al2O3 and FeO association has been discussed. The modified quasi-chemical viscosity model has been optimized in the SiO2-"FeO"-Al2O3 system in equilibrium with metallic Fe to describe the viscosity measurements of the present study.

Stabilization of hydrodynamic flows by small viscosity variations.

PubMed

Govindarajan, Rama; L'vov, Victor S; Procaccia, Itamar; Sameen, A

2003-02-01

Motivated by the large effect of turbulent drag reduction by minute concentrations of polymers, we study the effects of a weakly space-dependent viscosity on the stability of hydrodynamic flows. In a recent paper [Phys. Rev. Lett. 87, 174501, (2001)], we exposed the crucial role played by a localized region where the energy of fluctuations is produced by interactions with the mean flow (the "critical layer"). We showed that a layer of a weakly space-dependent viscosity placed near the critical layer can have a very large stabilizing effect on hydrodynamic fluctuations, retarding significantly the onset of turbulence. In this paper we extend these observations in two directions: first we show that the strong stabilization of the primary instability is also obtained when the viscosity profile is realistic (inferred from simulations of turbulent flows with a small concentration of polymers). Second, we analyze the secondary instability (around the time-dependent primary instability) and find similar strong stabilization. Since the secondary instability develops around a time-dependent solution and is three dimensional, this brings us closer to the turbulent case. We reiterate that the large effect is not due to a modified dissipation (as is assumed in some theories of drag reduction), but due to reduced energy intake from the mean flow to the fluctuations. We propose that similar physics act in turbulent drag reduction.

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)

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

Utilization of modified starch from avocado (Persea americana Mill.) seed in cream soup production

NASA Astrophysics Data System (ADS)

Cornelia, M.; Christianti, A.

2018-01-01

Avocado (Persea americana Mill.) seed was often seen as waste and underutilized resources, especially in the food industry. The aim of this research was to modify the structure of avocado seed starch using the cross-linking method, to improve the viscosity stability in the cream soup. In the preliminary research, starch was isolated from the seed and modified by STPP (sodium tripolyphosphate) with 2%, 4%, and 6% concentration and were reacted for 1, 2, and 3 hours. Starches were analyzed for moisture and ash content, paste clarity, gel strength, swelling power, solubility, yield, and degree of whiteness. Based on the analysis results, the best reaction time and STPP concentration was 6% at 1 hour reaction time. Native starch and the best-modified starch were applied in the cream soup and compared with commercial cream soup. Cream soups were analyzed for viscosity stability using viscometer in 0, 1, 3, and 5 hours after storage in room temperature. The result showed that cream soup using modified starch has better viscosity stability than native starch and commercial cream soup after 5 hours storage, which was 181.7 ± 4.85 cP. Sensory analysis showed that cream soup using modified starch was more acceptable than the others. Avocado seed modified starch has phosphate group that strengthen the starch chain to prevent viscosity breakdown.

Pressure Dependence of Komatiite Liquid Viscosity and Implications for Magma Ocean Rheology

NASA Astrophysics Data System (ADS)

O'Dwyer Brown, L.; Lesher, C. E.; Terasaki, H. G.; Yamada, A.; Sakamaki, T.; Shibazaki, Y.; Ohtani, E.

2009-12-01

The viscosities of komatiite liquids at high pressures and temperatures were investigated using the in-situ falling sphere technique at BL04B1, SPring-8. Komatiites are naturally occurring magmas, rich in network modifying cations. Despite the refractory and fluid nature of komatiite, we successfully measured the viscosity of molten komatiites from Gorgona Island, Colombia (MgO = 17.8 wt.%; NBO/T = 1.5) between 11 and 13 GPa at 2000 C, and from Belingwe, Zimbabwe (MgO = 28.14 wt.%; NBO/T = 2.1) from 12 to 14 GPa at 2000 C. Under isothermal conditions, the viscosity of Gorgona Island komatiite melt increased with pressure, consistent with our previous measurements at lower pressures for this composition. We interpreted this positive pressure dependence as the result of reductions in interatomic space diminishing the free volume of the liquid when compressed. The viscosity of molten komatiite from Belingwe also increased up to 12 GPa, however between 12 and 14 GPa the viscosity is nearly constant. In previous studies of depolymerized silicate liquids, the pressure dependence of viscosity has been shown to reverse from positive to negative between 8 and 10 GPa with corresponding changes in activation volume [1] [2]. In contrast, the activation volume for Belingwe liquid decreases to near zero, but does not become negative above 11 GPa. Similarly, the activation volume for Gorgona Island komatiite remains positive throughout the pressure range investigated. Molecular dynamics simulations of simple MgO-SiO2 liquids with NBO/T > 2 also show a positive pressure dependence, reflecting the dominant control of free-volume reduction on the viscosity of depolymerized melts. However, the more rapid reduction in activation volume with pressure in komatiite liquids may be related to the presence of Al, Ti and other cations that interact and undergo coordination changes unavailable in simple silicate liquids. Along Hadean and post-Hadean mantle adiabats the net effect of

A bulk viscosity approach for shock capturing on unstructured grids

NASA Astrophysics Data System (ADS)

Shoeybi, Mohammad; Larsson, Nils Johan; Ham, Frank; Moin, Parviz

2008-11-01

The bulk viscosity approach for shock capturing (Cook and Cabot, JCP, 2005) augments the bulk part of the viscous stress tensor. The intention is to capture shock waves without dissipating turbulent structures. The present work extends and modifies this method for unstructured grids. We propose a method that properly scales the bulk viscosity with the grid spacing normal to the shock for unstructured grid for which the shock is not necessarily aligned with the grid. The magnitude of the strain rate tensor used in the original formulation is replaced with the dilatation, which appears to be more appropriate in the vortical turbulent flow regions (Mani et al., 2008). The original form of the model is found to have an impact on dilatational motions away form the shock wave, which is eliminated by a proposed localization of the bulk viscosity. Finally, to allow for grid adaptation around shock waves, an explicit/implicit time advancement scheme has been developed that adaptively identifies the stiff regions. The full method has been verified with several test cases, including 2D shock-vorticity entropy interaction, homogenous isotropic turbulence, and turbulent flow over a cylinder.

Nanoscale simple-fluid behavior under steady shear.

PubMed

Yong, Xin; Zhang, Lucy T

2012-05-01

In this study, we use two nonequilibrium molecular dynamics algorithms, boundary-driven shear and homogeneous shear, to explore the rheology and flow properties of a simple fluid undergoing steady simple shear. The two distinct algorithms are designed to elucidate the influences of nanoscale confinement. The results of rheological material functions, i.e., viscosity and normal pressure differences, show consistent Newtonian behaviors at low shear rates from both systems. The comparison validates that confinements of the order of 10 nm are not strong enough to deviate the simple fluid behaviors from the continuum hydrodynamics. The non-Newtonian phenomena of the simple fluid are further investigated by the homogeneous shear simulations with much higher shear rates. We observe the "string phase" at high shear rates by applying both profile-biased and profile-unbiased thermostats. Contrary to other findings where the string phase is found to be an artifact of the thermostats, we perform a thorough analysis of the fluid microstructures formed due to shear, which shows that it is possible to have a string phase and second shear thinning for dense simple fluids.

High-resolution NMR spectroscopy of encapsulated proteins dissolved in low-viscosity fluids

PubMed Central

Nucci, Nathaniel V.; Valentine, Kathleen G.; Wand, A. Joshua

2014-01-01

High-resolution multi-dimensional solution NMR is unique as a biophysical and biochemical tool in its ability to examine both the structure and dynamics of macromolecules at atomic resolution. Conventional solution NMR approaches, however, are largely limited to examinations of relatively small (< 25 kDa) molecules, mostly due to the spectroscopic consequences of slow rotational diffusion. Encapsulation of macromolecules within the protective nanoscale aqueous interior of reverse micelles dissolved in low viscosity fluids has been developed as a means through which the ‘slow tumbling problem’ can be overcome. This approach has been successfully applied to diverse proteins and nucleic acids ranging up to 100 kDa, considerably widening the range of biological macromolecules to which conventional solution NMR methodologies may be applied. Recent advances in methodology have significantly broadened the utility of this approach in structural biology and molecular biophysics. PMID:24656086

On the abrupt growth dynamics of nonlinear resistive tearing mode and the viscosity effects

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

Ali, A.; Li, Jiquan, E-mail: lijq@energy.kyoto-u.ac.jp; Kishimoto, Y.

2014-05-15

The nonlinear evolution of the resistive tearing mode exhibits an abrupt growth after an X-point collapse once the magnetic island exceeds a certain critical width Δ′w{sub c} for large instability parameter Δ′, leading to a current sheet formation [N. F. Loureiro et al., Phys. Rev. Lett. 95, 235003 (2005)]. In this work, we investigate the underlying mechanism of the X-point collapse as well as the current sheet formation including the viscosity effects, based on a secondary instability analysis. The secondary instability is excited due to the quasilinear current modification by the zonal current. In particular, it is identified that themore » current peaking effect is plausibly responsible for the onset of the X-point collapse and the current sheet formation, leading to the explosive growth of reconnected flux. In the presence of finite viscosity, the Δ′w{sub c} scaling with the resistivity gets modified. A transition behavior is revealed at P{sub r}≈1 for the viscosity dependence of Δ′w{sub c} and the linear tearing instability. However, the explosive growth seems to be independent of the viscosity in the magnetic Prandtl number P{sub r}<1 regime, while large viscosity plays a strong dissipation role.« less

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.

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.

Rocket Science at the Nanoscale.

PubMed

Li, Jinxing; Rozen, Isaac; Wang, Joseph

2016-06-28

Autonomous propulsion at the nanoscale represents one of the most challenging and demanding goals in nanotechnology. Over the past decade, numerous important advances in nanotechnology and material science have contributed to the creation of powerful self-propelled micro/nanomotors. In particular, micro- and nanoscale rockets (MNRs) offer impressive capabilities, including remarkable speeds, large cargo-towing forces, precise motion controls, and dynamic self-assembly, which have paved the way for designing multifunctional and intelligent nanoscale machines. These multipurpose nanoscale shuttles can propel and function in complex real-life media, actively transporting and releasing therapeutic payloads and remediation agents for diverse biomedical and environmental applications. This review discusses the challenges of designing efficient MNRs and presents an overview of their propulsion behavior, fabrication methods, potential rocket fuels, navigation strategies, practical applications, and the future prospects of rocket science and technology at the nanoscale.

Nanoscale octahedral molecular sieves: Syntheses, characterization, and applications

NASA Astrophysics Data System (ADS)

Liu, Jia

The major part of this research consists of studies on novel synthesis methods, characterization, and catalytic applications of nanoscale manganese oxide octahedral molecular sieves. The second part involves studies of new applications of bulk porous molecular sieve and layered materials (MSLM), zeolites, and inorganic powder materials for diminishing wound bleeding. Manganese oxide octahedral molecular sieves (OMS) are very important microporous materials. They have been used widely as bulk materials in catalysis, separations, chemical sensors, and batteries, due to their unique tunnel structures and useful properties. Novel methods have been developed to synthesize novel nanoscale octahedral molecular sieve manganese oxides (OMS) and metal-substituted OMS materials in order to modify their physical and chemical properties and to improve their catalytic applications. Different synthetic routes were investigated to find better, faster, and cheaper pathways to produce nanoscale or metal-substituted OMS materials. In the synthetic study of nanosize OMS materials, a combination of sol-gel synthesis and hydrothermal reaction was used to prepare pure crystalline nanofibrous todorokite-type (OMS-1) and cryptomelane-typed (OMS-2) manganese oxides using four alkali cations (Li+, K+, Na +, Rb+) and NH4+ cations. In the synthesis study of nanoscale and metal-substituted OMS materials, a combination of sol-gel synthesis and solid-state reaction was used to prepare transition metal-substituted OMS-2 nanorods, nanoneedles, and nanowires. Preparative parameters of syntheses, such as cation templates, heating temperature and time, were investigated in these syntheses of OMS-1 and OMS-2 materials. The catalytic activities of the novel synthetic nanoscale OMS materials has been evaluated on green oxidation of alcohols and toluene and were found to be much higher than their correspondent bulk materials. New applications of bulk manganese oxide molecular sieve and layered materials

Noncontact surface tension and viscosity measurements of molten oxides with a pressurized hybrid electrostatic-aerodynamic levitator

NASA Astrophysics Data System (ADS)

Ishikawa, Takehiko; Yu, Jianding; Paradis, Paul-François

2006-05-01

In order to measure the surface tension and the viscosity of molten oxides, the oscillation drop technique has been applied on a pressurized hybrid electrostatic-aerodynamic levitator. To suppress the electrical discharge between the top and bottom electrodes, the drop excitation method which has been used with high vacuum electrostatic levitators has been modified. As a demonstration, the surface tension and viscosity of liquid BaTiO3 were measured using this new method. Over the 1500-2000K interval, the surface tension was measured as γ(T )=349-0.03 (T-Tm) (10-3N/m), where Tm=1893K is the melting temperature. Similarly, the viscosity was determined as η(T )=0.53exp[5.35×104/(RT)](10-3Pas) over the same temperature interval.

Nanoscale Ionic Liquids

DTIC Science & Technology

2006-11-01

Technical Report 11 December 2005 - 30 November 2006 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER Nanoscale Ionic Liquids 5b. GRANT NUMBER FA9550-06-1-0012...Title: Nanoscale Ionic Liquids Principal Investigator: Emmanuel P. Giannelis Address: Materials Science and Engineering, Bard Hall, Cornell University...based fluids exhibit high ionic conductivity. The NFs are typically synthesized by grafting a charged, oligomeric corona onto the nanoparticle cores

Unprecedented Synergistic Effects of Nanoscale Nutrients on Growth, Productivity of Sweet Sorghum [Sorghum bicolor (L.) Moench], and Nutrient Biofortification.

PubMed

Naseeruddin, Ramapuram; Sumathi, Vupprucherla; Prasad, Tollamadugu N V K V; Sudhakar, Palagiri; Chandrika, Velaga; Ravindra Reddy, Balam

2018-02-07

Evidence-based synergistic effects of nanoscale materials (size of <100 nm in at least one dimension) were scantly documented in agriculture at field scale. Herein, we report for the first time on effects of nanoscale zinc oxide (n-ZnO), calcium oxide (n-CaO), and magnesium oxide (n-MgO) on growth and productivity of sweet sorghum [Sorghum bicolor (L.) Moench]. A modified sol-gel method was used to prepare nanoscale materials under study. Characterization was performed using transmission and scanning electron microscopies, X-ray diffraction, and dynamic light scattering. Average sizes (25, 53.7, and 53.5 nm) and ζ potentials (-10.9, -28.2, and -16.2 mV) of n-ZnO, n-CaO, and n-MgO were measured, respectively. The significant grain yield (17.8 and 14.2%), cane yield (7.2 and 8.0%), juice yield (10 and 12%), and higher sucrose yield (21.8 and 20.9%) were recorded with the application of nanoscale materials in the years 2014 and 2015, respectively. Nutrient uptake was significant with foliar application of nanoscale nutrients.

Size Effects in Nanoscale Structural Phenomena

NASA Astrophysics Data System (ADS)

McElhinny, Kyle Matthew

The creation of nanostructures offers the opportunity to modify and tune properties in ways inaccessible in bulk materials. A key component in this development is the introduction of size effects which reduce the physical size, dimensionality, and increase the contribution of surface effects. The size effects strongly modify the structural dynamics in nanoscale systems and leads to changes in the vibrational, electrical, and optical properties. An increased level of understanding and control of nanoscale structural dynamics will enable more precise control over nanomaterial transport properties. My work has shown that 1D spatial confinement through the creation of semiconducting nanomembranes modifies the phonon population and dispersion. X ray thermal diffuse scattering distributions show an excess in intensity for nanomembranes less than 100 nm in thickness, for phonon modes with wavevectors spanning the entire Brillouin zone. This excess intensity indicates the development of new low energy phonon modes or the softening of elastic constants. Furthermore, an additional anisotropy in the phonon dispersion is observed with a symmetry matching the direction of spatial confinement. This work has also extended x ray thermal diffuse scattering for use in studying nanomaterials. In electro- and photoactive monolayers a structural reconfiguration can be produced by external optical stimuli. I have developed an electro and photoactive molecular monolayers on oxide surfaces. Using x ray reflectivity, I have evaluated the organization and reconfiguration of molecular monolayers deposited by Langmuir Blodgett technique. I have designed and probed the reconfiguration of optically reconfigurable monolayers of azobenzene donor molecules on semiconducting surfaces. These monolayers reconfigure through a cooperative switching process leading to the development of large isomeric domains. This work represents an advancement in the interpretation of x ray reflectivity from molecular

Experimental and Theoretical Investigations on Viscosity of Fe-Ni-C Liquids at High Pressures

NASA Astrophysics Data System (ADS)

Chen, B.; Lai, X.; Wang, J.; Zhu, F.; Liu, J.; Kono, Y.

2016-12-01

Understanding and modeling of Earth's core processes such as geodynamo and heat flow via convection in liquid outer cores hinges on the viscosity of candidate liquid iron alloys under core conditions. Viscosity estimates from various methods of the metallic liquid of the outer core, however, span up to 12 orders of magnitude. Due to experimental challenges, viscosity measurements of iron liquids alloyed with lighter elements are scarce and conducted at conditions far below those expected for the outer core. In this study, we adopt a synergistic approach by integrating experiments at experimentally-achievable conditions with computations up to core conditions. We performed viscosity measurements based on the modified Stokes' floating sphere viscometry method for the Fe-Ni-C liquids at high pressures in a Paris-Edinburgh press at Sector 16 of the Advanced Photon Source, Argonne National Laboratory. Our results show that the addition of 3-5 wt.% carbon to iron-nickel liquids has negligible effect on its viscosity at pressures lower than 5 GPa. The viscosity of the Fe-Ni-C liquids, however, becomes notably higher and increases by a factor of 3 at 5-8 GPa. Similarly, our first-principles molecular dynamics calculations up to Earth's core pressures show a viscosity change in Fe-Ni-C liquids at 5 GPa. The significant change in the viscosity is likely due to a liquid structural transition of the Fe-Ni-C liquids as revealed by our X-ray diffraction measurements and first-principles molecular dynamics calculations. The observed correlation between structure and physical properties of liquids permit stringent benchmark test of the computational liquid models and contribute to a more comprehensive understanding of liquid properties under high pressures. The interplay between experiments and first-principles based modeling is shown to be a practical and effective methodology for studying liquid properties under outer core conditions that are difficult to reach with the current

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.

Friction laws at the nanoscale.

PubMed

Mo, Yifei; Turner, Kevin T; Szlufarska, Izabela

2009-02-26

Macroscopic laws of friction do not generally apply to nanoscale contacts. Although continuum mechanics models have been predicted to break down at the nanoscale, they continue to be applied for lack of a better theory. An understanding of how friction force depends on applied load and contact area at these scales is essential for the design of miniaturized devices with optimal mechanical performance. Here we use large-scale molecular dynamics simulations with realistic force fields to establish friction laws in dry nanoscale contacts. We show that friction force depends linearly on the number of atoms that chemically interact across the contact. By defining the contact area as being proportional to this number of interacting atoms, we show that the macroscopically observed linear relationship between friction force and contact area can be extended to the nanoscale. Our model predicts that as the adhesion between the contacting surfaces is reduced, a transition takes place from nonlinear to linear dependence of friction force on load. This transition is consistent with the results of several nanoscale friction experiments. We demonstrate that the breakdown of continuum mechanics can be understood as a result of the rough (multi-asperity) nature of the contact, and show that roughness theories of friction can be applied at the nanoscale.

Rheology behaviour of modified silicone-dammar as a natural resin coating

NASA Astrophysics Data System (ADS)

Zakaria, Rosnah; Ahmad, Azizah Hanom

2015-08-01

Modified silicone-dammar (SD) was prepared by various weight percent from 5 - 45 wt% of dammar added. The n-value (viscosity index) of silicone with 5 and 10 % were turn to be 1.6 and 1.3 of viscosity index. While 15, 20, 25 and 30 wt% of dammar added gave 0.7, 0.3, 0.2 and 0.1 of viscosity index. On the other hand, 35, 40 and 45 wt% of dammar gave a fixed value of viscosity index of 0.03. This n-value shows the dispersion quality of paint mixture indicates that the modified silicone-dammar was followed the Bingham's Model. The rheology measurement of SD mixture was analysed by plotting ln shear stress vs shear rate value. Analysis of the graph showed a Bingham plastic model with regression R2 equivalent to 0.99. The linear viscoelastic behaviour of SD samples increased in parallel with increasing dammar content indicate that the suspension of dammar in silicone resin could flow steadily with time giving a pseudoplastic behaviour.

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.

Optimization of NMR spectroscopy of encapsulated proteins dissolved in low viscosity fluids

PubMed Central

Nucci, Nathaniel V.; Marques, Bryan S.; Bédard, Sabrina; Dogan, Jakob; Gledhill, John M.; Moorman, Veronica R.; Peterson, Ronald W.; Valentine, Kathleen G.; Wand, Alison L.; Wand, A. Joshua

2014-01-01

Comprehensive application of solution NMR spectroscopy to studies of macromolecules remains fundamentally limited by the molecular rotational correlation time. For proteins, molecules larger than 30 kDa require complex experimental methods, such as TROSY in conjunction with isotopic labeling schemes that are often expensive and generally reduce the potential information available. We have developed the reverse micelle encapsulation strategy as an alternative approach. Encapsulation of proteins within the protective nano-scale water pool of a reverse micelle dissolved in ultra-low viscosity nonpolar solvents overcomes the slow tumbling problem presented by large proteins. Here, we characterize the contributions from the various components of the protein-containing reverse micelle system to the rotational correlation time of the encapsulated protein. Importantly, we demonstrate that the protein encapsulated in the reverse micelle maintains a hydration shell comparable in size to that seen in bulk solution. Using moderate pressures, encapsulation in ultra-low viscosity propane or ethane can be used to magnify this advantage. We show that encapsulation in liquid ethane can be used to reduce the tumbling time of the 43 kDa maltose binding protein from ~23 ns to ~10 ns. These conditions enable, for example, acquisition of TOCSY-type data resolved on the adjacent amide NH for the 42 kDa encapsulated maltose binding protein dissolved in liquid ethane, which is typically impossible for proteins of such size without use of extensive deuteration or the TROSY effect. PMID:21748265

Viscosity of dilute suspensions of rodlike particles: A numerical simulation method

NASA Astrophysics Data System (ADS)

Yamamoto, Satoru; Matsuoka, Takaaki

1994-02-01

The recently developed simulation method, named as the particle simulation method (PSM), is extended to predict the viscosity of dilute suspensions of rodlike particles. In this method a rodlike particle is modeled by bonded spheres. Each bond has three types of springs for stretching, bending, and twisting deformation. The rod model can therefore deform by changing the bond distance, bond angle, and torsion angle between paired spheres. The rod model can represent a variety of rigidity by modifying the bond parameters related to Young's modulus and the shear modulus of the real particle. The time evolution of each constituent sphere of the rod model is followed by molecular-dynamics-type approach. The intrinsic viscosity of a suspension of rodlike particles is derived from calculating an increased energy dissipation for each sphere of the rod model in a viscous fluid. With and without deformation of the particle, the motion of the rodlike particle was numerically simulated in a three-dimensional simple shear flow at a low particle Reynolds number and without Brownian motion of particles. The intrinsic viscosity of the suspension of rodlike particles was investigated on orientation angle, rotation orbit, deformation, and aspect ratio of the particle. For the rigid rodlike particle, the simulated rotation orbit compared extremely well with theoretical one which was obtained for a rigid ellipsoidal particle by use of Jeffery's equation. The simulated dependence of the intrinsic viscosity on various factors was also identical with that of theories for suspensions of rigid rodlike particles. For the flexible rodlike particle, the rotation orbit could be obtained by the particle simulation method and it was also cleared that the intrinsic viscosity decreased as occurring of recoverable deformation of the rodlike particle induced by flow.

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.

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.

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

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.

An evaluation method for nanoscale wrinkle

NASA Astrophysics Data System (ADS)

Liu, Y. P.; Wang, C. G.; Zhang, L. M.; Tan, H. F.

2016-06-01

In this paper, a spectrum-based wrinkling analysis method via two-dimensional Fourier transformation is proposed aiming to solve the difficulty of nanoscale wrinkle evaluation. It evaluates the wrinkle characteristics including wrinkling wavelength and direction simply using a single wrinkling image. Based on this method, the evaluation results of nanoscale wrinkle characteristics show agreement with the open experimental results within an error of 6%. It is also verified to be appropriate for the macro wrinkle evaluation without scale limitations. The spectrum-based wrinkling analysis is an effective method for nanoscale evaluation, which contributes to reveal the mechanism of nanoscale wrinkling.

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.

Research on preparation of phosphate-modified animal glue binder for foundry use

NASA Astrophysics Data System (ADS)

Wang, Tian-Shu; Liu, Wei-Hua; Li, Ying-Min

2018-03-01

In this paper, three phosphates were used as modifiers to modify animal glue binder. The structural characteristics and thermal properties of animal glue binder treated with phosphates were studied by Fourier transform-infrared spectroscopy, gel permeation chromatography and derivative thermogravimetric analysis. The results showed that the modified animal glue binder had better sand tensile strength and lower viscosity than untreated animal glue binder. The best modification process was as follows: the optimal amount of sodium carbonate was 4 wt% to animal glue; the optimal weight ratio of the modifiers was sodium pyrophosphate : sodium tripolyphosphate : sodium hexametaphosphate : animal glue = 3 : 3 : 4 : 100, and the optimal reaction should be performed at 80°C for a reaction time of 120 min. A final tensile strength of approximately 3.20 MPa was achieved and the viscosity value was approximately 880 mPa s.

Bacterial accumulation in viscosity gradients

NASA Astrophysics Data System (ADS)

Waisbord, Nicolas; Guasto, Jeffrey

2016-11-01

Cell motility is greatly modified by fluid rheology. In particular, the physical environments in which cells function, are often characterized by gradients of viscous biopolymers, such as mucus and extracellular matrix, which impact processes ranging from reproduction to digestion to biofilm formation. To understand how spatial heterogeneity of fluid rheology affects the motility and transport of swimming cells, we use hydrogel microfluidic devices to generate viscosity gradients in a simple, polymeric, Newtonian fluid. Using video microscopy, we characterize the random walk motility patterns of model bacteria (Bacillus subtilis), showing that both wild-type ('run-and-tumble') cells and smooth-swimming mutants accumulate in the viscous region of the fluid. Through statistical analysis of individual cell trajectories and body kinematics in both homogeneous and heterogeneous viscous environments, we discriminate passive, physical effects from active sensing processes to explain the observed cell accumulation at the ensemble level.

Endocytosis of Nanoscale Systems for Cancer Treatments.

PubMed

Chen, Kai; Li, Xue; Zhu, Hongyan; Gong, Qiyong; Luo, Kui

2017-04-28

Advances of nanoscale systems for cancer treatment have been involved in enabling highly regulated site-specific localization to sub cellular organelles hidden beneath cell membranes. Thus far, the cellular entry of these nanoscale systems has been not fully understood. Endocytosisis a form of active transport in which cell transports elected extracellular molecules (such as proteins, viruses, micro-organisms and nanoscale systems) are allowed into cell interiors by engulfing them in an energy-dependent process. This process appears at the plasma membrane surface and contains internalization of the cell membrane as well as the membrane proteins and lipids of cell. There are multiform pathways of endocytosis for nanoscale systems. Further comprehension for the mechanisms of endocytosis is achieved with a combination of efficient genetic manipulations, cell dynamic imaging, and chemical endocytosis inhibitors. This review provides an account of various endocytic pathways, itemizes current methods to study endocytosis of nanoscale systems, discusses some factors associated with cellular uptake for nanoscale systems and introduces the trafficking behavior for nanoscale systems with active targeting. An insight into the endocytosis mechanism is urgent and significant for developing safe and efficient nanoscale systems for cancer diagnosis and therapy. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

On Technological Properties of Modified Epoxy Composites

NASA Astrophysics Data System (ADS)

Gavrilov, M.

2017-11-01

The technological properties of epoxy composite materials based on constructional and chemical waste have been reviewed. The viscosity and component wettability of modified epoxy composites have been researched. The use of plasticizing additives to improve mixtures forming has been justified.

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.

Center for Nanoscale Science and Technology

National Institute of Standards and Technology Data Gateway

NIST Center for Nanoscale Science and Technology (Program website, free access)   Currently there is no database matching your keyword search, but the NIST Center for Nanoscale Science and Technology website may be of interest. The Center for Nanoscale Science and Technology enables science and industry by providing essential measurement methods, instrumentation, and standards to support all phases of nanotechnology development, from discovery to production.

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.

Transient effects of drying creep in nanoporous solids: understanding the effects of nanoscale energy barriers

NASA Astrophysics Data System (ADS)

Sinko, Robert; Vandamme, Matthieu; Bažant, Zdeněk P.; Keten, Sinan

2016-07-01

The Pickett effect is the phenomenon of creep enhancement during transient drying. It has been observed for many nanoporous solids, including concrete, wood and Kevlar. While the existing micromechanical models can partially explain this effect, they have yet to consider nanoscale dynamic effects of water in nanopores, which are believed to be of paramount importance. Here, we examine how creep deformations in a slit pore are accelerated by the motion of water due to drying forces using coarse-grained molecular dynamics simulations. We find that the drying that drives water flow in the nanopores lowers both the activation energy of pore walls sliding past one another and the apparent viscosity of confined water molecules. This lowering can be captured with an analytical Arrhenius relationship accounting for the role of water flow in overcoming the energy barriers. Notably, we use this model and simulation results to demonstrate that the drying creep strain is not linearly dependent on the applied creep stress at the nanopore level. Our findings establish the scaling relationships that explain how the creep driving force, drying force and fluid properties are related. Thus, we establish the nanoscale origins of the Pickett effect and provide strategies for minimizing the additional displacements arising from this effect.

Transient effects of drying creep in nanoporous solids: understanding the effects of nanoscale energy barriers

PubMed Central

Sinko, Robert; Vandamme, Matthieu; Keten, Sinan

2016-01-01

The Pickett effect is the phenomenon of creep enhancement during transient drying. It has been observed for many nanoporous solids, including concrete, wood and Kevlar. While the existing micromechanical models can partially explain this effect, they have yet to consider nanoscale dynamic effects of water in nanopores, which are believed to be of paramount importance. Here, we examine how creep deformations in a slit pore are accelerated by the motion of water due to drying forces using coarse-grained molecular dynamics simulations. We find that the drying that drives water flow in the nanopores lowers both the activation energy of pore walls sliding past one another and the apparent viscosity of confined water molecules. This lowering can be captured with an analytical Arrhenius relationship accounting for the role of water flow in overcoming the energy barriers. Notably, we use this model and simulation results to demonstrate that the drying creep strain is not linearly dependent on the applied creep stress at the nanopore level. Our findings establish the scaling relationships that explain how the creep driving force, drying force and fluid properties are related. Thus, we establish the nanoscale origins of the Pickett effect and provide strategies for minimizing the additional displacements arising from this effect. PMID:27493584

Transient effects of drying creep in nanoporous solids: understanding the effects of nanoscale energy barriers.

PubMed

Sinko, Robert; Vandamme, Matthieu; Bažant, Zdeněk P; Keten, Sinan

2016-07-01

The Pickett effect is the phenomenon of creep enhancement during transient drying. It has been observed for many nanoporous solids, including concrete, wood and Kevlar. While the existing micromechanical models can partially explain this effect, they have yet to consider nanoscale dynamic effects of water in nanopores, which are believed to be of paramount importance. Here, we examine how creep deformations in a slit pore are accelerated by the motion of water due to drying forces using coarse-grained molecular dynamics simulations. We find that the drying that drives water flow in the nanopores lowers both the activation energy of pore walls sliding past one another and the apparent viscosity of confined water molecules. This lowering can be captured with an analytical Arrhenius relationship accounting for the role of water flow in overcoming the energy barriers. Notably, we use this model and simulation results to demonstrate that the drying creep strain is not linearly dependent on the applied creep stress at the nanopore level. Our findings establish the scaling relationships that explain how the creep driving force, drying force and fluid properties are related. Thus, we establish the nanoscale origins of the Pickett effect and provide strategies for minimizing the additional displacements arising from this effect.

Modified Antifreeze Liquids for Use on Surfaces

NASA Technical Reports Server (NTRS)

Lynn, R. O.

1983-01-01

Report presents results of evaluation of two antifreeze liquids, dimethyl sulfoxide and ethylene glycol and five viscosity modifiers: gelatin, gum tragacanth, starch, agarose powder and citrus pectin. Purpose of evaluation to find best way of dealing with frost formation on Space Shuttle.

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.

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

Orienting Periodic Organic-Inorganic Nanoscale Domains Through One-Step Electrodeposition

PubMed Central

Herman, David J.; Goldberger, Joshua E.; Chao, Stephen; Martin, Daniel T.; Stupp, Samuel I

2011-01-01

One of the challenges in the synthesis of hybrid materials with nanoscale structure is to precisely control morphology across length scales. Using a one-step electrodeposition process on indium tin oxide (ITO) substrates followed by annealing, we report here the preparation of materials with preferentially oriented lamellar domains of electron donor surfactants and the semiconductor ZnO. We found that either increasing the concentration of surfactant or the water to dimethyl sulfoxide ratio of solutions used resulted in the suppression of bloom-like morphologies and enhanced the density of periodic domains on ITO substrates. Furthermore, by modifying the surface of the ITO substrate with the conductive polymer blend poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate), we were able to alter the orientation of these electrodeposited lamellar domains to be perpendicular to the substrate. The long-range orientation achieved was characterized by 2D grazing incidence small angle X-ray scattering. This high degree of orientation in electronically active hybrids with alternating nanoscale p-type and n-type domains is of potential interest in photovoltaics or thermoelectric materials. PMID:21142087

Nanoscale potentiometry.

PubMed

Bakker, Eric; Pretsch, Ernö

2008-01-01

Potentiometric sensors share unique characteristics that set them apart from other electrochemical sensors. Potentiometric nanoelectrodes have been reported and successfully used for many decades, and we review these developments. Current research chiefly focuses on nanoscale films at the outer or the inner side of the membrane, with outer layers for increasing biocompatibility, expanding the sensor response, or improving the limit of detection (LOD). Inner layers are mainly used for stabilizing the response and eliminating inner aqueous contacts or undesired nanoscale layers of water. We also discuss the ultimate detectability of ions with such sensors and the power of coupling the ultra-low LODs of ion-selective electrodes with nanoparticle labels to give attractive bioassays that can compete with state-of-the-art electrochemical detection.

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.

Single-nanotube tracking reveals the nanoscale organization of the extracellular space in the live brain

NASA Astrophysics Data System (ADS)

Godin, Antoine G.; Varela, Juan A.; Gao, Zhenghong; Danné, Noémie; Dupuis, Julien P.; Lounis, Brahim; Groc, Laurent; Cognet, Laurent

2017-03-01

The brain is a dynamic structure with the extracellular space (ECS) taking up almost a quarter of its volume. Signalling molecules, neurotransmitters and nutrients transit via the ECS, which constitutes a key microenvironment for cellular communication and the clearance of toxic metabolites. The spatial organization of the ECS varies during sleep, development and aging and is probably altered in neuropsychiatric and degenerative diseases, as inferred from electron microscopy and macroscopic biophysical investigations. Here we show an approach to directly observe the local ECS structures and rheology in brain tissue using super-resolution imaging. We inject single-walled carbon nanotubes into rat cerebroventricles and follow the near-infrared emission of individual nanotubes as they diffuse inside the ECS for tens of minutes in acute slices. Because of the interplay between the nanotube geometry and the ECS local environment, we can extract information about the dimensions and local viscosity of the ECS. We find a striking diversity of ECS dimensions down to 40 nm, and as well as of local viscosity values. Moreover, by chemically altering the extracellular matrix of the brains of live animals before nanotube injection, we reveal that the rheological properties of the ECS are affected, but these alterations are local and inhomogeneous at the nanoscale.

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.

Tin doped indium oxide anodes with artificially controlled nano-scale roughness using segregated Ag nanoparticles for organic solar cells

NASA Astrophysics Data System (ADS)

Kim, Hyo-Joong; Ko, Eun-Hye; Noh, Yong-Jin; Na, Seok-In; Kim, Han-Ki

2016-09-01

Nano-scale surface roughness in transparent ITO films was artificially formed by sputtering a mixed Ag and ITO layer and wet etching of segregated Ag nanoparticles from the surface of the ITO film. Effective removal of self-segregated Ag particles from the grain boundaries and surface of the crystalline ITO film led to a change in only the nano-scale surface morphology of ITO film without changes in the sheet resistance and optical transmittance. A nano-scale rough surface of the ITO film led to an increase in contact area between the hole transport layer and the ITO anode, and eventually increased the hole extraction efficiency in the organic solar cells (OSCs). The heterojunction OSCs fabricated on the ITO anode with a nano-scale surface roughness exhibited a higher power conversion efficiency of 3.320%, than that (2.938%) of OSCs made with the reference ITO/glass. The results here introduce a new method to improve the performance of OSCs by simply modifying the surface morphology of the ITO anodes.

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

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.

Giant and Tunable Anisotropy of Nanoscale Friction in Graphene

NASA Astrophysics Data System (ADS)

Capaz, Rodrigo; Menezes, Marcos; Almeida, Clara; de Cicco, Marcelo; Achete, Carlos; Fragneaud, Benjamin; Cançado, Luiz Gustavo; Paupitz, Ricardo; Galvão, Douglas; Prioli, Rodrigo

The nanoscale friction between an atomic force microscopy tip and graphene is investigated using friction force microscopy (FFM). During the tip movement, friction forces are observed to increase and then saturate in a highly anisotropic manner. As a result, the friction coefficient of graphene is highly dependent on the scanning direction: Under some conditions, the energy dissipated along the armchair direction can be 80% higher than along the zigzag direction. In comparison, for highly-oriented pyrolitic graphite (HOPG), the friction anisotropy between armchair and zigzag directions is only 15%. This giant friction anisotropy in graphene results from anisotropies in the amplitudes of flexural deformations of the graphene sheet driven by the tip movement, not present in HOPG. The effect can be seen as a novel manifestation of the classical phenomenon of Euler buckling at the nanoscale, which provides the non-linear ingredients that amplify friction anisotropy. Simulations based on a novel version of the 2D Tomlinson model (modified to include the effects of flexural deformations), as well as fully atomistic molecular dynamics simulations and first-principles density-functional theory (DFT) calculations, are able to reproduce and explain the experimental observations.

Giant and Tunable Anisotropy of Nanoscale Friction in Graphene

NASA Astrophysics Data System (ADS)

Almeida, Clara M.; Prioli, Rodrigo; Fragneaud, Benjamin; Cançado, Luiz Gustavo; Paupitz, Ricardo; Galvão, Douglas S.; de Cicco, Marcelo; Menezes, Marcos G.; Achete, Carlos A.; Capaz, Rodrigo B.

2016-08-01

The nanoscale friction between an atomic force microscopy tip and graphene is investigated using friction force microscopy (FFM). During the tip movement, friction forces are observed to increase and then saturate in a highly anisotropic manner. As a result, the friction forces in graphene are highly dependent on the scanning direction: under some conditions, the energy dissipated along the armchair direction can be 80% higher than along the zigzag direction. In comparison, for highly-oriented pyrolitic graphite (HOPG), the friction anisotropy between armchair and zigzag directions is only 15%. This giant friction anisotropy in graphene results from anisotropies in the amplitudes of flexural deformations of the graphene sheet driven by the tip movement, not present in HOPG. The effect can be seen as a novel manifestation of the classical phenomenon of Euler buckling at the nanoscale, which provides the non-linear ingredients that amplify friction anisotropy. Simulations based on a novel version of the 2D Tomlinson model (modified to include the effects of flexural deformations), as well as fully atomistic molecular dynamics simulations and first-principles density-functional theory (DFT) calculations, are able to reproduce and explain the experimental observations.

Molecular insight into nanoscale water films dewetting on modified silica surfaces.

PubMed

Zhang, Jun; Li, Wen; Yan, Youguo; Wang, Yefei; Liu, Bing; Shen, Yue; Chen, Haixiang; Liu, Liang

2015-01-07

In this work, molecular dynamics simulations are adopted to investigate the microscopic dewetting mechanism of nanoscale water films on methylated silica surfaces. The simulation results show that the dewetting process is divided into two stages: the appearance of dry patches and the quick contraction of the water film. First, the appearance of dry patches is due to the fluctuation in the film thickness originating from capillary wave instability. Second, for the fast contraction of water film, the unsaturated electrostatic and hydrogen bond interactions among water molecules are the driving forces, which induce the quick contraction of the water film. Finally, the effect of film thickness on water films dewetting is studied. Research results suggest that upon increasing the water film thickness from 6 to 8 Å, the final dewetting patterns experience separate droplets and striation-shaped structures, respectively. But upon further increasing the water film thickness, the water film is stable and there are no dry patches. The microscopic dewetting behaviors of water films on methylated silica surfaces discussed here are helpful in understanding many phenomena in scientific and industrial processes better.

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.

A modified carbothermal reduction method for preparation of high-performance nano-scale core/shell Cu 6Sn 5 alloy anodes in Li-ion batteries

NASA Astrophysics Data System (ADS)

Cui, Wangjun; Wang, Fei; Wang, Jie; Liu, Haijing; Wang, Congxiao; Xia, Yongyao

Core-shell structured, carbon-coated, nano-scale Cu 6Sn 5 has been prepared by a modified carbothermal reduction method using polymer coated mixed oxides of CuO and SnO 2 as precursors. On heat treatment, the mixture oxides were converted into Cu 6Sn 5 alloy by carbothermal reduction. Simultaneously, the remnants carbon was coated on the surface of the Cu 6Sn 5 particles to form a core-shell structure. Transmission electron microscope (TEM) images demonstrate that the well-coated carbon layer effectively prevents the encapsulated, low melting point alloy from out flowing in a high-temperature treatment process. Core-shell structured, carbon coated Cu 6Sn 5 delivers a reversible capacity of 420 mAh g -1 with capacity retention of 80% after 50 cycles. The improvement in the cycling ability can be attributed to the fact that the carbon-shell prevents aggregation and pulverization of nano-sized tin-based alloy particles during charge/discharge cycling.

NANOSCALE BIOSENSORS IN ECOSYSTEM EXPOSURE RESEARCH

EPA Science Inventory

This powerpoint presentation presented information on nanoscale biosensors in ecosystem exposure research. The outline of the presentation is as follows: nanomaterials environmental exposure research; US agencies involved in nanosensor research; nanoscale LEDs in biosensors; nano...

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.

Single molecule-level study of donor-acceptor interactions and nanoscale environment in blends

NASA Astrophysics Data System (ADS)

Quist, Nicole; Grollman, Rebecca; Rath, Jeremy; Robertson, Alex; Haley, Michael; Anthony, John; Ostroverkhova, Oksana

2017-02-01

Organic semiconductors have attracted considerable attention due to their applications in low-cost (opto)electronic devices. The most successful organic materials for applications that rely on charge carrier generation, such as solar cells, utilize blends of several types of molecules. In blends, the local environment strongly influences exciton and charge carrier dynamics. However, relationship between nanoscale features and photophysics is difficult to establish due to the lack of necessary spatial resolution. We use functionalized fluorinated pentacene (Pn) molecule as single molecule probes of intermolecular interactions and of the nanoscale environment in blends containing donor and acceptor molecules. Single Pn donor (D) molecules were imaged in PMMA in the presence of acceptor (A) molecules using wide-field fluorescence microscopy. Two sample configurations were realized: (i) a fixed concentration of Pn donor molecules, with increasing concentration of acceptor molecules (functionalized indenflouorene or PCBM) and (ii) a fixed concentration of acceptor molecules with an increased concentration of the Pn donor. The D-A energy transfer and changes in the donor emission due to those in the acceptor- modified polymer morphology were quantified. The increase in the acceptor concentration was accompanied by enhanced photobleaching and blinking of the Pn donor molecules. To better understand the underlying physics of these processes, we modeled photoexcited electron dynamics using Monte Carlo simulations. The simulated blinking dynamics were then compared to our experimental data, and the changes in the transition rates were related to the changes in the nanoscale environment. Our study provides insight into evolution of nanoscale environment during the formation of bulk heterojunctions.

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.

Melter feed viscosity during conversion to glass: Comparison between low-activity waste and high-level waste feeds

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

Jin, Tongan; Chun, Jaehun; Dixon, Derek R.

During nuclear waste vitrification, a melter feed (generally a slurry-like mixture of a nuclear waste and various glass forming and modifying additives) is charged into the melter where undissolved refractory constituents are suspended together with evolved gas bubbles from complex reactions. Knowledge of flow properties of various reacting melter feeds is necessary to understand their unique feed-to-glass conversion processes occurring within a floating layer of melter feed called a cold cap. The viscosity of two low-activity waste (LAW) melter feeds were studied during heating and correlated with volume fractions of undissolved solid phase and gas phase. In contrast to themore » high-level waste (HLW) melter feed, the effects of undissolved solid and gas phases play comparable roles and are required to represent the viscosity of LAW melter feeds. This study can help bring physical insights to feed viscosity of reacting melter feeds with different compositions and foaming behavior in nuclear waste vitrification.« less

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

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.

Modified Method of Adaptive Artificial Viscosity for Solution of Gas Dynamics Problems on Parallel Computer Systems

NASA Astrophysics Data System (ADS)

Popov, Igor; Sukov, Sergey

2018-02-01

A modification of the adaptive artificial viscosity (AAV) method is considered. This modification is based on one stage time approximation and is adopted to calculation of gasdynamics problems on unstructured grids with an arbitrary type of grid elements. The proposed numerical method has simplified logic, better performance and parallel efficiency compared to the implementation of the original AAV method. Computer experiments evidence the robustness and convergence of the method to difference solution.

Nanoscale chemical mapping of laser-solubilized silk

NASA Astrophysics Data System (ADS)

Ryu, Meguya; Kobayashi, Hanae; Balčytis, Armandas; Wang, Xuewen; Vongsvivut, Jitraporn; Li, Jingliang; Urayama, Norio; Mizeikis, Vygantas; Tobin, Mark; Juodkazis, Saulius; Morikawa, Junko

2017-11-01

A water soluble amorphous form of silk was made by ultra-short laser pulse irradiation and detected by nanoscale IR mapping. An optical absorption-induced nanoscale surface expansion was probed to yield the spectral response of silk at IR molecular fingerprinting wavelengths with a high  ˜ 20 nm spatial resolution defined by the tip of the probe. Silk microtomed sections of 1-5 μm in thickness were prepared for nanoscale spectroscopy and a laser was used to induce amorphisation. Comparison of silk absorbance measurements carried out by table-top and synchrotron Fourier transform IR spectroscopy proved that chemical imaging obtained at high spatial resolution and specificity (able to discriminate between amorphous and crystalline silk) is reliably achieved by nanoscale IR. Differences in absorbance and spectral line-shapes of the bands are related to the different sensitivity of the applied methods to real and imaginary parts of permittivity. A nanoscale material characterization by combining synchrotron IR radiation and nano-IR is discussed.

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.

Nanoscale phase change memory materials.

PubMed

Caldwell, Marissa A; Jeyasingh, Rakesh Gnana David; Wong, H-S Philip; Milliron, Delia J

2012-08-07

Phase change memory materials store information through their reversible transitions between crystalline and amorphous states. For typical metal chalcogenide compounds, their phase transition properties directly impact critical memory characteristics and the manipulation of these is a major focus in the field. Here, we discuss recent work that explores the tuning of such properties by scaling the materials to nanoscale dimensions, including fabrication and synthetic strategies used to produce nanoscale phase change memory materials. The trends that emerge are relevant to understanding how such memory technologies will function as they scale to ever smaller dimensions and also suggest new approaches to designing materials for phase change applications. Finally, the challenges and opportunities raised by integrating nanoscale phase change materials into switching devices are discussed.

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.

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.

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.

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

Physical properties study on partially bio-based lubricant blends: Thermally modified soybean oil with popular commercial esters

USDA-ARS?s Scientific Manuscript database

An initial evaluation of several oils, including: soybean oil (SBO), high oleic SBO, and thermally modified SBO, compared their acid values and viscosities over 28 days stored at 85 deg C. As expected, the acid values and viscosities increased and the high oleic oil demonstrated a smaller effect. ...

GLASS VISCOSITY AS A FUNCTION OF TEMPERATURE AND COMPOSITION: A MODEL BASED ON ADAM-GIBBS EQUATION

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

Hrma, Pavel R.

2008-07-01

Within the temperature range and composition region of processing and product forming, the viscosity of commercial and waste glasses spans over 12 orders of magnitude. This paper shows that a generalized Adam-Gibbs relationship reasonably approximates the real behavior of glasses with four temperature-independent parameters of which two are linear functions of the composition vector. The equation is subjected to two constraints, one requiring that the viscosity-temperature relationship approaches the Arrhenius function at high temperatures with a composition-independent pre-exponential factor and the other that the viscosity value is independent of composition at the glass-transition temperature. Several sets of constant coefficients weremore » obtained by fitting the generalized Adam-Gibbs equation to data of two glass families: float glass and Hanford waste glass. Other equations (the Vogel-Fulcher-Tammann equation, original and modified, the Avramov equation, and the Douglass-Doremus equation) were fitted to float glass data series and compared with the Adam-Gibbs equation, showing that Adam-Gibbs glass appears an excellent approximation of real glasses even as compared with other candidate constitutive relations.« less

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.

Direct-write nanoscale printing of nanogranular tunnelling strain sensors for sub-micrometre cantilevers

PubMed Central

Dukic, Maja; Winhold, Marcel; Schwalb, Christian H.; Adams, Jonathan D.; Stavrov, Vladimir; Huth, Michael; Fantner, Georg E.

2016-01-01

The sensitivity and detection speed of cantilever-based mechanical sensors increases drastically through size reduction. The need for such increased performance for high-speed nanocharacterization and bio-sensing, drives their sub-micrometre miniaturization in a variety of research fields. However, existing detection methods of the cantilever motion do not scale down easily, prohibiting further increase in the sensitivity and detection speed. Here we report a nanomechanical sensor readout based on electron co-tunnelling through a nanogranular metal. The sensors can be deposited with lateral dimensions down to tens of nm, allowing the readout of nanoscale cantilevers without constraints on their size, geometry or material. By modifying the inter-granular tunnel-coupling strength, the sensors' conductivity can be tuned by up to four orders of magnitude, to optimize their performance. We show that the nanoscale printed sensors are functional on 500 nm wide cantilevers and that their sensitivity is suited even for demanding applications such as atomic force microscopy. PMID:27666316

Nonlocally sensing the magnetic states of nanoscale antiferromagnets with an atomic spin sensor

PubMed Central

Yan, Shichao; Malavolti, Luigi; Burgess, Jacob A. J.; Droghetti, Andrea; Rubio, Angel; Loth, Sebastian

2017-01-01

The ability to sense the magnetic state of individual magnetic nano-objects is a key capability for powerful applications ranging from readout of ultradense magnetic memory to the measurement of spins in complex structures with nanometer precision. Magnetic nano-objects require extremely sensitive sensors and detection methods. We create an atomic spin sensor consisting of three Fe atoms and show that it can detect nanoscale antiferromagnets through minute, surface-mediated magnetic interaction. Coupling, even to an object with no net spin and having vanishing dipolar stray field, modifies the transition matrix element between two spin states of the Fe atom–based spin sensor that changes the sensor’s spin relaxation time. The sensor can detect nanoscale antiferromagnets at up to a 3-nm distance and achieves an energy resolution of 10 μeV, surpassing the thermal limit of conventional scanning probe spectroscopy. This scheme permits simultaneous sensing of multiple antiferromagnets with a single-spin sensor integrated onto the surface. PMID:28560346

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.

Nanoscale decomposition of Nb-Ru-O

NASA Astrophysics Data System (ADS)

Music, Denis; Geyer, Richard W.; Chen, Yen-Ting

2016-11-01

A correlative theoretical and experimental methodology has been employed to explore the decomposition of amorphous Nb-Ru-O at elevated temperatures. Density functional theory based molecular dynamics simulations reveal that amorphous Nb-Ru-O is structurally modified within 10 ps at 800 K giving rise to an increase in the planar metal - oxygen and metal - metal population and hence formation of large clusters, which signifies atomic segregation. The driving force for this atomic segregation process is 0.5 eV/atom. This is validated by diffraction experiments and transmission electron microscopy of sputter-synthesized Nb-Ru-O thin films. Room temperature samples are amorphous, while at 800 K nanoscale rutile RuO2 grains, self-organized in an amorphous Nb-O matrix, are observed, which is consistent with our theoretical predictions. This amorphous/crystalline interplay may be of importance for next generation of thermoelectric devices.

Atomistic Design and Simulations of Nanoscale Machines and Assembly

NASA Technical Reports Server (NTRS)

Goddard, William A., III; Cagin, Tahir; Walch, Stephen P.

2000-01-01

Over the three years of this project, we made significant progress on critical theoretical and computational issues in nanoscale science and technology, particularly in:(1) Fullerenes and nanotubes, (2) Characterization of surfaces of diamond and silicon for NEMS applications, (3) Nanoscale machine and assemblies, (4) Organic nanostructures and dendrimers, (5) Nanoscale confinement and nanotribology, (6) Dynamic response of nanoscale structures nanowires (metals, tubes, fullerenes), (7) Thermal transport in nanostructures.

Urea modified cottonseed protein adhesive for wood composite products

USDA-ARS?s Scientific Manuscript database

Cottonseed protein has the potential to be used as renewable and environmentally friendly adhesives in wood products industry. However, the industry application was limited by its low mechanical properties, low water resistance and viscosity. In this work, urea modified cottonseed protein adhesive w...

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.

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.

Effects of eddy viscosity and thermal conduction and Coriolis force in the dynamics of gravity wave driven fluctuations in the OH nightglow

NASA Technical Reports Server (NTRS)

Hickey, M. P.

1988-01-01

The chemical-dynamical model of Walterscheid et al. (1987), which describes wave-driven fluctuations in OH nightglow, was modified to include the effects of both eddy thermal conduction and viscosity, as well as the Coriolis force (with the shallow atmosphere approximation). Using the new model, calculations were performed for the same nominal case as used by Walterscheid et al. but with only wave periods considered. For this case, the Coriolis force was found to be unimportant at any wave period. For wave periods greater than 2 or 3 hours, the inclusion of thermal conduction alone greatly modified the results (in terms of a complex ratio 'eta' which expresses the relationship between the intensity oscillation about the time-averaged intensity and the temperature oscillation about the time-averaged temperature); this effect was reduced with the further inclusion of the eddy viscosity.

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.

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

Johnson, Kyle J.; Glynos, Emmanouil; Maroulas, Serafeim-Dionysios

Incorporating nanoparticles (NPs) within a polymer host to create polymer nanocomposites (PNCs) while having the effect of increasing the functionality (e.g., sensing, energy conversion) of these materials influences other properties. One challenge is to understand the effects of nanoparticles on the viscosity of nanoscale thick polymer films. A new mechanism that contributes to an enhancement of the viscosity of nanoscale thick polymer/nanoparticle films is identified. We show that while the viscosities of neat homopolymer poly(2-vinylpyridine) (P2VP) films as thin as 50 nm remained the same as the bulk, polymer/nanoparticle films containing P2VP brush-coated gold NPs, spaced 50 nm apart, exhibitedmore » unprecedented increases in viscosities of over an order of magnitude. For thicker films or more widely separated NPs, the chain dynamics and viscosities were comparable to the bulk values. These results - NP proximities and suppression of their dynamics - suggest a new mechanism by which the viscosities of polymeric liquids could be controlled for nanoscale applications.« less

EDITORIAL: Nanoscale metrology Nanoscale metrology

NASA Astrophysics Data System (ADS)

Picotto, G. B.; Koenders, L.; Wilkening, G.

2009-08-01

Instrumentation and measurement techniques at the nanoscale play a crucial role not only in extending our knowledge of the properties of matter and processes in nanosciences, but also in addressing new measurement needs in process control and quality assurance in industry. Micro- and nanotechnologies are now facing a growing demand for quantitative measurements to support the reliability, safety and competitiveness of products and services. Quantitative measurements presuppose reliable and stable instruments and measurement procedures as well as suitable calibration artefacts to ensure the quality of measurements and traceability to standards. This special issue of Measurement Science and Technology presents selected contributions from the Nanoscale 2008 seminar held at the Istituto Nazionale di Ricerca Metrologica (INRIM), Torino, in September 2008. This was the 4th Seminar on Nanoscale Calibration Standards and Methods and the 8th Seminar on Quantitative Microscopy (the first being held in 1995). The seminar was jointly organized by the Nanometrology Group within EUROMET (The European Collaboration in Measurement Standards), the German Nanotechnology Competence Centre 'Ultraprecise Surface Figuring' (CC-UPOB), the Physikalisch-Technische Bundesanstalt (PTB) and INRIM. A special event during the seminar was the 'knighting' of Günter Wilkening from PTB, Braunschweig, Germany, as the 1st Knight of Dimensional Nanometrology. Günter Wilkening received the NanoKnight Award for his outstanding work in the field of dimensional nanometrology over the last 20 years. The contributions in this special issue deal with the developments and improvements of instrumentation and measurement methods for scanning force microscopy (SFM), electron and optical microscopy, high-resolution interferometry, calibration of instruments and new standards, new facilities and applications including critical dimension (CD) measurements on small and medium structures and nanoparticle

Dynamics of systems on the nanoscale

NASA Astrophysics Data System (ADS)

Korol, Andrei V.; Solov'yov, Andrey V.

2017-12-01

Various aspects of the structure formation and dynamics of animate and inanimate matter on the nanoscale is a highly interdisciplinary field of rapidly emerging research interest by both experimentalists and theorists. The International Conference on Dynamics of Systems on the Nanoscale (DySoN) is the premier forum to present cutting-edge research in this field. It was established in 2010 and the most recent conference was held in Bad Ems, Germany in October of 2016. This Topical Issue presents original research results from some of the participants, who attended this conference. Contribution to the Topical Issue "Dynamics of Systems at the Nanoscale", edited by Andrey Solov'yov and Andrei Korol.

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

Dynamics of Bulk vs. Nanoscale WS2: Local Strain and Charging Effects

NASA Astrophysics Data System (ADS)

Musfeldt, J. L.; Brown, S.; Luttrell, R. D.; Cao, J.; Rosentsveig, R.; Tenne, R.

2006-03-01

We measured the infrared vibrational properties of bulk and nanoparticle WS2 in order to investigate the structure- property relations in these novel materials. In addition to the symmetry-breaking effects of local strain, nanoparticle curvature modifies the local charging environment of the bulk material. Performing a charge analysis on the xy-polarized E1u vibrational mode, we find an approximate 1.5:1 intralayer charge difference between the layered 2H material and inorganic fullerene-like (IF) nanoparticles. This effective charge difference may impact the solid-state lubrication properties of nanoscale metal dichalcogenides.

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

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

[Smart drug delivery systems based on nanoscale ZnO].

PubMed

Huang, Xiao; Chen, Chun; Yi, Caixia; Zheng, Xi

2018-04-01

In view of the excellent biocompatibility as well as the low cost, nanoscale ZnO shows great potential for drug delivery application. Moreover, The charming character enable nanoscale ZnO some excellent features (e.g. dissolution in acid, ultrasonic permeability, microwave absorbing, hydrophobic/hydrophilic transition). All of that make nanoscale ZnO reasonable choices for smart drug delivery. In the recent decade, more and more studies have focused on controlling the drug release behavior via smart drug delivery systems based on nanoscale ZnO responsive to some certain stimuli. Herein, we review the recent exciting progress on the pH-responsive, ultrasound-responsive, microwave-responsive and UV-responsive nanoscale ZnO-based drug delivery systems. A brief introduction of the drug controlled release behavior and its effect of the drug delivery systems is presented. The biocompatibility of nanoscale ZnO is also discussed. Moreover, its development prospect is looked forward.

EDITORIAL: Nanoscale metrology Nanoscale metrology

NASA Astrophysics Data System (ADS)

Klapetek, P.; Koenders, L.

2011-09-01

This special issue of Measurement Science and Technology presents selected contributions from the NanoScale 2010 seminar held in Brno, Czech Republic. It was the 5th Seminar on Nanoscale Calibration Standards and Methods and the 9th Seminar on Quantitative Microscopy (the first being held in 1995). The seminar was jointly organized with the Czech Metrology Institute (CMI) and the Nanometrology Group of the Technical Committee-Length of EURAMET. There were two workshops that were integrated into NanoScale 2010: first a workshop presenting the results obtained in NANOTRACE, a European Metrology Research Project (EMRP) on displacement-measuring optical interferometers, and second a workshop about the European metrology landscape in nanometrology related to thin films, scanning probe microscopy and critical dimension. The aim of this workshop was to bring together developers, applicants and metrologists working in this field of nanometrology and to discuss future needs. For more information see www.co-nanomet.eu. The articles in this special issue of Measurement Science and Technology cover some novel scientific results. This issue can serve also as a representative selection of topics that are currently being investigated in the field of European and world-wide nanometrology. Besides traditional topics of dimensional metrology, like development of novel interferometers or laser stabilization techniques, some novel interesting trends in the field of nanometrology are observed. As metrology generally reflects the needs of scientific and industrial research, many research topics addressed refer to current trends in nanotechnology, too, focusing on traceability and improved measurement accuracy in this field. While historically the most studied standards in nanometrology were related to simple geometric structures like step heights or 1D or 2D gratings, now we are facing tasks to measure 3D structures and many unforeseen questions arising from interesting physical

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.

New directions for nanoscale thermoelectric materials research

NASA Technical Reports Server (NTRS)

Dresselhaus, M. S.; Chen, G.; Tang, M. Y.; Yang, R. G.; Lee, H.; Wang, D. Z.; Ren, F.; Fleurial, J. P.; Gogna, P.

2005-01-01

Many of the recent advances in enhancing the thermoelectric figure of merit are linked to nanoscale phenomena with both bulk samples containing nanoscale constituents and nanoscale materials exhibiting enhanced thermoelectric performance in their own right. Prior theoretical and experimental proof of principle studies on isolated quantum well and quantum wire samples have now evolved into studies on bulk samples containing nanostructured constituents. In this review, nanostructural composites are shown to exhibit nanostructures and properties that show promise for thermoelectric applications. A review of some of the results obtained to date are presented.

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...

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.

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.

Creating nanoscale emulsions using condensation.

PubMed

Guha, Ingrid F; Anand, Sushant; Varanasi, Kripa K

2017-11-08

Nanoscale emulsions are essential components in numerous products, ranging from processed foods to novel drug delivery systems. Existing emulsification methods rely either on the breakup of larger droplets or solvent exchange/inversion. Here we report a simple, scalable method of creating nanoscale water-in-oil emulsions by condensing water vapor onto a subcooled oil-surfactant solution. Our technique enables a bottom-up approach to forming small-scale emulsions. Nanoscale water droplets nucleate at the oil/air interface and spontaneously disperse within the oil, due to the spreading dynamics of oil on water. Oil-soluble surfactants stabilize the resulting emulsions. We find that the oil-surfactant concentration controls the spreading behavior of oil on water, as well as the peak size, polydispersity, and stability of the resulting emulsions. Using condensation, we form emulsions with peak radii around 100 nm and polydispersities around 10%. This emulsion formation technique may open different routes to creating emulsions, colloidal systems, and emulsion-based materials.

Dynamics of bulk versus nanoscale W S2 : Local strain and charging effects

NASA Astrophysics Data System (ADS)

Luttrell, R. D.; Brown, S.; Cao, J.; Musfeldt, J. L.; Rosentsveig, R.; Tenne, R.

2006-01-01

We measured the infrared vibrational properties of bulk and nanoparticle WS2 in order to investigate the structure-property relations in these materials. In addition to the symmetry-breaking effects of local strain, nanoparticle curvature modifies the local charging environment of the bulk material. Performing a charge analysis on the xy -polarized E1u vibrational mode, we find an approximate 1.5:1 intralayer charge difference between the layered 2H material and inorganic fullerene-like (IF) nanoparticles. This effective charge difference may impact the solid-state lubrication properties of nanoscale metal dichalcogenides.

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.

Nanoscale thermal transport: Theoretical method and application

NASA Astrophysics Data System (ADS)

Zeng, Yu-Jia; Liu, Yue-Yang; Zhou, Wu-Xing; Chen, Ke-Qiu

2018-03-01

With the size reduction of nanoscale electronic devices, the heat generated by the unit area in integrated circuits will be increasing exponentially, and consequently the thermal management in these devices is a very important issue. In addition, the heat generated by the electronic devices mostly diffuses to the air in the form of waste heat, which makes the thermoelectric energy conversion also an important issue for nowadays. In recent years, the thermal transport properties in nanoscale systems have attracted increasing attention in both experiments and theoretical calculations. In this review, we will discuss various theoretical simulation methods for investigating thermal transport properties and take a glance at several interesting thermal transport phenomena in nanoscale systems. Our emphasizes will lie on the advantage and limitation of calculational method, and the application of nanoscale thermal transport and thermoelectric property. Project supported by the Nation Key Research and Development Program of China (Grant No. 2017YFB0701602) and the National Natural Science Foundation of China (Grant No. 11674092).

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.

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.

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.

Organically Modified Silicas on Metal Nanowires

PubMed Central

2010-01-01

Organically modified silica coatings were prepared on metal nanowires using a variety of silicon alkoxides with different functional groups (i.e., carboxyl groups, polyethylene oxide, cyano, dihydroimidazole, and hexyl linkers). Organically modified silicas were deposited onto the surface of 6-μm-long, ∼300-nm-wide, cylindrical metal nanowires in suspension by the hydrolysis and polycondensation of silicon alkoxides. Syntheses were performed at several ratios of tetraethoxysilane to an organically modified silicon alkoxide to incorporate desired functional groups into thin organosilica shells on the nanowires. These coatings were characterized using transmission electron microscopy, X-ray photoelectron spectroscopy, and infrared spectroscopy. All of the organically modified silicas prepared here were sufficiently porous to allow the removal of the metal nanowire cores by acid etching to form organically modified silica nanotubes. Additional functionality provided to the modified silicas as compared to unmodified silica prepared using only tetraethoxysilane precursors was demonstrated by chromate adsorption on imidazole-containing silicas and resistance to protein adsorption on polyethyleneoxide-containing silicas. Organically modified silica coatings on nanowires and other nano- and microparticles have potential application in fields such as biosensing or nanoscale therapeutics due to the enhanced properties of the silica coatings, for example, the prevention of biofouling. PMID:20715881

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.

Rheological characterization of modified foodstuffs with food grade thickening agents

NASA Astrophysics Data System (ADS)

Reyes-Ocampo, I.; Aguayo-Vallejo, JP; Ascanio, G.; Córdova-Aguilar, MS

2017-01-01

This work describes a rheological characterization in terms of shear and extensional properties of whole milk, modified with food grade thickening agents (xanthan and carboxymethyl cellulose) with the purpose of being utilized in dysphagia treatment. Shear viscosity of the thickened fluids (2% wt. of xanthan and CMC) were measured in a stress-controlled rheometer and for extensional viscosity, a custom-built orifice flowmeter was used, with elongation rates from 20 to 3000 s-1. Such elongation-rate values represent the entire swallowing process, including the pharyngeal and esophageal phases. The steady-state shear and extensional flow curves were compared with the flow curve of a pudding consistency BaSO4 suspension (α=05), typically used as a reference fluid for the specialized commercial dysphagia products. The modified fluids presented non-Newtonian behavior in both, shear and extensional flows, and the comparison with the reference fluid show that the thickened milk prepared here, can be safely used for consumption by patients with severe dysphagia.

Nanoscale tissue engineering: spatial control over cell-materials interactions

PubMed Central

Wheeldon, Ian; Farhadi, Arash; Bick, Alexander G.; Jabbari, Esmaiel; Khademhosseini, Ali

2011-01-01

Cells interact with the surrounding environment by making tens to hundreds of thousands of nanoscale interactions with extracellular signals and features. The goal of nanoscale tissue engineering is to harness the interactions through nanoscale biomaterials engineering in order to study and direct cellular behaviors. Here, we review the nanoscale tissue engineering technologies for both two- and three-dimensional studies (2- and 3D), and provide a holistic overview of the field. Techniques that can control the average spacing and clustering of cell adhesion ligands are well established and have been highly successful in describing cell adhesion and migration in 2D. Extension of these engineering tools to 3D biomaterials has created many new hydrogel and nanofiber scaffolds technologies that are being used to design in vitro experiments with more physiologically relevant conditions. Researchers are beginning to study complex cell functions in 3D, however, there is a need for biomaterials systems that provide fine control over the nanoscale presentation of bioactive ligands in 3D. Additionally, there is a need for 2- and 3D techniques that can control the nanoscale presentation of multiple bioactive ligands and the temporal changes in cellular microenvironment. PMID:21451238

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.

Enhanced Remedial Amendment Delivery through Fluid Viscosity Modifications: Experiments and numerical simulations

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

Zhong, Lirong; Oostrom, Martinus; Wietsma, Thomas W.

2008-07-29

Abstract Heterogeneity is often encountered in subsurface contamination characterization and remediation. Low-permeability zones are typically bypassed when remedial fluids are injected into subsurface heterogeneous aquifer systems. Therefore, contaminants in the bypassed areas may not be contacted by the amendments in the remedial fluid, which may significantly prolong the remediation operations. Laboratory experiments and numerical studies have been conducted to develop the Mobility-Controlled Flood (MCF) technology for subsurface remediation and to demonstrate the capability of this technology in enhancing the remedial amendments delivery to the lower permeability zones in heterogeneous systems. Xanthan gum, a bio-polymer, was used to modify the viscositymore » of the amendment-containing remedial solutions. Sodium mono-phosphate and surfactant were the remedial amendment used in this work. The enhanced delivery of the amendments was demonstrated in two-dimensional (2-D) flow cell experiments, packed with heterogeneous systems. The impact of polymer concentration, fluid injection rate, and permeability contract in the heterogeneous systems has been studied. The Subsurface Transport over Multiple Phases (STOMP) simulator was modified to include polymer-induced shear thinning effects. Shear rates of polymer solutions were computed from pore-water velocities using a relationship proposed in the literature. Viscosity data were subsequently obtained from empirical viscosity-shear rate relationships derived from laboratory data. The experimental and simulation results clearly show that the MCF technology is capable of enhancing the delivery of remedial amendments to subsurface lower permeability zones. The enhanced delivery significantly improved the NAPL removal from these zones and the sweeping efficiency on a heterogeneous system was remarkably increased when a polymer fluid was applied. MCF technology is also able to stabilize the fluid displacing front when

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 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

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.

Traceable nanoscale measurement at NML-SIRIM

NASA Astrophysics Data System (ADS)

Dahlan, Ahmad M.; Abdul Hapip, A. I.

2012-06-01

The role of national metrology institute (NMI) has always been very crucial in national technology development. One of the key activities of the NMI is to provide traceable measurement in all parameters under the International System of Units (SI). Dimensional measurement where size and shape are two important features investigated, is one of the important area covered by NMIs. To support the national technology development, particularly in manufacturing sectors and emerging technology such nanotechnology, the National Metrology Laboratory, SIRIM Berhad (NML-SIRIM), has embarked on a project to equip Malaysia with state-of-the-art nanoscale measurement facility with the aims of providing traceability of measurement at nanoscale. This paper will look into some of the results from current activities at NML-SIRIM related to measurement at nanoscale particularly on application of atomic force microscope (AFM) and laser based sensor in dimensional measurement. Step height standards of different sizes were measured using AFM and laser-based sensors. These probes are integrated into a long-range nanoscale measuring machine traceable to the international definition of the meter thus ensuring their traceability. Consistency of results obtained by these two methods will be discussed and presented. Factors affecting their measurements as well as their related uncertainty of measurements will also be presented.

Neuromorphic computing with nanoscale spintronic oscillators.

PubMed

Torrejon, Jacob; Riou, Mathieu; Araujo, Flavio Abreu; Tsunegi, Sumito; Khalsa, Guru; Querlioz, Damien; Bortolotti, Paolo; Cros, Vincent; Yakushiji, Kay; Fukushima, Akio; Kubota, Hitoshi; Yuasa, Shinji; Stiles, Mark D; Grollier, Julie

2017-07-26

Neurons in the brain behave as nonlinear oscillators, which develop rhythmic activity and interact to process information. Taking inspiration from this behaviour to realize high-density, low-power neuromorphic computing will require very large numbers of nanoscale nonlinear oscillators. A simple estimation indicates that to fit 10 8 oscillators organized in a two-dimensional array inside a chip the size of a thumb, the lateral dimension of each oscillator must be smaller than one micrometre. However, nanoscale devices tend to be noisy and to lack the stability that is required to process data in a reliable way. For this reason, despite multiple theoretical proposals and several candidates, including memristive and superconducting oscillators, a proof of concept of neuromorphic computing using nanoscale oscillators has yet to be demonstrated. Here we show experimentally that a nanoscale spintronic oscillator (a magnetic tunnel junction) can be used to achieve spoken-digit recognition with an accuracy similar to that of state-of-the-art neural networks. We also determine the regime of magnetization dynamics that leads to the greatest performance. These results, combined with the ability of the spintronic oscillators to interact with each other, and their long lifetime and low energy consumption, open up a path to fast, parallel, on-chip computation based on networks of oscillators.

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…

Jeans instability of magnetized quantum plasma: Effect of viscosity, rotation and finite Larmor radius corrections

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

Jain, Shweta, E-mail: jshweta09@gmail.com; Sharma, Prerana; Chhajlani, R. K.

2015-07-31

The Jeans instability of self-gravitating quantum plasma is examined considering the effects of viscosity, finite Larmor radius (FLR) corrections and rotation. The analysis is done by normal mode analysis theory with the help of relevant linearized perturbation equations of the problem. The general dispersion relation is obtained using the quantum magneto hydrodynamic model. The modified condition of Jeans instability is obtained and the numerical calculations have been performed to show the effects of various parameters on the growth rate of Jeans instability.

Bench-scale synthesis of nanoscale materials

NASA Technical Reports Server (NTRS)

Buehler, M. F.; Darab, J. G.; Matson, D. W.; Linehan, J. C.

1994-01-01

A novel flow-through hydrothermal method used to synthesize nanoscale powders is introduced by Pacific Northwest Laboratory. The process, Rapid Thermal Decomposition of precursors in Solution (RTDS), uniquely combines high-pressure and high-temperature conditions to rapidly form nanoscale particles. The RTDS process was initially demonstrated on a laboratory scale and was subsequently scaled up to accommodate production rates attractive to industry. The process is able to produce a wide variety of metal oxides and oxyhydroxides. The powders are characterized by scanning and transmission electron microscopic methods, surface-area measurements, and x-ray diffraction. Typical crystallite sizes are less than 20 nanometers, with BET surface areas ranging from 100 to 400 sq m/g. A description of the RTDS process is presented along with powder characterization results. In addition, data on the sintering of nanoscale ZrO2 produced by RTDS are included.

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

Advanced Ceramics from Preceramic Polymers Modified at the Nano-Scale: A Review.

PubMed

Bernardo, Enrico; Fiocco, Laura; Parcianello, Giulio; Storti, Enrico; Colombo, Paolo

2014-03-06

Preceramic polymers, i.e. , polymers that are converted into ceramics upon heat treatment, have been successfully used for almost 40 years to give advanced ceramics, especially belonging to the ternary SiCO and SiCN systems or to the quaternary SiBCN system. One of their main advantages is the possibility of combining the shaping and synthesis of ceramics: components can be shaped at the precursor stage by conventional plastic-forming techniques, such as spinning, blowing, injection molding, warm pressing and resin transfer molding, and then converted into ceramics by treatments typically above 800 °C. The extension of the approach to a wider range of ceramic compositions and applications, both structural and thermo-structural (refractory components, thermal barrier coatings) or functional (bioactive ceramics, luminescent materials), mainly relies on modifications of the polymers at the nano-scale, i.e. , on the introduction of nano-sized fillers and/or chemical additives, leading to nano-structured ceramic components upon thermal conversion. Fillers and additives may react with the main ceramic residue of the polymer, leading to ceramics of significant engineering interest (such as silicates and SiAlONs), or cause the formation of secondary phases, significantly affecting the functionalities of the polymer-derived matrix.

Advanced Ceramics from Preceramic Polymers Modified at the Nano-Scale: A Review

PubMed Central

Bernardo, Enrico; Fiocco, Laura; Parcianello, Giulio; Storti, Enrico; Colombo, Paolo

2014-01-01

Preceramic polymers, i.e., polymers that are converted into ceramics upon heat treatment, have been successfully used for almost 40 years to give advanced ceramics, especially belonging to the ternary SiCO and SiCN systems or to the quaternary SiBCN system. One of their main advantages is the possibility of combining the shaping and synthesis of ceramics: components can be shaped at the precursor stage by conventional plastic-forming techniques, such as spinning, blowing, injection molding, warm pressing and resin transfer molding, and then converted into ceramics by treatments typically above 800 °C. The extension of the approach to a wider range of ceramic compositions and applications, both structural and thermo-structural (refractory components, thermal barrier coatings) or functional (bioactive ceramics, luminescent materials), mainly relies on modifications of the polymers at the nano-scale, i.e., on the introduction of nano-sized fillers and/or chemical additives, leading to nano-structured ceramic components upon thermal conversion. Fillers and additives may react with the main ceramic residue of the polymer, leading to ceramics of significant engineering interest (such as silicates and SiAlONs), or cause the formation of secondary phases, significantly affecting the functionalities of the polymer-derived matrix. PMID:28788548

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.

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.

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.

Nanoscale platforms for messenger RNA delivery.

PubMed

Li, Bin; Zhang, Xinfu; Dong, Yizhou

2018-05-04

Messenger RNA (mRNA) has become a promising class of drugs for diverse therapeutic applications in the past few years. A series of clinical trials are ongoing or will be initiated in the near future for the treatment of a variety of diseases. Currently, mRNA-based therapeutics mainly focuses on ex vivo transfection and local administration in clinical studies. Efficient and safe delivery of therapeutically relevant mRNAs remains one of the major challenges for their broad applications in humans. Thus, effective delivery systems are urgently needed to overcome this limitation. In recent years, numerous nanoscale biomaterials have been constructed for mRNA delivery in order to protect mRNA from extracellular degradation and facilitate endosomal escape after cellular uptake. Nanoscale platforms have expanded the feasibility of mRNA-based therapeutics, and enabled its potential applications to protein replacement therapy, cancer immunotherapy, therapeutic vaccines, regenerative medicine, and genome editing. This review focuses on recent advances, challenges, and future directions in nanoscale platforms designed for mRNA delivery, including lipid and lipid-derived nanoparticles, polymer-based nanoparticles, protein derivatives mRNA complexes, and other types of nanomaterials. This article is categorized under: Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Biology-Inspired Nanomaterials > Lipid-Based Structures Biology-Inspired Nanomaterials > Nucleic Acid-Based Structures. © 2018 Wiley Periodicals, Inc.

Design of surface modifications for nanoscale sensor applications.

PubMed

Reimhult, Erik; Höök, Fredrik

2015-01-14

Nanoscale biosensors provide the possibility to miniaturize optic, acoustic and electric sensors to the dimensions of biomolecules. This enables approaching single-molecule detection and new sensing modalities that probe molecular conformation. Nanoscale sensors are predominantly surface-based and label-free to exploit inherent advantages of physical phenomena allowing high sensitivity without distortive labeling. There are three main criteria to be optimized in the design of surface-based and label-free biosensors: (i) the biomolecules of interest must bind with high affinity and selectively to the sensitive area; (ii) the biomolecules must be efficiently transported from the bulk solution to the sensor; and (iii) the transducer concept must be sufficiently sensitive to detect low coverage of captured biomolecules within reasonable time scales. The majority of literature on nanoscale biosensors deals with the third criterion while implicitly assuming that solutions developed for macroscale biosensors to the first two, equally important, criteria are applicable also to nanoscale sensors. We focus on providing an introduction to and perspectives on the advanced concepts for surface functionalization of biosensors with nanosized sensor elements that have been developed over the past decades (criterion (iii)). We review in detail how patterning of molecular films designed to control interactions of biomolecules with nanoscale biosensor surfaces creates new possibilities as well as new challenges.

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.

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.

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.

Comparative evaluation of microleakage of nano-filled resin-modified glass ionomer: An in vitro study

PubMed Central

Eronat, Nesrin; Yilmaz, Emir; Kara, Nazan; Topaloglu, Ak Asli

2014-01-01

Objective: This in vitro study evaluated the microleakage of a nano-filled resin-modified glass ionomer and a high viscosity glass-ionomer restorations in class V cavities. Materials and Methods: Thirty-two class V cavities prepared on the buccal and lingual surfaces of 16 sound, third molar teeth were randomly assigned into two groups and restored by one of the glass ionomer material; Group A: A high viscosity (Ketac Molar, 3M ESPE) Group B: A nano-filled resin-modified (Ketac N100, 3M ESPE) glass ionomer. One clinician prepared all the cavities. The materials were used according to the manufacturers’ recommendations. The restored teeth were then stored in distilled water at 37°C for 24 h, thermocycled at 5-55°C for 1000 cycles. The specimens were immersed in aqueous solution of Indian ink dye for 48 h at room temperature. They were embedded in resin polyester and sectioned longitudinally in a buccolingual direction. Microleakage was assessed according to the depth of dye penetration along the restoration. The extent of dye penetration at the occlusal and gingival margins was assessed using a stereo microscope. Randomly selected samples from each group were prepared for scanning electron microscope evaluation. The data were statistically analyzed with Friedman and Wilcoxon signed ranks tests. Results: There were statistically significant differences between the microleakage scores of the two groups for both occlusal and gingival scores (P = 0.001). Occlusal and gingival scores for high viscosity glass ionomer (P = 0.024) and nanoionomer (P = 0.021) using Wilcoxon signed ranks tests showed statistically significant differences. High viscosity glass ionomer showed significantly less microleakage compared to the nano-filled resin-modified glass-ionomer (RMGIs) at occlusal margin (P = 0.001). No significant differences were found between the groups at gingival margin (P = 0.0317). Conclusion: Within the limitations of this in vitro study, nano-filled RMGIs

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

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

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.

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.

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.

Treatment of wet blue with fillers produced from quebracho-modified gelatin

USDA-ARS?s Scientific Manuscript database

Gelatin modified with quebracho to produce high molecular weight, high viscosity products was investigated as a filler in leather processing. The uptake of quebracho/gelatin product by the wet blue was on the average about 55% of the 10% gelatin/quebracho product offered; the reaction appeared to be...

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

Nanoscale superstructures assembled by polymerase chain reaction (PCR): programmable construction, structural diversity, and emerging applications.

PubMed

Kuang, Hua; Ma, Wei; Xu, Liguang; Wang, Libing; Xu, Chuanlai

2013-11-19

Polymerase chain reaction (PCR) is an essential tool in biotechnology laboratories and is becoming increasingly important in other areas of research. Extensive data obtained over the last 12 years has shown that the combination of PCR with nanoscale dispersions can resolve issues in the preparation DNA-based materials that include both inorganic and organic nanoscale components. Unlike conventional DNA hybridization and antibody-antigen complexes, PCR provides a new, effective assembly platform that both increases the yield of DNA-based nanomaterials and allows researchers to program and control assembly with predesigned parameters including those assisted and automated by computers. As a result, this method allows researchers to optimize to the combinatorial selection of the DNA strands for their nanoparticle conjugates. We have developed a PCR approach for producing various nanoscale assemblies including organic motifs such as small molecules, macromolecules, and inorganic building blocks, such as nanorods (NRs), metal, semiconductor, and magnetic nanoparticles (NPs). We start with a nanoscale primer and then modify that building block using the automated steps of PCR-based assembly including initialization, denaturation, annealing, extension, final elongation, and final hold. The intermediate steps of denaturation, annealing, and extension are cyclic, and we use computer control so that the assembled superstructures reach their predetermined complexity. The structures assembled using a small number of PCR cycles show a lower polydispersity than similar discrete structures obtained by direct hybridization between the nanoscale building blocks. Using different building blocks, we assembled the following structural motifs by PCR: (1) discrete nanostructures (NP dimers, NP multimers including trimers, pyramids, tetramers or hexamers, etc.), (2) branched NP superstructures and heterochains, (3) NP satellite-like superstructures, (4) Y-shaped nanostructures and DNA

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.

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.

PREFACE: Superconductivity in ultrathin films and nanoscale systems Superconductivity in ultrathin films and nanoscale systems

NASA Astrophysics Data System (ADS)

Bianconi, Antonio; Bose, Sangita; Garcia-Garcia, Antonio Miguel

2012-12-01

The recent technological developments in the synthesis and characterization of high-quality nanostructures and developments in the theoretical techniques needed to model these materials, have motivated this focus section of Superconductor Science and Technology. Another motivation is the compelling evidence that all new superconducting materials, such as iron pnictides and chalcogenides, diborides (doped MgB2) and fullerides (alkali-doped C60 compounds), are heterostrucures at the atomic limit, such as the cuprates made of stacks of nanoscale superconducting layers intercalated by different atomic layers with nanoscale periodicity. Recently a great amount of interest has been shown in the role of lattice nano-architecture in controlling the fine details of Fermi surface topology. The experimental and theoretical study of superconductivity in the nanoscale started in the early 1960s, shortly after the discovery of the BCS theory. Thereafter there has been rapid progress both in experiments and the theoretical understanding of nanoscale superconductors. Experimentally, thin films, granular films, nanowires, nanotubes and single nanoparticles have all been explored. New quantum effects appear in the nanoscale related to multi-component condensates. Advances in the understanding of shape resonances or Fano resonances close to 2.5 Lifshitz transitions near a band edge in nanowires, 2D films and superlattices [1, 2] of these nanosized modules, provide the possibility of manipulating new quantum electronic states. Parity effects and shell effects in single, isolated nanoparticles have been reported by several groups. Theoretically, newer techniques based on solving Richardson's equation (an exact theory incorporating finite size effects to the BCS theory) numerically by path integral methods or solving the entire Bogoliubov-de Gennes equation in these limits have been attempted, which has improved our understanding of the mechanism of superconductivity in these confined

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.

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

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.

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.

Design of Surface Modifications for Nanoscale Sensor Applications

PubMed Central

Reimhult, Erik; Höök, Fredrik

2015-01-01

Nanoscale biosensors provide the possibility to miniaturize optic, acoustic and electric sensors to the dimensions of biomolecules. This enables approaching single-molecule detection and new sensing modalities that probe molecular conformation. Nanoscale sensors are predominantly surface-based and label-free to exploit inherent advantages of physical phenomena allowing high sensitivity without distortive labeling. There are three main criteria to be optimized in the design of surface-based and label-free biosensors: (i) the biomolecules of interest must bind with high affinity and selectively to the sensitive area; (ii) the biomolecules must be efficiently transported from the bulk solution to the sensor; and (iii) the transducer concept must be sufficiently sensitive to detect low coverage of captured biomolecules within reasonable time scales. The majority of literature on nanoscale biosensors deals with the third criterion while implicitly assuming that solutions developed for macroscale biosensors to the first two, equally important, criteria are applicable also to nanoscale sensors. We focus on providing an introduction to and perspectives on the advanced concepts for surface functionalization of biosensors with nanosized sensor elements that have been developed over the past decades (criterion (iii)). We review in detail how patterning of molecular films designed to control interactions of biomolecules with nanoscale biosensor surfaces creates new possibilities as well as new challenges. PMID:25594599

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

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.

Development of high-viscosity, two-paste bioactive bone cements.

PubMed

Deb, S; Aiyathurai, L; Roether, J A; Luklinska, Z B

2005-06-01

Self-curing two-paste bone cements have been developed using methacrylate monomers with a view to formulate cements with low polymerization exotherm, low shrinkage, better mechanical properties, and improved adhesion to bone and implant surfaces. The monomers include bis-phenol A glycidyl dimethacrylate (bis-GMA), urethane dimethacrylate (UDMA) and triethylene glycol dimethacrylate (TEGDMA) as a viscosity modifier. Two-paste systems were formulated containing 60% by weight of a bioactive ceramic, hydroxyapatite. A methacroyloxy silane (A174) was used as a coupling agent due to its higher water stability in comparison to other aminosilanes to silanate the hydroxyapatite particles prior to composite formulation. A comparison of the FT-infrared spectrum of hydroxyapatite and silanated hydroxyapatite showed the presence of the carbonyl groups ( approximately 1720 cm(-1)), -C=C-( approximately 1630 cm(-1)) and Si-O- (1300-1250 cm(-1)) which indicated the availability of silane groups on the filler surface. Two methods of mixing were effected to form the bone cement: firstly by mixing in an open bowl and secondly by extruding the two pastes by an auto-mixing tip using a gun to dispense the pastes. Both types of cements yielded low polymerization exotherms with good mechanical properties; however, the lower viscosity of UDMA allowed better extrusion and handling properties. A biologically active apatite layer formed on the bone cement surface within a short period after its immersion in simulated body fluid, demonstrating in vitro bioactivity of the composite. This preliminary data thus suggests that UDMA is a viable alternative to bis-GMA as a polymerizable matrix in the formation of bone cements.

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.

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.

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.

Direct optical imaging of nanoscale internal organization of polymer films

NASA Astrophysics Data System (ADS)

Suran, Swathi; Varma, Manoj

2018-02-01

Owing to its sensitivity and precise control at the nanoscale, polyelectrolytes have been immensely used to modify surfaces. Polyelectrolyte multilayers are generally water made and are easy to fabricate on any surface by the layer-by-layer (LbL) self-assembly process due to electrostatic interactions. Polyelectrolyte multilayers or PEMs can be assembled to form ultrathin membranes which can have potential applications in water filtration and desalination [1-3]. Hydration in PEMs is a consequence of both the bulk and surface phenomenon [4-7]. Bulk behavior of polymer membranes are well understood. Several techniques including reflectivity and contact angle measurements were used to measure the hydration in the bulk of polymer membranes [4, 8]. On the other hand their internal organization at the molecular level which can have a profound contribution in the transport mechanism, are not understood well. Previously, we engineered a technique, which we refer to as Bright-field Nanoscopy, which allows nanoscale optical imaging using local heterogeneities in a water-soluble germanium (Ge) thin film ( 25 nm thick) deposited on gold [8]. We use this technique to study the water transport in PEMs. It is understood that the surface charge and outer layers of the PEMs play a significant role in water transport through polymers [9-11]. This well-known `odd-even' effect arising on having different surface termination of the PEMs was optically observed with a spatial resolution unlike any other reported previously [12]. In this communication, we report that on increasing the etchant's concentration, one can control the lateral etching of the Ge film. This allowed the visualization of the nanoscale internal organization in the PEMs. Knowledge of the internal structure would allow one to engineer polymer membranes specific to applications such as drug delivering capsules, ion transport membranes and barriers etc. We also demonstrate a mathematical model involving a surface

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.

Morphological transitions in nanoscale patterns produced by concurrent ion sputtering and impurity co-deposition

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

Bradley, R. Mark

2016-04-07

We modify the theory of nanoscale patterns produced by ion bombardment with concurrent impurity deposition to take into account the effect that the near-surface impurities have on the collision cascades. As the impurity concentration is increased, the resulting theory successively yields a flat surface, a rippled surface with its wavevector along the projected direction of ion incidence, and a rippled surface with its wavevector rotated by 90°. Exactly the same morphological transitions were observed in recent experiments in which silicon was bombarded with an argon ion beam and gold was co-deposited [Moon et al., e-print arXiv:1601.02534].

Dynamic structural disorder in supported nanoscale catalysts

NASA Astrophysics Data System (ADS)

Rehr, J. J.; Vila, F. D.

2014-04-01

We investigate the origin and physical effects of "dynamic structural disorder" (DSD) in supported nano-scale catalysts. DSD refers to the intrinsic fluctuating, inhomogeneous structure of such nano-scale systems. In contrast to bulk materials, nano-scale systems exhibit substantial fluctuations in structure, charge, temperature, and other quantities, as well as large surface effects. The DSD is driven largely by the stochastic librational motion of the center of mass and fluxional bonding at the nanoparticle surface due to thermal coupling with the substrate. Our approach for calculating and understanding DSD is based on a combination of real-time density functional theory/molecular dynamics simulations, transient coupled-oscillator models, and statistical mechanics. This approach treats thermal and dynamic effects over multiple time-scales, and includes bond-stretching and -bending vibrations, and transient tethering to the substrate at longer ps time-scales. Potential effects on the catalytic properties of these clusters are briefly explored. Model calculations of molecule-cluster interactions and molecular dissociation reaction paths are presented in which the reactant molecules are adsorbed on the surface of dynamically sampled clusters. This model suggests that DSD can affect both the prefactors and distribution of energy barriers in reaction rates, and thus can significantly affect catalytic activity at the nano-scale.

Probing and manipulating magnetization at the nanoscale

NASA Astrophysics Data System (ADS)

Samarth, Nitin

2012-02-01

Combining semiconductors with magnetism in hetero- and nano-structured geometries provides a powerful means of exploring the interplay between spin-dependent transport and nanoscale magnetism. We describe two recent studies in this context. First, we use spin-dependent transport in ferromagnetic semiconductor thin films to provide a new window into nanoscale magnetism [1]: here, we exploit the large anomalous Hall effect in a ferromagnetic semiconductor as a nanoscale probe of the reversible elastic behavior of magnetic domain walls and gain insight into regimes of domain wall behavior inaccessible to more conventional optical techniques. Next, we describe novel ways to create self-assembled hybrid semiconductor/ferromagnet core-shell nanowires [2] and show how magnetoresistance measurements in single nanowires, coupled with micromagnetic simulations, can provide detailed insights into the magnetization reversal process in nanoscale ferromagnets [3]. The work described here was carried out in collaboration with Andrew Balk, Jing Liang, Nicholas Dellas, Mark Nowakowski, David Rench, Mark Wilson, Roman Engel-Herbert, Suzanne Mohney, Peter Schiffer and David Awschalom. This work is supported by ONR, NSF and the NSF-MRSEC program.[4pt] [1] A. L. Balk et al., Phys. Rev.Lett. 107, 077205 (2011).[0pt] [2] N. J. Dellas et al., Appl. Phys. Lett. 97, 072505 (2010).[0pt] [3] J. Liang et al., in preparation.

Method to determine thermal profiles of nanoscale circuitry

DOEpatents

Zettl, Alexander K; Begtrup, Gavi E

2013-04-30

A platform that can measure the thermal profiles of devices with nanoscale resolution has been developed. The system measures the local temperature by using an array of nanoscale thermometers. This process can be observed in real time using a high resolution imagining technique such as electron microscopy. The platform can operate at extremely high temperatures.

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

Nanoscale Membrane Curvature detected by Polarized Localization Microscopy

NASA Astrophysics Data System (ADS)

Kelly, Christopher; Maarouf, Abir; Woodward, Xinxin

Nanoscale membrane curvature is a necessary component of countless cellular processes. Here we present Polarized Localization Microscopy (PLM), a super-resolution optical imaging technique that enables the detection of nanoscale membrane curvature with order-of-magnitude improvements over comparable optical techniques. PLM combines the advantages of polarized total internal reflection fluorescence microscopy and fluorescence localization microscopy to reveal single-fluorophore locations and orientations without reducing localization precision by point spread function manipulation. PLM resolved nanoscale membrane curvature of a supported lipid bilayer draped over polystyrene nanoparticles on a glass coverslip, thus creating a model membrane with coexisting flat and curved regions and membrane radii of curvature as small as 20 nm. Further, PLM provides single-molecule trajectories and the aggregation of curvature-inducing proteins with super-resolution to reveal the correlated effects of membrane curvature, dynamics, and molecular sorting. For example, cholera toxin subunit B has been observed to induce nanoscale membrane budding and concentrate at the bud neck. PLM reveals a previously hidden and critical information of membrane topology.

Understanding the impact of nanoscale aggregation on charge transport and structural dynamics in room temperature ionic liquids

NASA Astrophysics Data System (ADS)

Griffin, Philip; Holt, Adam; Wang, Yangyang; Sokolov, Alexei

2015-03-01

Amphiphilic room temperature ionic liquids (ILs) segregate on the nanoscale, forming intricate networks of charge-rich ionic domains intercalated with charge-poor aliphatic domains. While this structural phenomenon has been well established through x-ray diffraction studies and atomistic MD simulations, the precise effects of nanophase segregation on ion transport and structural dynamics in ILs remains poorly understood. Using a combination of broadband dielectric spectroscopy, light scattering spectroscopy, and rheology, we have characterized the ionic conductivity, structural dynamics, and shear viscosity of a homologous series of quaternary ammonium ionic liquids over a wide temperature range. Upon increasing the length and volume fraction of the alkyl side chains of these quaternary ammonium ILs, ionic conductivity decreases precipitously, although no corresponding slowing of the structural dynamics is observed. Instead, we identify the dynamical signature of supramolecular aggregates. Our results directly demonstrate the role that chemical structure and ionic aggregation plays in determining the charge transport properties of amphiphilic ILs.

Evidence for a Role of Vascular Endothelium in the Control of Arterial Wall Viscosity in Humans.

PubMed

Roca, Frederic; Iacob, Michele; Remy-Jouet, Isabelle; Bellien, Jeremy; Joannides, Robinson

2018-01-01

Arterial wall viscosity (AWV) is a major cause of energy dissipation along the arterial tree. Its determinants remain controversial but an active endothelial regulation has been suggested. Our objective was to assess in humans the physiological role of endothelium-derived nitric oxide (NO), epoxyeicosatrienoic acids and the effect of modulating smooth muscle tone in the regulation of AWV. We simultaneously measured radial artery diameter, wall thickness, and arterial pressure in healthy volunteers during the local infusion of inhibitors of NO-synthase ( N G -monomethyl-l-arginine), epoxyeicosatrienoic acids synthesis by cytochrome P450 (fluconazole), the epoxyeicosatrienoic acids cellular targets calcium-activated potassium channels (tetraethylammonium), alone and in combination. AWV was estimated from the relative viscosity expressed as the ratio of the area of the hysteresis loop of the pressure-diameter relationship to the area under the loading phase. Arterial tone was assessed by measuring change in wall stiffness and midwall stress. N G -monomethyl-l-arginine paradoxically reduced relative viscosity (34.9±8.9%-28.9±8.6%). Conversely, relative viscosity was not modified by fluconazole (33.5±15.5%-32.0±13.6%) but increased by tetraethylammonium (31.7±6.6%-35.7±8.0%). This increase was more marked with N G -monomethyl-l-arginine+fluconazole (31.1±10.7%-43.3±13.2%) and N G -monomethyl-l-arginine+tetraethylammonium (29.5±2.3%-41.5±11.1%) compared with inhibitors alone. Sodium nitroprusside decreased AWV (35.4±2.9%-28.7±2.0%). These effects were associated with parallel change in tone but of different magnitude for similar variations in viscosity, suggesting tone-dependent and independent mechanisms. In conclusion, this is the first demonstration that the endothelial factors, NO and epoxyeicosatrienoic acids, regulate AWV in humans and support the role of arterial tone in this regulation. URL: https://eudract.ema.europa.eu. Unique identifier: RCB2007-A

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

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.

Physical and rheological properties of Titanium Dioxide modified asphalt

NASA Astrophysics Data System (ADS)

Buhari, Rosnawati; Ezree Abdullah, Mohd; Khairul Ahmad, Mohd; Chong, Ai Ling; Haini, Rosli; Khatijah Abu Bakar, Siti

2018-03-01

Titanium Dioxide (TiO2) has been known as a useful photocatalytic material that is attributed to the several characteristics includes high photocatalytic activity compared with other metal oxide photocatalysts, compatible with traditional construction materials without changing any original performance. This study investigates the physical and rheological properties of modified asphalt with TiO2. Five samples of asphalt with different concentration of TiO2 were studied, namely asphalt 2%, 4%, 6% 8% and 10% TiO2. The tests includes are penetration, softening point, ductility, rotational viscosity and dynamic shear rheometer (DSR) test. From the results of this study, it is noted that addition of TiO2 has significant effect on the physical properties of asphalt. The viscosity tests revealed that asphalt 10% TiO2 has good workability among with reducing approximately 15°C compared to base asphalt. Based on the results from DSR measurements, asphalt 10% TiO2 has reduced temperature susceptibility and increase stiffness and elastic behaviour in comparison to base asphalt. As a result, TiO2 can be considered to be an additive to modify the properties of asphalt.

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.

A field-validated model for in situ transport of polymer-stabilized nZVI and implications for subsurface injection.

PubMed

Krol, Magdalena M; Oleniuk, Andrew J; Kocur, Chris M; Sleep, Brent E; Bennett, Peter; Xiong, Zhong; O'Carroll, Denis M

2013-07-02

Nanoscale zerovalent iron (nZVI) particles have significant potential to remediate contaminated source zones. However, the transport of these particles through porous media is not well understood, especially at the field scale. This paper describes the simulation of a field injection of carboxylmethyl cellulose (CMC) stabilized nZVI using a 3D compositional simulator, modified to include colloidal filtration theory (CFT). The model includes composition dependent viscosity and spatially and temporally variable velocity, appropriate for the simulation of push-pull tests (PPTs) with CMC stabilized nZVI. Using only attachment efficiency as a fitting parameter, model results were in good agreement with field observations when spatially variable viscosity effects on collision efficiency were included in the transport modeling. This implies that CFT-modified transport equations can be used to simulate stabilized nZVI field transport. Model results show that an increase in solution viscosity, resulting from injection of CMC stabilized nZVI suspension, affects nZVI mobility by decreasing attachment as well as changing the hydraulics of the system. This effect is especially noticeable with intermittent pumping during PPTs. Results from this study suggest that careful consideration of nZVI suspension formulation is important for optimal delivery of nZVI which can be facilitated with the use of a compositional simulator.

Dopant atoms as quantum components in silicon nanoscale devices

NASA Astrophysics Data System (ADS)

Zhao, Xiaosong; Han, Weihua; Wang, Hao; Ma, Liuhong; Li, Xiaoming; Zhang, Wang; Yan, Wei; Yang, Fuhua

2018-06-01

Recent progress in nanoscale fabrication allows many fundamental studies of the few dopant atoms in various semiconductor nanostructures. Since the size of nanoscale devices has touched the limit of the nature, a single dopant atom may dominate the performance of the device. Besides, the quantum computing considered as a future choice beyond Moore's law also utilizes dopant atoms as functional units. Therefore, the dopant atoms will play a significant role in the future novel nanoscale devices. This review focuses on the study of few dopant atoms as quantum components in silicon nanoscale device. The control of the number of dopant atoms and unique quantum transport characteristics induced by dopant atoms are presented. It can be predicted that the development of nanoelectronics based on dopant atoms will pave the way for new possibilities in quantum electronics. Project supported by National Key R&D Program of China (No. 2016YFA0200503).

Analysis of Jeans instability of optically thick quantum plasma under the effect of modified Ohms law

NASA Astrophysics Data System (ADS)

Pensia, R. K.; Sutar, D. L.; Sharma, S.

2018-05-01

The Jeans instability of self-gravitating optically thick quantum plasma is reanalyzed in the framework of viscosity, black body radiation and modify ohms law. The usual magnetohydrodynamic (MHD) equation is used for the present configuration with black body radiation, viscosity, electrical resistivity and quantum corrections. A general dispersion relation is obtained with the help of linearized perturbation equations. It is found that the quantum correction has stabilizing effect on the system. The instability of system is discussed for various cases as our interest.

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.

Non-Newtonian behavior of plagioclase-bearing basaltic magma: Subliquidus viscosity measurement of the 1707 basalt of Fuji volcano, Japan

NASA Astrophysics Data System (ADS)

Ishibashi, Hidemi

2009-03-01

Laboratory measurements of viscosity were done for basalt erupted in 1707 AD from Fuji volcano, Japan, using a concentric cylinder rotational viscometer at temperatures of 1297-1157 °C, 1 atm pressure, and fO 2 near the Ni-NiO buffer. On cooling, elongated plagioclase crystals with a mean length/width ratio of ca. 8.5 appeared at 1237 °C, followed by olivine at 1157 °C. At progressively lower temperatures, the total crystal volume fraction increased monotonously to ca. 0.25; viscosity increased from 38.9 to 765 Pa s at a shear strain rate of 1 s - 1 . This basalt magma behaves as a Newtonian fluid at temperatures greater than 1217 °C, but shear-thinning behavior occurs at temperatures less than 1197 °C because of the suspended plagioclase crystals. This behavior is well approximated as a power law fluid. At the onset of shear thinning, the crystal volume fraction was between 0.06 and 0.13, which is attributed to the pronounced lath-shape of plagioclase crystals. The relative viscosity increases monotonously with increase of crystal volume fraction at a constant shear strain rate, and with decrease of shear strain rate at a constant crystal volume fraction. A modified form of the Krieger-Dougherty equation is introduced herein. It enables us to describe the dependencies of relative viscosity on both the crystal volume fraction and shear strain rate, and consequently the onset of shear-thinning behavior.

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.

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.

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

Johnson, Kyle J.; Glynos, Emmanouil; Maroulas, Serafeim-Dionysios

Incorporating nanoparticles (NPs) within a polymer host to create polymer nanocomposites (PNCs) while having the effect of increasing the functionality (e.g.: sensing, energy conversion) of these materials, introduces additional complications with regard to the processing-morphology-function behavior. A primary challenge is to understand and control the viscosity of a PNC with decreasing film thickness confinement for nanoscale applications. Using a combination of X-ray photon correlation spectroscopy (XPCS) and X-ray standing wave based resonance enhanced XPCS to study the dynamics of neat poly-2-vinyl pyridine (P2VP) chains and the nanoparticle dynamics, respectively, we identified a new mechanism that dictates the viscosity of PNCmore » films in the nanoscale regime. We show that while the viscosities of neat P2VP films as thin as 50 nm remained the same as the bulk, PNC films containing P2VP brush-coated gold NPs, spaced 50 nm apart, exhibited unprecedented increases in viscosities of over an order of magnitude. For thicker films or more widely separated NPs, the chain dynamics and viscosities were equal to the bulk values. These results -NP proximities and suppression of their dynamics -suggest a new mechanism by which the viscosities of polymeric liquids could be controlled for 2D and 3D nanoscale applications.« less

Mixed electrochemical–ferroelectric states in nanoscale ferroelectrics

DOE PAGES

Yang, Sang Mo; Morozovska, Anna N.; Kumar, Rajeev; ...

2017-05-01

Ferroelectricity on the nanoscale has been the subject of much fascination in condensed-matter physics for over half a century. In recent years, multiple reports claiming ferroelectricity in ultrathin ferroelectric films based on the formation of remnant polarization states, local electromechanical hysteresis loops, and pressure-induced switching were made. But, similar phenomena were reported for traditionally non-ferroelectric materials, creating a significant level of uncertainty in the field. We show that in nanoscale systems the ferroelectric state is fundamentally inseparable from the electrochemical state of the surface, leading to the emergence of a mixed electrochemical–ferroelectric state. We explore the nature, thermodynamics, and thicknessmore » evolution of such states, and demonstrate the experimental pathway to establish its presence. Our analysis reconciles multiple prior studies, provides guidelines for studies of ferroelectric materials on the nanoscale, and establishes the design paradigm for new generations of ferroelectric-based devices.« less

Understanding Cooperative Chirality at the Nanoscale

NASA Astrophysics Data System (ADS)

Yu, Shangjie; Wang, Pengpeng; Govorov, Alexander; Ouyang, Min

Controlling chirality of organic and inorganic structures plays a key role in many physical, chemical and biochemical processes, and may offer new opportunity to create technology applications based on chiroptical effect. In this talk, we will present a theoretical model and simulation to demonstrate how to engineer nanoscale chirality in inorganic nanostructures via synergistic control of electromagnetic response of both lattice and geometry, leading to rich tunability of chirality at the nanoscale. Our model has also been applied to understand recent materials advancement of related control with excellent agreement, and can elucidate physical origins of circular dichroism features in the experiment.

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

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.

Experimental Study of Electron and Phonon Dynamics in Nanoscale Materials by Ultrafast Laser Time-Domain Spectroscopy

NASA Astrophysics Data System (ADS)

Shen, Xiaohan

less than 100 nm was observed. The longitudinal acoustic phonon transport in silicon (Si) nanorod with confined diameter and length was investigated. The guided phonon modes in Si nanorod with different frequencies and wave vectors were observed. The mean-free-path of the guided phonons in Si nanorod was found to be larger than the effective phonon mean-free-path in Si film, because of the limited phonon scattering channels in Si nanorod. The phonon density of states and dispersion relation strongly depend on the size and boundary conditions of nanorod. Our work demonstrates the possibility of modifying the phonon transport properties in nanoscale materials by designing the size and boundary conditions, hence the control of thermal conductivity. In addition, the periodicity effect of nanostructures on acoustic phonon transport was investigated in silicon dioxide (SiO2) nanorod arrays. The lattice modes and mechanical eigenmodes were observed, and the pitch effect on lattice modes was discussed. A narrowband acoustic phonon spectroscopic technique with tunable frequency and spectral width throughout GHz frequency range has been developed to investigate the frequency-dependent acoustic phonon transport in nanoscale materials. The quadratic frequency dependence of acoustic attenuation of SiO2 and indium tin oxide (ITO) thin films was observed, and the acoustic attenuation of ITO was found to be larger than SiO2. Moreover, the acoustic control on mechanical resonance of nanoscale materials using the narrowband acoustic phonon source was demonstrated in tungsten thin film.

Democratization of Nanoscale Imaging and Sensing Tools Using Photonics

PubMed Central

2015-01-01

Providing means for researchers and citizen scientists in the developing world to perform advanced measurements with nanoscale precision can help to accelerate the rate of discovery and invention as well as improve higher education and the training of the next generation of scientists and engineers worldwide. Here, we review some of the recent progress toward making optical nanoscale measurement tools more cost-effective, field-portable, and accessible to a significantly larger group of researchers and educators. We divide our review into two main sections: label-based nanoscale imaging and sensing tools, which primarily involve fluorescent approaches, and label-free nanoscale measurement tools, which include light scattering sensors, interferometric methods, photonic crystal sensors, and plasmonic sensors. For each of these areas, we have primarily focused on approaches that have either demonstrated operation outside of a traditional laboratory setting, including for example integration with mobile phones, or exhibited the potential for such operation in the near future. PMID:26068279

Democratization of Nanoscale Imaging and Sensing Tools Using Photonics.

PubMed

McLeod, Euan; Wei, Qingshan; Ozcan, Aydogan

2015-07-07

Providing means for researchers and citizen scientists in the developing world to perform advanced measurements with nanoscale precision can help to accelerate the rate of discovery and invention as well as improve higher education and the training of the next generation of scientists and engineers worldwide. Here, we review some of the recent progress toward making optical nanoscale measurement tools more cost-effective, field-portable, and accessible to a significantly larger group of researchers and educators. We divide our review into two main sections: label-based nanoscale imaging and sensing tools, which primarily involve fluorescent approaches, and label-free nanoscale measurement tools, which include light scattering sensors, interferometric methods, photonic crystal sensors, and plasmonic sensors. For each of these areas, we have primarily focused on approaches that have either demonstrated operation outside of a traditional laboratory setting, including for example integration with mobile phones, or exhibited the potential for such operation in the near future.

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.

Facile Fabrication of Binary Nanoscale Interface for No-Loss Microdroplet Transportation.

PubMed

Liang, Weitao; Zhu, Liqun; Li, Weiping; Xu, Chang; Liu, Huicong

2016-06-07

Binary nanoscale interfacial materials are fundamental issues in many applications for smart surfaces. A binary nanoscale interface with binary surface morphology and binary wetting behaviors has been prepared by a facile wet-chemical method. The prepared surface presents superhydrophobicity and high adhesion with the droplet at the same time. The composition, surface morphology, and wetting behaviors of the prepared surface have been systematic studied. The special wetting behaviors can be contributed to the binary nanoscale effect. The stability of the prepared surface was also investigated. As a primary application, a facile device based on the prepared binary nanoscale interface with superhydrophobicity and high adhesion was constructed for microdroplet transportation.

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.

Nanoscale modification of porous gelatin scaffolds with chondroitin sulfate for corneal stromal tissue engineering

PubMed Central

Lai, Jui-Yang; Li, Ya-Ting; Cho, Ching-Hsien; Yu, Ting-Chun

2012-01-01

Recent studies reflect the importance of using naturally occurring biopolymers as three-dimensional corneal keratocyte scaffolds and suggest that the porous structure of gelatin materials may play an important role in controlling nutrient uptake. In the current study, the authors further consider the application of carbodiimide cross-linked porous gelatin as an alternative to collagen for corneal stromal tissue engineering. The authors developed corneal keratocyte scaffolds by nanoscale modification of porous gelatin materials with chondroitin sulfate (CS) using carbodiimide chemistry. Scanning electron microscopy/energy dispersive X-ray spectroscopy and Fourier transform infrared spectroscopy showed that the amount of covalently incorporated polysaccharide was significantly increased when the CS concentration was increased from 0% to 1.25% (w/v). In addition, as demonstrated by dimethylmethylene blue assays, the CS content in these samples was in the range of 0.078–0.149 nmol per 10 mg scaffold. When compared with their counterparts without CS treatment, various CS-modified porous gelatin membranes exhibited higher levels of water content, light transmittance, and amount of permeated nutrients but possessed lower Young’s modulus and resistance against protease digestion. The hydrophilic and mechanical properties of scaffolds modified with 0.25% CS were comparable with those of native corneas. The samples from this group were biocompatible with the rabbit corneal keratocytes and showed enhanced proliferative and biosynthetic capacity of cultured cells. In summary, the authors found that the nanoscale-level modification has influence on the characteristics and cell-material interactions of CS-containing gelatin hydrogels. Porous membranes with a CS content of 0.112 ± 0.003 nmol per 10 mg scaffold may hold potential for use in corneal stromal tissue engineering. PMID:22403490

Viscosity of diluted suspensions of vegetal particles in water

NASA Astrophysics Data System (ADS)

Szydłowska, Adriana; Hapanowicz, Jerzy

2017-10-01

Viscosity and rheological behaviour of sewage as well as sludge are essential while designing apparatuses and operations employed in the sewage treatment process and its processing. With reference to these substances, the bio-suspensions samples of three size fractions ((i) 150÷212 μm, (ii) 106÷150 μm and (iii) below106 μm) of dry grass in water with solid volume fraction 8%, 10% and 11% were prepared. After twenty four hours prior to their preparation time, the suspension samples underwent rheometeric measurements with the use of a rotational rheometer with coaxial cylinders. On the basis of the obtained results, flow curves were plotted and described with both the power model and Herschel-Bulkley model. Moreover, the viscosity of the studied substances was determined that allowed to conclude that the studied bio-suspensions display features of viscoelastic fluids. The experimentally established viscosity was compared to the calculated one according to Manley and Manson equation, recommended in the literature. It occurred that the measured viscosity values substantially exceed the calculation viscosity values, even by 105 times. The observations suggest that it stems from water imbibition of fibrous vegetal particles, which causes their swelling and decreases the amount of liquid phase in the suspension.

Cellular Viscosity in Prokaryotes and Thermal Stability of Low Molecular Weight Biomolecules.

PubMed

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

2016-08-23

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

Estimation of the Viscosities of Liquid Sn-Based Binary Lead-Free Solder Alloys

NASA Astrophysics Data System (ADS)

Wu, Min; Li, Jinquan

2018-01-01

The viscosity of a binary Sn-based lead-free solder alloy was calculated by combining the predicted model with the Miedema model. The viscosity factor was proposed and the relationship between the viscosity and surface tension was analyzed as well. The investigation result shows that the viscosity of Sn-based lead-free solders predicted from the predicted model shows excellent agreement with the reported values. The viscosity factor is determined by three physical parameters: atomic volume, electronic density, and electro-negativity. In addition, the apparent correlation between the surface tension and viscosity of the binary Sn-based Pb-free solder was obtained based on the predicted model.

Viscosity measurements of metallic melts using the oscillating drop technique

NASA Astrophysics Data System (ADS)

Heintzmann, P.; Yang, F.; Schneider, S.; Lohöfer, G.; Meyer, A.

2016-06-01

By means of benchmarking reduced gravity experiments, we have verified the measured viscosity of binary Zr-Ni glass forming liquids utilizing the oscillating drop technique combined with ground-based electrostatic levitation (ESL). Reliable viscosity data can be obtained as long as internal viscous damping of a single oscillation mode of a levitated drop dominates external perturbations. This can be verified by the absence of a sample mass dependence of the results. Hence, ESL is an excellent tool for studying the viscosity of metallic glass forming melts in the range of about 10-250 mPa s, with sample masses below 100 mg. To this end, we show that, for binary Zr-Ni melts, the viscosity is qualitatively controlled by the packing density.

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

Measurement of gas viscosity using photonic crystal fiber

NASA Astrophysics Data System (ADS)

Gao, R.-K.; Sheehe, S. L.; Kurtz, J.; O'Byrne, S.

2016-11-01

A new measurement technique for gas viscosity coefficient is designed and demonstrated using the technique of tunable diode laser absorption spectroscopy (TDLAS). Gas flow is driven by a pressure gradient between two gas cells, through a photonic crystal fiber (PCF) surrounded by a furnace for temperature adjustment. PCF with 20-micron diameter affords physical space for gas-light interaction and provides a basis for gas viscosity measurement by determining the time for flow to exit a capillary tube under the influence of a pressure gradient. Infrared radiation from a diode laser is coupled into the fiber to be guided through the gas, and the light attenuation due to absorption from the molecular absorbing species is measured by a photo detector placed at the exit of the fiber. A numerical model from Sharipov and Graur describing local number density distribution in a unsteady state is applied for the determination of gas viscosity, based on the number density of gas measured by the absorption of the laser light, using the Beer-Lambert law. The measurement system is confirmed by measuring the viscosity of CO2 as a reference gas.

Passive non-linear microrheology for determining extensional viscosity

NASA Astrophysics Data System (ADS)

Hsiao, Kai-Wen; Dinic, Jelena; Ren, Yi; Sharma, Vivek; Schroeder, Charles M.

2017-12-01

Extensional viscosity is a key property of complex fluids that greatly influences the non-equilibrium behavior and processing of polymer solutions, melts, and colloidal suspensions. In this work, we use microfluidics to determine steady extensional viscosity for polymer solutions by directly observing particle migration in planar extensional flow. Tracer particles are suspended in semi-dilute solutions of DNA and polyethylene oxide, and a Stokes trap is used to confine single particles in extensional flows of polymer solutions in a cross-slot device. Particles are observed to migrate in the direction transverse to flow due to normal stresses, and particle migration is tracked and quantified using a piezo-nanopositioning stage during the microfluidic flow experiment. Particle migration trajectories are then analyzed using a second-order fluid model that accurately predicts that migration arises due to normal stress differences. Using this analytical framework, extensional viscosities can be determined from particle migration experiments, and the results are in reasonable agreement with bulk rheological measurements of extensional viscosity based on a dripping-onto-substrate method. Overall, this work demonstrates that non-equilibrium properties of complex fluids can be determined by passive yet non-linear microrheology.

Coherence properties of blackbody radiation and application to energy harvesting and imaging with nanoscale rectennas

NASA Astrophysics Data System (ADS)

Lerner, Peter B.; Cutler, Paul H.; Miskovsky, Nicholas M.

2015-01-01

Modern technology allows the fabrication of antennas with a characteristic size comparable to the electromagnetic wavelength in the optical region. This has led to the development of new technologies using nanoscale rectifying antennas (rectennas) for solar energy conversion and sensing of terahertz, infrared, and visible radiation. For example, a rectenna array can collect incident radiation from an emitting source and the resulting conversion efficiency and operating characteristics of the device will depend on the spatial and temporal coherence properties of the absorbed radiation. For solar radiation, the intercepted radiation by a micro- or nanoscale array of devices has a relatively narrow spatial and angular distribution. Using the Van Cittert-Zernike theorem, we show that the coherence length (or radius) of solar radiation on an antenna array is, or can be, tens of times larger than the characteristic wavelength of the solar spectrum, i.e., the thermal wavelength, λT=2πℏc/(kBT), which for T=5000 K is about 3 μm. Such an effect is advantageous, making possible the rectification of solar radiation with nanoscale rectenna arrays, whose size is commensurate with the coherence length. Furthermore, we examine the blackbody radiation emitted from an array of antennas at temperature T, which can be quasicoherent and lead to a modified self-image, analogous to the Talbot-Lau self-imaging process but with thermal rather than monochromatic radiation. The self-emitted thermal radiation may be important as a nondestructive means for quality control of the array.

Adsorption Behavior of Heat Modified Soybean Oil via Boundary Lubrication Coefficient of Friction Measurements

USDA-ARS?s Scientific Manuscript database

The frictional behaviors of soybean oil and heat modified soybean oils with different Gardner scale viscosities as additives in hexadecane have been examined in a boundary lubrication test regime (steel contacts) using Langmuir adsorption model. The free energy of adsorption (delta-Gads) of various...

Control of Nanoscale Materials under the Toxic Substances Control Act

EPA Pesticide Factsheets

Many nanoscale materials are regarded as chemical substances, but they may have different properties than their larger counterparts. EPA is working to ensure that nanoscale materials are manufactured and used in ways that prevent risk to health.

Time evolution of the eddy viscosity in two-dimensional navier-stokes flow

PubMed

Chaves; Gama

2000-02-01

The time evolution of the eddy viscosity associated with an unforced two-dimensional incompressible Navier-Stokes flow is analyzed by direct numerical simulation. The initial condition is such that the eddy viscosity is isotropic and negative. It is shown by concrete examples that the Navier-Stokes dynamics stabilizes negative eddy viscosity effects. In other words, this dynamics moves monotonically the initial negative eddy viscosity to positive values before relaxation due to viscous term occurs.

Nanoscale welding of multi-walled carbon nanotubes by 1064 nm fiber laser

NASA Astrophysics Data System (ADS)

Yuan, Yanping; Liu, Zhi; Zhang, Kaihu; Han, Weina; Chen, Jimin

2018-07-01

This study proposes an efficient approach which uses 1064 nm continuous fiber laser to achieve nanoscale welding of crossed multi-walled carbon nanotubes (MWCNTs). By changing the irradiation time, different quality of nanoscale welding is obtained. The morphology changes are investigated by scanning electron microscope (SEM) and transmission electron microscope (TEM). The experiments demonstrate that better quality of MWCNTs nanoscale welding after 3 s irradiation can be obtained. It is found that new graphene layers between crossed nanotubes induced by laser make the nanoscale welding achieved due to the absorption of laser energy.

Viscosity of aqueous and cyanate ester suspensions containing alumina nanoparticles

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

Lawler, Katherine

2009-01-01

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

Anomalous-viscosity current drive

DOEpatents

Stix, T.H.; Ono, M.

1986-04-25

The present invention relates to a method and apparatus for maintaining a steady-state current for magnetically confining the plasma in a toroidal magnetic confinement device using anomalous viscosity current drive. A second aspect of this invention relates to an apparatus and method for the start-up of a magnetically confined toroidal plasma.

Temperature dependent viscosity of cobalt ferrite / ethylene glycol ferrofluids

NASA Astrophysics Data System (ADS)

Kharat, Prashant B.; Somvanshi, Sandeep B.; Kounsalye, Jitendra S.; Deshmukh, Suraj S.; Khirade, Pankaj P.; Jadhav, K. M.

2018-04-01

In the present work, cobalt ferrite / ethylene glycol ferrofluid is prepared in 0 to 1 (in the step of 0.2) volume fraction of cobalt ferrite nanoparticles synthesized by co-precipitation method. The XRD results confirmed the formation of single phase spinel structure. The Raman spectra have been deconvoluted into individual Lorentzian peaks. Cobalt ferrite has cubic spinel structure with Fd3m space group. FT-IR spectra consist of two major absorption bands, first at about 586 cm-1 (υ1) and second at about 392 cm-1 (υ2). These absorption bands confirm the formation of spinel-structured cobalt ferrite. Brookfield DV-III viscometer and programmable temperature-controlled bath was used to study the relationship between viscosity and temperature. Viscosity behavior with respect to temperature has been studied and it is revealed that the viscosity of cobalt ferrite / ethylene glycol ferrofluids increases with an increase in volume fraction of cobalt ferrite. The viscosity of the present ferrofluid was found to decrease with increase in temperature.

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.

Early stages of transition in viscosity-stratified channel flow

NASA Astrophysics Data System (ADS)

Govindarajan, Rama; Jose, Sharath; Brandt, Luca

2013-11-01

In parallel shear flows, it is well known that transition to turbulence usually occurs through a subcritical process. In this work we consider a flow through a channel across which there is a linear temperature variation. The temperature gradient leads to a viscosity variation across the channel. A large body of work has been done in the linear regime for this problem, and it has been seen that viscosity stratification can lead to considerable changes in stability and transient growth characteristics. Moreover contradictory effects of introducing a non uniform viscosity in the system have been reported. We conduct a linear stability analysis and direct numerical simulations (DNS) for this system. We show that the optimal initial structures in the viscosity-stratified case, unlike in unstratified flow, do not span the width of the channel, but are focussed near one wall. The nonlinear consequences of the localisation of the structures will be discussed.

Utilization of Low Gravity Environment for Measuring Liquid Viscosity

NASA Technical Reports Server (NTRS)

Antar, Basil N.; Ethridge, Edwin

1998-01-01

The method of drop coalescence is used for determining the viscosity of highly viscous undercooled liquids. Low gravity environment is necessary in order to allow for examining large volumes affording much higher accuracy for the viscosity calculations than possible for smaller volumes available under 1 - g conditions. The drop coalescence method is preferred over the drop oscillation technique since the latter method can only be applied for liquids with vanishingly small viscosities. The technique developed relies on both the highly accurate solution of the Navier-Stokes equations as well as on data from experiments conducted in near zero gravity environment. Results are presented for method validation experiments recently performed on board the NASA/KC-135 aircraft. While the numerical solution was produced using the Boundary Element Method. In these tests the viscosity of a highly viscous liquid, glycerine at room temperature, was determined using the liquid coalescence method. The results from these experiments will be discussed.

Modeling Self-Heating Effects in Nanoscale Devices

NASA Astrophysics Data System (ADS)

Raleva, K.; Shaik, A. R.; Vasileska, D.; Goodnick, S. M.

2017-08-01

Accurate thermal modeling and the design of microelectronic devices and thin film structures at the micro- and nanoscales poses a challenge to electrical engineers who are less familiar with the basic concepts and ideas in sub-continuum heat transport. This book aims to bridge that gap. Efficient heat removal methods are necessary to increase device performance and device reliability. The authors provide readers with a combination of nanoscale experimental techniques and accurate modeling methods that must be employed in order to determine a device's temperature profile.

Research on viscosity of metal at high pressure

NASA Astrophysics Data System (ADS)

Li, Y.; Liu, F.; Ma, X.; Zhang, M.

2016-11-01

A new experimental technique, the flyer-impact method, is proposed in this article to investigate the viscosity coefficient of shocked metals. In this technique, a shock wave with a sinusoidal perturbation on the front is induced by the sinusoidal profile of the impact surface of the sample by use of a two-stage light-gas gun, and the oscillatory damping process of the perturbation amplitude is monitored by electric pins. The damping processes of aluminum at 78 and 101 GPa and iron at 159 and 103 GPa are obtained by this technique, which supplement the existing data by measuring the viscosity coefficient via a dynamic high-pressure method. Applying the formula of Miller and Ahrens to fit the experimental data, the shear viscosity coefficients of aluminum at 78 and 101 GPa are 1350 ± 500 and 1200 ± 500 Pa s, respectively, and those of iron at 159 and 103 GPa are 1150 ± 1000 and 4800 ± 1000 Pa s, respectively. The values measured by the flyer-impact method, approximately 103 Pa s, are consistent with those measured by Sakharov's method, while still greatly differing from those measured by static high-pressure methods. In dynamic high-pressure experiments, the shear viscosity is related to dislocation motion in the solid material, while that in static high-pressure experiments is related to the diffusion motion of atoms or molecules in liquids. Therefore, there are different physical meanings of shear viscosity in dynamic and static high-pressure experiments, and there is no comparability among these results.

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.

Knee stiffness and viscosity: New implementation and perspectives in prosthesis development

PubMed Central

Bohinc, Klemen; Vantur, Nejc; Torkar, Drago; Lampe, Tomaž; Hribernik, Marija; Jakovljević, Miroljub

2017-01-01

The pendulum test is a method applied to measure passive resistance of the knee. A new and simple pendulum test with instrumentation based on infrared camera was used to evaluate knee stiffness and viscosity on a female human cadaver. The stiffness and viscosity were calculated based on the kinetic data. During the measurements, the periarticular and intraarticular soft tissue of the knee was gradually removed to determine the stiffness and viscosity as a function of the tissue removal rate. The measurements showed that the removal of tissue around the joint reduces the damping of leg oscillation, and therefore decreases the stiffness and viscosity. The contribution to knee joint damping was 10% for the skin, 20% for ligaments, and 40% for muscles and tendons. Tissue removal has a very large impact on the knee stiffness and viscosity. PMID:28422623

Knee stiffness and viscosity: New implementation and perspectives in prosthesis development.

PubMed

Bohinc, Klemen; Vantur, Nejc; Torkar, Drago; Lampe, Tomaž; Hribernik, Marija; Jakovljević, Miroljub

2017-05-20

The pendulum test is a method applied to measure passive resistance of the knee. A new and simple pendulum test with instrumentation based on infrared camera was used to evaluate knee stiffness and viscosity on a female human cadaver. The stiffness and viscosity were calculated based on the kinetic data. During the measurements, the periarticular and intraarticular soft tissue of the knee was gradually removed to determine the stiffness and viscosity as a function of the tissue removal rate. The measurements showed that the removal of tissue around the joint reduces the damping of leg oscillation, and therefore decreases the stiffness and viscosity. The contribution to knee joint damping was 10% for the skin, 20% for ligaments, and 40% for muscles and tendons. Tissue removal has a very large impact on the knee stiffness and viscosity.

Viscosity of komatiite liquid at high pressure and temperature

NASA Astrophysics Data System (ADS)

O Dwyer, L.; Lesher, C. E.; Wang, Y.

2006-12-01

The viscosities of komatiite liquids at high pressures and temperatures are being investigated by the in-situ falling sphere technique, using the T-25 multianvil apparatus at the GSECARS 13 ID-D beamline at the Advanced Photon Source, ANL. The refractory and fluid nature of komatiite and other ultramafic liquids relevant to the Earth's deep interior, presents unique challenges for this approach. To reach superliquidus temperatures we use a double reservoir configuration, where marker spheres are placed at the top of both a main melt reservoir and an overlying reservoir containing a more refractory composition. Using this approach, we have successfully measured the viscosity of a komatiite from Gorgona Island (GOR-94-29; MgO - 17.8 wt.%; NBO/T = 1.6) up to 6 GPa and 1900 K. Under isothermal conditions, viscosity increases with pressure, consistent with the depolymerized nature of the komatiite. At 1900 K, viscosity increases from 1.5 (+- 0.3) Pa s at 3.5 GPa to 3.4 (+- 0.3) Pa s at 6 GPa, corresponding to an activation volume of 2.2 cm3/mol. At high pressures, the viscosities of Gorgona Island komatiite melt are an order of magnitude higher than those measured by Liebske et al. (2005, EPSL, v. 240) for peridotite melt (MgO 37.1 wt.%; NBO/T = 2.5), and similar in magnitude to molten diopside (NBO/T = 2) (Reid et al. 2003, PEPI, v. 139). The positive pressure dependence is consistent with the reduction in interatomic space diminishing the free volume of the liquid as it is compressed. Above 6 GPa the free volume reduction may become less important with the production of high-coordinated network formers, as attributed to the reversal of the pressure dependence of viscosity for peridotite melt at ~8.5 GPa and diopside melt at ~10 GPa. Experiments at higher pressures are underway to determine if a similar viscosity maximum occurs for komatiite melt and whether its pressure is greater than 10 GPa, as suggested by the data for peridotite and diopside melts.

Viscosity, relaxation time, and dynamics within a model asphalt of larger molecules

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

Li, Derek D.; Greenfield, Michael L., E-mail: greenfield@egr.uri.edu

2014-01-21

The dynamics properties of a new “next generation” model asphalt system that represents SHRP AAA-1 asphalt using larger molecules than past models is studied using molecular simulation. The system contains 72 molecules distributed over 12 molecule types that range from nonpolar branched alkanes to polar resins and asphaltenes. Molecular weights range from 290 to 890 g/mol. All-atom molecular dynamics simulations conducted at six temperatures from 298.15 to 533.15 K provide a wealth of correlation data. The modified Kohlrausch-Williams-Watts equation was regressed to reorientation time correlation functions and extrapolated to calculate average rotational relaxation times for individual molecules. The rotational relaxationmore » rate of molecules decreased significantly with increasing size and decreasing temperature. Translational self-diffusion coefficients followed an Arrhenius dependence. Similar activation energies of ∼42 kJ/mol were found for all 12 molecules in the model system, while diffusion prefactors spanned an order of magnitude. Viscosities calculated directly at 533.15 K and estimated at lower temperatures using the Debye-Stokes-Einstein relationship were consistent with experimental data for asphalts. The product of diffusion coefficient and rotational relaxation time showed only small changes with temperature above 358.15 K, indicating rotation and translation that couple self-consistently with viscosity. At lower temperatures, rotation slowed more than diffusion.« less

Quantitatively Mapping Cellular Viscosity with Detailed Organelle Information via a Designed PET Fluorescent Probe

PubMed Central

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

2014-01-01

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

Viscosity scaling in concentrated dispersions and its impact on colloidal aggregation.

PubMed

Nicoud, Lucrèce; Lattuada, Marco; Lazzari, Stefano; Morbidelli, Massimo

2015-10-07

Gaining fundamental knowledge about diffusion in crowded environments is of great relevance in a variety of research fields, including reaction engineering, biology, pharmacy and colloid science. In this work, we determine the effective viscosity experienced by a spherical tracer particle immersed in a concentrated colloidal dispersion by means of Brownian dynamics simulations. We characterize how the effective viscosity increases from the solvent viscosity for small tracer particles to the macroscopic viscosity of the dispersion when large tracer particles are employed. Our results show that the crossover between these two regimes occurs at a tracer particle size comparable to the host particle size. In addition, it is found that data points obtained in various host dispersions collapse on one master curve when the normalized effective viscosity is plotted as a function of the ratio between the tracer particle size and the mean host particle size. In particular, this master curve was obtained by varying the volume fraction, the average size and the polydispersity of the host particle distribution. Finally, we extend these results to determine the size dependent effective viscosity experienced by a fractal cluster in a concentrated colloidal system undergoing aggregation. We include this scaling of the effective viscosity in classical aggregation kernels, and we quantify its impact on the kinetics of aggregate growth as well as on the shape of the aggregate distribution by means of population balance equation calculations.

Measuring viscosity with a resonant magnetic perturbation in the MST RFP

NASA Astrophysics Data System (ADS)

Fridström, Richard; Munaretto, Stefano; Frassinetti, Lorenzo; Chapman, Brett; Brunsell, Per; Sarff, John; MST Team

2016-10-01

Application of an m = 1 resonant magnetic perturbation (RMP) causes braking and locking of naturally rotating m = 1 tearing modes (TMs) in the MST RFP. The experimental TM dynamics are replicated by a theoretical model including the interaction between the RMP and multiple TMs [Fridström PoP 23, 062504 (2016)]. The viscosity is the only free parameter in the model, and it is chosen such that model TM velocity evolution matches that of the experiment. The model does not depend on the means by which the natural rotation is generated. The chosen value of the viscosity, about 40 m2/s, is consistent with separate measurements in MST using a biased probe to temporarily spin up the plasma. This viscosity is about 100 times larger than the classical prediction, likely due to magnetic stochasticity in the core of these plasmas. Viscosity is a key parameter in visco-resistive MHD codes like NIMROD. The validation of these codes requires measurement of the viscosity over a broad parameter range, which will now be possible with the RMP technique that, unlike the biased probe, is not limited to low-energy-density plasmas. Estimation with the RMP technique of the viscosity in several MST discharges suggests that the viscosity decreases as the electron beta increases. Work supported by USDOE.

Gravimetric capillary method for kinematic viscosity measurements

NASA Technical Reports Server (NTRS)

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

1992-01-01

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

Nanoscale array structures suitable for surface enhanced raman scattering and methods related thereto

DOEpatents

Bond, Tiziana C.; Miles, Robin; Davidson, James C.; Liu, Gang Logan

2014-07-22

Methods for fabricating nanoscale array structures suitable for surface enhanced Raman scattering, structures thus obtained, and methods to characterize the nanoscale array structures suitable for surface enhanced Raman scattering. Nanoscale array structures may comprise nanotrees, nanorecesses and tapered nanopillars.

Nanoscale array structures suitable for surface enhanced raman scattering and methods related thereto

DOEpatents

Bond, Tiziana C.; Miles, Robin; Davidson, James C.; Liu, Gang Logan

2015-07-14

Methods for fabricating nanoscale array structures suitable for surface enhanced Raman scattering, structures thus obtained, and methods to characterize the nanoscale array structures suitable for surface enhanced Raman scattering. Nanoscale array structures may comprise nanotrees, nanorecesses and tapered nanopillars.

Nanoscale array structures suitable for surface enhanced raman scattering and methods related thereto

DOEpatents

Bond, Tiziana C; Miles, Robin; Davidson, James; Liu, Gang Logan

2015-11-03

Methods for fabricating nanoscale array structures suitable for surface enhanced Raman scattering, structures thus obtained, and methods to characterize the nanoscale array structures suitable for surface enhanced Raman scattering. Nanoscale array structures may comprise nanotrees, nanorecesses and tapered nanopillars.

Constraints on mantle viscosity from convection models with plate motion history

NASA Astrophysics Data System (ADS)

Mao, W.; Zhong, S.

2017-12-01

The Earth's long-wavelength geoid and dynamic topography are mainly controlled by the mantle buoyancy and viscosity structure. Previous dynamical models for the geoid provide constraints on the 1-D mantle viscosity, using mantle buoyancy derived from seismic topography models. However, it is a challenge in these studies on how to convert seismic velocity to density anomalies and mantle buoyancy. Furthermore, these studies provide constraints only on relative viscosity variations but not on absolute magnitude of viscosity. In this study, we formulate time-dependent 3-D spherical mantle convection models with imposed plate motion history and seek constraints on mantle viscosity structure for both its radial relative variations and its absolute magnitude (i.e., Rayleigh number), using the geoid from the convection models. We found that the geoid at intermediate wavelengths of degrees 4-9 is mainly controlled by the subducted slabs in the upper mantle and the upper part of lower mantle that result from subduction from the last 50 Myr or the Cenozoic. To fit the degrees 4-9 geoid, we need viscosity contrast β defined as the ratio of the lower mantle viscosity and the asthenospheric viscosity to be larger than 2000 and Ra to be 1e8 (defined by the Earth's radius). The best fit model leads to 57% variance reduction and 76% correlation between the model and the observations. However, the long-wavelength geoid at degrees 2-3 is controlled by the lower mantle structure which requires much longer time scale to develop, as seen from our modeling. The preferred viscosity structure and Rayleigh number as constrained by the Cenozoic plate motion and the degrees 4-9 geoid no longer provide adequate fit to the geoid in models with the plate motion history for the last 450 Myr. The degrees 4-9 geoid amplitude is smaller for the models with longer plate motion history and a smaller Ra is required to fit the observation. In order to satisfy the relative amplitude between degrees 2

Rheological properties of styrene-butadiene rubber filled with electron beam modified surface treated dual phase fillers

NASA Astrophysics Data System (ADS)

Shanmugharaj, A. M.; Bhowmick, Anil K.

2004-01-01

The rheological properties of styrene-butadiene rubber (SBR) loaded with dual phase filler were measured using Monsanto Processability Tester (MPT) at three different temperatures (100°C, 110°C and 130°C) and four different shear rates (61.3, 306.3, 613, and 1004.5 s -1). The effect of electron beam modification of dual phase filler in absence and presence of trimethylol propane triacrylate (TMPTA) or triethoxysilylpropyltetrasulphide (Si-69) on melt flow properties of SBR was also studied. The viscosity of all the systems decreases with shear rate indicating their pseudoplastic or shear thinning nature. The higher shear viscosity for the SBR loaded with the electron beam modified filler is explained in terms of variation in structure of the filler upon electron beam irradiation. Die swell of the modified filler loaded SBR is slightly higher than that of the unmodified filler loaded rubber, which is explained by calculating normal stress difference for the systems. Activation energy of the modified filler loaded SBR systems is also slightly higher than that of the control filler loaded SBR system.

Towards adjoint-based inversion of time-dependent mantle convection with nonlinear viscosity

NASA Astrophysics Data System (ADS)

Li, Dunzhu; Gurnis, Michael; Stadler, Georg

2017-04-01

We develop and study an adjoint-based inversion method for the simultaneous recovery of initial temperature conditions and viscosity parameters in time-dependent mantle convection from the current mantle temperature and historic plate motion. Based on a realistic rheological model with temperature-dependent and strain-rate-dependent viscosity, we formulate the inversion as a PDE-constrained optimization problem. The objective functional includes the misfit of surface velocity (plate motion) history, the misfit of the current mantle temperature, and a regularization for the uncertain initial condition. The gradient of this functional with respect to the initial temperature and the uncertain viscosity parameters is computed by solving the adjoint of the mantle convection equations. This gradient is used in a pre-conditioned quasi-Newton minimization algorithm. We study the prospects and limitations of the inversion, as well as the computational performance of the method using two synthetic problems, a sinking cylinder and a realistic subduction model. The subduction model is characterized by the migration of a ridge toward a trench whereby both plate motions and subduction evolve. The results demonstrate: (1) for known viscosity parameters, the initial temperature can be well recovered, as in previous initial condition-only inversions where the effective viscosity was given; (2) for known initial temperature, viscosity parameters can be recovered accurately, despite the existence of trade-offs due to ill-conditioning; (3) for the joint inversion of initial condition and viscosity parameters, initial condition and effective viscosity can be reasonably recovered, but the high dimension of the parameter space and the resulting ill-posedness may limit recovery of viscosity parameters.

Nanoscale density variations induced by high energy heavy ions in amorphous silicon nitride and silicon dioxide

NASA Astrophysics Data System (ADS)

Mota-Santiago, P.; Vazquez, H.; Bierschenk, T.; Kremer, F.; Nadzri, A.; Schauries, D.; Djurabekova, F.; Nordlund, K.; Trautmann, C.; Mudie, S.; Ridgway, M. C.; Kluth, P.

2018-04-01

The cylindrical nanoscale density variations resulting from the interaction of 185 MeV and 2.2 GeV Au ions with 1.0 μm thick amorphous SiN x :H and SiO x :H layers are determined using small angle x-ray scattering measurements. The resulting density profiles resembles an under-dense core surrounded by an over-dense shell with a smooth transition between the two regions, consistent with molecular-dynamics simulations. For amorphous SiN x :H, the density variations show a radius of 4.2 nm with a relative density change three times larger than the value determined for amorphous SiO x :H, with a radius of 5.5 nm. Complementary infrared spectroscopy measurements exhibit a damage cross-section comparable to the core dimensions. The morphology of the density variations results from freezing in the local viscous flow arising from the non-uniform temperature profile in the radial direction of the ion path. The concomitant drop in viscosity mediated by the thermal conductivity appears to be the main driving force rather than the presence of a density anomaly.

75 FR 49487 - Nanomaterial Case Study: Nanoscale Silver in Disinfectant Spray

Federal Register 2010, 2011, 2012, 2013, 2014

2010-08-13

... Study: Nanoscale Silver in Disinfectant Spray AGENCY: Environmental Protection Agency (EPA). ACTION... document ``Nanomaterial Case Study: Nanoscale Silver in Disinfectant Spray'' (EPA/600/R-10/081). The... 49488

Do Clustering Monoclonal Antibody Solutions Really Have a Concentration Dependence of Viscosity?

PubMed Central

Pathak, Jai A.; Sologuren, Rumi R.; Narwal, Rojaramani

2013-01-01

Protein solution rheology data in the biophysics literature have incompletely identified factors that govern hydrodynamics. Whereas spontaneous protein adsorption at the air/water (A/W) interface increases the apparent viscosity of surfactant-free globular protein solutions, it is demonstrated here that irreversible clusters also increase system viscosity in the zero shear limit. Solution rheology measured with double gap geometry in a stress-controlled rheometer on a surfactant-free Immunoglobulin solution demonstrated that both irreversible clusters and the A/W interface increased the apparent low shear rate viscosity. Interfacial shear rheology data showed that the A/W interface yields, i.e., shows solid-like behavior. The A/W interface contribution was smaller, yet nonnegligible, in double gap compared to cone-plate geometry. Apparent nonmonotonic composition dependence of viscosity at low shear rates due to irreversible (nonequilibrium) clusters was resolved by filtration to recover a monotonically increasing viscosity-concentration curve, as expected. Although smaller equilibrium clusters also existed, their size and effective volume fraction were unaffected by filtration, rendering their contribution to viscosity invariant. Surfactant-free antibody systems containing clusters have complex hydrodynamic response, reflecting distinct bulk and interface-adsorbed protein as well as irreversible cluster contributions. Literature models for solution viscosity lack the appropriate physics to describe the bulk shear viscosity of unstable surfactant-free antibody solutions. PMID:23442970

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

Designing nanoscale constructs from atomic thin sheets of graphene, boron nitride and gold nanoparticles for advanced material applications

NASA Astrophysics Data System (ADS)

Jasuja, Kabeer

2011-12-01

Nanoscale materials invite immense interest from diverse scientific disciplines as these provide access to precisely understand the physical world at their most fundamental atomic level. In concert with this aim of enhancing our understanding of the fundamental behavior at nanoscale, this dissertation presents research on three nanomaterials: Gold nanoparticles (GNPs), Graphene and ultra-thin Boron Nitride sheets (UTBNSs). The three-fold goals which drive this research are: incorporating mobility in nanoparticle based single-electron junction constructs, developing effective strategies to functionalize graphene with nano-forms of metal, and exfoliating ultrathin sheets of Boron Nitride. Gold nanoparticle based electronic constructs can achieve a new degree of operational freedom if nanoscale mobility is incorporated in their design. We achieved such a nano-electromechanical construct by incorporating elastic polymer molecules between GNPs to form 2-dimensional (2-D) molecular junctions which show a nanoscale reversible motion on applying macro scale forces. This GNP-polymer assembly works like a molecular spring opening avenues to maneuver nano components and store energy at nano-scale. Graphene is the first isolated nanomaterial that displays single-atom thickness. It exhibits quantum confinement that enables it to possess a unique combination of fascinating electronic, optical, and mechanical properties. Modifying the surface of graphene is extremely significant to enable its incorporation into applications of interest. We demonstrated the ability of chemically modified graphene sheets to act as GNP stabilizing templates in solution, and utilized this to process GNP composites of graphene. We discovered that GNPs synthesized by chemical or microwave reduction stabilize on graphene-oxide sheets to form snow-flake morphologies and bare-surfaces respectively. These hybrid nano constructs were extensively studied to understand the effect and nature of GNPs

Viscosity Depressants for Coal Liquefaction

NASA Technical Reports Server (NTRS)

Kalfayan, S. H.

1983-01-01

Proposed process modification incorporates viscosity depressants to prevent coal from solidifying during liquefaction. Depressants reduce amount of heat needed to liquefy coal. Possible depressants are metallic soaps, such as stearate, and amides, such as stearamide and dimer acid amides.

Swimming at low Reynolds number in fluids with odd, or Hall, viscosity.

PubMed

Lapa, Matthew F; Hughes, Taylor L

2014-04-01

We apply the geometric theory of swimming at low Reynolds number to the study of nearly circular swimmers in two-dimensional fluids with nonvanishing "odd," or Hall, viscosity. The odd viscosity gives an off-diagonal contribution to the fluid stress tensor, which results in a number of striking effects. In particular, we find that a swimmer whose area is changing will experience a torque proportional to the rate of change of the area, with the constant of proportionality given by the coefficient ηo of odd viscosity. After working out the general theory of swimming in fluids with odd viscosity for a class of simple swimmers, we give a number of example swimming strokes which clearly demonstrate the differences between swimming in a fluid with conventional viscosity and a fluid which also has an odd viscosity. We also include a discussion of the extension of the famous Scallop theorem of low Reynolds number swimming to the case where the fluid has a nonzero odd viscosity. A number of more technical results, including a proof of the torque-area relation for swimmers of more general shape, are explained in a set of Appendixes.

Hall viscosity of a chiral two-orbital superconductor at finite temperatures

NASA Astrophysics Data System (ADS)

Yazdani-Hamid, Meghdad; Shahzamanian, Mohammad Ali

2018-06-01

The Hall viscosity known as the anti-symmetric part of the viscosity fourth-rank tensor. Such dissipationless response which appears for systems with broken time reversal symmetry. We calculate this non-dissipative quantity for a chiral two-orbital superconductor placed in a viscoelastic magnetic field using the linear response theory and apply our calculations to the putative multiband chiral superconductor Sr2RuO4. The chirality origin of a multiband superconductor arises from the interorbital coupling of the superconducting state. This feature leads to the robustness of the Hall viscosity against temperature and impurity effects. We study the temperature effect on the Hall viscosity at the one-loop approximation.

Measuring Viscosities of Gases at Atmospheric Pressure

NASA Technical Reports Server (NTRS)

Singh, Jag J.; Mall, Gerald H.; Hoshang, Chegini

1987-01-01

Variant of general capillary method for measuring viscosities of unknown gases based on use of thermal mass-flowmeter section for direct measurement of pressure drops. In technique, flowmeter serves dual role, providing data for determining volume flow rates and serving as well-characterized capillary-tube section for measurement of differential pressures across it. New method simple, sensitive, and adaptable for absolute or relative viscosity measurements of low-pressure gases. Suited for very complex hydrocarbon mixtures where limitations of classical theory and compositional errors make theoretical calculations less reliable.

Viscosity of colloidal suspensions

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

Cohen, E.G.D.; Schepper, I.M. de

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

Nanoscale hotspots due to nonequilibrium thermal transport.

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

Sinha, Sanjiv; Goodson, Kenneth E.

2004-01-01

Recent experimental and modeling efforts have been directed towards the issue of temperature localization and hotspot formation in the vicinity of nanoscale heat generating devices. The nonequilibrium transport conditions which develop around these nanoscale devices results in elevated temperatures near the heat source which can not be predicted by continuum diffusion theory. Efforts to determine the severity of this temperature localization phenomena in silicon devices near and above room temperature are of technological importance to the development of microelectronics and other nanotechnologies. In this work, we have developed a new modeling tool in order to explore the magnitude of themore » additional thermal resistance which forms around nanoscale hotspots from temperatures of 100-1000K. The models are based on a two fluid approximation in which thermal energy is transferred between ''stationary'' optical phonons and fast propagating acoustic phonon modes. The results of the model have shown excellent agreement with experimental results of localized hotspots in silicon at lower temperatures. The model predicts that the effect of added thermal resistance due to the nonequilibrium phonon distribution is greatest at lower temperatures, but is maintained out to temperatures of 1000K. The resistance predicted by the numerical code can be easily integrated with continuum models in order to predict the temperature distribution around nanoscale heat sources with improved accuracy. Additional research efforts also focused on the measurements of the thermal resistance of silicon thin films at higher temperatures, with a focus on polycrystalline silicon. This work was intended to provide much needed experimental data on the thermal transport properties for micro and nanoscale devices built with this material. Initial experiments have shown that the exposure of polycrystalline silicon to high temperatures may induce recrystallization and radically increase the thermal

Rheological characterization of geopolymer binder modified by organic resins

NASA Astrophysics Data System (ADS)

Cekalová, M.; Kovárík, T.; Rieger, D.

2017-01-01

The purpose of this study is going to investigate properties of alkali-activated powder (calcined kaoilinitic clay and granulated blast furnace slag) prepared as a geopolymer paste and modified by various amount of organic resin. Hybrid organic-inorganic binders were prepared as a mix of organic resin and geopolymer inorganic paste under vacuum conditions. The process of solidification was investigated by measurements of storage (G’) and loss modulus ( G’) in torsion. The measurement was conducted in oscillatory mode by constant strain of 0.01 %. This strain is set in linear visco-elastic region for minimization influence of paste structure. The effect of organic resin is presented and determined by changes of viscosity (‘n*), modules in torsion and tangent of loss angle (tan 8). Results indicate that addition of organic resin significantly affects the initial viscosity and hardening kinetics.

WDM Nanoscale Laser Diodes for Si Photonic Interconnects

DTIC Science & Technology

2016-07-25

mounting on silicon. The nanoscale VCSELs can achieve small optical modes and present a compact laser diode that is also robust. In this work we have used...Distribution Unlimited UU UU UU UU 25-07-2016 1-Feb-2012 31-Dec-2015 Final Report: WDM Nanoscale Laser Diodes for Si Photonic Interconnects The views...P.O. Box 12211 Research Triangle Park, NC 27709-2211 VCSEL, optical interconnect, laser diode , semiconductor laser, microcavity REPORT DOCUMENTATION

Reference Correlation for the Viscosity of Ethane

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

Vogel, Eckhard, E-mail: eckhard.vogel@uni-rostock.de; Span, Roland; Herrmann, Sebastian

2015-12-15

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

Nanoscale integration is the next frontier for nanotechnology

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

Picraux, Samuel T

2009-01-01

Nanoscale integration of materials and structures is the next critical step to exploit the promise of nanomaterials. Many novel and fascinating properties have been revealed for nanostructured materials. But if nanotechnology is to live up to its promise we must incorporate these nanoscale building blocks into functional systems that connect to the micro- and macroscale world. To do this we will inevitably need to understand and exploit the resulting combined unique properties of these integrated nanosystems. Much science waits to be discovered in the process. Nanoscale integration extends from the synthesis and fabrication of individual nanoscale building blocks, to themore » assembly of these building blocks into composite structures, and finally to the formation of complex functional systems. As illustrated in Figure 1, the building blocks may be homogeneous or heterogeneous, the composite materials may be nanocomposite or patterned structures, and the functional systems will involve additional combinations of materials. Nanoscale integration involves assembling diverse nanoscale materials across length scales to design and achieve new properties and functionality. At each stage size-dependent properties, the influence of surfaces in close proximity, and a multitude of interfaces all come into play. Whether the final system involves coherent electrons in a quantum computing approach, the combined flow of phonons and electrons for a high efficiency thermoelectric micro-generator, or a molecular recognition structure for bio-sensing, the combined effects of size, surface, and interface will be critical. In essence, one wants to combine the novel functions available through nanoscale science to achieve unique multi-functionalities not available in bulk materials. Perhaps the best-known example of integration is that of combining electronic components together into very large scale integrated circuits (VLSI). The integrated circuit has revolutionized electronics

The differences in analysing strategy of viscosity experiment between freshmen and laboratory assistant

NASA Astrophysics Data System (ADS)

Anggrayni, S.; Mubarok, H.; Putri, N. P.; Suprapto, N.; Kholiq, A.

2018-03-01

The viscosity is defined by dimension of a fluid that resists the force tending to motive the fluid to flow. The aim of viscosity experiment is to determine the fluid viscosity coefficient value. By using graphical analysis, the result of oil viscosity coefficient value which performed by laboratory assistant showed: (1) 0.20 Pa.s using solid ball with accuracy 99.64% and (2) 0.21 Pa.s using smaller solid ball with accuracy 99.17%. Meanwhile, the result of oil viscosity coefficient value which performed by freshmen showed: (1) 0.44 Pa.s using solid ball with accuracy 87.85% and (2) 0.32 Pa.s using smaller solid ball with accuracy 89.84%. The differences result of the freshmen and assistant laboratory viscosity experiment are caused by the freshmen calculated the coefficient viscosity value without velocity correction factor and they used small range fluid so the times are not identified well.

Low Melt Viscosity Resins for Resin Transfer Molding

NASA Technical Reports Server (NTRS)

Harris, Frank W.

2002-01-01

In recent years, resin transfer molding (RTM) has become one of the methods of choice for high performance composites. Its cost effectiveness and ease of fabrication are major advantages of RTM. RTM process usually requires resins with very low melt viscosity (less than 10 Poise). The optimum RTM resins also need to display high thennal-oxidative stability, high glass transition temperature (T(sub g)), and good toughness. The traditional PMR-type polyimides (e.g. PMR-15) do not fit this requirement, because the viscosities are too high and the nadic endcap cures too fast. High T(sub g), low-melt viscosity resins are highly desirable for aerospace applications and NASA s Reusable Launch Vehicle (RLV) program. The objective of this work is to prepare low-melt viscosity polyimide resins for RTM or resin film infusion (RFI) processes. The approach involves the synthesis of phenylethynyl-terminated imide oligomers. These materials have been designed to minimize their melt viscosity so that they can be readily processed. During the cure, the oligomers undergo both chain extension and crosslinking via the thermal polymerization of the phenylethynyl groups. The Phenylethynyl endcap is preferred over the nadic group due to its high curing temperature, which provides broader processing windows. This work involved the synthesis and polymerization of oligomers containing zig-zag backbones and twisted biphenyl structures. Some A-B type precursors which possessed both nitro and anhydride functionality, or both nitro and amine functionality, were also synthesized in order to obtain the well defined oligomers. The resulting zig-zag structured oligomers were then end-capped with 4-phenylethynylphthalic anhydride (PEPA) for further cure. The properties of these novel imide oligomers are evaluated.

Estimation of the viscosities of liquid binary alloys

NASA Astrophysics Data System (ADS)

Wu, Min; Su, Xiang-Yu

2018-01-01

As one of the most important physical and chemical properties, viscosity plays a critical role in physics and materials as a key parameter to quantitatively understanding the fluid transport process and reaction kinetics in metallurgical process design. Experimental and theoretical studies on liquid metals are problematic. Today, there are many empirical and semi-empirical models available with which to evaluate the viscosity of liquid metals and alloys. However, the parameter of mixed energy in these models is not easily determined, and most predictive models have been poorly applied. In the present study, a new thermodynamic parameter Δ G is proposed to predict liquid alloy viscosity. The prediction equation depends on basic physical and thermodynamic parameters, namely density, melting temperature, absolute atomic mass, electro-negativity, electron density, molar volume, Pauling radius, and mixing enthalpy. Our results show that the liquid alloy viscosity predicted using the proposed model is closely in line with the experimental values. In addition, if the component radius difference is greater than 0.03 nm at a certain temperature, the atomic size factor has a significant effect on the interaction of the binary liquid metal atoms. The proposed thermodynamic parameter Δ G also facilitates the study of other physical properties of liquid metals.

Biosafe Nanoscale Pharmaceutical Adjuvant Materials

PubMed Central

Jin, Shubin; Li, Shengliang; Wang, Chongxi; Liu, Juan; Yang, Xiaolong; Wang, Paul C.; Zhang, Xin; Liang, Xing-Jie

2014-01-01

Thanks to developments in the field of nanotechnology over the past decades, more and more biosafe nanoscale materials have become available for use as pharmaceutical adjuvants in medical research. Nanomaterials possess unique properties which could be employed to develop drug carriers with longer circulation time, higher loading capacity, better stability in physiological conditions, controlled drug release, and targeted drug delivery. In this review article, we will review recent progress in the application of representative organic, inorganic and hybrid biosafe nanoscale materials in pharmaceutical research, especially focusing on nanomaterial-based novel drug delivery systems. In addition, we briefly discuss the advantages and notable functions that make these nanomaterials suitable for the design of new medicines; the biosafety of each material discussed in this article is also highlighted to provide a comprehensive understanding of their adjuvant attributes. PMID:25429253

Reliable Viscosity Calculation from Equilibrium Molecular Dynamics Simulations: A Time Decomposition Method.

PubMed

Zhang, Yong; Otani, Akihito; Maginn, Edward J

2015-08-11

Equilibrium molecular dynamics is often used in conjunction with a Green-Kubo integral of the pressure tensor autocorrelation function to compute the shear viscosity of fluids. This approach is computationally expensive and is subject to a large amount of variability because the plateau region of the Green-Kubo integral is difficult to identify unambiguously. Here, we propose a time decomposition approach for computing the shear viscosity using the Green-Kubo formalism. Instead of one long trajectory, multiple independent trajectories are run and the Green-Kubo relation is applied to each trajectory. The averaged running integral as a function of time is fit to a double-exponential function with a weighting function derived from the standard deviation of the running integrals. Such a weighting function minimizes the uncertainty of the estimated shear viscosity and provides an objective means of estimating the viscosity. While the formal Green-Kubo integral requires an integration to infinite time, we suggest an integration cutoff time tcut, which can be determined by the relative values of the running integral and the corresponding standard deviation. This approach for computing the shear viscosity can be easily automated and used in computational screening studies where human judgment and intervention in the data analysis are impractical. The method has been applied to the calculation of the shear viscosity of a relatively low-viscosity liquid, ethanol, and relatively high-viscosity ionic liquid, 1-n-butyl-3-methylimidazolium bis(trifluoromethane-sulfonyl)imide ([BMIM][Tf2N]), over a range of temperatures. These test cases show that the method is robust and yields reproducible and reliable shear viscosity values.

Drop splashing: the role of surface wettability and liquid viscosity

NASA Astrophysics Data System (ADS)

Almohammadi, Hamed; Amirfazli, Alidad; -Team

2017-11-01

There are seemingly contradictory results in the literature about the role of surface wettability and drop viscosity for the splashing behavior of a drop impacting onto a surface. Motivated by such issues, we conducted a systematic experimental study where splashing behavior for a wide range of the liquid viscosity (1-100 cSt) and surface wettability (hydrophilic to hydrophobic) are examined. The experiments were performed for the liquids with both low and high surface tensions ( 20 and 72 mN/m). We found that the wettability affects the splashing threshold at high or low contact angle values. At the same drop velocity, an increase of the viscosity (up to 4 cSt) promotes the splashing; while, beyond such value, any increase in viscosity shows the opposite effect. It is also found that at a particular combination of liquid surface tension and viscosity (e.g. silicone oil, 10 cSt), an increase in the drop velocity changes the splashing to spreading. We relate such behaviors to the thickness, shape, and the velocity of the drop's lamella. Finally, to predict the splashing, we developed an empirical correlation which covers all of the previous reported data, hence clarifying the ostensible existing contradictions.

Nanomaterial Case Study: Nanoscale Silver in Disinfectant Spray (Final Report)

EPA Science Inventory

EPA announced the release of the final report, Nanomaterial Case Study: Nanoscale Silver in Disinfectant Spray. This report represents a case study of engineered nanoscale silver (nano-Ag), focusing on the specific example of nano-Ag as possibly used in disinfectant spr...

The thermo magnetic instability in hot viscose plasmas

NASA Astrophysics Data System (ADS)

Haghani, A.; Khosravi, A.; Khesali, A.

2017-10-01

Magnetic Rotational Instability (MRI) can not performed well in accretion disks with strong magnetic field. Studies have indicated a new type of instability called thermomagnetic instability (TMI) in systems where Nernst coefficient and gradient temperature were considered. Nernst coefficient would appear if Boltzman equation could be expanded through ω_{Be} (cyclotron frequency). However, the growth rate of this instability was two magnitude orders below MRI growth (Ωk), which could not act the same as MRI. Therefor, a higher growth rate of unstable modes was needed. In this paper, rotating viscid hot plasma with strong magnetic filed was studied. Firstly, a constant alpha viscosity was studied and then a temperature sensitive viscosity. The results showed that the temperature sensitive viscosity would be able to increase the growth rate of TMI modes significantly, hence capable of acting similar to MRI.

Viscosities encountered during the cryopreservation of dimethyl sulphoxide systems.

PubMed

Kilbride, P; Morris, G J

2017-06-01

This study determined the viscous conditions experienced by cells in the unfrozen freeze concentrated channels between ice crystals in slow cooling protocols. This was examined for both the binary Me 2 SO-water and the ternary Me 2 SO-NaCl-water systems. Viscosity increases from 6.9 ± 0.1 mPa s at -14.4 ± 0.3 °C to 958 ± 27 mPa s at -64.3 ± 0.4 °C in the binary system, and up to 55387 ± 1068 mPa s at -75 ± 0.5 °C in the ternary (10% Me 2 SO, 0.9% NaCl by weight) solution were seen. This increase in viscosity limits molecular diffusion, reducing adsorption onto the crystal plane. These viscosities are significantly lower than observed in glycerol based systems and so cells in freeze concentrated channels cooled to between -60 °C and -75 °C will reside in a thick fluid not a near-solid state as is often assumed. In addition, the viscosities experienced during cooling of various Me 2 SO based vitrification solutions is determined to below -70 °C, as is the impact which additional solutes exert on viscosity. These data show that additional solutes in a cryopreservation system cause disproportionate increases in viscosity. This in turn impacts diffusion rates and mixing abilities of high concentrations of cryoprotectants, and have applications to understanding the fundamental cooling responses of cells to Me 2 SO based cryopreservation solutions. Copyright © 2017 Elsevier Inc. All rights reserved.

Nanoscale relaxation oscillator

DOEpatents

Zettl, Alexander K.; Regan, Brian C.; Aloni, Shaul

2009-04-07

A nanoscale oscillation device is disclosed, wherein two nanoscale droplets are altered in size by mass transport, then contact each other and merge through surface tension. The device may also comprise a channel having an actuator responsive to mechanical oscillation caused by expansion and contraction of the droplets. It further has a structure for delivering atoms between droplets, wherein the droplets are nanoparticles. Provided are a first particle and a second particle on the channel member, both being made of a chargeable material, the second particle contacting the actuator portion; and electrodes connected to the channel member for delivering a potential gradient across the channel and traversing the first and second particles. The particles are spaced apart a specified distance so that atoms from one particle are delivered to the other particle by mass transport in response to the potential (e.g. voltage potential) and the first and second particles are liquid and touch at a predetermined point of growth, thereby causing merging of the second particle into the first particle by surface tension forces and reverse movement of the actuator. In a preferred embodiment, the channel comprises a carbon nanotube and the droplets comprise metal nanoparticles, e.g. indium, which is readily made liquid.

Phenomenological consequences of enhanced bulk viscosity near the QCD critical point

DOE PAGES

Monnai, Akihiko; Mukherjee, Swagato; Yin, Yi

2017-03-06

In the proximity of the QCD critical point the bulk viscosity of quark-gluon matter is expected to be proportional to nearly the third power of the critical correlation length, and become significantly enhanced. Here, this work is the first attempt to study the phenomenological consequences of enhanced bulk viscosity near the QCD critical point. For this purpose, we implement the expected critical behavior of the bulk viscosity within a non-boost-invariant, longitudinally expanding 1 + 1 dimensional causal relativistic hydrodynamical evolution at nonzero baryon density. We demonstrate that the critically enhanced bulk viscosity induces a substantial nonequilibrium pressure, effectively softening themore » equation of state, and leads to sizable effects in the flow velocity and single-particle distributions at the freeze-out. In conclusion, the observable effects that may arise due to the enhanced bulk viscosity in the vicinity of the QCD critical point can be used as complementary information to facilitate searches for the QCD critical point.« less

Investigating Nanoscale Electrochemistry with Surface- and Tip-Enhanced Raman Spectroscopy.

PubMed

Zaleski, Stephanie; Wilson, Andrew J; Mattei, Michael; Chen, Xu; Goubert, Guillaume; Cardinal, M Fernanda; Willets, Katherine A; Van Duyne, Richard P

2016-09-20

The chemical sensitivity of surface-enhanced Raman spectroscopy (SERS) methodologies allows for the investigation of heterogeneous chemical reactions with high sensitivity. Specifically, SERS methodologies are well-suited to study electron transfer (ET) reactions, which lie at the heart of numerous fundamental processes: electrocatalysis, solar energy conversion, energy storage in batteries, and biological events such as photosynthesis. Heterogeneous ET reactions are commonly monitored by electrochemical methods such as cyclic voltammetry, observing billions of electrochemical events per second. Since the first proof of detecting single molecules by redox cycling, there has been growing interest in examining electrochemistry at the nanoscale and single-molecule levels. Doing so unravels details that would otherwise be obscured by an ensemble experiment. The use of optical spectroscopies, such as SERS, to elucidate nanoscale electrochemical behavior is an attractive alternative to traditional approaches such as scanning electrochemical microscopy (SECM). While techniques such as single-molecule fluorescence or electrogenerated chemiluminescence have been used to optically monitor electrochemical events, SERS methodologies, in particular, have shown great promise for exploring electrochemistry at the nanoscale. SERS is ideally suited to study nanoscale electrochemistry because the Raman-enhancing metallic, nanoscale substrate duly serves as the working electrode material. Moreover, SERS has the ability to directly probe single molecules without redox cycling and can achieve nanoscale spatial resolution in combination with super-resolution or scanning probe microscopies. This Account summarizes the latest progress from the Van Duyne and Willets groups toward understanding nanoelectrochemistry using Raman spectroscopic methodologies. The first half of this Account highlights three techniques that have been recently used to probe few- or single-molecule electrochemical

High pressure rheology of gas hydrate formed from multiphase systems using modified Couette rheometer.

PubMed

Pandey, Gaurav; Linga, Praveen; Sangwai, Jitendra S

2017-02-01

Conventional rheometers with concentric cylinder geometries do not enhance mixing in situ and thus are not suitable for rheological studies of multiphase systems under high pressure such as gas hydrates. In this study, we demonstrate the use of modified Couette concentric cylinder geometries for high pressure rheological studies during the formation and dissociation of methane hydrate formed from pure water and water-decane systems. Conventional concentric cylinder Couette geometry did not produce any hydrates in situ and thus failed to measure rheological properties during hydrate formation. The modified Couette geometries proposed in this work observed to provide enhanced mixing in situ, thus forming gas hydrate from the gas-water-decane system. This study also nullifies the use of separate external high pressure cell for such measurements. The modified geometry was observed to measure gas hydrate viscosity from an initial condition of 0.001 Pa s to about 25 Pa s. The proposed geometries also possess the capability to measure dynamic viscoelastic properties of hydrate slurries at the end of experiments. The modified geometries could also capture and mimic the viscosity profile during the hydrate dissociation as reported in the literature. The present study acts as a precursor for enhancing our understanding on the rheology of gas hydrate formed from various systems containing promoters and inhibitors in the context of flow assurance.

High pressure rheology of gas hydrate formed from multiphase systems using modified Couette rheometer

NASA Astrophysics Data System (ADS)

Pandey, Gaurav; Linga, Praveen; Sangwai, Jitendra S.

2017-02-01

Conventional rheometers with concentric cylinder geometries do not enhance mixing in situ and thus are not suitable for rheological studies of multiphase systems under high pressure such as gas hydrates. In this study, we demonstrate the use of modified Couette concentric cylinder geometries for high pressure rheological studies during the formation and dissociation of methane hydrate formed from pure water and water-decane systems. Conventional concentric cylinder Couette geometry did not produce any hydrates in situ and thus failed to measure rheological properties during hydrate formation. The modified Couette geometries proposed in this work observed to provide enhanced mixing in situ, thus forming gas hydrate from the gas-water-decane system. This study also nullifies the use of separate external high pressure cell for such measurements. The modified geometry was observed to measure gas hydrate viscosity from an initial condition of 0.001 Pa s to about 25 Pa s. The proposed geometries also possess the capability to measure dynamic viscoelastic properties of hydrate slurries at the end of experiments. The modified geometries could also capture and mimic the viscosity profile during the hydrate dissociation as reported in the literature. The present study acts as a precursor for enhancing our understanding on the rheology of gas hydrate formed from various systems containing promoters and inhibitors in the context of flow assurance.

Neuromorphic computing with nanoscale spintronic oscillators

PubMed Central

Torrejon, Jacob; Riou, Mathieu; Araujo, Flavio Abreu; Tsunegi, Sumito; Khalsa, Guru; Querlioz, Damien; Bortolotti, Paolo; Cros, Vincent; Fukushima, Akio; Kubota, Hitoshi; Yuasa, Shinji; Stiles, M. D.; Grollier, Julie

2017-01-01

Neurons in the brain behave as non-linear oscillators, which develop rhythmic activity and interact to process information1. Taking inspiration from this behavior to realize high density, low power neuromorphic computing will require huge numbers of nanoscale non-linear oscillators. Indeed, a simple estimation indicates that, in order to fit a hundred million oscillators organized in a two-dimensional array inside a chip the size of a thumb, their lateral dimensions must be smaller than one micrometer. However, despite multiple theoretical proposals2–5, and several candidates such as memristive6 or superconducting7 oscillators, there is no proof of concept today of neuromorphic computing with nano-oscillators. Indeed, nanoscale devices tend to be noisy and to lack the stability required to process data in a reliable way. Here, we show experimentally that a nanoscale spintronic oscillator8,9 can achieve spoken digit recognition with accuracies similar to state of the art neural networks. We pinpoint the regime of magnetization dynamics leading to highest performance. These results, combined with the exceptional ability of these spintronic oscillators to interact together, their long lifetime, and low energy consumption, open the path to fast, parallel, on-chip computation based on networks of oscillators. PMID:28748930

Plasmon-mediated chemical surface functionalization at the nanoscale

NASA Astrophysics Data System (ADS)

Nguyen, Mai; Lamouri, Aazdine; Salameh, Chrystelle; Lévi, Georges; Grand, Johan; Boubekeur-Lecaque, Leïla; Mangeney, Claire; Félidj, Nordin

2016-04-01

Controlling the surface grafting of species at the nanoscale remains a major challenge, likely to generate many opportunities in materials science. In this work, we propose an original strategy for chemical surface functionalization at the nanoscale, taking advantage of localized surface plasmon (LSP) excitation. The surface functionalization is demonstrated through aryl film grafting (derived from a diazonium salt), covalently bonded at the surface of gold lithographic nanostripes. The aryl film is specifically grafted in areas of maximum near field enhancement, as confirmed by numerical calculation based on the discrete dipole approximation method. The energy of the incident light and the LSP wavelength are shown to be crucial parameters to monitor the aryl film thickness of up to ~30 nm. This robust and versatile strategy opens up exciting prospects for the nanoscale confinement of functional layers on surfaces, which should be particularly interesting for molecular sensing or nanooptics.Controlling the surface grafting of species at the nanoscale remains a major challenge, likely to generate many opportunities in materials science. In this work, we propose an original strategy for chemical surface functionalization at the nanoscale, taking advantage of localized surface plasmon (LSP) excitation. The surface functionalization is demonstrated through aryl film grafting (derived from a diazonium salt), covalently bonded at the surface of gold lithographic nanostripes. The aryl film is specifically grafted in areas of maximum near field enhancement, as confirmed by numerical calculation based on the discrete dipole approximation method. The energy of the incident light and the LSP wavelength are shown to be crucial parameters to monitor the aryl film thickness of up to ~30 nm. This robust and versatile strategy opens up exciting prospects for the nanoscale confinement of functional layers on surfaces, which should be particularly interesting for molecular sensing

Fabrication of Nanoscale Circuits on Inkjet-Printing Patterned Substrates.

PubMed

Chen, Shuoran; Su, Meng; Zhang, Cong; Gao, Meng; Bao, Bin; Yang, Qiang; Su, Bin; Song, Yanlin

2015-07-08

Nanoscale circuits are fabricated by assembling different conducting materials (e.g., metal nanoparticles, metal nano-wires, graphene, carbon nanotubes, and conducting polymers) on inkjet-printing patterned substrates. This non-litho-graphy strategy opens a new avenue for integrating conducting building blocks into nanoscale devices in a cost-efficient manner. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A Theoretical Review on Interfacial Thermal Transport at the Nanoscale.

PubMed

Zhang, Ping; Yuan, Peng; Jiang, Xiong; Zhai, Siping; Zeng, Jianhua; Xian, Yaoqi; Qin, Hongbo; Yang, Daoguo

2018-01-01

With the development of energy science and electronic technology, interfacial thermal transport has become a key issue for nanoelectronics, nanocomposites, energy transmission, and conservation, etc. The application of thermal interfacial materials and other physical methods can reliably improve the contact between joined surfaces and enhance interfacial thermal transport at the macroscale. With the growing importance of thermal management in micro/nanoscale devices, controlling and tuning the interfacial thermal resistance (ITR) at the nanoscale is an urgent task. This Review examines nanoscale interfacial thermal transport mainly from a theoretical perspective. Traditional theoretical models, multiscale models, and atomistic methodologies for predicting ITR are introduced. Based on the analysis and summary of the factors that influence ITR, new methods to control and reduce ITR at the nanoscale are described in detail. Furthermore, the challenges facing interfacial thermal management and the further progress required in this field are discussed. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Nanoscale RRAM-based synaptic electronics: toward a neuromorphic computing device.

PubMed

Park, Sangsu; Noh, Jinwoo; Choo, Myung-Lae; Sheri, Ahmad Muqeem; Chang, Man; Kim, Young-Bae; Kim, Chang Jung; Jeon, Moongu; Lee, Byung-Geun; Lee, Byoung Hun; Hwang, Hyunsang

2013-09-27

Efforts to develop scalable learning algorithms for implementation of networks of spiking neurons in silicon have been hindered by the considerable footprints of learning circuits, which grow as the number of synapses increases. Recent developments in nanotechnologies provide an extremely compact device with low-power consumption.In particular, nanoscale resistive switching devices (resistive random-access memory (RRAM)) are regarded as a promising solution for implementation of biological synapses due to their nanoscale dimensions, capacity to store multiple bits and the low energy required to operate distinct states. In this paper, we report the fabrication, modeling and implementation of nanoscale RRAM with multi-level storage capability for an electronic synapse device. In addition, we first experimentally demonstrate the learning capabilities and predictable performance by a neuromorphic circuit composed of a nanoscale 1 kbit RRAM cross-point array of synapses and complementary metal-oxide-semiconductor neuron circuits. These developments open up possibilities for the development of ubiquitous ultra-dense, ultra-low-power cognitive computers.

Calculation of shear viscosity using Green-Kubo relations within a parton cascade

NASA Astrophysics Data System (ADS)

Wesp, C.; El, A.; Reining, F.; Xu, Z.; Bouras, I.; Greiner, C.

2011-11-01

The shear viscosity of a gluon gas is calculated using the Green-Kubo relation. Time correlations of the energy-momentum tensor in thermal equilibrium are extracted from microscopic simulations using a parton cascade solving various Boltzmann collision processes. We find that the perturbation-QCD- (pQCD-) based gluon bremsstrahlung described by Gunion-Bertsch processes significantly lowers the shear viscosity by a factor of 3 to 8 compared to elastic scatterings. The shear viscosity scales with the coupling as η˜1/[αs2log(1/αs)]. For constant αs the shear viscosity to entropy density ratio η/s has no dependence on temperature. Replacing the pQCD-based collision angle distribution of binary scatterings by an isotropic form decreases the shear viscosity by a factor of 3.

The effect of shear and extensional viscosity on atomization in medical inhaler.

PubMed

Broniarz-Press, L; Ochowiak, M; Matuszak, M; Włodarczak, S

2014-07-01

The paper contains the results of experimental studies of water, aqueous solutions of glycerol and aqueous solutions of glycerol-polyethylene oxide (PEO) atomization process in a medical inhaler obtained by the use of the digital microphotography method. The effect of the shear and extensional viscosity on the drop size, drop size histogram and mean drop diameter has been analyzed. The obtained results have shown that the drop size increases with the increase in shear and extensional viscosity of liquid atomized. Extensional viscosity has a greater impact on the spraying process. It has been shown that the change in liquid viscosity leads to significant changes in drop size distribution. The correlation for Sauter mean diameter as function of the shear and extensional viscosity was proposed. Copyright © 2014 Elsevier B.V. All rights reserved.

Temperature and pressure dependences of kimberlite melts viscosity (experimental-theoretical study)

NASA Astrophysics Data System (ADS)

Persikov, Eduard; Bykhtiyarov, Pavel; Cokol, Alexsander

2016-04-01

Experimental data on temperature and pressure dependences of viscosity of model kimberlite melts (silicate 82 + carbonate 18, wt. %, 100NBO/T = 313) have been obtained for the first time at 100 MPa of CO2 pressure and at the lithostatic pressures up to 7.5 GPa in the temperature range 1350 oC - 1950 oC using radiation high gas pressure apparatus and press free split-sphere multi - anvil apparatus (BARS). Experimental data obtained on temperature and pressure dependences of viscosity of model kimberlite melts at moderate and high pressures is compared with predicted data on these dependences of viscosity of basaltic melts (100NBO/T = 58) in the same T, P - range. Dependences of the viscosity of model kimberlite and basaltic melts on temperature are consistent to the exponential Arrenian equation in the T, P - range of experimental study. The correct values of activation energies of viscous flow of kimberlite melts have been obtained for the first time. The activation energies of viscous flow of model kimberlite melts exponentially increase with increasing pressure and are equal: E = 130 ± 1.3 kJ/mole at moderate pressure (P = 100 MPa) and E = 160 ± 1.6 kJ/mole at high pressure (P = 5.5 GPa). It has been established too that the viscosity of model kimberlite melts exponentially increases on about half order of magnitude with increasing pressures from 100 MPa to 7.5 GPa at the isothermal condition (1800 oC). It has been established that viscosity of model kimberlite melts at the moderate pressure (100 MPa) is lover on about one order of magnitude to compare with the viscosity of basaltic melts, but at high pressure range (5.5 - 7.5 GPa), on the contrary, is higher on about half order of magnitude at the same values of the temperatures. Here we use both a new experimental data on viscosity of kimberlite melts and our structural chemical model for calculation and prediction the viscosity of magmatic melts [1] to determine the fundamental features of viscosity of

Non-linear, non-monotonic effect of nano-scale roughness on particle deposition in absence of an energy barrier: Experiments and modeling

PubMed Central

Jin, Chao; Glawdel, Tomasz; Ren, Carolyn L.; Emelko, Monica B.

2015-01-01

Deposition of colloidal- and nano-scale particles on surfaces is critical to numerous natural and engineered environmental, health, and industrial applications ranging from drinking water treatment to semi-conductor manufacturing. Nano-scale surface roughness-induced hydrodynamic impacts on particle deposition were evaluated in the absence of an energy barrier to deposition in a parallel plate system. A non-linear, non-monotonic relationship between deposition surface roughness and particle deposition flux was observed and a critical roughness size associated with minimum deposition flux or “sag effect” was identified. This effect was more significant for nanoparticles (<1 μm) than for colloids and was numerically simulated using a Convective-Diffusion model and experimentally validated. Inclusion of flow field and hydrodynamic retardation effects explained particle deposition profiles better than when only the Derjaguin-Landau-Verwey-Overbeek (DLVO) force was considered. This work provides 1) a first comprehensive framework for describing the hydrodynamic impacts of nano-scale surface roughness on particle deposition by unifying hydrodynamic forces (using the most current approaches for describing flow field profiles and hydrodynamic retardation effects) with appropriately modified expressions for DLVO interaction energies, and gravity forces in one model and 2) a foundation for further describing the impacts of more complicated scales of deposition surface roughness on particle deposition. PMID:26658159

Non-linear, non-monotonic effect of nano-scale roughness on particle deposition in absence of an energy barrier: Experiments and modeling

NASA Astrophysics Data System (ADS)

Jin, Chao; Glawdel, Tomasz; Ren, Carolyn L.; Emelko, Monica B.

2015-12-01

Deposition of colloidal- and nano-scale particles on surfaces is critical to numerous natural and engineered environmental, health, and industrial applications ranging from drinking water treatment to semi-conductor manufacturing. Nano-scale surface roughness-induced hydrodynamic impacts on particle deposition were evaluated in the absence of an energy barrier to deposition in a parallel plate system. A non-linear, non-monotonic relationship between deposition surface roughness and particle deposition flux was observed and a critical roughness size associated with minimum deposition flux or “sag effect” was identified. This effect was more significant for nanoparticles (<1 μm) than for colloids and was numerically simulated using a Convective-Diffusion model and experimentally validated. Inclusion of flow field and hydrodynamic retardation effects explained particle deposition profiles better than when only the Derjaguin-Landau-Verwey-Overbeek (DLVO) force was considered. This work provides 1) a first comprehensive framework for describing the hydrodynamic impacts of nano-scale surface roughness on particle deposition by unifying hydrodynamic forces (using the most current approaches for describing flow field profiles and hydrodynamic retardation effects) with appropriately modified expressions for DLVO interaction energies, and gravity forces in one model and 2) a foundation for further describing the impacts of more complicated scales of deposition surface roughness on particle deposition.

Microfluidic method for measuring viscosity using images from smartphone

NASA Astrophysics Data System (ADS)

Kim, Sooyeong; Kim, Kyung Chun; Yeom, Eunseop

2018-05-01

The viscosity of a fluid is the most important characteristic in fluid rheology. Many microfluidic devices have been proposed for easily measuring the fluid viscosity of small samples. A hybrid system consisting of a smartphone and microfluidic device can offer a mobile laboratory for performing a wide range of detection and analysis functions related to healthcare. In this study, a new mobile sensing method based on a microfluidic device was proposed for fluid viscosity measurements. By separately delivering sample and reference fluids into the two inlets of a Y-shaped microfluidic device, an interfacial line is induced at downstream of the device. Because the interfacial width (W) between the sample and reference fluid flows was determined by their pressure ratio, the viscosity (μ) of the sample could be estimated by measuring the interfacial width. To distinguish the interfacial width of a sample, optical images of the flows at downstream of the Y-shaped microfluidic device were acquired using a smartphone. To check the measurement accuracy of the proposed method, the viscosities of glycerol mixtures were compared with those measured by a conventional viscometer. The proposed technique was applied to monitor the variations in blood and oil samples depending on storage or rancidity. We expect that this mobile sensing method based on a microfluidic device could be utilized as a viscometer with significant advantages in terms of mobility, ease-of-operation, and data management.

Experimental Investigation of the Viscosity of Iron-rich Silicate Melts under Pressure

NASA Astrophysics Data System (ADS)

Edwards, P. M.; Lesher, C. E.; Pommier, A.; O'Dwyer Brown, L.

2017-12-01

The transport properties of silicate melts govern diffusive flow of momentum, heat, and mass in the interior of terrestrial planets. In particular, constraining melt viscosity is critical for dynamic modeling of igneous processes and is thus key to our understanding of magma convection and mixing, melt migration in the mantle, and crystal-liquid fractionation. Among the different constituents of silicate melts, iron is of significant importance as it highly influences some of their properties, such as surface tension, compressibility, and density. We present an experimental study of the viscosity of natural and synthetic iron-rich silicate melts under pressure. In situ falling-sphere measurements of viscosity have been conducted on hedenbergite (CaFeSi2O6) and iron-rich peridotite melts from 1 to 7 GPa and at temperatures between 1750 and 2100 K, using the multi-anvil apparatus at the GSECARS beamline at the Advanced Photon Source, Argonne National Lab. We used double reservoir capsules, with the bottom reservoir containing the sample, while a more refractory material is placed in the upper reservoir (e.g., diopside, enstatite, forsterite). This configuration allows the fall of two rhenium spheres across the sample at different temperatures. Melt viscosity is calculated using Stokes' law and the terminal velocity of the spheres. We observe that melt viscosity slightly decreases with increasing temperature and increasing pressure: for instance, the viscosity of the hedenbergite melt decreases from 1.26 Pa•s to 0.43 Pa•s over the 1 - 3.5 GPa pressure range and between 1820 and 1930 K. Our experimental data are used to develop a viscosity model of iron-rich silicate melts under pressure. Results will be compared with previous viscosity works on iron-free and iron-bearing silicate liquids in order to discuss the effect of iron on melt viscosity and structure at pressure and temperature conditions relevant to terrestrial mantles.

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

After more than four years of orbiting Mercury, NASA's MESSENGER spacecraft came to an end in late April 2015. MESSENGER has provided many new and surprising results. This session will again highlight the latest results on Mercury based on MESSENGER observations or updated modelling. The session will further address instrument calibration and science performance both retrospective on MESSENGER and on the ESA/JAXA BepiColombo mission. Papers covering additional themes related to Mercury are also welcomed. Please be aware that this session will be held as a PICO session. This will allow an intensive exchange of expertise and experience between the individual instruments and mission. NVP melt/magma viscosity: insight on Mercury lava flows S. Rossi1, D. Morgavi1, O. Namur2, D. Perugini1, F.Vetere1, P. Mancinelli1 and C. Pauselli1 1 Dipartimento di Fisica e Geologia, Università di Perugia, piazza Università 1, 06123 Perugia, Italy 2 Uni Hannover Institut für Mineralogie, Leibniz Universität Hannover, Callinstraβe 3, 30167 Hannover, Germany In this contribution we report new measurements of viscosity of synthetic komatitic melts, used the behaviour of silicate melts erupted at the surface of Mercury. Composition of Mercurian surface magmas was calculated using the most recent maps produced from MESSENGER XRS data (Weider et al., 2015). We focused on the northern hemisphere (Northern Volcanic Province, NVP, the largest lava flow on Mercury and possibly in the Solar System) for which the spatial resolution of MESSENGER measurements is high and individual maps of Mg/Si, Ca/Si, Al/Si and S/Si were combined. The experimental starting material contains high Na2O content (≈7 wt.%) that strongly influences viscosity. High temperature viscosity measurements were carried out at 1 atm using a concentric cylinder apparatus equipped with an Anton Paar RheolabQC viscometer head at the Department of Physics and Geology (PVRG_lab) at the University of Perugia (Perugia, Italy

Clinical investigations of polymethylmethacrylate cement viscosity during vertebroplasty and related in vitro measurements

PubMed Central

Boger, A.; Schenk, B.; Heini, P. F.

2009-01-01

Percutaneous vertebroplasty, comprising an injection of polymethylmethacrylate (PMMA) into vertebral bodies, is a practical procedure for the stabilization of osteoporotic compression fractures as well as other weakening lesions. Cement leakage is considered to be one of the major and most severe complications during percutaneous vertebroplasty. The viscosity of the material plays a key role in this context. In order to enhance the safety for the patient, a rheometer system was developed to measure the cement viscosity intraoperatively. For this development, it is of great importance to know the proper viscosity to start the procedure determined by experienced surgeons and the relation between the time period when different injection devices are used and the cement viscosity. The purpose of the study was to investigate the viscosity ranges for different injection systems during conventional vertebroplasty. Clinically observed viscosity values and related time periods showed high scattering. In order to get a better understanding of the clinical observations, cement viscosity during hardening at different ambient temperatures and by simulation of the body temperature was investigated in vitro. It could be concluded, that the direct viscosity assessment with a rheometer during vertebroplasty can help clinicians to define a lower threshold viscosity and thereby decrease the risk of leakage and make adjustments to their injection technique in real time. Secondly, the acceleration in hardening of PMMA-based cements at body temperature can be useful in minimizing leakages by addressing them with a short injection break. PMID:19479285

Nanoscale Substances on the TSCA Inventory

EPA Pesticide Factsheets

This document is to help the regulated community comply with the requirements of the Toxic Substances Control Act (TSCA) Section 5 Premanufacturing Notice (PMN) Program for nanoscale chemical substances.

ARRHENIUS MODEL FOR HIGH-TEMPERATURE GLASS VISCOSITY WITH A CONSTANT PRE-EXPONENTIAL FACTOR

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

Hrma, Pavel R.

2008-04-15

A simplified form of the Arrhenius equation, ln η = A + B(x)/T, where η is the viscosity, T the temperature, x the composition vector, and A and B the Arrhenius coefficients, was fitted to glass-viscosity data for the processing temperature range (the range at which the viscosity is within 1 to 103 Pa.s) while setting A = constant and treating B(x) as a linear function of mass fractions of major components. Fitting the Arrhenius equation to over 550 viscosity data of commercial glasses and approximately 1000 viscosity data of glasses for nuclear-waste glasses resulted in the A values ofmore » -11.35 and -11.48, respectively. The R2 value ranged from 0.92 to 0.99 for commercial glasses and was 0.98 for waste glasses. The Arrhenius models estimate viscosities for melts of commercial glasses containing 42 to 84 mass% SiO2 within the temperature range of 1100 to 1550°C and viscosity range of 5 to 400 Pa.s and for waste glasses containing 32 to 60 mass% SiO2 within the temperature range of 850 to 1450°C and viscosity range of 0.4 to 250 Pa.s.« less

Specific decrease in solution viscosity of antibodies by arginine for therapeutic formulations.

PubMed

Inoue, Naoto; Takai, Eisuke; Arakawa, Tsutomu; Shiraki, Kentaro

2014-06-02

Unacceptably high viscosity is observed in high protein concentration formulations due to extremely large therapeutic dose of antibodies and volume restriction of subcutaneous route of administration. Here, we show that a protein aggregation suppressor, arginine hydrochloride (ArgHCl), specifically decreases viscosity of antibody formulations. The viscosities of bovine gamma globulin (BGG) solution at 250 mg/mL and human gamma globulin (HGG) solution at 292 mg/mL at a physiological pH were too high for subcutaneous injections, but decreased to an acceptable level (below 50 cP) in the presence of 1,000 mM ArgHCl. ArgHCl also decreased the viscosity of BGG solution at acidic and alkaline pHs. Interestingly, ArgHCl decreased the viscosity of antibody solutions (BGG, HGG, and human immunoglobulin G) but not globular protein solutions (α-amylase and α-chymotrypsin). These results indicate not only high potency of ArgHCl as an excipient to decrease the solution viscosity of high concentration antibodies formulations but also specific interactions between ArgHCl and antibodies.

The determination of viscosity at liquid mixtures - Comparison of approaches

NASA Astrophysics Data System (ADS)

Michal, Schmirler; Hana, Netřebská; Jan, Kolínský

2017-09-01

The research of flow field parameters for non-stationary flow of non-Newtonian fluids carried out at the Institute of Fluid Mechanics and Thermodynamics of CTU showed the need for knowledge of determination of the resulting viscosity of a mixture of several liquids. There are several sources for determining viscosity of mixtures. It is possible either to find theoretical relations in the literature or use technical tables based on experimentally measured data. This article focuses on comparing these approaches with an experiment. The experiment was performed by a Rheotest RN 4.1 rotating viscometer produced by the company RHEOTEST Medingen. The research was carried out using a solution of glycerol and water. The research has shown great differences in results in different approaches for determining the viscosity of the liquid mixtures. The result of this paper is to determine the method of viscosity calculation that is closest to the experimental data.

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

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

Zhao, Ake; Wang, Yuming; Liu, Jiajia

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

Direct Probing of Polarization Charge at Nanoscale Level

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

Kwon, Owoong; Seol, Daehee; Lee, Dongkyu

Ferroelectric materials possess spontaneous polarization that can be used for multiple applications. Owing to a long-term development of reducing the sizes of devices, the preparation of ferroelectric materials and devices is entering the nanometer-scale regime. In order to evaluate the ferroelectricity, there is a need to investigate the polarization charge at the nanoscale. Nonetheless, it is generally accepted that the detection of polarization charges using a conventional conductive atomic force microscopy (CAFM) without a top electrode is not feasible because the nanometer-scale radius of an atomic force microscopy (AFM) tip yields a very low signal-to-noise ratio. But, the detection ismore » unrelated to the radius of an AFM tip and, in fact, a matter of the switched area. In this work, the direct probing of the polarization charge at the nanoscale is demonstrated using the positive-up-negative-down method based on the conventional CAFM approach without additional corrections or circuits to reduce the parasitic capacitance. The polarization charge densities of 73.7 and 119.0 µC cm -2 are successfully probed in ferroelectric nanocapacitors and thin films, respectively. The results we obtained show the feasibility of the evaluation of polarization charge at the nanoscale and provide a new guideline for evaluating the ferroelectricity at the nanoscale.« less

Laser-Induced Translative Hydrodynamic Mass Snapshots: Noninvasive Characterization and Predictive Modeling via Mapping at Nanoscale

NASA Astrophysics Data System (ADS)

Wang, X. W.; Kuchmizhak, A. A.; Li, X.; Juodkazis, S.; Vitrik, O. B.; Kulchin, Yu. N.; Zhakhovsky, V. V.; Danilov, P. A.; Ionin, A. A.; Kudryashov, S. I.; Rudenko, A. A.; Inogamov, N. A.

2017-10-01

Subwavelength structures (meta-atoms) with artificially engineered permittivity and permeability have shown promising applications for guiding and controlling the flow of electromagnetic energy on the nanoscale. Ultrafast laser nanoprinting emerges as a promising single-step, green and flexible technology in fabricating large-area arrays of meta-atoms through the translative or ablative modification of noble-metal thin films. Ultrafast laser energy deposition in noble-metal films produces irreversible, intricate nanoscale translative mass redistributions after resolidification of the transient thermally assisted hydrodynamic melt perturbations. Such mass redistribution results in the formation of a radially symmetric frozen surface with modified hidden nanofeatures, which strongly affect the optical response harnessed in plasmonic sensing and nonlinear optical applications. Here, we demonstrate that side-view electron microscopy and ion-beam cross sections together with low-energy electron x-ray dispersion microscopy provide exact information about such three-dimensional patterns, enabling an accurate acquisition of their cross-sectional mass distributions. Such nanoscale solidified structures are theoretically modeled, considering the underlying physical processes associated with laser-induced energy absorption, electron-ion energy exchange, acoustic relaxation, and hydrodynamic flows. A theoretical approach, separating slow and fast physical processes and combining hybrid analytical two-temperature calculations, scalable molecular-dynamics simulations, and a semianalytical thin-shell model is synergistically applied. These advanced characterization approaches are required for a detailed modeling of near-field electromagnetic response and pave the way to a fully automated noninvasive in-line control of a high-throughput and large-scale laser fabrication. This theoretical modeling provides an accurate prediction of scales and topographies of the laser

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.

A "distorted-BODIPY"-based fluorescent probe for imaging of cellular viscosity in live cells.

PubMed

Zhu, Hao; Fan, Jiangli; Li, Miao; Cao, Jianfang; Wang, Jingyun; Peng, Xiaojun

2014-04-14

Cellular viscosity is a critical factor in governing diffusion-mediated cellular processes and is linked to a number of diseases and pathologies. Fluorescent molecular rotors (FMRs) have recently been developed to determine viscosity in solutions or biological fluid. Herein, we report a "distorted-BODIPY"-based probe BV-1 for cellular viscosity, which is different from the conventional "pure rotors". In BV-1, the internal steric hindrance between the meso-CHO group and the 1,7-dimethyl group forced the boron-dipyrrin framework to be distorted, which mainly caused nonradiative deactivation in low-viscosity environment. BV-1 gave high sensitivity (x=0.62) together with stringent selectivity to viscosity, thus enabling viscosity mapping in live cells. Significantly, the increase of cytoplasmic viscosity during apoptosis was observed by BV-1 in real time. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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.

Systems engineering at the nanoscale

NASA Astrophysics Data System (ADS)

Benkoski, Jason J.; Breidenich, Jennifer L.; Wei, Michael C.; Clatterbaughi, Guy V.; Keng, Pei Yuin; Pyun, Jeffrey

2012-06-01

Nanomaterials have provided some of the greatest leaps in technology over the past twenty years, but their relatively early stage of maturity presents challenges for their incorporation into engineered systems. Perhaps even more challenging is the fact that the underlying physics at the nanoscale often run counter to our physical intuition. The current state of nanotechnology today includes nanoscale materials and devices developed to function as components of systems, as well as theoretical visions for "nanosystems," which are systems in which all components are based on nanotechnology. Although examples will be given to show that nanomaterials have indeed matured into applications in medical, space, and military systems, no complete nanosystem has yet been realized. This discussion will therefore focus on systems in which nanotechnology plays a central role. Using self-assembled magnetic artificial cilia as an example, we will discuss how systems engineering concepts apply to nanotechnology.

Thermal transport at the nanoscale: A Fourier's law vs. phonon Boltzmann equation study

NASA Astrophysics Data System (ADS)

Kaiser, J.; Feng, T.; Maassen, J.; Wang, X.; Ruan, X.; Lundstrom, M.

2017-01-01

Steady-state thermal transport in nanostructures with dimensions comparable to the phonon mean-free-path is examined. Both the case of contacts at different temperatures with no internal heat generation and contacts at the same temperature with internal heat generation are considered. Fourier's law results are compared to finite volume method solutions of the phonon Boltzmann equation in the gray approximation. When the boundary conditions are properly specified, results obtained using Fourier's law without modifying the bulk thermal conductivity are in essentially exact quantitative agreement with the phonon Boltzmann equation in the ballistic and diffusive limits. The errors between these two limits are examined in this paper. For the four cases examined, the error in the apparent thermal conductivity as deduced from a correct application of Fourier's law is less than 6%. We also find that the Fourier's law results presented here are nearly identical to those obtained from a widely used ballistic-diffusive approach but analytically much simpler. Although limited to steady-state conditions with spatial variations in one dimension and to a gray model of phonon transport, the results show that Fourier's law can be used for linear transport from the diffusive to the ballistic limit. The results also contribute to an understanding of how heat transport at the nanoscale can be understood in terms of the conceptual framework that has been established for electron transport at the nanoscale.

Quantifying Nanoscale Order in Amorphous Materials via Fluctuation Electron Microscopy

ERIC Educational Resources Information Center

Bogle, Stephanie Nicole

2009-01-01

Fluctuation electron microscopy (FEM) has been used to study the nanoscale order in various amorphous materials. The method is explicitly sensitive to 3- and 4-body atomic correlation functions in amorphous materials; this is sufficient to establish the existence of structural order on the nanoscale, even when the radial distribution function…

Charge separation at nanoscale interfaces: energy-level alignment including two-quasiparticle interactions.

PubMed

Li, Huashan; Lin, Zhibin; Lusk, Mark T; Wu, Zhigang

2014-10-21

The universal and fundamental criteria for charge separation at interfaces involving nanoscale materials are investigated. In addition to the single-quasiparticle excitation, all the two-quasiparticle effects including exciton binding, Coulomb stabilization, and exciton transfer are considered, which play critical roles on nanoscale interfaces for optoelectronic applications. We propose a scheme allowing adding these two-quasiparticle interactions on top of the single-quasiparticle energy level alignment for determining and illuminating charge separation at nanoscale interfaces. Employing the many-body perturbation theory based on Green's functions, we quantitatively demonstrate that neglecting or simplifying these crucial two-quasiparticle interactions using less accurate methods is likely to predict qualitatively incorrect charge separation behaviors at nanoscale interfaces where quantum confinement dominates.

Viscosity rather than quantity of dietary fibre predicts cholesterol-lowering effect in healthy individuals.

PubMed

Vuksan, Vladimir; Jenkins, Alexandra L; Rogovik, Alexander L; Fairgrieve, Christopher D; Jovanovski, Elena; Leiter, Lawrence A

2011-11-01

The well-documented lipid-lowering effects of fibre may be related to its viscosity, a phenomenon that has been understudied, especially when fibre is given against the background of a typical North American (NA) diet. In this three-arm experiment, we compared the lipid-lowering effect of low-viscosity wheat bran (WB), medium-viscosity psyllium (PSY) and a high-viscosity viscous fibre blend (VFB), as part of a fibre intervention aimed at increasing fibre intake to recommended levels within the context of a NA diet in apparently healthy individuals. Using a randomised cross-over design, twenty-three participants (twelve males and eleven females; age 35 (SD 12) years; LDL-cholesterol (C) 2.9 (SEM 0.6) mmol/l) consuming a typical NA diet received a standard, fibre-enriched cereal, where approximately one-third of the fibre was either a low-viscosity (570 centipoise (cP)) WB, medium-viscosity (14,300 cP) PSY or a high-viscosity (136,300 cP) novel VFB, for 3 weeks separated by washout periods of ≥ 2 weeks. There were no differences among the treatments in the amount of food consumed, total dietary fibre intake, reported physical activity and body weight. Final intake of the WB, PSY and VFB was 10.8, 9.0 and 5.1 g, respectively. Reduction in LDL-C was greater with the VFB compared with the medium-viscosity PSY (-12.6 (SEM 3.5) %, P = 0.002) and low-viscosity WB (-14.6 (SEM 4.2) %, P = 0.003). The magnitude of LDL-C reduction showed a positive association with fibre apparent viscosity (r - 0.41, P = 0.001). Despite the smaller quantity consumed, the high-viscosity fibre lowered LDL-C to a greater extent than lower-viscosity fibres. These data support the inclusion of high-viscosity fibre in the diet to reduce plasma lipids among apparently healthy individuals consuming a typical NA diet.

Modeling the viscosity of polydisperse suspensions: Improvements in prediction of limiting behavior

NASA Astrophysics Data System (ADS)

Mwasame, Paul M.; Wagner, Norman J.; Beris, Antony N.

2016-06-01

The present study develops a fully consistent extension of the approach pioneered by Farris ["Prediction of the viscosity of multimodal suspensions from unimodal viscosity data," Trans. Soc. Rheol. 12, 281-301 (1968)] to describe the viscosity of polydisperse suspensions significantly improving upon our previous model [P. M. Mwasame, N. J. Wagner, and A. N. Beris, "Modeling the effects of polydispersity on the viscosity of noncolloidal hard sphere suspensions," J. Rheol. 60, 225-240 (2016)]. The new model captures the Farris limit of large size differences between consecutive particle size classes in a suspension. Moreover, the new model includes a further generalization that enables its application to real, complex suspensions that deviate from ideal non-colloidal suspension behavior. The capability of the new model to predict the viscosity of complex suspensions is illustrated by comparison against experimental data.

Blood viscosity monitoring during cardiopulmonary bypass based on pressure-flow characteristics of a Newtonian fluid.

PubMed

Okahara, Shigeyuki; Zu Soh; Takahashi, Shinya; Sueda, Taijiro; Tsuji, Toshio

2016-08-01

We proposed a blood viscosity estimation method based on pressure-flow characteristics of oxygenators used during cardiopulmonary bypass (CPB) in a previous study that showed the estimated viscosity to correlate well with the measured viscosity. However, the determination of the parameters included in the method required the use of blood, thereby leading to high cost of calibration. Therefore, in this study we propose a new method to monitor blood viscosity, which approximates the pressure-flow characteristics of blood considered as a non-Newtonian fluid with characteristics of a Newtonian fluid by using the parameters derived from glycerin solution to enable ease of acquisition. Because parameters used in the estimation method are based on fluid types, bovine blood parameters were used to calculate estimated viscosity (ηe), and glycerin parameters were used to estimate deemed viscosity (ηdeem). Three samples of whole bovine blood with different hematocrit levels (21.8%, 31.0%, and 39.8%) were prepared and perfused into the oxygenator. As the temperature changed from 37 °C to 27 °C, the oxygenator mean inlet pressure and outlet pressure were recorded for flows of 2 L/min and 4 L/min, and the viscosity was estimated. The value of deemed viscosity calculated with the glycerin parameters was lower than estimated viscosity calculated with bovine blood parameters by 20-33% at 21.8% hematocrit, 12-27% at 31.0% hematocrit, and 10-15% at 39.8% hematocrit. Furthermore, deemed viscosity was lower than estimated viscosity by 10-30% at 2 L/min and 30-40% at 4 L/min. Nevertheless, estimated and deemed viscosities varied with a similar slope. Therefore, this shows that deemed viscosity achieved using glycerin parameters may be capable of successfully monitoring relative viscosity changes of blood in a perfusing oxygenator.

Viscosities of Fe Ni, Fe Co and Ni Co binary melts

NASA Astrophysics Data System (ADS)

Sato, Yuzuru; Sugisawa, Koji; Aoki, Daisuke; Yamamura, Tsutomu

2005-02-01

Viscosities of three binary molten alloys consisting of the iron group elements, Fe, Ni and Co, have been measured by using an oscillating cup viscometer over the entire composition range from liquidus temperatures up to 1600 °C with high precision and excellent reproducibility. The viscosities measured showed good Arrhenius linearity for all the compositions. The viscosities of Fe, Ni and Co as a function of temperature are as follows: \\eqalign{ & \\log \\eta={-}0.6074 + 2493/T\\qquad for\\quad Fe\\\\ & \\log \\eta={-}0.5695 + 2157/T\\qquad for\\quad Ni \\\\ & \\log \\eta={-}0.6620 + 2430/T\\qquad for\\quad Co.} The isothermal viscosities of Fe-Ni and Fe-Co binary melts increase monotonically with increasing Fe content. On the other hand, in Ni-Co binary melt, the isothermal viscosity decreases slightly and then increases with increasing Co. The activation energy of Fe-Co binary melt increased slightly on mixing, and those of Fe-Ni and Ni-Co melts decreased monotonically with increasing Ni content. The above behaviour is discussed based on the thermodynamic properties of the alloys.

A Comparison of the Viscosities of Thickened Liquids for Pediatric Dysphagia.

NASA Astrophysics Data System (ADS)

Wijesinghe, Ranjith; Clifton, Mekale; Tarlton, Morgan; Heinsohn, Erica; Ewing, Mary

It has been reported that Speech Language Pathologists in different facilities across the nation use a variety of thickening agents and recipes as therapeutic measures for infants and children diagnosed with dysphagia. Limited research has been completed in this area. Viscosity was tested to determine the thickness of each thickening agent mixed with infant formula. The values were then compared to the National Dysphagia Diet liquid levels to determine which thickening agent resulted in the desired viscosity levels. The thickeners were mixed with common infant formulas and soy formulas to determine if the type of formula impacted the viscosity. The main goal was to determine if the assumed thickness level (viscosity) of prescribed thickened liquids was actually being met. This topic is of high concern because of its impact on the safety and well-being of clients with dysphagia. A viscometer was used to collect the viscosity levels. Commercially available formulas selected for this study. The final results of our investigation will be presented during the APS meeting. This work is supported by a Ball State University Immersive Learning Grant.

A Thermal Diode Based on Nanoscale Thermal Radiation.

PubMed

Fiorino, Anthony; Thompson, Dakotah; Zhu, Linxiao; Mittapally, Rohith; Biehs, Svend-Age; Bezencenet, Odile; El-Bondry, Nadia; Bansropun, Shailendra; Ben-Abdallah, Philippe; Meyhofer, Edgar; Reddy, Pramod

2018-05-23

In this work we demonstrate thermal rectification at the nanoscale between doped Si and VO 2 surfaces. Specifically, we show that the metal-insulator transition of VO 2 makes it possible to achieve large differences in the heat flow between Si and VO 2 when the direction of the temperature gradient is reversed. We further show that this rectification increases at nanoscale separations, with a maximum rectification coefficient exceeding 50% at ∼140 nm gaps and a temperature difference of 70 K. Our modeling indicates that this high rectification coefficient arises due to broadband enhancement of heat transfer between metallic VO 2 and doped Si surfaces, as compared to narrower-band exchange that occurs when VO 2 is in its insulating state. This work demonstrates the feasibility of accomplishing near-field-based rectification of heat, which is a key component for creating nanoscale radiation-based information processing devices and thermal management approaches.

Exploring Ultimate Water Capillary Evaporation in Nanoscale Conduits.

PubMed

Li, Yinxiao; Alibakhshi, Mohammad Amin; Zhao, Yihong; Duan, Chuanhua

2017-08-09

Capillary evaporation in nanoscale conduits is an efficient heat/mass transfer strategy that has been widely utilized by both nature and mankind. Despite its broad impact, the ultimate transport limits of capillary evaporation in nanoscale conduits, governed by the evaporation/condensation kinetics at the liquid-vapor interface, have remained poorly understood. Here we report experimental study of the kinetic limits of water capillary evaporation in two dimensional nanochannels using a novel hybrid channel design. Our results show that the kinetic-limited evaporation fluxes break down the limits predicated by the classical Hertz-Knudsen equation by an order of magnitude, reaching values up to 37.5 mm/s with corresponding heat fluxes up to 8500 W/cm 2 . The measured evaporation flux increases with decreasing channel height and relative humidity but decreases as the channel temperature decreases. Our findings have implications for further understanding evaporation at the nanoscale and developing capillary evaporation-based technologies for both energy- and bio-related applications.

A 3D Finite Element Model with Improved Spatial Resolution to Investigate the Effect of Varying Viscosity on Antarctica

NASA Astrophysics Data System (ADS)

Blank, B.; van der Wal, W.; Pappa, F.; Ebbing, J.

2017-12-01

B. Blank1, H. Hu1, W. van der Wal1, F Pappa2, J. Ebbing21Delft University of Technology 2Christian-Albrechts-University of KielSince the beginning of the 2000's time-variable gravity data from GRACE has proved to be an effective method for mapping ice mass loss in Antarctica. However, Glacial Isostatic Adjustment (GIA) models are required to correct for GIA induced mass changes. While most GIA models have adopted an Earth model that only varies radially in parameters, it has long been clear that the Earth structure also varies with longitude and latitude. For this study a new global 3D GIA model has been developed within the finite element software package ABAQUS, which can be modified to operate on a spatial resolution down to 50 km locally. The model is being benchmarked against normal model models for surface loading. It will be used to investigate the effects of a 3D varying lithosphere and upper asthenosphere in Antarctica. Viscosity which will be computed from temperature estimates with laboratory based flow laws. A new 3D temperature map of the Antarctic lithosphere has been developed within ESA's GOCE+ project based on seismic data as well as on GOCE and GRACE inferred gravity gradients. Output from the GIA model with this new temperature estimates will be compared to that of 1D viscosity profiles and other recent 3D viscosity models based on seismic data. From these side to side comparisons we want to investigate the influence of the viscosity map on uplift rates and horizontal movement. Finally the results can be compared to GPS measurement to investigate the validity of all models.

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.

Sensitivity of viscosity Arrhenius parameters to polarity of liquids

NASA Astrophysics Data System (ADS)

Kacem, R. B. H.; Alzamel, N. O.; Ouerfelli, N.

2017-09-01

Several empirical and semi-empirical equations have been proposed in the literature to estimate the liquid viscosity upon temperature. In this context, this paper aims to study the effect of polarity of liquids on the modeling of the viscosity-temperature dependence, considering particularly the Arrhenius type equations. To achieve this purpose, the solvents are classified into three groups: nonpolar, borderline polar and polar solvents. Based on adequate statistical tests, we found that there is strong evidence that the polarity of solvents affects significantly the distribution of the Arrhenius-type equation parameters and consequently the modeling of the viscosity-temperature dependence. Thus, specific estimated values of parameters for each group of liquids are proposed in this paper. In addition, the comparison of the accuracy of approximation with and without classification of liquids, using the Wilcoxon signed-rank test, shows a significant discrepancy of the borderline polar solvents. For that, we suggested in this paper new specific coefficient values of the simplified Arrhenius-type equation for better estimation accuracy. This result is important given that the accuracy in the estimation of the viscosity-temperature dependence may affect considerably the design and the optimization of several industrial processes.

On the measurement of the relative viscosity of suspensions

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

Acrivos, A.; Fan, X.; Mauri, R.

The relative viscosity of a suspension of rigid, noncolloidal particles immersed in a Newtonian fluid was measured in a Couette device and was found to be shear thinning even for values of the solids fraction as low as 20%. Although such behavior was reported previously, no satisfactory explanation appears to have been given thus far. It shall be shown presently, however, that, at least for our systems, this shear-thinning effect was due to a slight mismatch in the densities of the two phases. Moreover, the apparent relative viscosities measured in our apparatus were found to be in excellent agreement withmore » those predicted theoretically using a model, originally proposed by Leighton and Acrivos [Chem. Eng. Sci. [bold 41], 1377--1384 (1986)], to describe viscous resuspension, according to which the measured relative viscosity should depend on the bulk particle concentration and on the dimensionless Shields number [ital A], and should attain its correct value for a well-mixed suspension only as [ital A][r arrow][infinity]. The predictions of this model are also in excellent agreement with the measured transient response of the apparent relative viscosity due to a sudden change in the shear rate.« less

Tribological performance of ultra-low viscosity composite base fluid with bio-derived fluid

USDA-ARS?s Scientific Manuscript database

One obvious approach to increase efficiencies in many lubricated systems such as ICE and gearbox is the reduction in viscosity of oil lubricant. Indeed, ultra-low viscosity engine oils are now commercially available. One approach to the development of ultra-low viscosity lubricants without compromis...

High-Performance Polymers Having Low Melt Viscosities

NASA Technical Reports Server (NTRS)

Jensen, Brian J.

2005-01-01

High-performance polymers that have improved processing characteristics, and a method of making them, have been invented. One of the improved characteristics is low (relative to corresponding prior polymers) melt viscosities at given temperatures. This characteristic makes it possible to utilize such processes as resin-transfer molding and resin-film infusion and to perform autoclave processing at lower temperatures and/or pressures. Another improved characteristic is larger processing windows that is, longer times at low viscosities. Other improved characteristics include increased solubility of uncured polymer precursors that contain reactive groups, greater densities of cross-links in cured polymers, improved mechanical properties of the cured polymers, and greater resistance of the cured polymers to chemical attack. The invention is particularly applicable to poly(arylene ether)s [PAEs] and polyimides [PIs] that are useful as adhesives, matrices of composite materials, moldings, films, and coatings. PAEs and PIs synthesized according to the invention comprise mixtures of branched, linear, and star-shaped molecules. The monomers of these polymers can be capped with either reactive end groups to obtain thermosets or nonreactive end groups to obtain thermoplastics. The synthesis of a polymeric mixture according to the invention involves the use of a small amount of a trifunctional monomer. In the case of a PAE, the trifunctional monomer is a trihydroxy- containing compound for example, 1,3,5-trihydroxybenzene (THB). In the case of a PI, the trifunctional monomer is a triamine for example, triamino pyrimidine or melamine. In addition to the aforementioned trifunctional monomer, one uses the difunctional monomers of the conventional formulation of the polymer in question (see figure). In cases of nonreactive end caps, the polymeric mixtures of the invention have melt viscosities and melting temperatures lower than those of the corresponding linear polymers of equal

Viscosity of nonelectrolyte liquid mixtures. IV. Binary mixtures containing p-Dioxane

NASA Astrophysics Data System (ADS)

Oswal, S. L.; Oswal, P.; Phalak, R. P.

1996-11-01

Measurements of the viscosity η and density p are reported for eight binary mixtures of p-dioxane with methylcyclohexane, l-chlorohexane, l-bromohexane, p-xylene, propylbenzene, methyl acetate, butyl acetate. anyl acetate at 303.15 K. The viscosity data haw been correlated with the equations of Grunbeng Nissan. of McAllister, and of Auslaendcr. The relation among the excess viscosity Δ In η, excess Gibbs energy of activation ΔG* E of viscous flow. and intermolecular interaction in these mixtures is discussed.

Bulk Viscosity of Bubbly Magmas and the Amplification of Pressure Waves

NASA Astrophysics Data System (ADS)

Navon, O.; Lensky, N. G.; Neuberg, J. W.; Lyakhovsky, V.

2001-12-01

The bulk viscosity of magma is needed in order to describe the dynamics of a compressible bubbly magma flowing in conduits and to follow the attenuation of pressure waves travelling through a compressible magma. We developed a model for the bulk viscosity of a suspension of gas bubbles in an incompressible Newtonian liquid that exsolves volatiles (e.g. magma). The suspension is modeled as a close pack of spherical cells, consisting of gas bubbles centered in spherical shells of a volatile-bearing liquid. Following a drop in the ambient pressure the resulting dilatational motion and driving pressure are obtained in terms of the two-phase cell parameters, i.e. bubble radius and gas pressure. By definition, the bulk viscosity of a fluid is the relation between changes of the driving pressure with respect to changes in the resulted expansion strain-rate. Thus, we can use the two-phase solution to define the bulk viscosity of a hypothetical cell, composed of a homogeneously compressible, one-phase, continuous fluid. The resulted bulk viscosity is highly non-linear. At the beginning of the expansion process, when gas exsolution is efficient, the expansion rate grows exponentially while the driving pressure decreases slightly. That means that bulk viscosity is formally negative. The negative value reflects the release of the energy stored in the supersaturated liquid (melt) and its conversion to mechanical work during exsolution. Later, when bubbles are large enough and the gas influx decreases significantly, the strain rate decelerates and the bulk viscosity becomes positive as expected in a dissipative system. We demonstrate that amplification of seismic wave travelling through a volcanic conduit filled with a volatile saturated magma may be attributed to the negative bulk viscosity of the compressible magma. Amplification of an expansion wave may, at some level in the conduit, damage the conduit walls and initiate opening of new pathways for magma to erupt.

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

Mapping photovoltaic performance with nanoscale resolution

DOE PAGES

Kutes, Yasemin; Aguirre, Brandon A.; Bosse, James L.; ...

2015-10-16

Photo-conductive AFM spectroscopy (‘pcAFMs’) is proposed as a high-resolution approach for investigating nanostructured photovoltaics, uniquely providing nanoscale maps of photovoltaic (PV) performance parameters such as the short circuit current, open circuit voltage, maximum power, or fill factor. The method is demonstrated with a stack of 21 images acquired during in situ illumination of micropatterned polycrystalline CdTe/CdS, providing more than 42,000 I/V curves spatially separated by ~5 nm. For these CdTe/CdS microcells, the calculated photoconduction ranges from 0 to 700 picoSiemens (pS) upon illumination with ~1.6 suns, depending on location and biasing conditions. Mean short circuit currents of 2 pA, maximummore » powers of 0.5 pW, and fill factors of 30% are determined. The mean voltage at which the detected photocurrent is zero is determined to be 0.7 V. Significantly, enhancements and reductions in these more commonly macroscopic PV performance metrics are observed to correlate with certain grains and grain boundaries, and are confirmed to be independent of topography. Furthermore, these results demonstrate the benefits of nanoscale resolved PV functional measurements, reiterate the importance of microstructural control down to the nanoscale for 'PV devices, and provide a widely applicable new approach for directly investigating PV materials.« less

A Look Inside Argonne's Center for Nanoscale Materials

ScienceCinema

Divan, Ralu; Rosenthal, Dan; Rose, Volker; Wai Hla

2018-05-23

At a very small, or "nano" scale, materials behave differently. The study of nanomaterials is much more than miniaturization - scientists are discovering how changes in size change a material's properties. From sunscreen to computer memory, the applications of nanoscale materials research are all around us. Researchers at Argonne's Center for Nanoscale Materials are creating new materials, methods and technologies to address some of the world's greatest challenges in energy security, lightweight but durable materials, high-efficiency lighting, information storage, environmental stewardship and advanced medical devices.

Study on viscosity of MDEA-MeOH aqueous solutions

NASA Astrophysics Data System (ADS)

Wang, F.; Wang, L. M.; Wang, S. Q.; Fu, D.

2017-03-01

The viscosities of the N-methyldiethanolamine (MDEA)-methanol (MeOH) aqueous solutions were measured at temperatures ranging from (303.2 to 323.2) K. The mass fraction of MDEA and MeOH respectively ranged from 0.2 to 0.4 and 0 to 0.15. On the basis of experimental measurement, the effects of temperature, mass fraction of MDEA and MeOH on viscosities were demonstrated.

Geometric rectification for nanoscale vibrational energy harvesting

NASA Astrophysics Data System (ADS)

Bustos-Marún, Raúl A.

2018-02-01

In this work, we present a mechanism that, based on quantum-mechanical principles, allows one to recover kinetic energy at the nanoscale. Our premise is that very small mechanical excitations, such as those arising from sound waves propagating through a nanoscale system or similar phenomena, can be quite generally converted into useful electrical work by applying the same principles behind conventional adiabatic quantum pumping. The proposal is potentially useful for nanoscale vibrational energy harvesting where it can have several advantages. The most important one is that it avoids the use of classical rectification mechanisms as it is based on what we call geometric rectification. We show that this geometric rectification results from applying appropriate but quite general initial conditions to damped harmonic systems coupled to electronic reservoirs. We analyze an analytically solvable example consisting of a wire suspended over permanent charges where we find the condition for maximizing the pumped charge. We also studied the effects of coupling the system to a capacitor including the effect of current-induced forces and analyzing the steady-state voltage of operation. Finally, we show how quantum effects can be used to boost the performance of the proposed device.

Nanoscale Reinforced, Polymer Derived Ceramic Matrix Coatings

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

Rajendra Bordia

The goal of this project was to explore and develop a novel class of nanoscale reinforced ceramic coatings for high temperature (600-1000 C) corrosion protection of metallic components in a coal-fired environment. It was focused on developing coatings that are easy to process and low cost. The approach was to use high-yield preceramic polymers loaded with nano-size fillers. The complex interplay of the particles in the polymer, their role in controlling shrinkage and phase evolution during thermal treatment, resulting densification and microstructural evolution, mechanical properties and effectiveness as corrosion protection coatings were investigated. Fe-and Ni-based alloys currently used in coal-firedmore » environments do not possess the requisite corrosion and oxidation resistance for next generation of advanced power systems. One example of this is the power plants that use ultra supercritical steam as the working fluid. The increase in thermal efficiency of the plant and decrease in pollutant emissions are only possible by changing the properties of steam from supercritical to ultra supercritical. However, the conditions, 650 C and 34.5 MPa, are too severe and result in higher rate of corrosion due to higher metal temperatures. Coating the metallic components with ceramics that are resistant to corrosion, oxidation and erosion, is an economical and immediate solution to this problem. Good high temperature corrosion protection ceramic coatings for metallic structures must have a set of properties that are difficult to achieve using established processing techniques. The required properties include ease of coating complex shapes, low processing temperatures, thermal expansion match with metallic structures and good mechanical and chemical properties. Nanoscale reinforced composite coatings in which the matrix is derived from preceramic polymers have the potential to meet these requirements. The research was focused on developing suitable material systems and

Variation of velocity profile according to blood viscosity in a microfluidic channel

NASA Astrophysics Data System (ADS)

Yeom, Eunseop; Kang, Yang Jun; Lee, Sang-Joon

2014-11-01

The shear-thinning effect of blood flows is known to change blood viscosity. Since blood viscosity and motion of red blood cells (RBCs) are closely related, hemorheological variations have a strong influence on hemodynamic characteristics. Therefore, understanding on the relationship between the hemorheological and hemodynamic properties is importance for getting more detailed information on blood circulation in microvessels. In this study, the blood viscosity and velocity profiles in a microfluidic channel were systematically investigated. Rat blood was delivered in the microfluidic device which can measure blood viscosity by monitoring the flow-switching phenomenon. Velocity profiles of blood flows in the microchannel were measured by using a micro-particle image velocimetry (PIV) technique. Shape of velocity profiles measured at different flow rates was quantified by using a curve-fitting equation. It was observed that the shape of velocity profiles is highly correlated with blood viscosity. The study on the relation between blood viscosity and velocity profile would be helpful to understand the roles of hemorheological and hemodynamic properties in cardiovascular diseases. This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea Government (MSIP) (No. 2008-0061991).

Sweetness and other sensory properties of model fruit drinks: Does viscosity have an impact?

PubMed

Brandenstein, Cai V S; Busch-Stockfisch, Mechthild; Fischer, Markus

2015-03-15

The impact of thickening agents and viscosity levels on sensory perception was studied in model fruit drinks. Four formulations were prepared that varied in the sweetener blend (erythritol, maltitol and/or steviol glycosides). Locust bean gum and its blends with either xanthan or carrageenan were used to adjust viscosity levels (20, 40, and 70 mPa s). The ranges of viscosity and sweetness level were selected to represent a typical concentration range in commercially available beverages. An increase in viscosity resulted in significant increases in pulpiness, sliminess and perceived viscosity (P-values ≤ 0.001), which were not dependent on sweeteners or hydrocolloid type. Taste perception remained largely unchanged irrespective of the hydrocolloid used. The impact of viscosity on sweetness and taste perception was much smaller in the concentrations used than has been generally reported. The effect of the type of hydrocolloid on the perception of taste attributes was greater than that of viscosity. © 2014 Society of Chemical Industry.

Nanoscale chirality in metal and semiconductor nanoparticles

PubMed Central

Thomas, K. George

2016-01-01

The field of chirality has recently seen a rejuvenation due to the observation of chirality in inorganic nanomaterials. The advancements in understanding the origin of nanoscale chirality and the potential applications of chiroptical nanomaterials in the areas of optics, catalysis and biosensing, among others, have opened up new avenues toward new concepts and design of novel materials. In this article, we review the concept of nanoscale chirality in metal nanoclusters and semiconductor quantum dots, then focus on recent experimental and theoretical advances in chiral metal nanoparticles and plasmonic chirality. Selected examples of potential applications and an outlook on the research on chiral nanomaterials are additionally provided. PMID:27752651

Nanoscale chirality in metal and semiconductor nanoparticles.

PubMed

Kumar, Jatish; Thomas, K George; Liz-Marzán, Luis M

2016-10-18

The field of chirality has recently seen a rejuvenation due to the observation of chirality in inorganic nanomaterials. The advancements in understanding the origin of nanoscale chirality and the potential applications of chiroptical nanomaterials in the areas of optics, catalysis and biosensing, among others, have opened up new avenues toward new concepts and design of novel materials. In this article, we review the concept of nanoscale chirality in metal nanoclusters and semiconductor quantum dots, then focus on recent experimental and theoretical advances in chiral metal nanoparticles and plasmonic chirality. Selected examples of potential applications and an outlook on the research on chiral nanomaterials are additionally provided.

On the penetration of a hot diapir through a strongly temperature-dependent viscosity medium

NASA Technical Reports Server (NTRS)

Daly, S. F.; Raefsky, A.

1985-01-01

The ascent of a hot spherical body through a fluid with a strongly temperature-dependent viscosity has been studied using an axisymmetric finite element method. Numerical solutions range over Peclet numbers of 0.1 - 1000 from constant viscosity up to viscosity variations of 100,000. Both rigid and stress-free boundary conditions were applied at the surface of the sphere. The dependence of drag on viscosity variation was shown to have no dependence on the stress boundary condition except for a Stokes flow scaling factor. A Nusselt number parameterization based on the stress-free constant viscosity functional dependence on the Peclet number scaled by a parameter depending on the viscosity structure fits both stress-free and rigid boundary condition data above viscosity variations of 100. The temperature scale height was determined as a function of sphere radius. For the simple physical model studied in this paper pre-heating is required to reduce the ambient viscosity of the country rock to less than 10 to the 22nd sq cm/s in order for a 10 km diapir to penetrate a distance of several radii.

A Difference Scheme with Autocontrol Artificial Viscosity to Predict Ablated Nosetip Shape

DTIC Science & Technology

1989-09-29

I FTD-ID(RS)T-0640-89 U) (0 FOREIGN TECHNOLOGY DIVISION A DIFFERENCE SCHEME WITH AUTOCONTROL ARTIFICIAL VISCOSITY TO PREDICT ABLATED NOSETIP SHAPE by...September 1989 MICROFICHE NR: FTD-89-C-000800 A DIFFERENCE SCHEME WITH AUTOCONTROL ARTIFICIAL VISCOSITY TO PREDICT ABLATED NOSETIP SHAPE By: Yang Maozhao...DIFFERENCE SCHEME WITH AUTOCONTROL ARTIFICIAL VISCOSITY TO PREDICT ABLATED NOSETIP SHAPE Yang Maozhao (China Aerodynamic Research and Development Centre

Viscosity minima in binary mixtures of ionic liquids + molecular solvents.

PubMed

Tariq, M; Shimizu, K; Esperança, J M S S; Canongia Lopes, J N; Rebelo, L P N

2015-05-28

The viscosity (η) of four binary mixtures (ionic liquids plus molecular solvents, ILs+MSs) was measured in the 283.15 < T/K < 363.15 temperature range. Different IL/MS combinations were selected in such a way that the corresponding η(T) functions exhibit crossover temperatures at which both pure components present identical viscosity values. Consequently, most of the obtained mixture isotherms, η(x), exhibit clear viscosity minima in the studied T-x range. The results are interpreted using auxiliary molecular dynamics (MD) simulation data in order to correlate the observed η(T,x) trends with the interactions in each mixture, including the balance between electrostatic forces and hydrogen bonding.

Astronaut Mike Fincke Conducts Fluid Merging Viscosity Measurement (FMVM) Experiment

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.

Manufacturing at the Nanoscale. Report of the National Nanotechnology Initiative Workshops, 2002-2004

DTIC Science & Technology

2007-01-01

positioning and assembling? • Do nanoscale properties remain once the nanostructures are integrated up to the microscale? • How do we measure...viii Manufacturing at the Nanoscale 1 1. VISION Employing the novel properties and processes that are associated with the nanoscale—in the...Theory, modeling, and simulation software are being developed to investigate nanoscale material properties and synthesis of macromolecular systems with

Reduction of Thermal Conductivity by Nanoscale 3D Phononic Crystal

PubMed Central

Yang, Lina; Yang, Nuo; Li, Baowen

2013-01-01

We studied how the period length and the mass ratio affect the thermal conductivity of isotopic nanoscale three-dimensional (3D) phononic crystal of Si. Simulation results by equilibrium molecular dynamics show isotopic nanoscale 3D phononic crystals can significantly reduce the thermal conductivity of bulk Si at high temperature (1000 K), which leads to a larger ZT than unity. The thermal conductivity decreases as the period length and mass ratio increases. The phonon dispersion curves show an obvious decrease of group velocities in 3D phononic crystals. The phonon's localization and band gap is also clearly observed in spectra of normalized inverse participation ratio in nanoscale 3D phononic crystal. PMID:23378898

Nanoscale thermal transport. II. 2003-2012

NASA Astrophysics Data System (ADS)

Cahill, David G.; Braun, Paul V.; Chen, Gang; Clarke, David R.; Fan, Shanhui; Goodson, Kenneth E.; Keblinski, Pawel; King, William P.; Mahan, Gerald D.; Majumdar, Arun; Maris, Humphrey J.; Phillpot, Simon R.; Pop, Eric; Shi, Li

2014-03-01

A diverse spectrum of technology drivers such as improved thermal barriers, higher efficiency thermoelectric energy conversion, phase-change memory, heat-assisted magnetic recording, thermal management of nanoscale electronics, and nanoparticles for thermal medical therapies are motivating studies of the applied physics of thermal transport at the nanoscale. This review emphasizes developments in experiment, theory, and computation in the past ten years and summarizes the present status of the field. Interfaces become increasingly important on small length scales. Research during the past decade has extended studies of interfaces between simple metals and inorganic crystals to interfaces with molecular materials and liquids with systematic control of interface chemistry and physics. At separations on the order of ˜ 1 nm , the science of radiative transport through nanoscale gaps overlaps with thermal conduction by the coupling of electronic and vibrational excitations across weakly bonded or rough interfaces between materials. Major advances in the physics of phonons include first principles calculation of the phonon lifetimes of simple crystals and application of the predicted scattering rates in parameter-free calculations of the thermal conductivity. Progress in the control of thermal transport at the nanoscale is critical to continued advances in the density of information that can be stored in phase change memory devices and new generations of magnetic storage that will use highly localized heat sources to reduce the coercivity of magnetic media. Ultralow thermal conductivity—thermal conductivity below the conventionally predicted minimum thermal conductivity—has been observed in nanolaminates and disordered crystals with strong anisotropy. Advances in metrology by time-domain thermoreflectance have made measurements of the thermal conductivity of a thin layer with micron-scale spatial resolution relatively routine. Scanning thermal microscopy and thermal

Viscosity and thermal conductivity of moderately dense gas mixtures.

NASA Technical Reports Server (NTRS)

Wakeham, W. A.; Kestin, J.; Mason, E. A.; Sandler, S. I.

1972-01-01

Derivation of a simple, semitheoretical expression for the initial density dependence of the viscosity and thermal conductivity of gaseous mixtures in terms of the appropriate properties of the pure components and of their interaction quantities. The derivation is based on Enskog's theory of dense gases and yields an equation in which the composition dependence of the linear factor in the density expansion is explicit. The interaction quantities are directly related to those of the mixture extrapolated to zero density and to a universal function valid for all gases. The reliability of the formulation is assessed with respect to the viscosity of several binary mixtures. It is found that the calculated viscosities of binary mixtures agree with the experimental data with a precision which is comparable to that of the most precise measurements.

A Comparative Study Between Modified Starch and Xanthan Gum Thickeners in Post-Stroke Oropharyngeal Dysphagia.

PubMed

Vilardell, N; Rofes, L; Arreola, V; Speyer, R; Clavé, P

2016-04-01

Thickeners are used in post-stroke oropharyngeal dysphagia (OD) as a compensatory therapeutic strategy against aspirations. To compare the therapeutic effects of modified starch (MS) and xanthan gum (XG) thickeners on swallow safety and efficacy in chronic post-stroke OD patients using clinical and videofluoroscopic (VFS) assessment. Patients were studied by clinical assessment (volume-viscosity swallow test, V-VST) and VFS using 3 volumes (5, 10, 20 mL) and 3 viscosities (liquid, nectar and spoon thick), comparing MS and XG. We studied 122 patients (46MS, 76XG). (A) V-VST showed that both thickeners similarly improved safety of swallow. Prevalence of safe swallowing significantly increased with enhanced viscosity (P < 0.001 vs liquid), MS: 47.83 % at liquid, 84.93 % at nectar and 92.96 % at spoon thick; XG: 55.31 % at liquid, 77.78 % at nectar and 97.84 % at spoon thick. Patients on MS reported higher prevalence of pharyngeal residue at spoon-thick viscosities. (B) VFS: increasing bolus viscosity with either thickener increased prevalence of safe swallows (P < 0.001 vs liquid), MS: 30.25 % liquid, 61.07 % nectar and 92.64 % spoon thick; XG: 29.12 % liquid, 71.30 % nectar and 89.91 % spoon thick. Penetration-aspiration scale score was significantly reduced with increased viscosity with both thickeners. MS increased oral and pharyngeal residues at nectar and spoon-thick viscosities but XG did not. Timing of airway protection mechanisms and bolus velocity were not affected by either thickener. Increasing bolus viscosity with MS and XG thickeners strongly and similarly improved safety of swallow in chronic post-stroke OD by a compensatory mechanism; in contrast only MS thickeners increased oropharyngeal residue.

Heritability and Seasonal Changes in Viscosity of Slash Pine Oleoresin

Treesearch

Robert D. McReynolds

1971-01-01

Oleoresin viscosity was measured in slash pine (Pinus elliottii var. elliottii) trees of known genetic origin over a 1-year period. A strong broad-sense heritability of this trait was found. Seasonal variation followed a definite pattern, with the highest viscosities occurring in early spring and a gradual decline occurring in...

Extraction of shear viscosity in stationary states of relativistic particle systems

NASA Astrophysics Data System (ADS)

Reining, F.; Bouras, I.; El, A.; Wesp, C.; Xu, Z.; Greiner, C.

2012-02-01

Starting from a classical picture of shear viscosity we construct a stationary velocity gradient in a microscopic parton cascade. Employing the Navier-Stokes ansatz we extract the shear viscosity coefficient η. For elastic isotropic scatterings we find an excellent agreement with the analytic values. This confirms the applicability of this method. Furthermore, for both elastic and inelastic scatterings with pQCD based cross sections we extract the shear viscosity coefficient η for a pure gluonic system and find a good agreement with already published calculations.

Dependence of Perpendicular Viscosity on Magnetic Fluctuations in a Stochastic Topology

NASA Astrophysics Data System (ADS)

Fridström, R.; Chapman, B. E.; Almagri, A. F.; Frassinetti, L.; Brunsell, P. R.; Nishizawa, T.; Sarff, J. S.

2018-06-01

In a magnetically confined plasma with a stochastic magnetic field, the dependence of the perpendicular viscosity on the magnetic fluctuation amplitude is measured for the first time. With a controlled, ˜ tenfold variation in the fluctuation amplitude, the viscosity increases ˜100 -fold, exhibiting the same fluctuation-amplitude-squared dependence as the predicted rate of stochastic field line diffusion. The absolute value of the viscosity is well predicted by a model based on momentum transport in a stochastic field, the first in-depth test of this model.

Nanoscale NMR spectroscopy and imaging of multiple nuclear species.