Effect of polycarboxylate ether comb-type polymer on viscosity and interfacial properties of kaolinite clay suspensions.

PubMed

Zhang, Ling; Lu, Qingye; Xu, Zhenghe; Liu, Qingxia; Zeng, Hongbo

2012-07-15

The interactions between kaolinite clay particles and a comb-type polymer (polycarboxylate ether or PCE), so-called PCE super-plasticizer, were investigated through viscosity and surface forces measurements by a rheometer and a Surface Forces Apparatus (SFA). The addition of PCE shows a strong impact on the viscosity of concentrated kaolinite suspensions in alkaline solutions (pH=8.3) but a weak effect under acidic conditions (pH=3.4). In acidic solutions, the high viscosity measured is attributed to the strong electrostatic interaction between negatively charged basal planes and positively charged edge surfaces of clay particles. Under the alkaline condition, the suspension viscosity was found to first increase significantly and then decrease with increasing PCE dosages. The results from surface forces measurement show that PCE molecules at low dosages can bridge the kaolinite particles in the concentrated suspensions via hydrogen bonding, leading to the formation of a kaolinite-PCE "network" and hence an increased suspension viscosity. At high PCE dosages, clay particles are fully covered by PCE molecules, leading to a more dispersed kaolinite suspensions and hence lower suspension viscosity due to steric repulsion between the adsorbed PCE molecules. The insights derived from measuring viscosity and interfacial properties of kaolinite suspensions containing varying amount of comb-type super-plasticizer PCE at different pH provide the foundation for many engineering applications and optimizing industrial processes. Copyright © 2012 Elsevier Inc. All rights reserved.

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.

Lowered pH Alters Decay but Not Speed of Tectorial Membrane Waves

NASA Astrophysics Data System (ADS)

Farrahi, Shirin; Ghaffari, Roozbeh; Freeman, Dennis M.

2011-11-01

Tectorial membrane (TM) traveling waves and mechanical shear impedances were measured in artificial endolymph baths at neutral and acidic pHs. Lowering pH from 7 to 4 significantly decreases the spatial extent of TM waves but has a relatively minor effect on wave speed. At pH 4, the imaginary component of TM shear impedance, which relates to the shear modulus, drops significantly; whereas, the real component, which relates to viscosity, is reduced less. These results suggest that shear modulus, and not viscosity, controls the extent of TM waves at lower pH.

Communication: Quantum molecular dynamics simulation of liquid para-hydrogen by nuclear and electron wave packet approach.

PubMed

Hyeon-Deuk, Kim; Ando, Koji

2014-05-07

Liquid para-hydrogen (p-H2) is a typical quantum liquid which exhibits strong nuclear quantum effects (NQEs) and thus anomalous static and dynamic properties. We propose a real-time simulation method of wave packet (WP) molecular dynamics (MD) based on non-empirical intra- and inter-molecular interactions of non-spherical hydrogen molecules, and apply it to condensed-phase p-H2. The NQEs, such as WP delocalization and zero-point energy, are taken into account without perturbative expansion of prepared model potential functions but with explicit interactions between nuclear and electron WPs. The developed MD simulation for 100 ps with 1200 hydrogen molecules is realized at feasible computational cost, by which basic experimental properties of p-H2 liquid such as radial distribution functions, self-diffusion coefficients, and shear viscosities are all well reproduced.

An evaluation of soluble cations and anions on the conductivity and rate of flocculation of kaolins

NASA Astrophysics Data System (ADS)

Fulton, Deborah Lee

1998-10-01

The focus of this project was to learn how ionic concentrations and their contributions to electric conductivity influence the flocculation behavior of kaolin/water suspensions. Sodium silicate, calcium chloride, and magnesium sulfate were used as chemical additives. The specific surface areas, particle size distributions, and methylene blue indices for two kaolins were measured. The SSA and MBI for these kaolins indicated that they possessed inherent differences in SSA and flocculation behaviors. Rheological studies were also performed. Testing included simultaneous gelation, deflocculation, and pH tests. Viscosity, pH, temperature, and chemical additive concentrations were monitored at each point. Testing was performed at 45/55 wt% solids. Effects of additions of various levels of deflocculant and flocculant to each of the kaolin/water suspensions were studied by making several suspensions from each kaolin. The concentrations of dispersant, and flocculant levels and types were varied to produce suspensions with different chemical additive "histories," but all with similar final apparent viscosities. Slurry filtrates were analyzed for conductivity, pH, temperature, and ion concentrations of (Al3+, Fe2+,3+, Ca 2+, Mg+, Na+, SO4 2--, and Cl--). Plastic properties were calculated to determine how variations in suspension histories affected conductivities, pH, and detectable ion contents of the suspensions. These analyses were performed on starting slurries which were under-, completely-, and over-deflocculated before further additions of flocculants and deflocculant were added to tune the slurries to the final, constant, target viscosity. Results showed that rates of flocculation and conductivities increased as concentrations of ions increased. By increasing conductivity correlations with increases in flocculation occurs, which yields higher rates of buildup, or RBU [1]. This is the single most important slip control property in the whitewares industry. Shear-thinning behavior of the bodies also increased with increases in ion concentrations and conductivities. Bingham viscosities decreased as ionic concentrations increased. Brookfield buildup (BBU), plasticity index, yield stress, and pseudoplastic index generally increased as chemical additions increased. Softness and plastic behavior of the bodies increased with increasing concentrations of additive chemicals and with increasing conductivity. Calcium, sodium, and sulfate ions were primarily responsible for increasing conductivity. Calcium chloride was a more effective flocculant than magnesium sulfate.

46 CFR 153.908 - Cargo viscosity and melting point information; measuring cargo temperature during discharge...

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 5 2014-10-01 2014-10-01 false Cargo viscosity and melting point information; measuring... Cargo viscosity and melting point information; measuring cargo temperature during discharge: Categories... lading, a written statement of the following: (1) For Category A or B NLS, the cargo's viscosity at 20 °C...

46 CFR 153.908 - Cargo viscosity and melting point information; measuring cargo temperature during discharge...

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 5 2013-10-01 2013-10-01 false Cargo viscosity and melting point information; measuring... Cargo viscosity and melting point information; measuring cargo temperature during discharge: Categories... lading, a written statement of the following: (1) For Category A or B NLS, the cargo's viscosity at 20 °C...

46 CFR 153.908 - Cargo viscosity and melting point information; measuring cargo temperature during discharge...

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 5 2012-10-01 2012-10-01 false Cargo viscosity and melting point information; measuring... Cargo viscosity and melting point information; measuring cargo temperature during discharge: Categories... lading, a written statement of the following: (1) For Category A or B NLS, the cargo's viscosity at 20 °C...

A pH-responsive wormlike micellar system of a noncovalent interaction-based surfactant with a tunable molecular structure.

PubMed

Kang, Wanli; Wang, Pengxiang; Fan, Haiming; Yang, Hongbin; Dai, Caili; Yin, Xia; Zhao, Yilu; Guo, Shujun

2017-02-08

Responsive wormlike micelles are very useful in a number of applications, whereas it is still challenging to create dramatic viscosity changes in wormlike micellar systems. Here we developed a pH-responsive wormlike micellar system based on a noncovalent constructed surfactant, which is formed by the complexation of N-erucamidopropyl-N,N-dimethylamine (UC 22 AMPM) and citric acid at the molar ratio of 3 : 1 (EACA). The phase behavior, aggregate microstructure and viscoelasticity of EACA solutions were investigated by macroscopic appearance observation, rheological and cryo-TEM measurements. It was found that the phase behavior of EACA solutions undergoes transition from transparent viscoelastic fluids to opalescent solutions and then phase separation with white floaters upon increasing the pH. Upon increasing the pH from 2.03 to 6.17, the viscosity of wormlike micelles in the transparent solutions continuously increased and reached ∼683 000 mPa s at pH 6.17. As the pH was adjusted to 7.31, the opalescent solution shows a water-like flowing behaviour and the η 0 rapidly declines to ∼1 mPa s. Thus, dramatic viscosity changes of about 6 magnitudes can be triggered by varying the pH values without any deterioration of the EACA system. This drastic variation in rheological behavior is attributed to the pH dependent interaction between UC 22 AMPM and citric acid. Furthermore, the dependence on concentration and temperature of the rheological behavior of EACA solutions was also studied to assist in obtaining the desired pH-responsive viscosity changes.

Intermolecular Interactions and the Viscosity of Highly Concentrated Monoclonal Antibody Solutions.

PubMed

Binabaji, Elaheh; Ma, Junfen; Zydney, Andrew L

2015-09-01

The large increase in viscosity of highly concentrated monoclonal antibody solutions can be challenging for downstream processing, drug formulation, and delivery steps. The objective of this work was to examine the viscosity of highly concentrated solutions of a high purity IgG1 monoclonal antibody over a wide range of protein concentrations, solution pH, ionic strength, and in the presence / absence of different excipients. Experiments were performed with an IgG1 monoclonal antibody provided by Amgen. The steady-state viscosity was evaluated using a Rheometrics strain-controlled rotational rheometer with a concentric cylinder geometry. The viscosity data were well-described by the Mooney equation. The data were analyzed in terms of the antibody virial coefficients obtained from osmotic pressure data evaluated under the same conditions. The viscosity coefficient in the absence of excipients was well correlated with the third osmotic virial coefficient, which has a negative value (corresponding to short range attractive interactions) at the pH and ionic strength examined in this work. These results provide important insights into the effects of intermolecular protein-protein interactions on the behavior of highly concentrated antibody solutions.

Heat and pH stability of alkali-extractable corn arabinoxylan and its xylanase-hydrolyzate and their viscosity behavior.

PubMed

Rumpagaporn, Pinthip; Kaur, Amandeep; Campanella, Osvaldo H; Patterson, John A; Hamaker, Bruce R

2012-01-01

In in vitro batch fermentations, both alkali-extractable corn arabinoxylan (CAX) and its xylanase-hydrolyzate (CH) were utilized by human fecal microbiota and produced similar short chain fatty acid (SCFA) contents and desirable long fermentation profiles with low initial gas production. Fortification of these arabinoxylans into processed foods would contribute desirable dietary fiber benefits to humans. Heat and pH stability, as well as viscosity behavior of CAX and CH were investigated. Size exclusion chromatography was used to analyze the molecular size distribution after treatment at different pH's and heating temperatures for different time periods. Treated under boiling and pressure cooking conditions at pH 3, CAX was degraded to a smaller molecular size, whereas the molecular size of the CH showed only a minor decrease. CAX and CH were mostly stable at neutral pH, except when CAX was treated under pressure for 60 min that slightly lowered molecular size. At 37 °C, neither CAX nor CH was adversely affected by treatment at low or neutral pH. The viscosities of solutions containing 5% and 10% of CAX were 48.7 and 637.0 mPa.s, respectively that were higher than those of solutions containing 5% and 10% of its hydrolyzate at shear rate 1 s⁻¹. The CAX solutions showed Newtonian flow behavior, whereas shear-thinning behavior was observed in CH solutions. In conclusion, the hydrolyzate of CAX has potential to be used in high fiber drinks due to its favorable fermentation properties, higher pH and heat stability, lower and shear-thinning viscosity, and lighter color than the native CAX. Arabinoxylan extracted by an alkali from corn bran is a soluble fiber with a desirable low initial and extended fermentation property. Corn arabinoxylan hydrolyzate using an endoxylanase was much more stable at different levels of acidity and heat than the native arabinoxylan, and showed lower solution viscosity and shear-thinning property that indicates its potential as an alternative functional dietary fiber for the beverage industry. © 2011 Institute of Food Technologists®

The physical properties of generic latanoprost ophthalmic solutions are not identical.

PubMed

Kolko, Miriam; Koch Jensen, Peter

2017-06-01

To compare various characteristics of Xalatan ® and five generic latanoprost ophthalmic solutions. Drop size, volume, pH values, buffer capacity, viscosity, hardness of bottles and costs were determined. Drop sizes were measured in triplicates by micropipettes, and the number of drops counted in three separate bottles of each generic product was determined. pH values were measured in triplicates by a calibrated pH meter. Buffer capacity was exploited by titrating known quantities of strong base into 2.5 ml of each brand and interpolated to neutral pH. Kinematic viscosity was determined by linear regression of timed gravity flow from a vertical syringe through a 21-G cannula. The hardness of the bottles was evaluated by gradually increasing tension on a hook placed around each bottle until a drop was expelled reading the tension on an attached spring scale. Drop sizes and the number of drops in the bottles varied significantly between the generic drugs. The control value of pH in the brand version (Xalatan ® ) was markedly lower compared to the generic latanoprost products. Titration of Xalatan ® to neutrality required substantially more NaOH compared to the generic latanoprost products. Finally, the viscosity revealed a significant variability between brands. Remarkable differences were found in bottle shapes, bottle hardness and costs of the latanoprost generics. Generic latanoprost eye drops should not be considered identical to the original brand version as regards to drop size, volumes, pH values, buffer capacity, viscosity, hardness of bottles and costs. It is likely that these issues affect compliance and intraocular pressure (IOP)-lowering effect. Therefore, re-evaluation of the requirements for introducing generic eye drops seems reasonable. © 2017 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

Intrinsic viscosity of binary gum mixtures with xanthan gum and guar gum: Effect of NaCl, sucrose, and pH.

PubMed

Bak, J H; Yoo, B

2018-05-01

The intrinsic viscosity ([η]) values of binary gum mixtures with xanthan gum (XG) and guar gum (GG) mixed with NaCl and sucrose at different concentrations as well as in the presence of different pH levels were examined in dilute solution as a function of XG/GG mixing ratio (100/0, 75/25, 50/50, and 0/100). Experimental values of concentration (C) and relative viscosity (η rel ) or specific viscosity (η sp ) of gums in dilute solution were fitted to five models to determine [η] values of binary gum mixtures including individual gums. A [η] model (η rel =1+[η]C) of Tanglertpaibul and Rao is recommended as the best model to estimate [η] values for the binary gum mixtures with XG and GG as affected by NaCl, sucrose, and pH. Overall, the synergistic interaction of XG-GG mixtures in the presence of NaCl and sucrose showed a greatly positive variation between measured and calculated values of [η]. In contrast, the binary gum mixtures showed synergy only under an acidic condition (pH3). These results suggest that the NaCl and sucrose addition or acidic condition appears to affect the intermolecular interaction occurred between XG and GG at different gum mixing ratios. Copyright © 2018 Elsevier B.V. All rights reserved.

Quality by design approach of a pharmaceutical gel manufacturing process, part 1: determination of the design space.

PubMed

Rosas, Juan G; Blanco, Marcel; González, Josep M; Alcalá, Manel

2011-10-01

This work was conducted in the framework of a quality by design project involving the production of a pharmaceutical gel. Preliminary work included the identification of the quality target product profiles (QTPPs) from historical values for previously manufactured batches, as well as the critical quality attributes for the process (viscosity and pH), which were used to construct a D-optimal experimental design. The experimental design comprised 13 gel batches, three of which were replicates at the domain center intended to assess the reproducibility of the target process. The viscosity and pH models established exhibited very high linearity and negligible lack of fit (LOF). Thus, R(2) was 0.996 for viscosity and 0.975 for pH, and LOF was 0.53 for the former parameter and 0.84 for the latter. The process proved reproducible at the domain center. Water content and temperature were the most influential factors for viscosity, and water content and acid neutralized fraction were the most influential factors for pH. A desirability function was used to find the best compromise to optimize the QTPPs. The body of information was used to identify and define the design space for the process. A model capable of combining the two response variables into a single one was constructed to facilitate monitoring of the process. Copyright © 2011 Wiley-Liss, Inc.

Fermentation of aqueous plant seed extracts by lactic acid bacteria

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

Schafner, D.W.; Beuchat, R.L.

1986-05-01

The effects of lactic acid bacterial fermentation on chemical and physical changes in aqueous extracts of cowpea (Vigna unguiculata), peanut (Arachis hypogea), soybean (Glycine max), and sorghum (Sorghum vulgare) were studied. The bacteria investigated were Lactobacillus helveticus, L. delbrueckii, L. casei, L. bulgaricus, L. acidophilus, and Streptococcus thermophilus. Organisms were inoculated individually into all of the seed extracts; L. bulgaricus and S. thermophilus were also evaluated together as inocula for fermenting the legume extracts. During fermentation, bacterial population and changes in titratable acidity, pH, viscosity, and color were measured over a 72 h period at 37 degrees C. Maximum bacterialmore » populations, titratable acidity, pH, and viscosity varied depending upon the type of extract and bacterial strain. The maximum population of each organism was influenced by fermentable carbohydrates, which, in turn, influenced acid production and change in pH. Change in viscosity was correlated with the amount of protein and titratable acidity of products. Color was affected by pasteurization treatment and fermentation as well as the source of extract. In the extracts inoculated simultaneously with L. bulgaricus and S. thermophilus, a synergistic effect resulted in increased bacterial populations, titratable acidity, and viscosity, and decreased pH in all the legume extracts when compared to the extracts fermented with either of these organisms individually. Fermented extracts offer potential as substitutes for cultured dairy products. 24 references.« less

Evaluation of the synergistic effects of milk proteins in a rapid viscosity analyzer.

PubMed

Stephani, Rodrigo; Borges de Souza, Alisson; Leal de Oliveira, Marcone Augusto; Perrone, Ítalo Tuler; Fernandes de Carvalho, Antônio; Cappa de Oliveira, Luiz Fernando

2015-12-01

Protein systems (PS) are routinely used by companies from Brazil and around the globe to improve the texture, yield, and palatability of processed foods. Understanding the synergistic behavior among the different protein structures of these systems during thermal treatment under the influence of pH can help to better define optimum conditions for products and processes. The interpretation of the reactions and interactions that occur simultaneously among the protein constituents of these systems as dispersions during thermal processing is still a major challenge. Here, using a rapid viscosity analyzer, we observed the rheological changes in the startup viscosities of 5 PS obtained by combining varying proportions of milk protein concentrate and whey protein concentrate under different conditions of pH (5.0, 6.5, and 7.0) and heat processing (85°C/15min and 95°C/5min). The solutions were standardized to 25% of total solids and 17% of protein. Ten analytical parameters were used to characterize each of the startup-viscosity ramps for 35 experiments conducted in a 2×3 × 5 mixed planning matrix, using principal component analysis to interpret behavioral similarities. The study showed the clear influence of pH 5.5 in the elevation of the initial temperature of the PS startup viscosity by at least 5°C, as well as the effect of different milk protein concentrate:whey protein concentrate ratios above 15:85 at pH 7.0 on the viscographic profile curves. These results suggested that the primary agent driving the changes was the synergism among the reactions and interactions of casein with whey proteins during processing. This study reinforces the importance of the rapid viscosity analyzer as an analytical tool for the simulation of industrial processes involving PS, and the use of the startup viscosity ramp as a means of interpreting the interactions of system components with respect to changes related to the treatment temperature. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

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

[Evaluation of the pharmaceutical stability of polaprezinc/sodium alginate gargle solution containing lidocaine].

PubMed

Myotoku, Michiaki; Matsuyama, Tatsuto; Umetani, Ryosuke; Nakamura, Sayaka; Oka, Takashi; Kitade, Naoko; Urashima, Yoko; Hirotani, Yoshihiko

2015-02-01

A gargle solution(L-P/AG)for the treatment of painful stomatitis was prepared by adding lidocaine to a polaprezinc/sodium alginate gargle solution(P/AG), and its pharmaceutical stability was evaluated. L-P/AG was stored at 5, 25, and 40°C. The strengths of polaprezinc and lidocaine were determined. The viscosity and pH of L-P/AG were also determined, and its appearance was evaluated. When stored at 5 or 25°C in a dark place, L-P/AG showed neither reduction in the strength of either drug nor did it show a change in the viscosity, pH, or appearance. When stored exposed to light at 40°C, L-P/AG showed reductions in the strength of both drugs, as well as in viscosity and pH; furthermore, a change in appearance was noted. L-P/AG prepared for the treatment of painful stomatitis remains pharmaceutically stable for 28 days when stored at 25°C in a dark place.

Contrasting the Influence of Cationic Amino Acids on the Viscosity and Stability of a Highly Concentrated Monoclonal Antibody.

PubMed

Dear, Barton J; Hung, Jessica J; Truskett, Thomas M; Johnston, Keith P

2017-01-01

To explain the effects of cationic amino acids and other co-solutes on the viscosity, stability and protein-protein interactions (PPI) of highly concentrated (≥200 mg/ml) monoclonal antibody (mAb) solutions to advance subcutaneous injection. The viscosities of ≥200 mg/ml mAb1 solutions with various co-solutes and pH were measured by capillary rheometry in some cases up to 70,000 s -1 . The viscosities are analyzed in terms of dilute PPI characterized by diffusion interaction parameters (k D ) from dynamic light scattering (DLS). MAb stability was measured by turbidity and size exclusion chromatography (SEC) after 4 weeks of 40°C storage. Viscosity reductions were achieved by reducing the pH, or adding histidine, arginine, imidazole or camphorsulfonic acid, each of which contains a hydrophobic moiety. The addition of inorganic electrolytes or neutral osmolytes only weakly affected viscosity. Systems with reduced viscosities also tended to be Newtonian, while more viscous systems were shear thinning. Viscosity reduction down to 20 cP at 220 mg/ml mAb1 was achieved with co-solutes that are both charged and contain a hydrophobic interaction domain for sufficient binding to the protein surface. These reductions are related to the DLS diffusion interaction parameter, k D , only after normalization to remove the effect of charge screening. Shear rate profiles demonstrate that select co-solutes reduce protein network formation.

[Characteristics, stability and in vitro efficacy of cleaning products for contact lenses].

PubMed

Coiffard, L; Rivalland, P; De Roeck-Holtzhauer, Y

1995-01-01

We characterized some market products designed for cleaning contact lenses and we compared their properties to the main requirements of eye-washes. We performed several physicochemical controls including pH determination, viscosity with a Baume apparatus and the decreasing of the freezing point following the method described by the French Pharmacopea. In addition, we carried out certain analytical controls, concerning three active principles (thiomersal, chlorhexidin digluconate, hydrogen peroxide), at the opening of the different package and after accelerated aging. A microbiological control was performed when opening the product and after a simulation of a 5-day aging. We finally determined the efficacy of the products on four bacterial strains for tests and of deproteinizing products on artificial dust. The pH values obtained ranged from 4.0 (oxygenated water solutions) to 7.8. The viscosity was close to a water solution one. Contents in active substances were usually similar to those stated on the package. At opening, the bacteriological quality was excellent. But, the multidose package were highly contaminated when used. Finally decontaminating efficacy against some germs was very good for the products tested. The results obtained show that the rincing products best answer the eye-wash criteria taken as references. Their main disadvantage is their contamination in the case of multidose packaging.

[Determination of physicochemical characteristics and evaluation of decontaminating efficacy and in vitro safety of cleaning products for contact lenses].

PubMed

Simon, M; Coiffard, L J; Rivalland, P; De Roeck-Holtzhauer, Y

1996-01-01

This work aims to characterize products designed for cleaning contact lenses and particularly their physicochemical properties, their efficiency and their ocular irritancy potential compared to the main requirements of eye-washes. The physicochemical controls include pH determination, viscosity and freezing point depression. In addition, we carried out the hydrogen peroxide assay for products containing this active substance. A microbiological control was performed when opening the product and after simulation of a 21-day aging. We determined the decontaminating efficacy of the products on four bacterial strains and a fungal strain. Finally, we tested their ocular allowance by an in vitro test. The pH values obtained ranged from 3.2 (oxygenated water solutions) to 7.6. The viscosity was close to a water solution one (about 1 centipoise). The different assays showed hydrogen peroxide content similar to that stated on the package: rate averaged to 3% and was negligible after neutralization. At opening and after simulation the bacteriological quality was excellent. Finally, decontaminating efficiency against germs was very good for the products tested. The products were classified as non-irritant by the ocular irritancy test. The results obtained show that the products tested met the reference criteria, particularly eye-wash criteria.

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

Food effect: The combined effect of media pH and viscosity on the gastrointestinal absorption of ciprofloxacin tablet.

PubMed

Radwan, Asma; Zaid, Abdel Naser; Jaradat, Nidal; Odeh, Yousef

2017-04-01

The clinical implications of food-drug interactions may have to be taken seriously into account with oral drugs administration in order to minimize variations in drug bioavailability. Food intake may alter physiological changes in the pH and viscosity of the gastrointestinal lumen, which could affect the oral absorption of drugs. The aim of the present study was to have an insight on the effect of media parameters: viscosity and pHon the oral absorption of ciprofloxacin HCl from solid formulations using a model food: Corchorus olitorius (Jute) Soup. In vitro disintegration and dissolution rates of ciprofloxacin tablet were evaluated using compendia buffer media in the presence/absence of C. olitorius leaves. These in vitro data were then input to GastroPlus™ to predict ciprofloxacin absorption profiles under fasted and fed states. The present study demonstrated the significance of luminal pH and viscosity on the dissolution and disintegration of solid formulations following postprandial ingestion of the viscous soup. The tablets showed prolonged disintegration times and reduced dissolution rates in this soup, which could be attributed to the postprandial elevation in media viscosity and reduced solubility at elevated gastricpH. The predicted model under fed state showed no impact on AUC but prolonged T max and a decrease in C max . Concomitant intake of C. olitorius soup with ciprofloxacin might have negative effect on the rate of drug release from conventional immediate release tablets. Copyright © 2017 Elsevier B.V. All rights reserved.

Field device to measure viscosity, density, and other slurry properties in drilled shafts : final report.

DOT National Transportation Integrated Search

2016-04-01

Proper performance of mineral slurries used to stabilize drilled shaft excavations is maintained by assuring the : density, viscosity, pH, and sand content stay within state specified limits. These limits have been set either by : past experience, re...

Field device to measure viscosity, density, and other slurry properties in drilled shafts [summary].

DOT National Transportation Integrated Search

2016-08-01

Proper performance of the mineral slurries used to stabilize drilled shaft excavations is : maintained by assuring that the density, viscosity, pH, and sand content of the slurry stay : within limits set by the Florida Department of Transportation (F...

Impact of additives on the formation of protein aggregates and viscosity in concentrated protein solutions.

PubMed

Bauer, Katharina Christin; Suhm, Susanna; Wöll, Anna Katharina; Hubbuch, Jürgen

2017-01-10

In concentrated protein solutions attractive protein interactions may not only cause the formation of undesired aggregates but also of gel-like networks with elevated viscosity. To guarantee stable biopharmaceutical processes and safe formulations, both phenomenons have to be avoided as these may hinder regular processing steps. This work screens the impact of additives on both phase behavior and viscosity of concentrated protein solutions. For this purpose, additives known for stabilizing proteins in solution or modulating the dynamic viscosity were selected. These additives were PEG 300, PEG 1000, glycerol, glycine, NaCl and ArgHCl. Concentrated lysozyme and glucose oxidase solutions at pH 3 and 9 served as model systems. Fourier-transformed-infrared spectroscopy was chosen to determine the conformational stability of selected protein samples. Influencing protein interactions, the impact of additives was strongly dependent on pH. Of all additives investigated, glycine was the only one that maintained protein conformational and colloidal stability while decreasing the dynamic viscosity. Low concentrations of NaCl showed the same effect, but increasing concentrations resulted in visible protein aggregation. Copyright © 2016 Elsevier B.V. All rights reserved.

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

Monnai, Akihiko; Mukherjee, Swagato; Yin, Yi

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

Reduction of the viscosity of solutions viscosified with xanthan gum polymers

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

Bridges, K.L.; Kalinski, K.L.

1991-10-08

This patent describes a process for reducing the viscosity of a drilling fluid containing Xanthan gum polymer solution. It comprises: contacting the drilling fluid with hydrogen peroxide and adjusting the pH of the solution to a level of at least about between 8 and 10.

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.

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

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

Debadutta Das; Sagarika Panigrahi; Pramila K. Misra

2008-05-15

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

Mechanism of gas saturated oil viscosity anomaly near to phase transition point

NASA Astrophysics Data System (ADS)

Suleimanov, Baghir A.; Abbasov, Elkhan M.; Sisenbayeva, Marziya R.

2017-01-01

The article presents experimental studies of the phase behavior by the flash liberation test and of the viscosity of the live oil at different pressures. Unlike the typical studies at the pressure near the saturation pressure, the measurements were conducted at a relatively small pressure increment of 0.08-0.25 MPa. The viscosity anomaly was discovered experimentally near to the phase transition point in the range of the pressure levels P/Pb = 1-1.14 (Pb—bubble point pressure) and shows that it decreases about 70 times in comparison to the viscosity at the reservoir pressure. It was found that the bubble point pressure decreases significantly (up to 36%) with surfactant addition. Furthermore, the viscosity of the live oil at the surfactant concentration of 5 wt. % decreases almost 37 times in comparison to the viscosity at the reservoir pressure. The mechanism of observed effects was suggested based on the formation of the stable subcritical gas nuclei and associated slippage effect. The mechanism for the stabilization of the subcritical nuclei by the combined action of the surface and electrical forces, as well as the morphology of the formed nanobubbles, was considered. The model for determining the oil viscosity taking into account the slippage effect was suggested.

Pharmaceutical grade phyllosilicate dispersions: the influence of shear history on floc structure.

PubMed

Viseras, C; Meeten, G H; Lopez-Galindo, A

1999-05-10

The effect of mixing conditions on the flow curves of some clay-water dispersions was studied. Two Spanish fibrous phyllosilicates (sepiolite from Vicálvaro and palygorskite from Turón) and a commercial bentonite (Bentopharm Copyright, UK) were selected as model clays. The disperse systems were made up using a rotor-stator mixer working at two different mixing rates (1000 and 8000 rpm), for periods of 1 and 10 min. Rheological measurements were taken and the corresponding flow curves obtained immediately after interposition and then after a period of 24 h under low shear caused by a roller apparatus. Aqueous sepiolite dispersions showed the highest viscosity and were easily interposed, whereas palygorskite dispersions were more difficult to obtain, resulting in low to medium viscosity gels. Bentonite dispersions provided medium viscosity systems, which greatly increased their viscosity after the low shear treatment (as a result of swelling), whereas the viscosity of the fibrous clays stayed at approximately the same values or even decreased. A linear relation was found between mixing energy and apparent viscosity in the bentonite systems, while apparent viscosity in the sepiolite samples was related to mixing power, with minor influence of mixing times. All the systems studied had thixotropic behaviour, changing from clearly positive to even negative thixotropy in some palygorskite systems. Finally, we studied the effect of drastic pH changes on the system structure. Results showed that rheological properties were highly sensitive to pH in the fibrous dispersions, but less sensitive behaviour was found in the laminar clay systems. Copyright.

Microbiological Characteristic and Nutrition Quality of Goat Milk Kefir Based on Vitamin D3 Fortification Time

NASA Astrophysics Data System (ADS)

Fauziyyah, F.; Panunggal, B.; Afifah, D. N.; Rustanti, N.; Anjani, G.

2018-02-01

Goat milk kefir fortified with vitamin D3 is expected to benefit individual with insulin resistance. Different vitamin D3 fortification time allegedly effect microbiological characteristic and nutrition quality of goat milk kefir due to its microbial growth curve, thus this study aimed to analyze those parameters. This study was an experimental research. This study contains five treatments (vitamin D3 fortification at 0, 6, 12, 18, or 24 hours of fermentation) and a group of control. Total lactic acid bacteria, vitamin D3, protein level, fat contain, crude fiber, viscosity, and pH was analyzed by Total Plate Count, spectrophotometry, Bradford method, Babcock method, gravimetric analysis, Ostwald method, and pH meter respectively. Time of vitamin D3 fortification significantly effect vitamin D3 content (p=0,021), fat content (p=0,001), crude fiber (p=0,0001), viscosity (p=0,010), and total lactic acid bacteria (p=0,048). The highest vitamin D3 content was found on the group fortified at 6 hours of fermentation. All treatment groups has lower fat content and crude fiber content than control group. Total LAB in all group meet the Codex standard (≥ 107 CFU/ml). Control group and fortification group at 24 hours of fermentation have higher viscosity than other groups. There was no significant difference found in goat milk kefir protein level (p=0,262) and pH (p=0,056) despite the difference of fortification time. Vitamin D3 fortification time effect vitamin D3 content, fat content, crude fiber, viscosity, and total lactic acid bacteria of goat milk kefir, but did not effect protein content and pH of goat milk kefir.

Representing ductile damage with the dual domain material point method

DOE PAGES

Long, C. C.; Zhang, D. Z.; Bronkhorst, C. A.; ...

2015-12-14

In this study, we incorporate a ductile damage material model into a computational framework based on the Dual Domain Material Point (DDMP) method. As an example, simulations of a flyer plate experiment involving ductile void growth and material failure are performed. The results are compared with experiments performed on high purity tantalum. We also compare the numerical results obtained from the DDMP method with those obtained from the traditional Material Point Method (MPM). Effects of an overstress model, artificial viscosity, and physical viscosity are investigated. Our results show that a physical bulk viscosity and overstress model are important in thismore » impact and failure problem, while physical shear viscosity and artificial shock viscosity have negligible effects. A simple numerical procedure with guaranteed convergence is introduced to solve for the equilibrium plastic state from the ductile damage model.« less

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.

Two-Point Microrheology of Phase-Separated Domains in Lipid Bilayers

PubMed Central

Hormel, Tristan T.; Reyer, Matthew A.; Parthasarathy, Raghuveer

2015-01-01

Though the importance of membrane fluidity for cellular function has been well established for decades, methods for measuring lipid bilayer viscosity remain challenging to devise and implement. Recently, approaches based on characterizing the Brownian dynamics of individual tracers such as colloidal particles or lipid domains have provided insights into bilayer viscosity. For fluids in general, however, methods based on single-particle trajectories provide a limited view of hydrodynamic response. The technique of two-point microrheology, in which correlations between the Brownian dynamics of pairs of tracers report on the properties of the intervening medium, characterizes viscosity at length-scales that are larger than that of individual tracers and has less sensitivity to tracer-induced distortions, but has never been applied to lipid membranes. We present, to our knowledge, the first two-point microrheological study of lipid bilayers, examining the correlated motion of domains in phase-separated lipid vesicles and comparing one- and two-point results. We measure two-point correlation functions in excellent agreement with the forms predicted by two-dimensional hydrodynamic models, analysis of which reveals a viscosity intermediate between those of the two lipid phases, indicative of global fluid properties rather than the viscosity of the local neighborhood of the tracer. PMID:26287625

Effect of Carboxymethylation on the Rheological Properties of Hyaluronan

PubMed Central

Wendling, Rian J.; Christensen, Amanda M.; Quast, Arthur D.; Atzet, Sarah K.; Mann, Brenda K.

2016-01-01

Chemical modifications made to hyaluronan to enable covalent crosslinking to form a hydrogel or to attach other molecules may alter the physical properties as well, which have physiological importance. Here we created carboxymethyl hyaluronan (CMHA) with varied degree of modification and investigated the effect on the viscosity of CMHA solutions. Viscosity decreased initially as modification increased, with a minimum viscosity for about 30–40% modification. This was followed by an increase in viscosity around 45–50% modification. The pH of the solution had a variable effect on viscosity, depending on the degree of carboxymethyl modification and buffer. The presence of phosphates in the buffer led to decreased viscosity. We also compared large-scale production lots of CMHA to lab-scale and found that large-scale required extended reaction times to achieve the same degree of modification. Finally, thiolated CMHA was disulfide crosslinked to create hydrogels with increased viscosity and shear-thinning aspects compared to CMHA solutions. PMID:27611817

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.

Opening a Can of Worm(‐like Micelle)s: The Effect of Temperature of Solutions of Functionalized Dipeptides

PubMed Central

Draper, Emily R.; Su, Hao; Brasnett, Christopher; Poole, Robert J.; Rogers, Sarah; Cui, Honggang; Seddon, Annela

2017-01-01

Abstract A simple heat/cool cycle can be used to significantly affect the properties of a solution of a low‐molecular‐weight gelator at high pH. The viscosity and extensional viscosity are increased markedly, leading to materials with very different properties than when the native solution is used. PMID:28653804

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.

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.

A comparison of capillary and rotational viscometry of aqueous solutions of hypromellose.

PubMed

Sklubalová, Z; Zatloukal, Z

2007-10-01

A comparison of capillary and rotational viscometry of gentle pseudoplastic solutions of hypromellose (HPMC 4000) by using only single-point value of viscosity is difficult. Single-point comparison becomes topical in consequence to the pharmacopoeial requirement that the apparent viscosity of 2% hypromellose solution should be read at the shear rate of approximately 10 s(-1). This communication is focused on the estimation of the suitable shear rate, D eta, at which the apparent viscosity read using the rotational viscometer is numerically equal to the dynamic viscosity read using a capillary viscometer. For the solutions of HPMC in concentrations up to 2% w/v, the non-linear regression equations generated showed the influencing of the D eta value by the dynamic viscosity and/or by the originally derived linear velocity of the solution flowing through the capillary viscometer tube. To compare the apparent viscosity read using the rotational viscometer with the dynamic viscosity read using capillary viscometer, the exact estimation of the shear rate D eta at which both viscosities are numerically equal is essential since it is markedly affected by the concentration of HPMC solution.

Formulation and in vitro evaluation of cysteamine hydrochloride viscous solutions for the treatment of corneal cystinosis.

PubMed

Bozdağ, Sibel; Gümüş, Koray; Gümüş, Ozlem; Unlü, Nurşen

2008-09-01

In the present study, viscous solutions of cysteamine hydrochloride (CH) were prepared by using 0.5%, 1.0%, 1.5% or 3.0% of hydroxypropylmethylcellulose (HPMC) and were evaluated for their in-vitro characteristics and stability. Osmolalities, pH and viscosity of the formulations were determined. The influence of benzalkonium chloride and autoclave sterilization on solution characteristics was also investigated. For stability assessment, the viscous solutions were stored at +4 and +25 degrees C over 12 months. In-vitro characteristics and CH contents of the stored solutions were monitored. Irritation tests for the formulations were evaluated on rabbit eyes. Dialysis sac technique was used to perform in vitro release study of the solutions containing 1.0% and 1.5% HPMC. All of the viscous solutions tested showed non-newtonian (dilatant) flow behavior. Osmolality values were ranked between 351.2+/-6.2 and 355.1+/-7.9 mOsm kg(-1), and pH values were between 3.97+/-0.1 and 3.98+/-0.2 for all the solutions. Furthermore, no significant changes in dilatant behavior, osmolality or pH values of the pure HPMC solutions were observed. After addition of the excipients or CH-excipients, increased viscosity values were noted in these formulations. Neither benzalkonium chloride nor autoclave sterilization had any influence on viscosity, pH or osmolality values of the solution containing 1.5% HPMC. Stability studies showed that a faster decrease in the concentration of CH was observed in the formulations stored at 25 degrees C compared to those kept at 4 degrees C; no changes were determined in osmolality values of the solutions at all storage conditions. Increased pH and decreased viscosity values were noted in HPMC solutions containing CH and excipients, while no changes in these values were observed for pure HPMC solutions kept at 4 and 25 degrees C. In vitro release tests revealed that 81.2% and 85.3% of CH were released from the viscous solutions containing 1.5% and 1% HPMC, respectively, in 8h. No irritation was observed when the viscous solutions were tested on rabbit and human eyes.

Effect of pH on turbidity, size, viscosity and the shape of sodium caseinate aggregates with light scattering and rheometry.

PubMed

Ghorbani Gorji, Sara; Ghorbani Gorji, Elham; Mohammadifar, Mohammad Amin

2015-03-01

The characterization of sodium caseinate solutions as a function of pH was determined using titration with HCL through turbidimetry in different concentrations (0.03 wt.%, 0.045 wt.%, 0.06 wt.%, 0.09 wt.%, 0.2 wt.%, and 0.3 wt.%). Additionally, the coupling of slow in situ acidification of the solution and rheometry was utilized to gain deeper insights into pH-induced structural transitions during the self assembly process and particle size distribution analysis have been used to determine the behavior of sodium caseinate solutions in different pHs. The formation of aggregates during the acidification process was clearly visualized using microscopy. Surprisingly the viscosity of sodium caseinate solution at pH 4.64 was maximum and decreased by lowering pH. Particle size analysis confirmed the onset of big aggregates on decreasing pH but further acidification led to formation of smaller aggregates. A small concentration effect on pI was seen where at sodium caseinate levels of 0.03 wt.% the pI occurred at 4.29, where at sodium caseinate levels of 0.30 wt.% pI value was 4.64.

Relationship between Physicochemical Properties of Saliva and Dental Caries and Periodontal Status among Female Teachers Living in Central Iran

PubMed Central

Hosseini-Yekani, Amene; Nadjarzadeh, Azadeh; Vossoughi, Mehrdad; Reza, Javad Zavvar; Golkari, Ali

2018-01-01

Objectives: There are inconsistent data about the association between saliva properties, dental caries, and periodontal status. In this study, we tried to examine the association between dental caries and periodontal status with salivary viscosity, flow rate, pH, and buffering capacity in adults. Methods: In the present cross-sectional study, 450 female teachers were randomly selected from schools located in Yazd, Iran. Oral examinations were conducted, and unstimulated saliva samples were collected. Salivary viscosity, flow rate, pH, and buffering capacity were assessed. The salivary physicochemical properties were compared among teachers with different types of oral health. Analyses were done using the Statistical Package for the Social Sciences version 16. Results: In total, 431 female teachers aged 40.45 ± 8.18 years were included in the study. Salivary flow rate, buffering capacity, pH, and viscosity, community periodontal index status were not significantly different in participants with and without tooth caries. There was a reverse linear association between salivary pH and flow rate with the decayed, missed, and filled teeth index (P < 0.05). The saliva buffering capacity was not significantly related to dental properties. Those with bleeding on probing had lower salivary pH, and buffering capacity compared to those with healthy gum. However, the salivary resting flow rate was not different in participants with bleeding on probing and healthy participants. Conclusion: Based on our results, saliva properties might be important predictors in oral health status. This means that any change in saliva combination might affect periodontal and dental diseases. Future prospective studies are recommended to confirm these results. PMID:29629329

In vitro analysis of the physical properties of contact lens blister pack solutions.

PubMed

Menzies, Kara L; Jones, Lyndon

2011-04-01

Since the initial development of silicone hydrogels, many modifications to the bulk and surface properties of the lenses have been undertaken to improve the wettability and comfort of the lenses. Recently, manufacturers have incorporated various "wetting agents" or surface-active agents into the blister packaging solutions (BPSs) of the lenses to improve initial comfort of the lens on eye. The purpose of this study was to measure and compare the pH, surface tension (ST), viscosity, and osmolality of BPSs for a variety of silicone hydrogel and polyHEMA-based hydrogel lenses. In addition, two saline solutions were tested for comparison purposes. The pH, osmolality, ST, and viscosity were measured for the BPSs for lotrafilcon B and lotrafilcon A and lotrafilcon B with a "modified BPS" (m-lotrafilcon A, m-lotrafilcon B) (CIBA Vision, Duluth, GA); balafilcon A (Bausch & Lomb, Rochester, NY); galyfilcon A, senofilcon A, and narafilcon A (Johnson & Johnson, Jacksonville, FL); and comfilcon A and enfilcon A (CooperVision, Pleasanton, CA) and BPSs from two conventional polyHEMA-based materials-etafilcon A (Johnson & Johnson) and omafilcon A (CooperVision). The two saline solutions tested were Unisol (Alcon, Fort Worth, TX) and Softwear Saline (CIBA Vision). The pH results for the two saline solutions and all BPSs remained in the pH range of tears (6.6-7.8). The ST of the modified BPS was significantly lower (p < 0.01) than the original non-modified BPS. Viscosity measurements ranged between 0.90 and 1.00 cP for all BPSs and saline solutions, except for the modified BPS, which had significantly higher viscosities (p < 0.001). Osmolality measurements were not significantly different (p > 0.05) between BPSs made by the same manufacturer but were significantly different compared with BPSs made by different manufacturers (p < 0.05). The incorporation of wetting agents and surfactants into BPSs does alter the physical properties of the BPSs, which may have clinical implications regarding initial in-eye comfort.

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.

Rheological Properties of Aqueous Colloidal Silica Suspensions Related to Amendment Delivery for Subsurface Remediation

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

Yang, Shuo; Zhong, Lirong; Li, Guanghe

Colloidal silica (fumed silica) suspensions are being tested as carriers for remedial amendment delivery in subsurface remediation and as media for underground contamination containment. The knowledge of the rheological behavior of the silica suspensions is lack in the literature while it is essential for the preparation and field injection of the suspensions. This contribution is focused on the rheological characteristics of colloidal silica suspensions under various environmental conditions relevant to amendment delivery for subsurface remediation. We investigated the influence of silica particle concentration, water source, ionic strength, pH, aging, amendment type and concentration, and subsurface sediment on the rheological behaviormore » of the suspensions. All tested suspension formulations exhibited shear thinning before gelation. Higher silica particle concentration and salinity (Na+ and K+) increased suspensions’ viscosity and the degree of shear thinning. The viscosity of suspensions increased with aging. The suspensions at natural pH exhibited the highest viscosity compared to the acidic and alkaline suspensions with the same silica concentration. Addition of KMnO4 amendment to aqueous silica suspensions increased viscosity, while addition of alcohol amendment decreased suspensions’ viscosity. The presence of amendment did not reduce shear thinning. The gelation rate of silica suspensions was increased with silica concentration and with the addition of sediments. The rheological characteristics of shear thinning aqueous fumed silica suspensions were compared to that of shear thinning solutions formed with organic polymer xanthan gum, which was applied for amendment delivery in subsurface remediation.« less

PH Sensitive Polymers for Improving Reservoir Sweep and Conformance Control in Chemical Flooring

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

Mukul Sharma; Steven Bryant; Chun Huh

There is an increasing opportunity to recover bypassed oil from depleted, mature oilfields in the US. The recovery factor in many reservoirs is low due to inefficient displacement of the oil by injected fluids (typically water). The use of chemical flooding methods to increase recovery efficiencies is severely constrained by the inability of the injected chemicals to contact the bypassed oil. Low sweep efficiencies are the primary cause of low oil recoveries observed in the field in chemical flooding operations even when lab studies indicate high oil recovery efficiency. Any technology that increases the ability of chemical flooding agents tomore » better contact the remaining oil and reduce the amount of water produced in conjunction with the produced oil will have a significant impact on the cost of producing oil domestically in the US. This translates directly into additional economically recoverable reserves, which extends the economic lives of marginal and mature wells. The objective of this research project was to develop a low-cost, pH-triggered polymer for use in IOR processes to improve reservoir sweep efficiency and reservoir conformance in chemical flooding. Rheological measurements made on the polymer solution, clearly show that it has a low viscosity at low pH and exhibits a sudden increase in viscosity (by 2 orders of magnitude or more) at a pH of 3.5 to 4. This implies that the polymer would preferentially flow into zones containing water since the effective permeability to water is highest in these zones. As the pH of the zone increases due to the buffering capacity of the reservoir rock, the polymer solution undergoes a liquid to gel transition causing a sharp increase in the viscosity of the polymer solution in these zones. This allows operationally robust, in-depth conformance treatment of such water bearing zones and better mobility control. The rheological properties of HPAM solutions were measured. These include: steady-shear viscosity and viscoelastic behavior as functions of pH; shear rate; polymer concentration; salinity, including divalent ion effects; polymer molecular weight; and degree of hydrolysis. A comprehensive rheological model was developed for HPAM solution rheology in terms of: shear rate; pH; polymer concentration; and salinity, so that the spatial and temporal changes in viscosity during the polymer flow in the reservoir can be accurately modeled. A series of acid coreflood experiments were conducted to understand the geochemical reactions relevant for both the near-wellbore injection profile control and for conformance control applications. These experiments showed that the use hydrochloric acid as a pre-flush is not viable because of the high reaction rate with the rock. The use of citric acid as a pre-flush was found to be quite effective. This weak acid has a slow rate of reaction with the rock and can buffer the pH to below 3.5 for extended periods of time. With the citric acid pre-flush the polymer could be efficiently propagated through the core in a low pH environment i.e. at a low viscosity. The transport of various HPAM solutions was studied in sandstones, in terms of permeability reduction, mobility reduction, adsorption and inaccessible pore volume with different process variables: injection pH, polymer concentration, polymer molecular weight, salinity, degree of hydrolysis, and flow rate. Measurements of polymer effluent profiles and tracer tests show that the polymer retention increases at the lower pH. A new simulation capability to model the deep-penetrating mobility control or conformance control using pH-sensitive polymer was developed. The core flood acid injection experiments were history matched to estimate geochemical reaction rates. Preliminary scale-up simulations employing linear and radial geometry floods in 2-layer reservoir models were conducted. It is clearly shown that the injection rate of pH-sensitive polymer solutions can be significantly increased by injecting it at a pH below 3.5 (at a fixed bottom-hole pressure). This improvement in injectivity by a factor of 2 to 10 can have a significant impact on the economics of chemical flooding and conformance control applications. Simulation tools and experimental data presented in this report help to design and implement such polymer injection projects.« less

Yogurt fermentation in the presence of starch-lipid composite.

PubMed

Singh, M; Kim, S

2009-03-01

The fermentation of yogurt in the presence of 0.5%, 1.0%, 1.5%, and 2.0% starch-lipid composite (SLC) was investigated. The pH, viscosity, and morphology of the mix were monitored during the fermentation process. The rate of drop in pH with time during incubation was not affected by the addition of SLC. However, it was found that the presence of SLC caused faster aggregation, which was clearly evidenced by the viscosity variation during the process of fermentation. An examination of the morphologies confirmed that aggregation occurred earlier in the presence of SLC and SLC did not form phase-separated domains. This study concludes that SLC would serve as a good additive (fat replacer and stabilizer) for the production of yogurt.

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.

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.

Possible ambiguities when testing viscosity in compendial monographs - characterisation of grades of cellulose ethers.

PubMed

Doelker, E

2010-10-01

The European Pharmacopoeia (Ph. Eur.) monographs for the water-soluble cellulose ethers require viscosity determination, either in the "Tests" section or in the non-mandatory "Functionality-related characteristics" section. Although the derivatives are chemically closely related and used for similar applications, the viscosity tests strongly differ. Some monographs generically speak of the rotating viscometer method (2.2.10) and a fixed shear rate (e.g. 10 s-1), which would necessitate an absolute measuring system, while others recommend the capillary viscometer method for product grades of less than 600 mPa∙s and the rotating viscometer method and given operating conditions for grades of higher nominal viscosity. Viscometer methods also differ between the United States Pharmacopeia/National Formulary (USP/NF) and the Japanese Pharmacopoeia (JP) monographs. In addition, for some cellulose ethers the tests sometimes diverge from one pharmacopoeia to the other, although the three compendiums are in a harmonisation process. But the main issue is that the viscometer methods originally employed by the product manufacturers are often not those described in the corresponding monographs and generally vary from one manufacturer to the other. The aim of this study was therefore to investigate whether such a situation could invalidate the present pharmacopoeial requirements. 2 per cent solutions of several viscosity grades of hydroxyethylcellulose, hypromellose and methylcellulose were prepared and their (apparent) viscosity determined using both relative and absolute viscometer methods. The viscometer method used not only affects the measured viscosity but experimental values generally do not correspond to the product nominal viscosities. It emerges that, in contrast to Newtonian solutions (i.e. those of grades of up to ca. 50 mPa∙s nominal viscosity), some of the viscometer methods currently specified in the monographs are not able unambiguously to characterise the grades exhibiting non-Newtonian behaviour. It is also concluded that, unless the various manufacturers redefine their product viscosity grades using a single compendial test, two strategies could be adopted, both based on the operating conditions specified in the labeling (i.e those of the manufacturer), the test appearing either in the mandatory section if this is acceptable to the pharmacopoeia (like in some USP/NF monographs) or, for the Ph. Eur., in the "Functionality-related characteristics" section.

An acidic pH independent piperazine–TPE AIEgen as a unique bioprobe for lysosome tracing† †Electronic supplementary information (ESI) available: NMR, single crystal X-ray crystallography of PIP–TPE, live cell and fixed cell fluorescence imaging, MTT, photostability, and theoretical calculations. CCDC 1555412. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c7sc03515b

PubMed Central

Cai, Yuanjing; Gui, Chen; Samedov, Kerim; Su, Huifang; Gu, Xinggui; Li, Shiwu; Luo, Wenwen; Sung, Herman H. Y.; Lam, Jacky W. Y.; Kwok, Ryan T. K.; Williams, Ian D.

2017-01-01

Lysosomes are involved in a multitude of cellular processes and their dysfunction is associated with various diseases. They are the most acidic organelles (pH 3.8–6.6, size 0.1–1.2 μm) with the highest viscosity (47–190 cP at 25 °C) in the cell. Because of their acidity, pH dependent non-AIE active fluorescent lysosomal probes have been developed that rely on protonation inhibited photoinduced electron transfer (PET). In this work, an acidic pH independent lysosome targetable piperazine–TPE (PIP–TPE) AIEgen has been designed with unique photophysical properties making it a suitable probe for quantifying viscosity. In a non-aggregated state PIP–TPE shows deep-blue emission as opposed to its yellowish-green emission in the bulk. It possesses high specificity for lysosomes with negligible cytotoxicity and good tracing ability due to its better photostability compared to LysoTracker Red. In contrast to most known lysosome probes that rely solely on PET, restriction of intramolecular motion (RIM) due to the larger viscosity inside the lysosomes is the mechanism responsible for PIP–TPE’s fluorescence. PIP–TPE’s high selectivity is attributed to its unique molecular design that features piperazine fragments providing a perfect balance between lipophilicity and polarity. PMID:29568423

Two-point active microrheology in a viscous medium exploiting a motional resonance excited in dual-trap optical tweezers

NASA Astrophysics Data System (ADS)

Paul, Shuvojit; Kumar, Randhir; Banerjee, Ayan

2018-04-01

Two-point microrheology measurements from widely separated colloidal particles approach the bulk viscosity of the host medium more reliably than corresponding single-point measurements. In addition, active microrheology offers the advantage of enhanced signal to noise over passive techniques. Recently, we reported the observation of a motional resonance induced in a probe particle in dual-trap optical tweezers when the control particle was driven externally [Paul et al., Phys. Rev. E 96, 050102(R) (2017), 10.1103/PhysRevE.96.050102]. We now demonstrate that the amplitude and phase characteristics of the motional resonance can be used as a sensitive tool for active two-point microrheology to measure the viscosity of a viscous fluid. Thus, we measure the viscosity of viscous liquids from both the amplitude and phase response of the resonance, and demonstrate that the zero crossing of the phase response of the probe particle with respect to the external drive is superior compared to the amplitude response in measuring viscosity at large particle separations. We compare our viscosity measurements with those using a commercial rheometer and obtain an agreement ˜1 % . The method can be extended to viscoelastic material where the frequency dependence of the resonance may provide further accuracy for active microrheological measurements.

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

Study on fracturing flowback fluid treatment technology for shale gas in Yangzhou

NASA Astrophysics Data System (ADS)

Shi, Shengwei; Du, Jiajia; Kang, Dingyu; Chen, Xinjian; Qu, Chengtun; Yu, Tao

2018-02-01

Shale gas fracturing flowback fluid has the characteristics of high viscosity, large displacement, complex components and difficult to deal with. Therefore, it is of great significance for environmental protection to treat and reuse it. In this paper, Yangzhou shale gas is taken as an object to study the treatment of shale gas fracturing flowback fluid. The results shown that the viscosity of the fracturing flowback fluid before treatment was 16.75mPa·s, and when the pH was adjusted to 3.5, with Cerium(III) sulfate and ferrous sulfate as catalyst and the dosage were 60mg/L and 120 mg/L respectively, and hydrogen peroxide dosage was 0.5%, the viscosity of fracturing folwback fluid was reduced from 16.75mPa·s to 1.97mPa·s After the oxidation treatment, adjusting pH to 7.5, and treating it with inorganic flocculant and organic flocculant, the water quality met the reinjection requirement of the average air permeability of less than or equal to 0.01 μm2.

Effect of Incubation Time and Sucrose Addition on the Characteristics of Cheese Whey Yoghurt

NASA Astrophysics Data System (ADS)

Nurhartadi, E.; Utami, R.; Nursiwi, A.; Sari, A. M.; Widowati, E.; Sanjaya, A. P.; Esnadewi, E. A.

2017-04-01

The effect of incubation time and concentration of sucrose addition on the characteristics of cheese whey yogurt (lactic acid content, pH, total lactic acid bacteria, antioxidant activity, viscosity) and sensory characteristics (color, odor, flavor, consistency, and overalls) were investigated. The cheese whey yogurt fermentation process was carried out for 24h and 36h with the addition of sucrose 8, 10, and 12% (w/w) of total solid, respectively. The results showed that the lactic acid content, total lactic acid bacteria, antioxidant activity, and viscosity of cheese whey yogurt were affected by the incubation time and sucrose addition. The level of pH of yogurt which was incubated at 24h and 36h were relatively in the same levels, which were 4.51 up to 4.63. Due the sensory characteristic of cheese whey yogurt the panellists gave the high score for the cheese whey yogurt which was incubated at 24h and sucrose addition 12% (w/w) of total solid. The cheese whey yogurt has 0.41% lactic acid content; pH 4.51; 7.09 log total lactic acid bacteria cells / ml; 5.78% antioxidant activity; and 5.97 cP viscosity. The best sensory and physico-chemical characteristic of cheese whey yogurt was achieved by 24h incubation time and 12% concentration of sucrose addition.

Progress on Acoustic Measurements of the Bulk Viscosity of Near-Critical Xenon (BVX)

NASA Technical Reports Server (NTRS)

Gillis, Keith A.; Shinder, Iosif I.; Moldover, Michael R.; Zimmerli, Gregory A.

2004-01-01

We plan to determine the bulk viscosity of xenon 10 times closer [in reduced temperature tau = (T-Tc)/Tc] to its liquid-vapor critical point than ever before. (Tc is the critical temperature.) To do so, we must measure the dispersion and attenuation of sound at frequencies 1/100 of those used previously. In general, sound attenuation has contributions from the bulk viscosity acting throughout the volume of the xenon as well as contributions from the thermal conductivity and the shear viscosity acting within thin thermoacoustic boundary layers at the interface between the xenon and the solid walls of the resonator. Thus, we can determine the bulk viscosity only when the boundary layer attenuation is small and well understood. We present a comparison of calculations and measurements of sound attenuation in the acoustic boundary layer of xenon near its liquid-vapor critical point.

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

PubMed

Raut, Ashlesha S; Kalonia, Devendra S

2016-01-01

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

A Model for Hydrogen Thermal Conductivity and Viscosity Including the Critical Point

NASA Technical Reports Server (NTRS)

Wagner, Howard A.; Tunc, Gokturk; Bayazitoglu, Yildiz

2001-01-01

In order to conduct a thermal analysis of heat transfer to liquid hydrogen near the critical point, an accurate understanding of the thermal transport properties is required. A review of the available literature on hydrogen transport properties identified a lack of useful equations to predict the thermal conductivity and viscosity of liquid hydrogen. The tables published by the National Bureau of Standards were used to perform a series of curve fits to generate the needed correlation equations. These equations give the thermal conductivity and viscosity of hydrogen below 100 K. They agree with the published NBS tables, with less than a 1.5 percent error for temperatures below 100 K and pressures from the triple point to 1000 KPa. These equations also capture the divergence in the thermal conductivity at the critical point

Industrial yogurt manufacture: monitoring of fermentation process and improvement of final product quality.

PubMed

Soukoulis, C; Panagiotidis, P; Koureli, R; Tzia, C

2007-06-01

Lactic acid fermentation during the production of skim milk and whole fat set-style yogurt was continuously monitored by measuring pH. The modified Gompertz model was successfully applied to describe the pH decline and viscosity development during the fermentation process. The viscosity and incubation time data were also fitted to linear models against ln(pH). The investigation of the yogurt quality improvement practices included 2 different heat treatments (80 degrees C for 30 min and 95 degrees C for 10 min), 3 milk protein fortifying agents (skim milk powder, whey powder, and milk protein concentrate) added at 2.0%, and 4 hydrocolloids (kappa-carrageenan, xanthan, guar gum, and pectin) added at 0.01% to whole fat and skim yogurts. Heat treatment significantly affected viscosity and acetaldehyde development without influencing incubation time and acidity. The addition of whey powder shortened the incubation time but had a detrimental effect on consistency, firmness, and overall acceptance of yogurts. On the other hand, addition of skim milk powder improved the textural quality and decreased the vulnerability of yogurts to syneresis. Anionic stabilizers (kappa-carrageenan and pectin) had a poor effect on the texture and palatability of yogurts. However, neutral gums (xanthan and guar gum) improved texture and prevented the wheying-off defect. Skim milk yogurts exhibited longer incubation times and higher viscosities, whereas they were rated higher during sensory evaluation than whole fat yogurts.

Physical and monolayer film properties of potential fatty ester biolubricants

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

Yao, Linxing; Hammond, Earl G; Wang, Tong

2014-04-03

The desire to replace petroleum-based lubricants with alternatives that are environmentally friendly and made from sustainable sources has encouraged the development of biolubricants based on vegetable oils. To be good lubricants, the materials should have low melting points, appropriate viscosity and oxidative stability. In this paper, we report the melting point and viscosity of oleate esters of ethylene glycol, 1,2-propanediol, 2,3-butanediol, and pentaerythritol as well as the decanoate esters of 2,3-butanediol and the 12-methyltetradecanoate esters of 1,2-propanediol. Polyol esters that have a free hydroxy group had lower melting points than the completely esterified polyols, but the completely esterified polyol estersmore » exhibited less change in viscosity with temperature than those having a free hydroxy group. 2, 3-Butanediol monooleate, which melted at -48.6°C shows promise as a biolubricant, but its viscosity index was estimated to be 100. Pentaerythritol oleate esters, with melting points below -10°C and viscosity indices in the range of 170–197, may be suitable candidates as biolubricants. The behavior of esters spread as a monomolecular film at air/water interface may provide insight into the way they behave when spread on metal or polar surfaces, so the pressure-area isotherms of 2,3-butanediol monoleate and selected esters are also reported.« less

Science Requirements for a Space Flight Experiment Entitled Critical Viscosity of Xenon

NASA Technical Reports Server (NTRS)

Berg, Robert F.; Moldover, Michael R.

1993-01-01

We propose to measure in low gravity the viscosity of xenon close to its critical point. The accuracy will be sufficient to eliminate uncertainties currently associated with the analysis of l-g experiments. The measurements will provide the first direct observation of the predicted power-law divergence of viscosity in a pure fluid. The measurements will also strengthen Zeno's test of mode coupling theory by greatly increasing the reliability of the extrapolation of viscosity to low reduced temperatures. Our scientific objectives are described in more detail in one of the attached reports. The low-gravity experiment will be the final stage of a program whose completed ground-based stages are: (1) theoretical studies by one of the principal investigators (MRM) and coworkers, (2) critical viscosity measurements of binary liquid mixtures, (3) critical viscosity measurements of pure fluids in l-g, and development of a suitable vibration-insensitive viscometer. Our technical approach is described in the draft Science Requirements Document. One of us (MRM) has reviewed opportunities for critical phenomena research in low gravity. Both of us were co-principal investigators in the Thermal Equilibration Experiment in the Critical Point Facility, flown on IML-1 in 1992. From this experience, and from the technical maturity of our ground-based work, we believe our critical point viscometer is ready for development as a flight experiment.

Mechanistic Insights into Dye-Decolorizing Peroxidase Revealed by Solvent Isotope and Viscosity Effects

PubMed Central

Shrestha, Ruben; Huang, Gaochao; Meekins, David A.; Geisbrecht, Brian V.; Li, Ping

2017-01-01

Dye-decolorizing peroxidases (DyPs) are a family of H2O2-dependent heme peroxidases, which have shown potential applications in lignin degradation and valorization. However, the DyP kinetic mechanism remains underexplored. Using structural biology and solvent isotope (sKIE) and viscosity effects, many mechanistic characteristics have been uncovered for the B-class ElDyP from Enterobacter lignolyticus. Its structure revealed that a water molecule acts as the sixth axial ligand with two channels at diameters of ~3.0 and 8.0 Å leading to the heme center. A conformational change of ERS* to ERS, which have identical spectral characteristics, was proposed as the final step in DyPs’ bisubstrate Ping-Pong mechanism. This step is also the rate-determining step in ABTS oxidation. The normal KIE of wild-type ElDyP with D2O2 at pH 3.5 suggested that cmpd 0 deprotonation by the distal aspartate is rate-limiting in the formation of cmpd I, which is more reactive under acidic pH than under neutral or alkaline pH. The viscosity effects and other biochemical methods implied that the reducing substrate binds with cmpd I instead of the free enzyme. The significant inverse sKIEs of kcat/KM and kERS* suggested that the aquo release in DyPs is mechanistically important and may explain the enzyme’s adoption of two-electron reduction for cmpd I. The distal aspartate is catalytically more important than the distal arginine and plays key roles in determining DyPs’ acidic pH optimum. The kinetic mechanism of D143H-ElDyP was also briefly studied. The results obtained will pave the way for future protein engineering to improve DyPs’ lignolytic activity. PMID:29308295

Measurement of Viscosity of Reacting Vinyl-Ester Resins Using Direct-Current Sensing

DTIC Science & Technology

2000-01-01

ARMY RESEARCH LABORATORY ___ ^:5T",g?"r/:"/:^SS^ fö’^^;^>.^.^^^^M^^^^^; Measurement of Viscosity of Reacting Vinyl-Ester Resins Using Direct...under development at the U.S. Army Research Laboratory (ARL) is sensors mounted as roving threads (SMARTweave), a patented sensor system that...in viscosity characterizes the initial stages of chain polymerization reaction. The point at which viscosity tends toward infinity is gelation and is

Microgravity

NASA Image and Video Library

2001-01-24

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.

A comparative analysis of salivary factors and maxillary denture retention in different arch forms: An in vivo study.

PubMed

Shekhar, Abhishek; Das, Samiran; Bhattacharyya, Jayanta; Goel, Preeti; Majumdar, Sayan; Ghosh, Soumitra

2018-01-01

This study aims to find the effect of change in different salivary factors before and after complete denture insertion and to measure the maxillary denture retention in different arch forms. Thirty completely edentulous individuals (10 each of square, tapered, and ovoid arch form of maxilla) belonging to the age group of 40-70 years were selected. Salivary factors (flow, density, pH, viscosity, and total protein) were evaluated before and after denture insertion. Retention of maxillary denture was measured in all the different arch forms. Student's independent sample's t -test was applied. The correlation was analyzed by Pearson's correlation analysis. While mean flow rate and pH of saliva increased, mean viscosity, total protein, and density of saliva decreased after maxillary complete denture insertion. A positive correlation was found between retention and total maxillary basal surface area. Retention value was found to be greatest in square type and least in tapered type. Complete denture acts as a mechanical stimulant thus increasing flow rate and pH immediately after complete denture insertion. Density, total protein, and viscosity of saliva decreased after complete denture insertion which may be due to increase in water content of saliva. The retention of maxillary complete denture does not seem to depend on the rate of change of the salivary factors, before and after complete denture insertion. Total basal surface area and maxillary denture retention values were highest in square arch form and least in tapered arch form.

Development of performance matrix for generic product equivalence of acyclovir topical creams.

PubMed

Krishnaiah, Yellela S R; Xu, Xiaoming; Rahman, Ziyaur; Yang, Yang; Katragadda, Usha; Lionberger, Robert; Peters, John R; Uhl, Kathleen; Khan, Mansoor A

2014-11-20

The effect of process variability on physicochemical characteristics and in vitro performance of qualitatively (Q1) and quantitatively (Q2) equivalent generic acyclovir topical dermatological creams was investigated to develop a matrix of standards for determining their in vitro bioequivalence with reference listed drug (RLD) product (Zovirax®). A fractional factorial design of experiment (DOE) with triplicate center point was used to create 11 acyclovir cream formulations with manufacturing variables such as pH of aqueous phase, emulsification time, homogenization speed, and emulsification temperature. Three more formulations (F-12-F-14) with drug particle size representing RLD were also prepared where the pH of the final product was adjusted. The formulations were subjected to physicochemical characterization (drug particle size, spreadability, viscosity, pH, and drug concentration in aqueous phase) and in vitro drug release studies against RLD. The results demonstrated that DOE formulations were structurally and functionally (e.g., drug release) similar (Q3) to RLD. Moreover, in vitro drug permeation studies showed that extent of drug bioavailability/retention in human epidermis from F-12-F-14 were similar to RLD, although differed in rate of permeation. The results suggested generic acyclovir creams can be manufactured to obtain identical performance as that of RLD with Q1/Q2/Q3. Published by Elsevier B.V.

Arginine and lysine reduce the high viscosity of serum albumin solutions for pharmaceutical injection.

PubMed

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

2014-05-01

Therapeutic protein solutions for subcutaneous injection must be very highly concentrated, which increases their viscosity through protein-protein interactions. However, maintaining a solution viscosity below 50 cP is important for the preparation and injection of therapeutic protein solutions. In this study, we examined the effect of various amino acids on the solution viscosity of very highly concentrated bovine serum albumin (BSA) and human serum albumin (HSA) at a physiological pH. Among the amino acids tested, l-arginine hydrochloride (ArgHCl) and l-lysine hydrochloride (LysHCl) (50-200 mM) successfully reduced the viscosity of both BSA and HSA solutions; guanidine hydrochloride (GdnHCl), NaCl, and other sodium salts were equally as effective, indicating the electrostatic shielding effect of these additives. Fourier transform infrared spectroscopy showed that BSA is in its native state even in the presence of ArgHCl, LysHCl, and NaCl at high protein concentrations. These results indicate that weakened protein-protein interactions play a key role in reducing solution viscosity. ArgHCl and LysHCl, which are also non-toxic compounds, will be used as additives to reduce the solution viscosity of concentrated therapeutic proteins. Copyright © 2013 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Critical Viscosity of Xenon

NASA Technical Reports Server (NTRS)

2001-01-01

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. Because xenon near the critical point will collapse under its own weight, experiments on Earth (green line) are limited as they get closer (toward the left) to the critical point. CVX in the microgravity of space (red line) moved into unmeasured territory that scientists had not been able to reach.

Physicochemical Properties of Meat Batter Added with Edible Silkworm Pupae (Bombyx mori) and Transglutaminase.

PubMed

Park, Yoo-Sun; Choi, Yun-Sang; Hwang, Ko-Eun; Kim, Tae-Kyung; Lee, Cheol-Won; Shin, Dong-Min; Han, Sung Gu

2017-01-01

This study was conducted to investigate the physicochemical properties of meat batters prepared with fresh pork meat, back fat, water, and salt and formulated with three different amounts (5%, 10%, and 15%) of silkworm pupae ( Bombyx mori ) powder and transglutaminase (TG). Meat batters formulated with silkworm pupae powder showed significantly higher contents of protein and ash than control batter. Addition of silkworm pupae to batter also showed significantly lower cooking loss than the control. Moreover, meat batter containing 15% silkworm pupae showed no significant difference in redness value compared to the control. In addition, pH, viscosity, hardness, gumminess, and chewiness were improved after the addition of silkworm pupae. Furthermore, meat batter formulated with TG and silkworm pupae showed improved hardness, gumminess, chewiness and viscosity compared to control batter. Addition of 1% TG with 15% silkworm pupae to meat batter resulted in significantly higher pH, textures, and viscosity. Our data suggest that both silkworm pupae and TG can be added to meat batter to improve its physicochemical properties. Therefore, combination of silkworm pupae and TG could be a new nutritional and functional source for meat products.

Physicochemical Properties of Meat Batter Added with Edible Silkworm Pupae (Bombyx mori) and Transglutaminase

PubMed Central

Choi, Yun-Sang

2017-01-01

This study was conducted to investigate the physicochemical properties of meat batters prepared with fresh pork meat, back fat, water, and salt and formulated with three different amounts (5%, 10%, and 15%) of silkworm pupae (Bombyx mori) powder and transglutaminase (TG). Meat batters formulated with silkworm pupae powder showed significantly higher contents of protein and ash than control batter. Addition of silkworm pupae to batter also showed significantly lower cooking loss than the control. Moreover, meat batter containing 15% silkworm pupae showed no significant difference in redness value compared to the control. In addition, pH, viscosity, hardness, gumminess, and chewiness were improved after the addition of silkworm pupae. Furthermore, meat batter formulated with TG and silkworm pupae showed improved hardness, gumminess, chewiness and viscosity compared to control batter. Addition of 1% TG with 15% silkworm pupae to meat batter resulted in significantly higher pH, textures, and viscosity. Our data suggest that both silkworm pupae and TG can be added to meat batter to improve its physicochemical properties. Therefore, combination of silkworm pupae and TG could be a new nutritional and functional source for meat products. PMID:28747820

Effects of blending on the properties of diesel and palm biodiesel

NASA Astrophysics Data System (ADS)

Bukkarapu, Kiran Raj; Srinivas Rahul, T.; Kundla, Sivaji; Vishnu Vardhan, G.

2018-03-01

Palm biodiesel is blended to diesel in different volume percentages to improve certain properties. This would help in having a good understanding of the dependence of the diesel properties on the biodiesel proportion. The properties of interest in the present work are density, kinematic viscosity, flash point and fire point of the blends which are determined and compared to petrodiesel. It is observed that the kinematic viscosity and density of the diesel increase with the palm biodiesel proportion and it is not preferable. Blends with higher palm content possess higher flash point and fire point. Apparently, blending worsens the conditions and hence might be of no use when compared to diesel, but when compared to neat palm biodiesel, blending helped in pulling down the density, viscosity, fire point and flash point of the latter. Using regression analysis and the properties data of respective blends, correlations are developed to predict the properties of diesel and biodiesel blends known the percentage of biodiesel added to diesel, which are validated using biodiesel and diesel blends which are not used as an input to develop them.

Preparation and properties of an immobilized pectinlyase for the treatment of fruit juices.

PubMed

Busto, M D; García-Tramontín, K E; Ortega, N; Perez-Mateos, M

2006-09-01

Pectinlyase, present in different commercial pectinases used in juice technology, was immobilized on alginate beads. The optimal conditions were: 0.17 g alginate ml(-1), 1.2% (w/v or v/v) enzyme concentration and acetic-HCl/glycine-HCl buffer at pH 3.6 or tris-HCl/imidazole buffer at pH 6.4. Maximum percentage of immobilization (10.6%) was obtained with Rapidase C80. Kinetic parameters of free and immobilized pectinlyase were also determined. The pH and temperature at which activity of soluble and immobilized enzyme was maximum were 7.2 and 55 degrees C. Thermal stability was not significantly altered by immobilization, especially at 40 degrees C, showing two periods of different stability. Free and immobilized preparation reduced the viscosity of highly esterified pectin from 1.09 to 0.70 and 0.72 mm(2) s(-1), respectively, after 30 min at 40 degrees C. Furthermore, the immobilized enzyme could be re-used through 4 cycles and the efficiency loss in viscosity reduction was found to be only 9.2%.

On geodynamo integrations conserving momentum flux

NASA Astrophysics Data System (ADS)

Wu, C.; Roberts, P. H.

2012-12-01

The equations governing the geodynamo are most often integrated by representing the magnetic field and fluid velocity by toroidal and poloidal scalars (for example, MAG code [1]). This procedure does not automatically conserve the momentum flux. The results can, particularly for flows with large shear, introduce significant errors, unless the viscosity is artificially increased. We describe a method that evades this difficulty, by solving the momentum equation directly while properly conserving momentum. It finds pressure by FFT and cyclic reduction, and integrates the governing equations on overlapping grids so avoiding the pole problem. The number of operations per time step is proportional to N3 where N is proportional to the number of grid points in each direction. This contrasts with the order N4 operations of standard spectral transform methods. The method is easily parallelized. It can also be easily adapted to schemes such as the Weighted Essentially Non-Oscillatory (WENO) method [2], a flux based procedure based on upwinding that is numerically stable even for zero explicit viscosity. The method has been successfully used to investigate the generation of magnetic fields by flows confined to spheroidal containers and driven by precessional and librational forcing [3, 4]. For spherical systems it satisfies dynamo benchmarks [5]. [1] MAG, http://www.geodynamics.org/cig/software/mag [2] Liu, XD, Osher, S and Chan, T, Weighted Essentially Nonoscillatory Schemes, J. Computational Physics, 115, 200-212, 1994. [3] Wu, CC and Roberts, PH, On a dynamo driven by topographic precession, Geophysical & Astrophysical Fluid Dynamics, 103, 467-501, (DOI: 10.1080/03091920903311788), 2009. [4] Wu, CC and Roberts, PH, On a dynamo driven topographically by longitudinal libration, Geophysical & Astrophysical Fluid Dynamics, DOI:10.1080/03091929.2012.682990, 2012. [5] Christensen, U, et al., A numerical dynamo benchmark, Phys. Earth Planet Int., 128, 25-34, 2001.

Comparison between sensitivity of a viscometric method and sensitivity of the alkaline elution assay for the determination of DNA damage induced by dimethylsulfate in vitro.

PubMed

Parodi, S; Balbi, C; Taningher, M; Abelmoschi, M L; Pala, M; Parodi, G; Santi, L

1982-03-01

DNA damage induced by dimethylsulfate (DMS) was measured with a new oscillating crucible viscometer, having a U-shaped circular channel. Rat liver nuclei were treated in vitro. Viscosity was measured by lysing nuclei in an aklaline lysing solution (pH 12.5; 25 degrees C). Nuclei were lysed immediately in the viscometer and released DNA started to uncoil. In control samples the viscosity increased very slowly with time, reaching a maximum only after about 8 h. A progressively more rapid increase in viscosity was seen with increasing concentrations of DMS. The time of DNA disentanglement was sensitive to about 30 times less breaks than the alkaline elution assay.

SLIP CASTING METHOD

DOEpatents

Allison, A.G.

1959-09-01

S>A process is described for preparing a magnesium oxide slip casting slurry which when used in conjunction with standard casting techniques results in a very strong "green" slip casting and a fired piece of very close dimensional tolerance. The process involves aging an aqueous magnestum oxide slurry, having a basic pH value, until it attains a specified critical viscosity at which time a deflocculating agent is added without upsetting the basic pH value.

Markedly lowering the viscosity of aqueous solutions of DNA by additives.

PubMed

Elkin, Igor; Weight, Alisha K; Klibanov, Alexander M

2015-10-15

Aqueous solutions of DNAs, while relevant in drug delivery and as a target of therapies, are often very viscous making them difficult to use. Since less viscous solutions could enable targeted drug delivery and/or therapies, the purpose of the present work was to explore compounds capable of "thinning" such DNA solutions under pharmaceutically relevant conditions. To this end, viscosities of aqueous solutions of DNAs and model polyanions were examined at 25 °C in the absence and presence of a number of bulky organic salts (and related compounds) previously found to substantially lower the viscosities of concentrated protein solutions. Out of two dozen compounds tested, only three were found to be effective; the FDA-approved local anesthetics lidocaine, mepivacaine, and prilocaine at near-isotonic concentrations and pH 6.4 lowered solution viscosity of three different DNAs up to about 20 fold. The observed multi-fold viscosity reductions appear to be due to these bulky organic salts' structure-specific non-covalent binding to nucleotide bases resulting in denaturation (unwinding) to, and stabilization of, single-stranded DNA. Copyright © 2015 Elsevier B.V. All rights reserved.

Physical and Chemical Properties of Bio-Oils From Microwave Pyrolysis of Corn Stover

NASA Astrophysics Data System (ADS)

Yu, Fei; Deng, Shaobo; Chen, Paul; Liu, Yuhuan; Wan, Yiqin; Olson, Andrew; Kittelson, David; Ruan, Roger

This study was aimed to understand the physical and chemical properties of pyrolytic bio-oils produced from microwave pyrolysis of corn stover regarding their potential use as gas turbine and home heating fuels. The ash content, solids content, pH, heating value, minerals, elemental ratio, moisture content, and viscosity of the bio-oils were determined. The water content was approx 15.2 wt%, solids content 0.22 wt%, alkali metal content 12 parts per million, dynamic viscosity 185 mPa·s at 40°C, and gross high heating value 17.5 MJ/kg for a typical bio-oil produced. Our aging tests showed that the viscosity and water content increased and phase separation occurred during the storage at different temperatures. Adding methanol and/or ethanol to the bio-oils reduced the viscosity and slowed down the increase in viscosity and water content during the storage. Blending of methanol or ethanol with the bio-oils may be a simple and cost-effective approach to making the pyrolytic bio-oils into a stable gas turbine or home heating fuels.

Physical and chemical properties of bio-oils from microwave pyrolysis of corn stover.

PubMed

Yu, Fei; Deng, Shaobo; Chen, Paul; Liu, Yuhuan; Wan, Yiqin; Olson, Andrew; Kittelson, David; Ruan, Roger

2007-04-01

This study was aimed to understand the physical and chemical properties of pyrolytic bio-oils produced from microwave pyrolysis of corn stover regarding their potential use as gas turbine and home heating fuels. The ash content, solids content, pH, heating value, minerals, elemental ratio, moisture content, and viscosity of the bio-oils were determined. The water content was approx 15.2 wt%, solids content 0.22 wt%, alkali metal content 12 parts per million, dynamic viscosity 185 mPa.s at 40 degrees C, and gross high heating value 17.5 MJ/kg for a typical bio-oil produced. Our aging tests showed that the viscosity and water content increased and phase separation occurred during the storage at different temperatures. Adding methanol and/or ethanol to the bio-oils reduced the viscosity and slowed down the increase in viscosity and water content during the storage. Blending of methanol or ethanol with the bio-oils may be a simple and cost-effective approach to making the pyrolytic bio-oils into a stable gas turbine or home heating fuels.

Soft matter strategies for controlling food texture: formation of hydrogel particles by biopolymer complex coacervation

NASA Astrophysics Data System (ADS)

Wu, Bi-cheng; Degner, Brian; McClements, David Julian

2014-11-01

Soft matter physics principles can be used to address important problems in the food industry. Starch granules are widely used in foods to create desirable textural attributes, but high levels of digestible starch may pose a risk of diabetes. Consequently, there is a need to find healthier replacements for starch granules. The objective of this research was to create hydrogel particles from protein and dietary fiber with similar dimensions and functional attributes as starch granules. Hydrogel particles were formed by mixing gelatin (0.5 wt%) with pectin (0 to 0.2 wt%) at pH values above the isoelectric point of the gelatin (pH 9, 30 °C). When the pH was adjusted to pH 5, the biopolymer mixture spontaneously formed micron-sized particles due to electrostatic attraction of cationic gelatin with anionic pectin through complex coacervation. Differential interference contrast (DIC) microscopy showed that the hydrogel particles were translucent and spheroid, and that their dimensions were determined by pectin concentration. At 0.01 wt% pectin, hydrogel particles with similar dimensions to swollen starch granules (D3,2 ≈ 23 µm) were formed. The resulting hydrogel suspensions had similar appearances to starch pastes and could be made to have similar textural attributes (yield stress and shear viscosity) by adjusting the effective hydrogel particle concentration. These hydrogel particles may therefore be used to improve the texture of reduced-calorie foods and thereby help tackle obesity and diabetes.

Macro-/micro-environment-sensitive chemosensing and biological imaging.

PubMed

Yang, Zhigang; Cao, Jianfang; He, Yanxia; Yang, Jung Ho; Kim, Taeyoung; Peng, Xiaojun; Kim, Jong Seung

2014-07-07

Environment-related parameters, including viscosity, polarity, temperature, hypoxia, and pH, play pivotal roles in controlling the physical or chemical behaviors of local molecules. In particular, in a biological environment, such factors predominantly determine the biological properties of the local environment or reflect corresponding status alterations. Abnormal changes in these factors would cause cellular malfunction or become a hallmark of the occurrence of severe diseases. Therefore, in recent years, they have increasingly attracted research interest from the fields of chemistry and biological chemistry. With the emergence of fluorescence sensing and imaging technology, several fluorescent chemosensors have been designed to respond to such parameters and to further map their distributions and variations in vitro/in vivo. In this work, we have reviewed a number of various environment-responsive chemosensors related to fluorescent recognition of viscosity, polarity, temperature, hypoxia, and pH that have been reported thus far.

Inkjet-printed Polyvinyl Alcohol Multilayers.

PubMed

Salaoru, Iulia; Zhou, Zuoxin; Morris, Peter; Gibbons, Gregory J

2017-05-11

Inkjet printing is a modern method for polymer processing, and in this work, we demonstrate that this technology is capable of producing polyvinyl alcohol (PVOH) multilayer structures. A polyvinyl alcohol aqueous solution was formulated. The intrinsic properties of the ink, such as surface tension, viscosity, pH, and time stability, were investigated. The PVOH-based ink was a neutral solution (pH 6.7) with a surface tension of 39.3 mN/m and a viscosity of 7.5 cP. The ink displayed pseudoplastic (non-Newtonian shear thinning) behavior at low shear rates, and overall, it demonstrated good time stability. The wettability of the ink on different substrates was investigated, and glass was identified as the most suitable substrate in this particular case. A proprietary 3D inkjet printer was employed to manufacture polymer multilayer structures. The morphology, surface profile, and thickness uniformity of inkjet-printed multilayers were evaluated via optical microscopy.

Enhanced t -3/2 long-time tail for the stress-stress time correlation function

NASA Astrophysics Data System (ADS)

Evans, Denis J.

1980-01-01

Nonequilibrium molecular dynamics is used to calculate the spectrum of shear viscosity for a Lennard-Jones fluid. The calculated zero-frequency shear viscosity agrees well with experimental argon results for the two state points considered. The low-frequency behavior of shear viscosity is dominated by an ω 1/2 cusp. Analysis of the form of this cusp reveals that the stress-stress time correlation function exhibits a t -3/2 "long-time tail." It is shown that for the state points studied, the amplitude of this long-time tail is between 12 and 150 times larger than what has been predicted theoretically. If the low-frequency results are truly asymptotic, they imply that the cross and potential contributions to the Kubo-Green integrand for shear viscosity exhibit a t -3/2 long-time tail. This result contradicts the established theory of such processes.

Nutrition Quality and Microbiology of Goat Milk Kefir Fortified with Vitamin B12 and Vitamin D3 during Storage

NASA Astrophysics Data System (ADS)

Dianti, EP; Anjani, G.; Afifah, DN; Rustanti, N.; Panunggal, B.

2018-02-01

Goat milk kefir fortified vitamin B12 and vitamin D3 can be an alternative to improve insulin resistance. Fortification of vitamin B12 and vitamin D3 could affect the balance of complex ecosystems of bacteria and yeasts in goat milk kefir. We analyzed the nutritional quality and microbiology of goat milk kefir during storage. This experiment was done with completely randomized design consisted of five treatments, ie storage day 0, 3rd, 6th, 9th, and 15th. Vitamin B12, vitamin D3, protein were analyzed using spectrophotometric, fat using babcock method, total lactic acid bacteria using total plate count, pH with pH meter, and viscosity using ostwald method. During 15 days in refrigerated storage, there was no significant difference (p>0,05) of vitamin B12 concentration, protein, fat, and viscosity of kefir. Storage time of the final product caused the decrease of vitamin D3 concentration between day 9 and 15 (p=0,038), pH (p=0,023), and total lactic acid of kefir (p=0,0001). Total lactic acid bacteria increased until 9 days of storage (6161 ± 1.296x107cfu / ml), but decreased to 24% on day 15 (150 ±7.78x107cfu/ml). pH kefir tends to fluctuate during storage with the highest pH value of 4,38 on day-3, and lowest 4.13 on day-9.

Both Reversible Self-Association and Structural Changes Underpin Molecular Viscoelasticity of mAb Solutions.

PubMed

Sarangapani, Prasad S; Weaver, Justin; Parupudi, Arun; Besong, Tabot M D; Adams, Gary G; Harding, Stephen E; Manikwar, Prakash; Castellanos, Maria M; Bishop, Steven M; Pathak, Jai A

2016-12-01

The role of antibody structure (conformation) in solution rheology is probed. It is demonstrated here that pH-dependent changes in the tertiary structure of 2 mAb solutions lead to viscoelasticity and not merely a shear viscosity (η) increase. Steady shear flow curves on mAb solutions are reported over broad pH (3.0 ≤ pH ≤ 8.7) and concentration (2 mg/mL ≤ c ≤ 120 mg/mL) ranges to comprehensively characterize their rheology. Results are interpreted using size exclusion chromatography, differential scanning calorimetry, analytical ultracentrifugation, near-UV circular dichroism, and dynamic light scattering. Changes in tertiary structure with concentration lead to elastic yield stress and increased solution viscosity in solution of "mAb1." These findings are supported by dynamic light scattering and differential scanning calorimetry, which show increased hydrodynamic radius of mAb1 at low pH and a reduced melting temperature T m , respectively. Conversely, another molecule at 120 mg/mL solution concentration is a strong viscoelastic gel due to perturbed tertiary structure (seen in circular dichroism) at pH 3.0, but the same molecule responds as a viscous liquid due to reversible self-association at pH 7.4 (verified by analytical ultracentrifugation). Both protein-protein interactions and structural perturbations govern pH-dependent viscoelasticity of mAb solutions. Copyright © 2016 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

Cross-linking proteins by laccase: Effects on the droplet size and rheology of emulsions stabilized by sodium caseinate.

PubMed

Sato, A C K; Perrechil, F A; Costa, A A S; Santana, R C; Cunha, R L

2015-09-01

The aim of this work was to evaluate the influence of laccase and ferulic acid on the characteristics of oil-in-water emulsions stabilized by sodium caseinate at different pH (3, 5 and 7). Emulsions were prepared by high pressure homogenization of soybean oil with sodium caseinate solution containing varied concentrations of laccase (0, 1 and 5mg/mL) and ferulic acid (5 and 10mM). Laccase treatment and pH exerted a strong influence on the properties with a consequent effect on stability, structure and rheology of emulsions stabilized by Na-caseinate. At pH7, O/W emulsions were kinetically stable due to the negative protein charge which enabled electrostatic repulsion between oil droplets resulting in an emulsion with small droplet size, low viscosity, pseudoplasticity and viscoelastic properties. The laccase treatment led to emulsions showing shear-thinning behavior as a result of a more structured system. O/W emulsions at pH5 and 3 showed phase separation due to the proximity to protein pI, but the laccase treatment improved their stability of emulsions especially at pH3. At pH3, the addition of ferulic acid and laccase produced emulsions with larger droplet size but with narrower droplet size distribution, increased viscosity, pseudoplasticity and viscoelastic properties (gel-like behavior). Comparing laccase treatments, the combined addition of laccase and ferulic acid generally produced emulsions with lower stability (pH5), larger droplet size (pH3, 5 and 7) and higher pseudoplasticity (pH5 and 7) than emulsion with only ferulic acid. The results suggested that the cross-linking of proteins by laccase and ferulic acid improved protein emulsifying properties by changing functional mechanisms of the protein on emulsion structure and rheology, showing that sodium caseinate can be successfully used in acid products when treated with laccase. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effect of Convection on Weld Pool Shape and Microstructure.

DTIC Science & Technology

1986-07-01

latent heat of fusion 11 u dynamic viscosity Iwo V kinematic viscosity P density a Stefan -Boltzman constant stress tensor 0, functions defined the...and temperature. The convections for velocities and temperature are based on a mixed Gauss- -* Seidel and Jacobi schemes, proceeding from line-to...line according to the Gauss- Seidel scheme, updating values as each line is completed. With each line, however, the point-by-point iteration is based on

Longitudinal spread of mechanical excitation through tectorial membrane traveling waves

PubMed Central

Sellon, Jonathan B.; Farrahi, Shirin; Ghaffari, Roozbeh; Freeman, Dennis M.

2015-01-01

The mammalian inner ear separates sounds by their frequency content, and this separation underlies important properties of human hearing, including our ability to understand speech in noisy environments. Studies of genetic disorders of hearing have demonstrated a link between frequency selectivity and wave properties of the tectorial membrane (TM). To understand these wave properties better, we developed chemical manipulations that systematically and reversibly alter TM stiffness and viscosity. Using microfabricated shear probes, we show that (i) reducing pH reduces TM stiffness with little change in TM viscosity and (ii) adding PEG increases TM viscosity with little change in TM stiffness. By applying these manipulations in measurements of TM waves, we show that TM wave speed is determined primarily by stiffness at low frequencies and by viscosity at high frequencies. Both TM viscosity and stiffness affect the longitudinal spread of mechanical excitation through the TM over a broad range of frequencies. Increasing TM viscosity or decreasing stiffness reduces longitudinal spread of mechanical excitation, thereby coupling a smaller range of best frequencies and sharpening tuning. In contrast, increasing viscous loss or decreasing stiffness would tend to broaden tuning in resonance-based TM models. Thus, TM wave and resonance mechanisms are fundamentally different in the way they control frequency selectivity. PMID:26438861

Description and comparative study of physico-chemical parameters of the teleost fish skin mucus.

PubMed

Guardiola, Francisco A; Cuartero, María; Del Mar Collado-González, María; Arizcún, Marta; Díaz Baños, F Guillermo; Meseguer, José; Cuesta, Alberto; Esteban, María A

2015-01-01

The study of mucosal surfaces, and in particular the fish skin and its secreted mucus, has been of great interest recently among immunologists. Measurement of the viscosity and other physico-chemical parameters (protein concentration, pH, conductivity, redox potential, osmolality and density) of the skin mucus can help to understand its biological functions. We have used five marine species of teleost: gilthead seabream (Sparus aurata L.), European sea bass (Dicentrarchus labrax L.), shi drum (Umbrina cirrosa L.), common dentex (Dentex dentex L.) and dusky grouper (Epinephelus marginatus L.), all of them with commercial interest in the aquaculture of the Mediterranean area. Mucus showed a direct shear- and temperature-dependent viscosity, with a non-Newtonian behavior, which differed however between two groups: one with higher viscosity (D. labrax, U. cirrosa, D. dentex) and the other with lower viscosity (S. aurata, E. marginatus). In addition, there was a clear interrelation between density and osmolality, as well as between density and temperature. Taking into account that high values of viscosity should improve the barrier effect against pathogens but low values of viscosity are needed for good locomotion characteristics, our results may help elucidate the relationship between physico-chemical and biological parameters of skin mucus, and disease susceptibility.

Production of ethanol from raw cassava starch by a nonconventional fermentation method

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

Ueda, S.; Zenin, C.T.; Monteiro, D.A.

Raw cassava root starch was transformed into ethanol in a one-step process of fermentation, in which are combined the conventional processes of liquefaction, saccharification, and fermentation to alcohol. Aspergillus awamori NRRL 3112 and Aspergillus niger were cultivated on wheat bran and used as Koji enzymes. Commercial A. niger amyloglucosidase was also used in this experiment. A raw cassava root homogenate-enzymes-yeast mixture fermented optimally at pH 3.5 and 30/degree/C, for five days and produced ethanol. Alcohol yields from raw cassava roots were between 82.3 and 99.6%. Fungal Koji enzymes effectively decreased the viscosity of cassava root fermentation mashes during incubation. Commercialmore » A. niger amyloglucosidase decreased the viscosity slightly. Reduction of viscosity of fermentation mashes was 40, 84, and 93% by commercial amyloglucosidase, A. awamori, and A. niger enzymes, respectively. The reduction of viscosity of fermentation mashes is probably due to the hydrolysis of pentosans by Koji enzymes. 12 refs.« less

The mouthfeel of white wine.

PubMed

Gawel, Richard; Smith, Paul A; Cicerale, Sara; Keast, Russell

2017-07-05

White wine mouthfeel which encompasses the tactile, chemosensory and taste attributes of perceived viscosity, astringency, hotness and bitterness is increasingly being recognized as an important component of overall white wine quality. This review summarizes the physiological basis for the perception of white wine mouthfeel and the direct and interactive effects of white wine composition, specifically those of low molecular weight phenolic compounds, polysaccharides, pH, ethanol, glycerol, dissolved carbon dioxide, and peptides. Ethyl alcohol concentration and pH play a direct role in determining most aspects of mouthfeel perception, and provide an overall framework on which the other minor wine components can interact to influence white wine mouthfeel. Phenolic compounds broadly impact on the mouthfeel by contributing to its viscosity, astringency, hotness and bitterness. Their breadth of influence likely results from their structural diversity which would allow them to activate multiple sensory mechanisms involved in mouthfeel perception. Conversely, polysaccharides have a small modulating effect on astringency and hotness perception, and glycerol does not affect perceived viscosity within the narrow concentration range found in white wine. Many of the major sensory attributes that contribute to the overall impression of mouthfeel are elicited by more than one class compound suggesting that different physiological mechanisms may be involved in the construct of mouthfeel percepts.

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.

49 CFR 173.121 - Class 3-Assignment of packing group.

Code of Federal Regulations, 2013 CFR

2013-10-01

... than 100 L (26.3 gallons); and (iv) The viscosity and flash point are in accordance with the following... paragraph (b)(1) of this section shall be performed are as follows: (i) Viscosity test. The flow time in...

49 CFR 173.121 - Class 3-Assignment of packing group.

Code of Federal Regulations, 2014 CFR

2014-10-01

... than 100 L (26.3 gallons); and (iv) The viscosity and flash point are in accordance with the following... paragraph (b)(1) of this section shall be performed are as follows: (i) Viscosity test. The flow time in...

49 CFR 173.121 - Class 3-Assignment of packing group.

Code of Federal Regulations, 2012 CFR

2012-10-01

...) The viscosity and flash point are in accordance with the following table: Flow time t in seconds Jet... shall be performed are as follows: (i) Viscosity test. The flow time in seconds is determined at 23 °C...

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.

Characteristic of Fermented Drink from Whey Cheese with Addition of Mango (Mangifera x odorata) Juice

NASA Astrophysics Data System (ADS)

Desnilasari, D.; Kumalasari, R.

2017-12-01

Whey cheese could be utilized become product such as fermented drink which is added by mango kweni juice to improve their acceptance. The aim of this research was to characterized physicochemical, sensory, and microbiology of fermented drink based on whey cheese with addition different concentration mango kweni juice of (0%, 5%, 10%, and 15%) by Lactobacillus casei. Color scale, viscosity, pH, total soluble solid, total free acid, fat, protein, total L. casei and sensory evaluation from panelist were examined after 24 hour of fermentation. Result showed that addition mango juice significantly affects the color scale, viscosity, pH, protein and number of L. casei of the product. The color of the product becomes more dark, red, and yellow. The product becomes more viscous. pH of the product become more acid and reduces protein content. Respectively total number of L. casei of the product increased 1 log. But addition of mango juice significantly did not affect sensory acceptance, total soluble solid, total free acid, and fat of the product. Sensory acceptance of the product range in dislike slightly and slightly like score that means formulation of the product need to be improved again.

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.

Diffusion of neutral and ionic species in charged membranes: boric acid, arsenite, and water.

PubMed

Goli, Esmaiel; Hiemstra, Tjisse; Van Riemsdijk, Willem H; Rahnemaie, Rasoul; Malakouti, Mohammad Jafar

2010-10-15

Dynamic ion speciation using DMT (Donnan membrane technique) requires insight into the physicochemical characteristics of diffusion in charged membranes (tortuosity, local diffusion coefficients) as well as ion accumulation. The latter can be precluded by studying the diffusion of neutral species, such as boric acid, B(OH)₃⁰(aq), arsenite, As(OH)₃⁰(aq), or water. In this study, the diffusion rate of B(OH)₃⁰ has been evaluated as a function of the concentration, pH, and ionic strength. The rate is linearly dependent on the concentration of solely the neutral species, without a significant contribution of negatively charged species such as B(OH)₄⁻, present at high pH. A striking finding is the very strong effect (factor of ~10) of the type of cation (K(+), Na(+), Ca(2+), Mg(2+), Al(3+), and H(+)) on the diffusion coefficient of B(OH)₃⁰ and also As(OH)₃⁰. The decrease of the diffusion coefficient can be rationalized as an enhancement of the mean viscosity of the confined solution in the membrane. The diffusion coefficients can be described by a semiempirical relationship, linking the mean viscosity of the confined solute of the membrane to the viscosity of the free solution. In proton-saturated membranes, as used in fuel cells, viscosity is relatively more enhanced; i.e., a stronger water network is formed. Extraordinarily, our B(OH)₃-calibrated model (in HNO₃) correctly predicts the reported diffusion coefficient of water (D(H₂O)), measured with ¹H NMR and quasi-elastic neutron scattering in H(+)-Nafion membranes. Upon drying these membranes, the local hydronium, H(H₂O)(n)(+), concentration and corresponding viscosity increase, resulting in a severe reduction of the diffusion coefficient (D(H₂O) ≈ 5-50 times), in agreement with the model. The present study has a second goal, i.e., development of the methodology for measuring the free concentration of neutral species in solution. Our data suggest that the free concentration can be measured with DMT in natural systems if one accounts for the variation in the cation composition of the membrane and corresponding viscosity/diffusion coefficient.

Shear-rate dependence of the viscosity of the Lennard-Jones liquid at the triple point

NASA Astrophysics Data System (ADS)

Ferrario, M.; Ciccotti, G.; Holian, B. L.; Ryckaert, J. P.

1991-11-01

High-precision molecular-dynamics (MD) data are reported for the shear viscosity η of the Lennard-Jones liquid at its triple point, as a function of the shear rate ɛ˙ for a large system (N=2048). The Green-Kubo (GK) value η(ɛ˙=0)=3.24+/-0.04 is estimated from a run of 3.6×106 steps (40 nsec). We find no numerical evidence of a t-3/2 long-time tail for the GK integrand (stress-stress time-correlation function). From our nonequilibrium MD results, obtained both at small and large values of ɛ˙, a consistent picture emerges that supports an analytical (quadratic at low shear rate) dependence of the viscosity on ɛ˙.

Protein gels and emulsions from mixtures of Cape hake and pea proteins.

PubMed

Tomé, Ana Sofia; Pires, Carla; Batista, Irineu; Sousa, Isabel; Raymundo, Anabela

2015-01-01

Portioning of frozen fish generates by-products such as fish 'sawdust' and cut-offs which can be further processed into protein concentrates and isolates. The objective of the present work was to produce gels and emulsions using recovered Cape hake protein powder (HPP). In previous works, the structures of the gels produced by HPP were found to be strong, with a high rubbery character. In this work, the addition of commercial pea proteins (PPC) to HPP gels and emulsions was studied. Physical properties of gels and emulsions prepared with different proportions of mixtures of PPC and HPP were evaluated. In general, gels and emulsions showed high values for whiteness and, as expected, the higher content of HPP in the protein mixtures led to higher firmness values of the gels. The gel network was rapidly formed upon heating due to the fish protein macromolecules and further reinforced by the pea protein macromolecules when cooled to 5 °C. Both visco-elastic parameters, storage and loss moduli, of the produced gels increased with the HPP proportion in the protein mixtures, corresponding to more structured systems. For the emulsions, two different pH environments were studied: 3.8 and 7.0. At neutral pH a synergy was found between the vegetable and fish protein, which is not so strong when pH is lowered to 3.8, near the isoelectric point of pea proteins (pI = 4.5). This evidence was supported by the results from the texture measurements, viscosity and visco-elastic parameters. Gels made from Cape hake proteins showed a softer texture and were less rubbery with the addition of pea proteins. Emulsions stabilised by these mixtures showed slightly different behaviour when produced at pH 7.0 or pH 3.8. © 2014 Society of Chemical Industry.

Stirring Up an Elastic Fluid: Critical Viscosity of Xenon-2 (CVX-2)

NASA Astrophysics Data System (ADS)

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

2002-12-01

Whipped cream stays in place even when turned upside down. Yet it readily flows through the nozzle of a spray can to reach the dessert plate. This demonstrates the phenomenon of shear thinning that is important to many industrial and physical processes. Paints, film emulsions, and other complex solutions that are highly viscous under normal conditions but become thin and flow easily under shear forces. A simple fluid, such as water, does not exhibit shear thinning under normal conditions. Very close to the liquid-vapor critical point, where the distinction between liquid and vapor disappears, the fluid becomes more complex and is predicted to display shear thinning. At the critical point, xenon atoms interact over long distances in a classical model of cooperative phenomena. Physicists rely on this system to learn how long-range order arises. The Critical Viscosity of Xenon Experiment (CVX-2) 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 fluids. Viscosity originates from the interactions of individual molecules. It is so complicated that, except for the simplest gas, it cannot be calculated accurately from theory. Tests with critical fluids can provide key data, but are limited on Earth because critical fluids are highly compressed by gravity. CVX-2 employs a tiny metal screen vibrating between two electrodes in a bath of critical xenon. The vibrations and how they dampen are used to measure viscosity. CVX flew on STS-85 (1997), where it revealed that, close to the critical point, the xenon is partly elastic: it can 'stretch' as well as flow. For STS-107, the hardware has been enhanced to determine if critical xenon is a shear-thinning fluid.

Stirring Up an Elastic Fluid: Critical Viscosity of Xenon-2 (CVX-2)

NASA Technical Reports Server (NTRS)

Berg, Robert F.; Moldover, Michael R.; Zimmerli, Gregory A.; Motil, Susan M. (Technical Monitor)

2002-01-01

Whipped cream stays in place even when turned upside down. Yet it readily flows through the nozzle of a spray can to reach the dessert plate. This demonstrates the phenomenon of shear thinning that is important to many industrial and physical processes. Paints, film emulsions, and other complex solutions that are highly viscous under normal conditions but become thin and flow easily under shear forces. A simple fluid, such as water, does not exhibit shear thinning under normal conditions. Very close to the liquid-vapor critical point, where the distinction between liquid and vapor disappears, the fluid becomes more complex and is predicted to display shear thinning. At the critical point, xenon atoms interact over long distances in a classical model of cooperative phenomena. Physicists rely on this system to learn how long-range order arises. The Critical Viscosity of Xenon Experiment (CVX-2) 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 fluids. Viscosity originates from the interactions of individual molecules. It is so complicated that, except for the simplest gas, it cannot be calculated accurately from theory. Tests with critical fluids can provide key data, but are limited on Earth because critical fluids are highly compressed by gravity. CVX-2 employs a tiny metal screen vibrating between two electrodes in a bath of critical xenon. The vibrations and how they dampen are used to measure viscosity. CVX flew on STS-85 (1997), where it revealed that, close to the critical point, the xenon is partly elastic: it can 'stretch' as well as flow. For STS-107, the hardware has been enhanced to determine if critical xenon is a shear-thinning fluid.

Stability of miscible displacements across stratified porous media

NASA Astrophysics Data System (ADS)

Shariati, Maryam; Yortsos, Yanis C.

2001-08-01

We consider the stability of miscible displacements across stratified porous media, where the heterogeneity is along the direction of displacement. Asymptotic results for long and short wavelengths are derived. It is found that heterogeneity has a long-wave effect on the instability, which, in the absence of gravity, becomes nontrivial when the viscosity profiles are nonmonotonic. In the latter case, profiles with end-point viscosities, predicted to be stable using the Saffman-Taylor criterion, can become unstable, if the permeability contrast in the direction of displacement is sufficiently large. Conversely, profiles with end-point viscosities predicted to be unstable, can become stable, if the permeability decrease in the direction of displacement is sufficiently large. Analogous results are found in the presence of gravity, but without the nonmonotonic restriction on the viscosity profile. The increase or decrease in the propensity for instability as the permeability increases or decreases, respectively, reflects the variation of the two different components of the effective fluid mobility. While permeability remains frozen in space, viscosity varies following the concentration field. Thus, the condition for instability does not solely depend on the overall fluid mobility, as in the case of displacements in homogeneous media, but it is additionally dependent on the permeability variation.

Anomalous viscosity effect in the early stages of the ion-assisted adhesion/fusion event between lipid bilayers: A theoretical and computational study

NASA Astrophysics Data System (ADS)

Raudino, Antonio; Marrink, Siewert J.; Pannuzzo, Martina

2013-06-01

The effect of viscosity on the encounter rate of two interacting membranes was investigated by combining a non-equilibrium Fokker-Planck model together with extensive Molecular Dynamics (MD) calculations. The encounter probability and stabilization of transient contact points represent the preliminary steps toward short-range adhesion and fusion of lipid leaflets. To strengthen our analytical model, we used a Coarse Grained MD method to follow the behavior of two charged palmitoyl oleoyl phosphatidylglycerol membranes embedded in a electrolyte-containing box at different viscosity regimes. Solvent friction was modulated by varying the concentration of a neutral, water-soluble polymer, polyethylene glycol, while contact points were stabilized by divalent ions that form bridges among juxtaposed membranes. While a naïve picture foresees a monotonous decrease of the membranes encounter rate with solvent viscosity, both the analytical model and MD simulations show a complex behavior. Under particular conditions, the encounter rate could exhibit a maximum at a critical viscosity value or for a critical concentration of bridging ions. These results seem to be confirmed by experimental observations taken from the literature.

White wine taste and mouthfeel as affected by juice extraction and processing.

PubMed

Gawel, Richard; Day, Martin; Van Sluyter, Steven C; Holt, Helen; Waters, Elizabeth J; Smith, Paul A

2014-10-15

The juice used to make white wine can be extracted using various physical processes that affect the amount and timing of contact of juice with skins. The influence of juice extraction processes on the mouthfeel and taste of white wine and their relationship to wine composition were determined. The amount and type of interaction of juice with skins affected both wine total phenolic concentration and phenolic composition. Wine pH strongly influenced perceived viscosity, astringency/drying, and acidity. Despite a 5-fold variation in total phenolics among wines, differences in bitter taste were small. Perceived viscosity was associated with higher phenolics but was not associated with either glycerol or polysaccharide concentration. Bitterness may be reduced by using juice extraction and handling processes that minimize phenolic concentration, but lowering phenolic concentration may also result in wines of lower perceived viscosity.

Physiochemical properties, microstructure, and probiotic survivability of nonfat goats' milk yogurt using heat-treated whey protein concentrate as fat replacer.

PubMed

Zhang, Tiehua; McCarthy, James; Wang, Guorong; Liu, Yanyan; Guo, Mingruo

2015-04-01

There is a market demand for nonfat fermented goats' milk products. A nonfat goats' milk yogurt containing probiotics (Lactobacillus acidophilus, and Bifidobacterium spp.) was developed using heat-treated whey protein concentrate (HWPC) as a fat replacer and pectin as a thickening agent. Yogurts containing untreated whey protein concentrate (WPC) and pectin, and the one with only pectin were also prepared. Skim cows' milk yogurt with pectin was also made as a control. The yogurts were analyzed for chemical composition, water holding capacity (syneresis), microstructure, changes in pH and viscosity, mold, yeast and coliform counts, and probiotic survivability during storage at 4 °C for 10 wk. The results showed that the nonfat goats' milk yogurt made with 1.2% HWPC (WPC solution heated at 85 °C for 30 min at pH 8.5) and 0.35% pectin had significantly higher viscosity (P < 0.01) than any of the other yogurts and lower syneresis than the goats' yogurt with only pectin (P < 0.01). Viscosity and pH of all the yogurt samples did not change much throughout storage. Bifidobacterium spp. remained stable and was above 10(6) CFU g(-1) during the 10-wk storage. However, the population of Lactobacillus acidophilus dropped to below 10(6) CFU g(-1) after 2 wk of storage. Microstructure analysis of the nonfat goats' milk yogurt by scanning electron microscopy revealed that HWPC interacted with casein micelles to form a relatively compact network in the yogurt gel. The results indicated that HWPC could be used as a fat replacer for improving the consistency of nonfat goats' milk yogurt and other similar products. © 2015 Institute of Food Technologists®

Mechanistic Insights into Dye-Decolorizing Peroxidase Revealed by Solvent Isotope and Viscosity Effects

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

Shrestha, Ruben; Huang, Gaochao; Meekins, David A.

Dye-decolorizing peroxidases (DyPs) are a family of H2O2-dependent heme peroxidases that have shown potential applications in lignin degradation and valorization. However, the DyP kinetic mechanism remains underexplored. Using structural biology and solvent isotope (sKIE) and viscosity effects, many mechanistic characteristics have been determined for the B-class ElDyP from Enterobacter lignolyticus. Its structure revealed that a water molecule acts as the sixth axial ligand and two channels at diameters of ~3.0 and 8.0 Å lead to the heme center. A conformational change of ERS* to ERS, which have identical spectral characteristics, was proposed as the final step in DyPs’ bisubstrate Ping-Pongmore » mechanism. This step is also the rate-determining step in ABTS oxidation. The normal KIE of wild-type ElDyP with D2O2 at pD 3.5 suggested that compound 0 deprotonation by the distal aspartate is rate-limiting in the formation of compound I, which is more reactive under acidic pH than under neutral or alkaline pH. The viscosity effects and other biochemical methods implied that the reducing substrate binds with compound I instead of the free enzyme. The significant inverse sKIEs of kcat/KM and kERS* suggested that the aquo release in ElDyP is mechanistically important and may explain the enzyme’s adoption of two-electron reduction for compound I. The distal aspartate is catalytically more important than the distal arginine and plays key roles in determining ElDyP’s optimum acidic pH. The kinetic mechanism of D143H-ElDyP was also briefly studied. The results obtained will pave the way for future protein engineering to improve DyPs’ lignolytic activity.« less

Formulation, in-vitro characterization and clinical evaluation of curcumin in-situ gel for treatment of periodontitis.

PubMed

Nasra, Maha M A; Khiri, Heba M; Hazzah, Heba A; Abdallah, Ossama Y

2017-11-01

This study aimed to develop syringeable in-situ curcumin (cur) gel for the treatment of periodontal pockets as well as to evaluate the clinical efficacy of Cur in-situ gel formulation. Different in-situ gel formulations of Cur were prepared using 30% of pluronic F127, and 1% of carbopol P934. The formulations were evaluated regarding gelation temperature, pH, viscosity, syringeability study, in-vitro release and chemical stability of cur. The effect of aging of gel formulations for 3months in refrigerator was investigated. The selected formulation was clinically evaluated through the determination of probing depth, plaque index, and bleeding index at baseline and 1 month after application. The formulations showed accepted gelation temperature ranging from 28 to 34 °C and all had pH value of 4. The viscosity of the formulations at 4 °C ranged from 19 000 to 37 000 cP. All formulations were easily syringeable through 21 gauge needle at cold temperature. Curcumin stability during the release study was maintained. Aging showed no significant effect on release profile, drug content, or the pH after 3 months, while it showed a slight increase in viscosity with concomitant decrease in gelation temperature. Selected formulations delivered into periodontal pocket evaluated clinically showed to be effective. The treated group revealed that the adjunctive use of intracrevicular 2% curcumin in-situ gel adjunct to mechanical treatment in patients with adult periodontitis could aid in significant clinical reduction of probing depth, bleeding index, and to less extent of plaque. This indicates that curcumin in this novel drug delivery system is an excellent candidate for periodontal disease treatment.

Therapeutic Antibody Engineering To Improve Viscosity and Phase Separation Guided by Crystal Structure.

PubMed

Chow, Chi-Kin; Allan, Barrett W; Chai, Qing; Atwell, Shane; Lu, Jirong

2016-03-07

Antibodies at high concentrations often reveal unanticipated biophysical properties suboptimal for therapeutic development. The purpose of this work was to explore the use of point mutations based on crystal structure information to improve antibody physical properties such as viscosity and phase separation (LLPS) at high concentrations. An IgG4 monoclonal antibody (Mab4) that exhibited high viscosity and phase separation at high concentration was used as a model system. Guided by the crystal structure, four CDR point mutants were made to evaluate the role of hydrophobic and charge interactions on solution behavior. Surprisingly and unpredictably, two of the charge mutants, R33G and N35E, showed a reduction in viscosity and a lower propensity to form LLPS at high concentration compared to the wild-type (WT), while a third charge mutant S28K showed an increased propensity to form LLPS compared to the WT. A fourth mutant, F102H, had reduced hydrophobicity, but unchanged viscosity and phase separation behavior. We further evaluated the correlation of various biophysical measurements including second virial coefficient (A2), interaction parameter (kD), weight-average molecular weight (WAMW), and hydrodynamic diameters (DH), at relatively low protein concentration (4 to 15 mg/mL) to physical properties, such as viscosity and liquid-liquid phase separation (LLPS), at high concentration. Surprisingly, kD measured using dynamic light scattering (DLS) at low antibody concentration correlated better with viscosity and phase separation than did A2 for Mab4. Our results suggest that the high viscosity and phase separation observed at high concentration for Mab4 are mainly driven by charge and not hydrophobicity.

Oil Palm Empty Fruit Bunch (OPEFB) Fiber as Lost Circulation Material (LCM) in Water Based Mud (WBM)

NASA Astrophysics Data System (ADS)

Ghazali, N. A.; Sauki, A.; Abu Bakar, N. F.; Mohamed, S.

2018-05-01

Lost Circulation Material (LCM) is an additive used to prevent lost of mud to the formation as a results from natural or induced fractured during drilling operation. Losses of mud could give great impact to the oil industry as it increases mud cost and rig time. The objective of this research was to investigate the effect of size and concentration of Oil Palm Empty Fruit Bunch (OPEFB) as LCM in water based mud (WBM). Several important properties of WBM rheology after adding the OPEFB namely plastic viscosity, apparent viscosity, yield point and gel strength were characterized. The sizes of OPEFB added into the WBM were 150μm, 250μm, 500μm and 1000μm while the concentration of OPEFB used were 5g, 10g, 15g and 20g in 350 mL of WBM. Results indicated that the plastic viscosity and apparent viscosity increased with increasing of the OPEFB concentrations. On the other hand, the plastic viscosity and apparent viscosity decreased with increasing sizes of OPEFB. Yield point increased as the concentration and size of OPEFB increases. This study indicated that OPEFB was effective to be used as LCM for size of 150μm and concentration of 15g whereby it produced least amount of filtrate volume as well as good control in mud rheology.

Application of Sodium Ligno Sulphonate as Surfactant in Enhanced Oil Recovery and Its Feasibility Test for TPN 008 Oil

NASA Astrophysics Data System (ADS)

Prakoso, N. I.; Rochmadi; Purwono, S.

2018-04-01

One of enhanced oil recovery (EOR) methods is using surfactants to reduce the interfacial tension between the injected fluid and the oil in old reservoir. The most important principle in enhanced oil recovery process is the dynamic interaction of surfactants with crude oil. Sodium ligno sulphonate (SLS) is a commercial surfactant and already synthesized from palm solid waste by another researcher. This work aimed to apply SLS as a surfactant for EOR especially in TPN 008 oil from Pertamina Indonesia. In its application as an EOR’s surfactant, SLS shall be passed feasibility test like IFT, thermal stability, compatibility, filtration, molecular weight, density, viscosity and pH tests. The feasibility test is very important for a preliminary test prior to another advanced test. The results demonstrated that 1% SLS solution in formation water (TPN 008) had 0.254 mN/M IFT value and was also great in thermal stability, compatibility, filtration, molecular weight, viscosity and pH test.

Stability of extemporaneous enalapril maleate suspensions for pediatric use prepared from commercially available tablets.

PubMed

Sosnowska, Katarzyna; Winnicka, Katarzyna; Czajkowska-Kośnik, Anna

2009-01-01

In this paper, the stability of enalapril maleate in oral formulations prepared from commercially available tablets was investigated. Extemporaneously compounded, 0.1 mg/mL and 1.0 mg/mL, oral suspensions of enalapril maleate in sugar-containing and sugar-free vehicles were stored in the absence of light at 4 degrees and 25 degrees C for 30 days. Enalapril maleate stability was quantified after 7, 14, 21, and 30 days using HPLC method. Viscosities and pH of prepared suspensions were measured on each study day and no appreciable changes from the initial pH and initial viscosities occurred in any of the samples both at 25 degrees and 4 degrees C. It was shown that all the formulations retain minimum 98% of the initial enalapril maleate concentration after 30 days of storage at 25 degrees and 4 degrees C and they may provide an option in situations where the marketed suspension is unavailable.

Spectroscopic analysis on the resveratrol-DNA binding interactions at physiological pH

NASA Astrophysics Data System (ADS)

Zhang, Shufang; Sun, Xuejun; Jing, Zhihong; Qu, Fengli

2011-11-01

The interaction of resveratrol with calf thymus deoxyribonucleic acid (ctDNA) under physiological conditions (Tris-HCl buffer solutions, pH 7.4) was studied by spectroscopy, fluorescence spectroscopy and viscosity measurement method, respectively. Results indicated that a complex of resveratrol with ctDNA was formed with a binding constant of K17 °C = 5.49 × 10 3 L mol -1 and K37 °C = 1.90 × 10 4 L mol -1. The fluorescence quenching mechanism of acridine orange (AO)-ctDNA by resveratrol was shown to be a static quenching type. The thermodynamic parameters of the complex were calculated by a double reciprocal method: ΔHms=4.64×10 J mol, ΔSms=231.8 J K mol and ΔGms=-2.54×10 J mol (37 °C). Spectroscopic techniques together with viscosity determination provided evidences of intercalation mode of binding for the interaction between resveratrol and ctDNA.

Elementary model of severe plastic deformation by KoBo process

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

Gusak, A.; Storozhuk, N.; Danielewski, M., E-mail: daniel@agh.edu.pl

2014-01-21

Self-consistent model of generation, interaction, and annihilation of point defects in the gradient of oscillating stresses is presented. This model describes the recently suggested method of severe plastic deformation by combination of pressure and oscillating rotations of the die along the billet axis (KoBo process). Model provides the existence of distinct zone of reduced viscosity with sharply increased concentration of point defects. This zone provides the high extrusion velocity. Presented model confirms that the Severe Plastic Deformation (SPD) in KoBo may be treated as non-equilibrium phase transition of abrupt drop of viscosity in rather well defined spatial zone. In thismore » very zone, an intensive lateral rotational movement proceeds together with generation of point defects which in self-organized manner make rotation possible by the decrease of viscosity. The special properties of material under KoBo version of SPD can be described without using the concepts of nonequilibrium grain boundaries, ballistic jumps and amorphization. The model can be extended to include different SPD processes.« less

Tribological Properties of a Pennzane(Registered Trademark)-Based Liquid Lubricant (Disubstituted Alkylated Cyclopentane) for Low Temperature Space Applications

NASA Technical Reports Server (NTRS)

Venier, Clifford; Casserly, Edward W.; Jones, William R., Jr.; Marchetti, Mario; Jansen, Mark J.; Predmore, Roamer E.

2002-01-01

The tribological properties of a disubstituted alkylated cyclopentane, Pennzane (registered) Synthesized Hydrocarbon Fluid X-1000, are presented. This compound is a lower molecular weight version of the commonly used multiply alkylated cyclopentane, Pennzane X-2000, currently used in many space mechanisms. New, lower temperature applications will require liquid lubricants with lower viscosities and pour points and acceptable vapor pressures. Properties reported include: friction and wear studies and lubricated lifetime in vacuum; additionally, typical physical properties (i.e., viscosity-temperature, pour point, flash and fire point, specific gravity, refractive index, thermal properties, volatility and vapor pressure) are reported.

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.

Viscosity of Hg(0.84)Zn(0.16)Te Pseudobinary Melt

NASA Technical Reports Server (NTRS)

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

1996-01-01

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

Feasibility study of a cosmetic cream added with aqueous extract and oil from date (Phoenix dactylifera L.) fruit seed using experimental design.

PubMed

Lecheb, Fatma; Benamara, Salem

2015-01-01

This article reports on the feasibility study of a cosmetic cream added with aqueous extract and oil from date (Phoenix dactylifera L.) fruit seed using experimental design. First, the mixture design was applied to optimize the cosmetic formula. The responses (dependent variables) were the spreadability (YSp) and viscosity (YVis), the factors (independent variables) being the weight proportions of the fatty phase (X1), the aqueous date seed extract (X2), and the beeswax (X3). Second, the cosmetic stability study was conducted by applying a full factorial design. Here, three responses were considered [spreadability (Sp), viscosity (Vis), and peroxide index (PI)], the independent variables being the concentration of the date seed oil (DSO) (x1), storage temperature (x2), and storage time (x3). Results showed that in the case of mixture design, the second-order polynomial equations correctly described experimental data. Globally, results show that there is a relatively wide composition range to ensure a suitable cosmetic cream from the point of view of Sp and Vis. Regarding the cosmetic stability, the storage time was found to be the most influential factor on both Vis and PI, which are considered here as indicators of physical and chemical stability of the emulsion, respectively. Finally, the elaborated and commercial cosmetics were compared in terms of pH, Sp, and centrifugation test (Ct).

The use of functionalized monoalkyl phosphates and phosphonates in the colloidal processing of oxide ceramic powders

NASA Astrophysics Data System (ADS)

Radsick, Timothy Carl

The purpose of this study was to develop phosphorous-based chemicals that could be used to modify the interparticle pair potential of several oxide ceramic particles, thereby enabling their use in colloidal processing schemes. Several procedures for the synthesis of 11-12 carbon alpha,o-functionalized monoalkyl phosphates and phosphonates were developed. Because of its simplicity and its use of mild reagents, a procedure based on the Michaelis-Arbuzov rearrangement was selected to produce the bulk of the chemicals used in this study. Carboxyl- and hydroxyl-terminated monoalkyl phosphonates were adsorbed onto alumina and zirconia powders using either aqueous-based or solvent-based methods to produce a monolayer of "brushlike" steric molecules. In the aqueous-based methods, powders were processed at pH values below their isoelectric point in order to produce a positive charge on the powder, thereby attracting the negatively charged phosphate or phosphonate group onto the powder surface to form the steric monolayer. In solvent-based methods, powder was suspended in an acetone solution of the phosphonates, heated at reflux, washed, dried and heat treated at 120°C under vacuum. The zeta potential of the coated powders was measured to quantify the degree of steric layer adsorption and the shift in the isoelectric point. Slurries of coated alumina and zirconia were prepared having 20 vol % powder. Rheological behavior was studied by measuring viscosity as a function of shear rate for slurries of various pH values and counterion concentrations. Slurries with powder processed via the solvent method were the least sensitive to changes in slurry pH and were straightforward to prepare. It is thought that the solvent-based coating procedure produced a stronger, multi-dentate powder-phosphonate bond than that of the aqueous-based procedure. Dispersed and coagulated slurries were able to be prepared over a wide pH range, including at the isoelectric point of the uncoated powders where a flocculated slurry would typically occur. Slurries were consolidated using pressure filtration. Compressive stress-strain behavior and packing efficiencies were determined. Through consolidation, powder volume fraction was increased to a maximum of 56%, yet through vibration the slurry could be induced to flow, enabling its use in Colloidal Isopressing.

Studies on improvement of pharmaceutical preparations prescribed in hospitals. IV. Dibekacin sulfate viscous solution for treatment of mouth and throat wounds.

PubMed

Namiki, N; Yokoyama, H; Moriya, K; Fukuda, M; Takashima, T; Uchida, Y; Yuasa, H; Kanaya, Y

1986-11-01

For the purpose of preventing suppuration of wounds of the oral cavity and throat, we attempted to develop a viscous solution of dibekacin sulfate (DKB) as a suitable medication. Solutions of different viscosity and antibacterial potency were prepared by mixing DKB, sodium carboxymethyl cellulose (CMC-Na), and water in varying proportions. Studies were then performed to ascertain relationships between the concentration of CMC-Na pH and viscosity, and between the viscosity and diffusion of DKB. The concentration of CMC-Na giving rise to optimal clinical efficacy was determined, and the concentration of DKB necessary for clinical treatment was estimated on the basis of the ionic binding constant between DKB and CMC-Na. As a result, the optimum CMC-Na concentration was found to be 2%, while the optimum DKB concentration was estimated to be 100 micrograms/ml.

Surface Tension and Viscosity of SCN and SCN-acetone Alloys at Melting Points and Higher Temperatures Using Surface Light Scattering Spectrometer

NASA Technical Reports Server (NTRS)

Tin, Padetha; deGroh, Henry C., III.

2003-01-01

Succinonitrile has been and is being used extensively in NASA's Microgravity Materials Science and Fluid Physics programs and as well as in several ground-based and microgravity studies including the Isothermal Dendritic Growth Experiment (IDGE). Succinonitrile (SCN) is useful as a model for the study of metal solidification, although it is an organic material, it has a BCC crystal structure and solidifies dendriticly like a metal. It is also transparent and has a low melting point (58.08 C). Previous measurements of succinonitrile (SCN) and alloys of succinonitrile and acetone surface tensions are extremely limited. Using the Surface Light Scattering technique we have determined non invasively, the surface tension and viscosity of SCN and SCN-Acetone Alloys at different temperatures. This relatively new and unique technique has several advantages over the classical methods such as, it is non invasive, has good accuracy and measures the surface tension and viscosity simultaneously. The accuracy of interfacial energy values obtained from this technique is better than 2% and viscosity about 10 %. Succinonitrile and succinonitrile-acetone alloys are well-established model materials with several essential physical properties accurately known - except the liquid/vapor surface tension at different elevated temperatures. We will be presenting the experimentally determined liquid/vapor surface energy and liquid viscosity of succinonitrile and succinonitrile-acetone alloys in the temperature range from their melting point to around 100 C using this non-invasive technique. We will also discuss about the measurement technique and new developments of the Surface Light Scattering Spectrometer.

Low-temperature-active and salt-tolerant β-mannanase from a newly isolated Enterobacter sp. strain N18.

PubMed

You, Jia; Liu, Jin-Feng; Yang, Shi-Zhong; Mu, Bo-Zhong

2016-02-01

A low-temperature-active and salt-tolerant β-mannanase produced by a novel mannanase-producer, Enterobacter sp. strain N18, was isolated, purified and then evaluated for its potential application as a gel-breaker in relation to viscosity reduction of guar-based hydraulic fracturing fluids used in oil field. The enzyme could lower the viscosity of guar gum solution by more than 95% within 10 min. The purified β-mannanase with molecular mass of 90 kDa displayed high activity in a broad range of pH and temperature: more than 70% of activity was retained in the pH range of 3.0-8.0 with the optimal pH 7.5, about 50% activity at 20°C with the optimal temperature 50°C. Furthermore, the enzyme retained >70% activity in the presence of 0.5-4.0 M NaCl. These properties implied that the enzyme from strain N18 had potential for serving as a gel-breaker for low temperature oil wells and other industrial fields, where chemical gel breakers were inactive due to low temperature. Copyright © 2015 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Modulating β-lactoglobulin nanofibril self-assembly at pH 2 using glycerol and sorbitol.

PubMed

Dave, Anant C; Loveday, Simon M; Anema, Skelte G; Jameson, Geoffrey B; Singh, Harjinder

2014-01-13

β-Lactoglobulin (β-lg) forms fibrils when heated at 80 °C, pH 2, and low ionic strength (<0.015 mM). When formed at protein concentrations <3%, these fibrils are made up of peptides produced from the acid hydrolysis of the β-lg monomer. The present study investigated the effects of the polyhydroxy alcohols (polyols) glycerol and sorbitol (0-50% w/v) on β-lg self-assembly at pH 2. Glycerol and sorbitol stabilize native protein structure and modulate protein functionality by preferential exclusion. In our study, both polyols decreased the rate of β-lg self-assembly but had no effect on the morphology of fibrils. The mechanism of these effects was studied using circular dichroism spectroscopy and SDS-PAGE. Sorbitol inhibited self-assembly by stabilizing β-lg against unfolding and hydrolysis, resulting in fewer fibrillogenic species, whereas glycerol inhibited nucleation without inhibiting hydrolysis. Both polyols increased the viscosity of the solutions, but viscosity appeared to have little effect on fibril assembly, and we believe that self-assembly was not diffusion-limited under these conditions. This is in agreement with previous reports for other proteins assembling under different conditions. The phenomenon of peptide self-assembly can be decoupled from protein hydrolysis using glycerol.

Optimization of a novel wax matrix system using aminoalkyl methacrylate copolymer E and ethylcellulose to suppress the bitter taste of acetaminophen.

PubMed

Shiino, Kai; Iwao, Yasunori; Miyagishima, Atsuo; Itai, Shigeru

2010-08-16

The purpose of the present study was to design and evaluate a novel wax matrix system containing various ratios of aminoalkyl methacrylate copolymer E (AMCE) and ethylcellulose (EC) as functional polymers in order to achieve the optimal acetaminophen (APAP) release rate for taste masking. A two factor, three level (3(2)) full factorial study design was used to optimize the ratios of AMCE and EC, and the release of APAP from the wax matrix was evaluated using a stationary disk in accordance with the paddle method. The disk was prepared by congealing glyceryl monostearate (GM), a wax with a low melting point, with various ratios of polymers and APAP. The criteria for release rate of APAP from the disk at pH 4.0 and pH 6.5 were calculated to be more than 0.5017 microg/(mlxmin) and less than 0.1414 microg/(mlxmin), respectively, under the assumption that the particle size of spherical matrix should be 100 microm. In multiple regression analysis, the release of APAP at pH 4.0 was found to increase markedly as the concentration of AMCE increased, whereas the release of APAP at pH 6.5 decreased as the EC concentration increased, even when a high level of AMCE was incorporated. Using principle component analysis, it was found that the viscosity of the matrix affects the pH-dependent release of APAP at pH 4.0 and pH 6.5. Furthermore, using multiple regression analysis, the optimum ratio of APAP:AMCE:EC:GM was found to be 30:7:10:53, and the release pattern of APAP from the optimum wax formulation nearly complied with the desired criteria. Therefore, the present study demonstrated that the incorporation of AMCE and EC into a wax matrix system enabled the appropriate release of APAP as a means of taste masking. Copyright (c) 2010 Elsevier B.V. All rights reserved.

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 multi-spectroscopic and molecular docking approach to investigate the interaction of antiviral drug oseltamivir with ct-DNA.

PubMed

Moghadam, Neda Hosseinpour; Salehzadeh, Sadegh; Shahabadi, Nahid; Golbedaghi, Reza

2017-07-03

The possible interaction between the antiviral drug oseltamivir and calf thymus DNA at physiological pH was studied by spectrophotometry, competitive spectrofluorimetry, differential pulse voltammogram (DPV), circular dichroism spectroscopy (CD), viscosity measurements, salt effect, and computational studies. Intercalation of oseltamivir between the base pairs of DNA was shown by a sharp increase in specific viscosity of DNA and a decrease of the peak current and a positive shift in differential pulse voltammogram. Competitive fluorescence experiments were performed using neutral red (NR) as a probe for the intercalation binding mode. The studies showed that oseltamivir is able to release the NR.

Elastic gauge fields and Hall viscosity of Dirac magnons

NASA Astrophysics Data System (ADS)

Ferreiros, Yago; Vozmediano, María A. H.

2018-02-01

We analyze the coupling of elastic lattice deformations to the magnon degrees of freedom of magnon Dirac materials. For a honeycomb ferromagnet we find that, as happens in the case of graphene, elastic gauge fields appear coupled to the magnon pseudospinors. For deformations that induce constant pseudomagnetic fields, the spectrum around the Dirac nodes splits into pseudo-Landau levels. We show that when a Dzyaloshinskii-Moriya interaction is considered, a topological gap opens in the system and a Chern-Simons effective action for the elastic degrees of freedom is generated. Such a term encodes a phonon Hall viscosity response, entirely generated by quantum fluctuations of magnons living in the vicinity of the Dirac points. The magnon Hall viscosity vanishes at zero temperature, and grows as temperature is raised and the states around the Dirac points are increasingly populated.

Resin characterization

Treesearch

Robert L. Geimer; Robert A. Follensbee; Alfred W. Christiansen; James A. Koutsky; George E. Myers

1990-01-01

Currently, thermosetting adhesives are characterized by physical andchemical features such as viscosity, solids content, pH, and molecular distribution, and their reaction in simple gel tests. Synthesis of a new resin for a particular application is usually accompanied by a series of empirical laboratory and plant trials. The purpose of the research outlined in this...

Composite solvers for linear saddle point problems arising from the incompressible Stokes equations with highly heterogeneous viscosity structure

NASA Astrophysics Data System (ADS)

Sanan, P.; Schnepp, S. M.; May, D.; Schenk, O.

2014-12-01

Geophysical applications require efficient forward models for non-linear Stokes flow on high resolution spatio-temporal domains. The bottleneck in applying the forward model is solving the linearized, discretized Stokes problem which takes the form of a large, indefinite (saddle point) linear system. Due to the heterogeniety of the effective viscosity in the elliptic operator, devising effective preconditioners for saddle point problems has proven challenging and highly problem-dependent. Nevertheless, at least three approaches show promise for preconditioning these difficult systems in an algorithmically scalable way using multigrid and/or domain decomposition techniques. The first is to work with a hierarchy of coarser or smaller saddle point problems. The second is to use the Schur complement method to decouple and sequentially solve for the pressure and velocity. The third is to use the Schur decomposition to devise preconditioners for the full operator. These involve sub-solves resembling inexact versions of the sequential solve. The choice of approach and sub-methods depends crucially on the motivating physics, the discretization, and available computational resources. Here we examine the performance trade-offs for preconditioning strategies applied to idealized models of mantle convection and lithospheric dynamics, characterized by large viscosity gradients. Due to the arbitrary topological structure of the viscosity field in geodynamical simulations, we utilize low order, inf-sup stable mixed finite element spatial discretizations which are suitable when sharp viscosity variations occur in element interiors. Particular attention is paid to possibilities within the decoupled and approximate Schur complement factorization-based monolithic approaches to leverage recently-developed flexible, communication-avoiding, and communication-hiding Krylov subspace methods in combination with `heavy' smoothers, which require solutions of large per-node sub-problems, well-suited to solution on hybrid computational clusters. To manage the combinatorial explosion of solver options (which include hybridizations of all the approaches mentioned above), we leverage the modularity of the PETSc library.

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

Microgravity Studies of Liquid-Liquid Phase Transitions in Alumina-Yttria Melts

NASA Technical Reports Server (NTRS)

Guynes, Buddy (Technical Monitor); Weber, Richard; Nordine, Paul

2004-01-01

The scientific objective of this research is to increase the fundamental knowledge base for liquid- phase processing of technologically important oxide materials. The experimental objective is to define conditions and hardware requirements for microgravity flight experiments to test and expand the experimental hypotheses that: 1. Liquid phase transitions can occur in undercooled melts by a diffusionless process. 2. Onset of the liquid phase transition is accompanied by a large change in the temperature dependence of melt viscosity. Experiments on undercooled YAG (Y3A15012)- and rare earth oxide aluminate composition liquids demonstrated a large departure from an Arrhenian temperature dependence of viscosity. Liquid YAG is nearly inviscid at its 2240 K melting point. Glass fibers were pulled from melts undercooled by ca. 600 K indicating that the viscosity is on the order of 100 Pans (1000 Poise) at 1600 K. This value of viscosity is 500 times greater than that obtained by extrapolation of data for temperatures above the melting point of YAG. These results show that the liquids are extremely fragile and that the onset of the highly non-Arrhenian viscosity-temperature relationship occurs at a temperature considerably below the equilibrium melting point of the solid phases. Further results on undercooled alumina-yttria melts containing 23-42 mole % yttrium oxide indicate that a congruent liquid-liquid phase transition occurs in the undercooled liquids. The rates of transition are inconsistent with a diffusion-limited process. This research is directed to investigation of the scientifically interesting phenomena of polyamorphism and fragility in undercooled rare earth oxide aluminum oxide liquids. The results bear on the technologically important problem of producing high value rare earth-based optical materials.

Arab light crude study focuses on kinematic viscosity

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

Beg, S.A.; Al-Mutawa, A.H.; Amin, M.B.

1989-02-01

Arab light crude oil has been characterized in terms of API gravity, total sulfur content, Reid vapor pressure, ash content, heating value, salt content, viscosity SUS, vanadium content as V/sub 2/O/sub 5/, pour point and analyses of various metals. The crude oil was fractionated into six true boiling point (TBP) fractions (IBP-95/sup 0/C, 95-205/sup 0/C, 205-260/sup 0/C, 260-345/sup 0/C, 345-455/sup 0/C and 455/sup 0/C+). These fractions were characterized in terms of API gravity, total sulfur, H/sub 2/S, mercaptan contents, molecular weight, elemental analyses for total carbon, hydrogen and nitrogen, and analyses of various metals. The kinematic viscosity data have beenmore » obtained for 95/sup 0/C+ TBP fractions for a wide range of temperature up to 200/sup 0/C.« less

Characterization of Arab medium crude fractions with emphasis on kinematic viscosity - temperature behavior

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

Beg, S.A.; Amin, M.B.; Hussain, I.

1986-01-01

Characterization of Arab medium Crude Oil, has been carried out in terms of API gravity, debutanized crude gravity, total sulfur content, Reid vapour pressure ash content, heating value, salt content, viscosity SUS, vanadium content as V/sub 2/O/sub 5/, pour point and analysis of various metals. Further, six true boiling point (TBP) fractions (IBP-95/sup 0/C, 95-205/sup 0/C, 205-260/sup 0/C, 260-345/sup 0/C, 345-455/sup 0/C and 455/sup 0/C+) of this crude were characterized in terms of API gravity, total sulfur contents H/sub 2/S content, mercaptons content, molecular weight, elemental analyses for total carbon, hydrogen and nitrogen, analyses of various metals and paraffin, aromaticmore » and naphthene contents of lighter fractions. The kinematic viscosity-temperature data have been obtained for 95/sup 0/C+ TBP fractions for a wide range of temperatures.« less

Computer simulation of immobilized pH gradients at acidic and alkaline extremes - A quest for extended pH intervals

NASA Technical Reports Server (NTRS)

Mosher, Richard A.; Bier, Milan; Righetti, Pier Giorgio

1986-01-01

Computer simulations of the concentration profiles of simple biprotic ampholytes with Delta pKs 1, 2, and 3, on immobilized pH gradients (IPG) at extreme pH values (pH 3-4 and pH 10-11) show markedly skewed steady-state profiles with increasing kurtosis at higher Delta pK values. Across neutrality, all the peaks are symmetric irrespective of their Delta pK values, but they show very high contribution to the conductivity of the background gel and significant alteration of the local buffering capacity. The problems of skewness, due to the exponential conductivity profiles at low and high pHs, and of gel burning due to a strong electroosmotic flow generated by the net charges in the gel matrix, also at low and high pHs, are solved by incorporating in the IPG gel a strong viscosity gradient. This is generated by a gradient of linear polyacrylamide which is trapped in the gel by the polymerization process.

Effects of high hydrostatic pressure on secondary structure and emulsifying behavior of sweet potato protein

NASA Astrophysics Data System (ADS)

Mehmood Khan, Nasir; Mu, Tai-Hua; Sun, Hong-Nan; Zhang, Miao; Chen, Jing-Wang

2015-04-01

In this study, secondary structures of sweet potato protein (SPP) after high hydrostatic pressure (HHP) treatment (200-600 MPa) were evaluated and emulsifying properties of emulsions with HHP-treated SPP solutions in different pH values (3, 6, and 9) were investigated. Circular dichroism analysis confirmed the modification of the SPP secondary structure. Surface hydrophobicity increased at pH 3 and decreased at 6 and 9. Emulsifying activity index at pH 6 increased with an increase in pressure, whereas emulsifying stability index increased at pH 6 and 9. Oil droplet sizes decreased, while volume frequency distribution of the smaller droplets increased at pH 3 and 6 with the HHP treatment. Emulsion viscosity increased at pH 6 and 9 and pseudo-plastic flow behaviors were not altered for all emulsions produced with HHP-treated SPP. These results suggested that HHP could modify the SPP structure for better emulsifying properties, which could increase the use of SPP emulsion in the food industry.

Formulation and evaluation of voriconazole ophthalmic solid lipid nanoparticles in situ gel.

PubMed

Pandurangan, Dinesh Kumar; Bodagala, Prathima; Palanirajan, Vijayaraj Kumar; Govindaraj, Saravanan

2016-01-01

In the present investigation, solid lipid nanoparticles (SLNs)-loaded in situ gel with voriconazole drug was formulated. Further, the formulation was characterized for pH, gelling capacity, entrapment efficiency, in vitro drug release, drug content, and viscosity. Voriconazole is an antifungal drug used to treat various infections caused by yeast or other types of fungi. Film hydration technique was used to prepared SLNs from lecithin and cholesterol. Based on the entrapment efficiency 67.2-97.3% and drug release, the optimized formulation NF1 of SLNs was incorporated into in situ gels. The in situ gels were prepared using viscosity-enhancing polymers such as Carbopol and (hydroxypropyl)methyl cellulose (HPMC). Formulated SLN in situ gel formulations were characterized, which showed pH 4.9-7.1, drug content 65.69-96.3%, and viscosity (100 rpm) 120-620 cps. From the characterizations given above, F6 was optimized and evaluated for microbial assay and ocular irritation studies. Microbial assay was conducted by the cup-plate method using Candida albicans as the test organism. An ocular irritation study was conducted on albino rabbits. The results revealed that there was no ocular damage to the cornea, conjunctiva, or iris. Stability studies were carried out on the F6 formulation for 3 months, which showed that the formulation had good stability. These results indicate that the studied SLNs-loaded in situ gel is a promising vehicle for ocular delivery.

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

PubMed

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

2014-05-28

Foods that enhance satiety can help consumers to resist environmental cues to eat, and improve the nutritional quality of their diets. Viscosity generated by oat β-glucan, influences gastrointestinal mechanisms that mediate satiety. Differences in the source, processing treatments, and interactions with other constituents in the food matrix affect the amount, solubility, molecular weight, and structure of the β-glucan in products, which in turn influences the viscosity. This study examined the effect of two types of oatmeal and an oat-based ready-to-eat breakfast cereal (RTEC) on appetite, and assessed differences in meal viscosity and β-glucan characteristics among the cereals. Forty-eight individuals were enrolled in a randomized crossover trial. Subjects consumed isocaloric breakfast meals containing instant oatmeal (IO), old-fashioned oatmeal (SO) or RTEC in random order at least a week apart. Each breakfast meal contained 218 kcal (150 kcal cereal, and 68 kcal milk) Visual analogue scales measuring appetite were completed before breakfast, and over four hours, following the meal. Starch digestion kinetics, meal viscosities, and β-glucan characteristics for each meal were determined. Appetite responses were analyzed by area under the curve. Mixed models were used to analyze response changes over time. IO increased fullness (p = 0.04), suppressed desire to eat (p = 0.01) and reduced prospective intake (p < 0.01) more than the RTEC over four hours, and consistently at the 60 minute time-point. SO reduced prospective intake (p = 0.04) more than the RTEC. Hunger scores were not significantly different except that IO reduced hunger more than the RTEC at the 60 minute time-point. IO and SO had higher β-glucan content, molecular weight, gastric viscosity, and larger hydration spheres than the RTEC, and IO had greater viscosity after oral and initial gastric digestion (initial viscosity) than the RTEC. IO and SO improved appetite control over four hours compared to RTEC. Initial viscosity of oatmeal may be especially important for reducing appetite.

The role of meal viscosity and oat β-glucan characteristics in human appetite control: a randomized crossover trial

PubMed Central

2014-01-01

Background Foods that enhance satiety can help consumers to resist environmental cues to eat, and improve the nutritional quality of their diets. Viscosity generated by oat β-glucan, influences gastrointestinal mechanisms that mediate satiety. Differences in the source, processing treatments, and interactions with other constituents in the food matrix affect the amount, solubility, molecular weight, and structure of the β-glucan in products, which in turn influences the viscosity. This study examined the effect of two types of oatmeal and an oat-based ready-to-eat breakfast cereal (RTEC) on appetite, and assessed differences in meal viscosity and β-glucan characteristics among the cereals. Methods Forty-eight individuals were enrolled in a randomized crossover trial. Subjects consumed isocaloric breakfast meals containing instant oatmeal (IO), old-fashioned oatmeal (SO) or RTEC in random order at least a week apart. Each breakfast meal contained 218 kcal (150 kcal cereal, and 68 kcal milk) Visual analogue scales measuring appetite were completed before breakfast, and over four hours, following the meal. Starch digestion kinetics, meal viscosities, and β-glucan characteristics for each meal were determined. Appetite responses were analyzed by area under the curve. Mixed models were used to analyze response changes over time. Results IO increased fullness (p = 0.04), suppressed desire to eat (p = 0.01) and reduced prospective intake (p < 0.01) more than the RTEC over four hours, and consistently at the 60 minute time-point. SO reduced prospective intake (p = 0.04) more than the RTEC. Hunger scores were not significantly different except that IO reduced hunger more than the RTEC at the 60 minute time-point. IO and SO had higher β-glucan content, molecular weight, gastric viscosity, and larger hydration spheres than the RTEC, and IO had greater viscosity after oral and initial gastric digestion (initial viscosity) than the RTEC. Conclusion IO and SO improved appetite control over four hours compared to RTEC. Initial viscosity of oatmeal may be especially important for reducing appetite. PMID:24884934

Influence of nitrogen source and pH value on undesired poly(γ-glutamic acid) formation of a protease producing Bacillus licheniformis strain.

PubMed

Meissner, Lena; Kauffmann, Kira; Wengeler, Timo; Mitsunaga, Hitoshi; Fukusaki, Eiichiro; Büchs, Jochen

2015-09-01

Bacillus spp. are used for the production of industrial enzymes but are also known to be capable of producing biopolymers such as poly(γ-glutamic acid). Biopolymers increase the viscosity of the fermentation broth, thereby impairing mixing, gas/liquid mass and heat transfer in any bioreactor system. Undesired biopolymer formation has a significant impact on the fermentation and downstream processing performance. This study shows how undesirable poly(γ-glutamic acid) formation of an industrial protease producing Bacillus licheniformis strain was prevented by switching the nitrogen source from ammonium to nitrate. The viscosity was reduced from 32 to 2.5 mPa s. A constant or changing pH value did not influence the poly(γ-glutamic acid) production. Protease production was not affected: protease activities of 38 and 46 U mL(-1) were obtained for ammonium and nitrate, respectively. With the presented results, protease production with industrial Bacillus strains is now possible without the negative impact on fermentation and downstream processing by undesired poly(γ-glutamic acid) formation.

Physicochemical properties of betaine monohydrate-carboxylic acid mixtures

NASA Astrophysics Data System (ADS)

Zahrina, I.; Nasikin, M.; Mulia, K.

2018-05-01

Green solvents are widely used to minimize environmental problems associated with the use of volatile organic solvents in many industries. DES are new green solvents in recent. The physicochemical properties of DES can be varied by properly combining of salts with different hydrogen bond donors. The objective of this work is to investigate the effect of varying molar ratios on the physicochemical properties of betaine monohydrate-carboxylic acid (i.e,. propionic or acetic acid) mixtures. Properties of mixtures were measured at 40°C. The viscosity, polarity scale (ENR), density, pH, and water content tend to decrease with the decrease in a molar ratio of betaine monohydrate to acid. Conversely, the ionic conductivity was increased. The physicochemical properties of these mixtures depend on the hydrogen bonding interactions between betaine, water and acid molecules. Betaine monohydratecarboxylic acid mixtures have wide range of polarity, low viscosity, high ionic conductivity, and density higher than 1 g·cm-3 that make them fit for numerous various applications. Additionally, due to these mixtures have acidic pH, it should be properly selected of metal type to minimize corrosion problems in industrial application.

Physical characteristic and irritation index of Syzigium aromaticum essential oil in O/W and W/O creams

NASA Astrophysics Data System (ADS)

Safriani, R.; Sugihartini, N.; Yuliani, S.

2017-11-01

Essential oil of Syzigium aromaticum has been formulated in O/W and W/O creams as anti-inflammatory dosage form. The purpose of this study was to evaluate the physical characteristic and irritation index of S. aromaticum essential oil in O/W and W/O creams. The creams were made by fusion method. The creams then were evaluated the physical characteristic including pH, viscosity, spreadability and adhesivity. The irritation index was obtained by irritation skin test in male rabbit. The results showed that the W/O and O/W creams have the value of pH: 6.3 and 6.27; spreadability: 3,18 and 4.17 cm2; adhesivity: 5.59 and 0.07 minutes; viscosity: 4.43 and 2.88 Pa.S, respectively. The irritation test showed that the control enhancer caused mild irritation in both of W/O and O/W creams. These findings indicated that type of cream might influence the physical characteristic and irritation index of S. aromaticum essential oil cream.

Bulk viscosity of the Lennard-Jones fluid for a wide range of states computed by equilibrium molecular dynamics

NASA Astrophysics Data System (ADS)

Hoheisel, C.; Vogelsang, R.; Schoen, M.

1987-12-01

Accurate data for the bulk viscosity ηv have been obtained by molecular dynamics calculations. Many thermodynamic states of the Lennard-Jones fluid were considered. The Green-Kubo integrand of ηv is analyzed in terms of partial correlation functions constituting the total one. These partial functions behave rather differently from those found for the shear viscosity or the thermal conductivity. Generally the total autocorrelation function of ηv shows a steeper initial decay and a more pronounced long time form than those of the shear viscosity or the thermal conductivity. For states near transition to solid phases, like the pseudotriple point of argon, the Green-Kubo integrand of ηv has a significantly longer ranged time behavior than that of the shear viscosity. Hence, for the latter states, a systematic error is expected for ηv using equilibrium molecular dynamics for its computation.

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.

Investigation of Damping Liquids for Aircraft Instruments : II

NASA Technical Reports Server (NTRS)

Houseman, M R; Keulegan, G H

1932-01-01

Data are presented on the kinematic viscosity, in the temperature range -50 degrees to +30 degrees C. of pure liquids and of solutions of animal oils, vegetable oils, mineral oils, glycerine, and ethylene glycol in various low freezing point solvents. It is shown that the thermal coefficient of kinematic viscosity as a function of the kinematic viscosity of the solutions of glycerine and ethylene glycol in alcohols is practically independent of the temperature and the chemical composition of the individual liquids. This is similarly true for the mineral oil group and, for a limited temperature interval, for the pure animal and vegetable oils. The efficiency of naphthol, hydroquinone, and diphenylamine to inhibit the change of viscosity of poppyseed and linseed oils was also investigated.

Finite element modeling of melting and fluid flow in the laser-heated diamond-anvil cell

NASA Astrophysics Data System (ADS)

Gomez-Perez, N.; Rodriguez, J. F.; McWilliams, R. S.

2017-04-01

The laser-heated diamond anvil cell is widely used in the laboratory study of materials behavior at high-pressure and high-temperature, including melting curves and liquid properties at extreme conditions. Laser heating in the diamond cell has long been associated with fluid-like motion in samples, which is routinely used to determine melting points and is often described as convective in appearance. However, the flow behavior of this system is poorly understood. A quantitative treatment of melting and flow in the laser-heated diamond anvil cell is developed here to physically relate experimental motion to properties of interest, including melting points and viscosity. Numerical finite-element models are used to characterize the temperature distribution, melting, buoyancy, and resulting natural convection in samples. We find that continuous fluid motion in experiments can be explained most readily by natural convection. Fluid velocities, peaking near values of microns per second for plausible viscosities, are sufficiently fast to be detected experimentally, lending support to the use of convective motion as a criterion for melting. Convection depends on the physical properties of the melt and the sample geometry and is too sluggish to detect for viscosities significantly above that of water at ambient conditions, implying an upper bound on the melt viscosity of about 1 mPa s when convective motion is detected. A simple analytical relationship between melt viscosity and velocity suggests that direct viscosity measurements can be made from flow speeds, given the basic thermodynamic and geometric parameters of samples are known.

Reference Correlation for the Viscosity of Ammonia from the Triple Point to 725 K and up to 50 MPa

NASA Astrophysics Data System (ADS)

Monogenidou, S. A.; Assael, M. J.; Huber, M. L.

2018-06-01

This paper presents a new wide-ranging correlation for the viscosity of ammonia based on critically evaluated experimental data. The correlation is designed to be used with a recently developed equation of state, and it is valid from the triple point to 725 K at pressures up to 50 MPa. The estimated uncertainty varies depending on the temperature and pressure, from 0.6% to 5%. The correlation behaves in a physically reasonable manner when extrapolated to 100 MPa; however, care should be taken when using the correlation outside of the validated range.

Optimization of experimental conditions for composite biodiesel production from transesterification of mixed oils of Jatropha and Pongamia

NASA Astrophysics Data System (ADS)

Yogish, H.; Chandrashekara, K.; Pramod Kumar, M. R.

2012-11-01

India is looking at the renewable alternative sources of energy to reduce its dependence on import of crude oil. As India imports 70 % of the crude oil, the country has been greatly affected by increasing cost and uncertainty. Biodiesel fuel derived by the two step acid transesterification of mixed non-edible oils from Jatropha curcas and Pongamia (karanja) can meet the requirements of diesel fuel in the coming years. In the present study, different proportions of Methanol, Sodium hydroxide, variation of Reaction time, Sulfuric acid and Reaction Temperature were adopted in order to optimize the experimental conditions for maximum biodiesel yield. The preliminary studies revealed that biodiesel yield varied widely in the range of 75-95 % using the laboratory scale reactor. The average yield of 95 % was obtained. The fuel and chemical properties of biodiesel, namely kinematic viscosity, specific gravity, density, flash point, fire point, calorific value, pH, acid value, iodine value, sulfur content, water content, glycerin content and sulfated ash values were found to be within the limits suggested by Bureau of Indian Standards (BIS 15607: 2005). The optimum combination of Methanol, Sodium hydroxide, Sulfuric acid, Reaction Time and Reaction Temperature are established.

Optimization of the new formulation of ice cream with native Iranian seed gums (Lepidium perfoliatum and Lepidium sativum) using response surface methodology (RSM).

PubMed

Azari-Anpar, M; Soltani Tehrani, N; Aghajani, N; Khomeiri, M

2017-01-01

In this study, effect of Qodume shahri ( Lepidium perfoliatum ) and cress ( Lepidium sativum ) on rheological properties of ice cream were investigated. The gums were added to the ice cream formulation and different quality attributes including pH, acidity, melting characteristics, viscosity, overrun, texture analysis and sensory evaluation were determined. Results showed that ice cream formulations containing both the gums had improved overrun, melting rate, first dripping time, viscosity, hardness and adhesiveness. The gum concentrations beyond 0.2% level led to a negative effect on gumminess and chewiness of ice cream. Both the gums addition to improved quality attributes and textural properties of ice cream.

Time dependent deformation and stress in the lithosphere. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Yang, M.

1980-01-01

Efficient computer programs incorporating frontal solution and time stepping procedure were developed for the modelling of geodynamic problems. This scheme allows for investigating the quasi static phenomena including the effects of the rheological structure of a tectonically active region. From three dimensional models of strike slip earthquakes, it was found that lateral variation of viscosity affects the characteristics of surface deformations. The vertical deformation is especially informative about the viscosity structure in a strike slip fault zone. A three dimensional viscoelastic model of a thrust earthquake indicated that the transient disturbance on plate velocity due to a great plate boundary earthquake is significant at intermediate distances, but becomes barely measurable 1000 km away from the source.

Spectroscopic and molecular docking studies on the interaction of antiviral drug nevirapine with calf thymus DNA.

PubMed

Moghadam, Neda Hosseinpour; Salehzadeh, Sadegh; Shahabadi, Nahid

2017-09-02

The interaction of calf thymus DNA with nevirapine at physiological pH was studied by using absorption, circular dichroism, viscosity, differential pulse voltammetry, fluorescence techniques, salt effect studies and computational methods. The drug binds to ct-DNA in a groove binding mode, as shown by slight variation in the viscosity of ct-DNA. Furthermore, competitive fluorimetric studies with Hoechst 33258 indicate that nevirapine binds to DNA via groove binding. Moreover, the structure of nevirapine was optimized by DFT calculations and was used for the molecular docking calculations. The molecular docking results suggested that nevirapine prefers to bind on the minor groove of ct-DNA.

Concentration-dependent changes in apparent diffusion coefficients as indicator for colloidal stability of protein solutions.

PubMed

Bauer, Katharina Christin; Göbel, Mathias; Schwab, Marie-Luise; Schermeyer, Marie-Therese; Hubbuch, Jürgen

2016-09-10

The colloidal stability of a protein solution during downstream processing, formulation, and storage is a key issue for the biopharmaceutical production process. Thus, knowledge about colloidal solution characteristics, such as the tendency to form aggregates or high viscosity, at various processing conditions is of interest. This work correlates changes in the apparent diffusion coefficient as a parameter of protein interactions with observed protein aggregation and dynamic viscosity of the respective protein samples. For this purpose, the diffusion coefficient, the protein phase behavior, and the dynamic viscosity in various systems containing the model proteins α-lactalbumin, lysozyme, and glucose oxidase were studied. Each of these experiments revealed a wide range of variations in protein interactions depending on protein type, protein concentration, pH, and the NaCl concentration. All these variations showed to be mirrored by changes in the apparent diffusion coefficient in the respective samples. Whereas stable samples with relatively low viscosity showed an almost linear dependence, the deviation from the concentration-dependent linearity indicated both an increase in the sample viscosity and probability of protein aggregation. This deviation of the apparent diffusion coefficient from concentration-dependent linearity was independent of protein type and solution properties for this study. Thus, this single parameter shows the potential to act as a prognostic tool for colloidal stability of protein solutions. Copyright © 2016 Elsevier B.V. All rights reserved.

Predicting the apparent viscosity and yield stress of mixtures of primary, secondary and anaerobically digested sewage sludge: Simulating anaerobic digesters.

PubMed

Markis, Flora; Baudez, Jean-Christophe; Parthasarathy, Rajarathinam; Slatter, Paul; Eshtiaghi, Nicky

2016-09-01

Predicting the flow behaviour, most notably, the apparent viscosity and yield stress of sludge mixtures inside the anaerobic digester is essential because it helps optimize the mixing system in digesters. This paper investigates the rheology of sludge mixtures as a function of digested sludge volume fraction. Sludge mixtures exhibited non-Newtonian, shear thinning, yield stress behaviour. The apparent viscosity and yield stress of sludge mixtures prepared at the same total solids concentration was influenced by the interactions within the digested sludge and increased with the volume fraction of digested sludge - highlighted using shear compliance and shear modulus of sludge mixtures. However, when a thickened primary - secondary sludge mixture was mixed with dilute digested sludge, the apparent viscosity and yield stress decreased with increasing the volume fraction of digested sludge. This was caused by the dilution effect leading to a reduction in the hydrodynamic and non-hydrodynamic interactions when dilute digested sludge was added. Correlations were developed to predict the apparent viscosity and yield stress of the mixtures as a function of the digested sludge volume fraction and total solids concentration of the mixtures. The parameters of correlations can be estimated using pH of sludge. The shear and complex modulus were also modelled and they followed an exponential relationship with increasing digested sludge volume fraction. Copyright © 2016 Elsevier Ltd. All rights reserved.

Atmospheric Pressure Plasma Jet Treatment of Poly-ε-caprolactone Polymer Solutions To Improve Electrospinning.

PubMed

Grande, Silvia; Van Guyse, Joachim; Nikiforov, Anton Y; Onyshchenko, Iuliia; Asadian, Mahtab; Morent, Rino; Hoogenboom, Richard; De Geyter, Nathalie

2017-09-27

An atmospheric pressure plasma jet (APPJ) specifically designed for liquid treatment has been used in this work to improve the electrospinnability of a 5 w/v % solution of poly-ε-caprolactone (PCL) in a mixture of chloroform and N,N-dimethylformamide. Untreated PCL solutions were found to result in nonuniform fibers containing a large number of beads, whereas plasma-treated solutions (exposure time of 2-5 min) enabled the generation of beadless, uniform nanofibers with an average diameter of 450 nm. This enhanced electrospinnability was found to be mainly due to the highly increased conductivity of the plasma-modified PCL solutions. Consequently, more stretching of the polymer jet occurred during electrospinning, leading to the generation of bead-free fibers. Plasma treatment also results in an increased viscosity and decreased pH values. To explain these observed changes, optical emission spectroscopy (OES) has been used to examine the excited species present in the APPJ in contact with the PCL solution. This study revealed that the peaks attributed to H, CH, CH 2 , and C 2 species could be responsible for the degradation of solvent molecules and/or PCL structures during the plasma treatment. Size exclusion chromatography and X-ray photoelectron spectroscopy results showed that the molecular weight and the chemical composition of PCL were not significantly affected by the APPJ treatment. Plasma exposure mainly results in the degradation of the solvent molecules instead of modifying the PCL macromolecules, preserving the original polymer as much as possible. A hypothesis for the observed macroscopic changes in viscosity and pH values could be the generation of new chemical species such as HCl and/or HNO 3 . These species are characterized by their high conductivity, low pH values, and strong polarity and could enhance the solvent quality for PCL, leading to the expansion of the polymer coil, which could in turn explain the observed enhanced viscosity after plasma modification.

Agrobacterium-assisted selenium nanoparticles: molecular aspect of antifungal activity

NASA Astrophysics Data System (ADS)

Kumar, Anil; Bera, Smritilekha; Singh, Man; Mondal, Dhananjoy

2018-03-01

Selenium nanoparticles (SeNPs) were synthesized through the bioreduction of sodium selenite (Na2SeO3) using gram-negative agrobacterium (AGBT) species. Subsequently, their physicochemical properties (pH, viscosity and surface tension) and medicinal activities as anti-dermatophyte against soil keratinophilic fungi at the molecular level were assessed. UV-visible and FTIR spectroscopic data of the biologically synthesized SeNPs were then recorded for confirming the presence of native biological materials adhered to nanoparticles, which are inherently required to enhance the stability and solubility through inhibition of the nanoparticle’s natural aggregation and agglomeration. The λ max value between 290-300 nm in the absorption spectra of the biogenic materials in different concentrations of the Na2SeO3 corroborated the presence of SeNPs in the solution. The interaction of SeNPs in solution state was further studied through the determination of pH, viscosity and surface tension values of agrobacterium-derived SeNPs in different solvents. The pH value of SeNPs dispersed in water is reported as above 7.0 and the average viscosity, and surface tensions of the SeNPs are appeared as near to the water. The particle size distribution was further determined by DLS and the highest % of particle size of the synthesized SeNPs is found in between 200-300 nm. The anti-dermatophyte activity and molecular interaction with fungi DNA molecules were assessed providing the highest anti-dermatophyte activity at 0.1 M concentration and it is observed that the quantities and qualities of fungi DNA were affected by SeNPs. Considering all the outcomes of the studies together, our findings suggest that agrobacterium-mediated synthesis of SeNPs is dependent on bacterial metabolisms but not on the concentration of Na2SeO3 and are promising selenium-derived species with potential application in the prevention of fungal infection through denaturation of fungi DNA.

Impact of plasma viscosity on microcirculatory flow after traumatic haemorrhagic shock: A prospective observational study.

PubMed

Naumann, David N; Hazeldine, Jon; Bishop, Jon; Midwinter, Mark J; Harrison, Paul; Nash, Gerard; Hutchings, Sam D

2018-05-19

Preclinical studies report that higher plasma viscosity improves microcirculatory flow after haemorrhagic shock and resuscitation, but no clinical study has tested this hypothesis. We investigated the relationship between plasma viscosity and sublingual microcirculatory flow in patients during resuscitation for traumatic haemorrhagic shock (THS). Sublingual video-microscopy was performed for 20 trauma patients with THS as soon as feasible in hospital, and then at 24 h and 48 h. Values were obtained for total vessel density, perfused vessel density, proportion of perfused vessels, microcirculatory flow index (MFI), microcirculatory heterogeneity index (MHI), and Point of Care Microcirculation (POEM) scores. Plasma viscosity was measured using a Wells-Brookfield cone and plate micro-viscometer. Logistic regression analyses examined relationships between microcirculatory parameters and plasma viscosity, adjusting for covariates (systolic blood pressure, heart rate, haematocrit, rate and volume of fluids, and rate of noradrenaline). Higher plasma viscosity was not associated with improved microcirculatory parameters. Instead, there were weakly significant associations between higher plasma viscosity and lower (poorer) MFI (p = 0.040), higher (worse) MHI (p = 0.033), and lower (worse) POEM scores (p = 0.039). The current study did not confirm the hypothesis that higher plasma viscosity improves microcirculatory flow dynamics in patients with THS. Further clinical investigations are warranted to determine whether viscosity is a physical parameter of importance during resuscitation of these patients.

Shear Elasticity and Shear Viscosity Imaging in Soft Tissue

NASA Astrophysics Data System (ADS)

Yang, Yiqun

In this thesis, a new approach is introduced that provides estimates of shear elasticity and shear viscosity using time-domain measurements of shear waves in viscoelastic media. Simulations of shear wave particle displacements induced by an acoustic radiation force are accelerated significantly by a GPU. The acoustic radiation force is first calculated using the fast near field method (FNM) and the angular spectrum approach (ASA). The shear waves induced by the acoustic radiation force are then simulated in elastic and viscoelastic media using Green's functions. A parallel algorithm is developed to perform these calculations on a GPU, where the shear wave particle displacements at different observation points are calculated in parallel. The resulting speed increase enables rapid evaluation of shear waves at discrete points, in 2D planes, and for push beams with different spatial samplings and for different values of the f-number (f/#). The results of these simulations show that push beams with smaller f/# require a higher spatial sampling rate. The significant amount of acceleration achieved by this approach suggests that shear wave simulations with the Green's function approach are ideally suited for high-performance GPUs. Shear wave elasticity imaging determines the mechanical parameters of soft tissue by analyzing measured shear waves induced by an acoustic radiation force. To estimate the shear elasticity value, the widely used time-of-flight method calculates the correlation between shear wave particle velocities at adjacent lateral observation points. Although this method provides accurate estimates of the shear elasticity in purely elastic media, our experience suggests that the time-of-flight (TOF) method consistently overestimates the shear elasticity values in viscoelastic media because the combined effects of diffraction, attenuation, and dispersion are not considered. To address this problem, we have developed an approach that directly accounts for all of these effects when estimating the shear elasticity. This new approach simulates shear wave particle velocities using a Green's function-based approach for the Voigt model, where the shear elasticity and viscosity values are estimated using an optimization-based approach that compares measured shear wave particle velocities with simulated shear wave particle velocities in the time-domain. The results are evaluated on a point-by-point basis to generate images. There is good agreement between the simulated and measured shear wave particle velocities, where the new approach yields much better images of the shear elasticity and shear viscosity than the TOF method. The new estimation approach is accelerated with an approximate viscoelastic Green's function model that is evaluated with shear wave data obtained from in vivo human livers. Instead of calculating shear waves with combinations of different shear elasticities and shear viscosities, shear waves are calculated with different shear elasticities on the GPU and then convolved with a viscous loss model, which accelerates the calculation dramatically. The shear elasticity and shear viscosity values are then estimated using an optimization-based approach by minimizing the difference between measured and simulated shear wave particle velocities. Shear elasticity and shear viscosity images are generated at every spatial point in a two-dimensional (2D) field-of-view (FOV). The new approach is applied to measured shear wave data obtained from in vivo human livers, and the results show that this new approach successfully generates shear elasticity and shear viscosity images from this data. The results also indicate that the shear elasticity values estimated with this approach are significantly smaller than the values estimated with the conventional TOF method and that the new approach demonstrates more consistent values for these estimates compared with the TOF method. This experience suggests that the new method is an effective approach for estimating the shear elasticity and the shear viscosity in liver and in other soft tissue.

Characterization of a beta-glucanase produced by Rhizopus microsporus var. microsporus, and its potential for application in the brewing industry.

PubMed

Celestino, Klecius R Silveira; Cunha, Ricardo B; Felix, Carlos R

2006-12-05

In the barley malting process, partial hydrolysis of beta-glucans begins with seed germination. However, the endogenous 1,3-1,4-beta-glucanases are heat inactivated, and the remaining high molecular weight beta-glucans may cause severe problems such as increased brewer mash viscosity and turbidity. Increased viscosity impairs pumping and filtration, resulting in lower efficiency, reduced yields of extracts, and lower filtration rates, as well as the appearance of gelatinous precipitates in the finished beer. Therefore, the use of exogenous beta-glucanases to reduce the beta-glucans already present in the malt barley is highly desirable. The zygomycete microfungus Rhizopus microsporus var. microsporus secreted substantial amounts of beta-glucanase in liquid culture medium containing 0.5% chitin. An active protein was isolated by gel filtration and ion exchange chromatographies of the beta-glucanase activity-containing culture supernatant. This isolated protein hydrolyzed 1,3-1,4-beta-glucan (barley beta-glucan), but showed only residual activity against 1,3-beta-glucan (laminarin), or no activity at all against 1,4-beta-glucan (cellulose), indicating that the R. microsporus var. microsporus enzyme is a member of the EC 3.2.1.73 category. The purified protein had a molecular mass of 33.7 kDa, as determined by mass spectrometry. The optimal pH and temperature for hydrolysis of 1,3-1,4-beta-glucan were in the ranges of 4-5, and 50-60 degrees C, respectively. The Km and Vmax values for hydrolysis of beta-glucan at pH 5.0 and 50 degrees C were 22.39 mg.mL-1 and 16.46 mg.min-1, respectively. The purified enzyme was highly sensitive to Cu+2, but showed less or no sensitivity to other divalent ions, and was able to reduce both the viscosity and the filtration time of a sample of brewer mash. In comparison to the values determined for the mash treated with two commercial glucanases, the relative viscosity value for the mash treated with the 1,3-1,4-beta-glucanase produced by R. microsporus var. microsporus. was determined to be consistently lower. The zygomycete microfungus R. microsporus var. microsporus produced a 1,3-1,4-beta-D-glucan 4-glucanhydrolase (EC 3.2.1.73) which is able to hydrolyze beta-D-glucan that contains both the 1,3- and 1,4-bonds (barley beta-glucans). Its molecular mass was 33.7 kDa. Maximum activity was detected at pH values in the range of 4-5, and temperatures in the range of 50-60 degrees C. The enzyme was able to reduce both the viscosity of the brewer mash and the filtration time, indicating its potential value for the brewing industry.

Out-of-Bounds Hydrodynamics in Anisotropic Dirac Fluids

NASA Astrophysics Data System (ADS)

Link, Julia M.; Narozhny, Boris N.; Kiselev, Egor I.; Schmalian, Jörg

2018-05-01

We study hydrodynamic transport in two-dimensional, interacting electronic systems with merging Dirac points at charge neutrality. The dispersion along one crystallographic direction is Dirac-like, while it is Newtonian-like in the orthogonal direction. As a result, the electrical conductivity is metallic in one and insulating in the other direction. The shear viscosity tensor contains six independent components, which can be probed by measuring an anisotropic thermal flow. One of the viscosity components vanishes at zero temperature leading to a generalization of the previously conjectured lower bound for the shear viscosity to entropy density ratio.

Mesoscopic Length Scale Controls the Rheology of Dense Suspensions

NASA Astrophysics Data System (ADS)

Bonnoit, Claire; Lanuza, Jose; Lindner, Anke; Clement, Eric

2010-09-01

From the flow properties of dense granular suspensions on an inclined plane, we identify a mesoscopic length scale strongly increasing with volume fraction. When the flowing layer height is larger than this length scale, a diverging Newtonian viscosity is determined. However, when the flowing layer height drops below this scale, we evidence a nonlocal effective viscosity, decreasing as a power law of the flow height. We establish a scaling relation between this mesoscopic length scale and the suspension viscosity. These results support recent theoretical and numerical results implying collective and clustered granular motion when the jamming point is approached from below.

Mesoscopic length scale controls the rheology of dense suspensions.

PubMed

Bonnoit, Claire; Lanuza, Jose; Lindner, Anke; Clement, Eric

2010-09-03

From the flow properties of dense granular suspensions on an inclined plane, we identify a mesoscopic length scale strongly increasing with volume fraction. When the flowing layer height is larger than this length scale, a diverging Newtonian viscosity is determined. However, when the flowing layer height drops below this scale, we evidence a nonlocal effective viscosity, decreasing as a power law of the flow height. We establish a scaling relation between this mesoscopic length scale and the suspension viscosity. These results support recent theoretical and numerical results implying collective and clustered granular motion when the jamming point is approached from below.

Multi-criteria manufacturability indices for ranking high-concentration monoclonal antibody formulations.

PubMed

Yang, Yang; Velayudhan, Ajoy; Thornhill, Nina F; Farid, Suzanne S

2017-09-01

The need for high-concentration formulations for subcutaneous delivery of therapeutic monoclonal antibodies (mAbs) can present manufacturability challenges for the final ultrafiltration/diafiltration (UF/DF) step. Viscosity levels and the propensity to aggregate are key considerations for high-concentration formulations. This work presents novel frameworks for deriving a set of manufacturability indices related to viscosity and thermostability to rank high-concentration mAb formulation conditions in terms of their ease of manufacture. This is illustrated by analyzing published high-throughput biophysical screening data that explores the influence of different formulation conditions (pH, ions, and excipients) on the solution viscosity and product thermostability. A decision tree classification method, CART (Classification and Regression Tree) is used to identify the critical formulation conditions that influence the viscosity and thermostability. In this work, three different multi-criteria data analysis frameworks were investigated to derive manufacturability indices from analysis of the stress maps and the process conditions experienced in the final UF/DF step. Polynomial regression techniques were used to transform the experimental data into a set of stress maps that show viscosity and thermostability as functions of the formulation conditions. A mathematical filtrate flux model was used to capture the time profiles of protein concentration and flux decay behavior during UF/DF. Multi-criteria decision-making analysis was used to identify the optimal formulation conditions that minimize the potential for both viscosity and aggregation issues during UF/DF. Biotechnol. Bioeng. 2017;114: 2043-2056. © 2017 The Authors. Biotechnology and Bioengineering Published by Wiley Perodicals, Inc. © 2017 The Authors. Biotechnology and Bioengineering Published by Wiley Perodicals, Inc.

Synthesis of oxidized guar gum by dry method and its application in reactive dye printing.

PubMed

Gong, Honghong; Liu, Mingzhu; Zhang, Bing; Cui, Dapeng; Gao, Chunmei; Ni, Boli; Chen, Jiucun

2011-12-01

The aim of this study was to prepare oxidized guar gum with a simple dry method, basing on guar gum, hydrogen peroxide and a small amount of solvent. To obtain a product with suitable viscosity for reactive dye printing, the effects of various factors such as the amount of oxidant and solvent, reaction temperature and time were studied with respect to the viscosity of reaction products. The product was characterized by Fourier transform infrared spectroscopy, size exclusion chromatography, scanning electron microscopy and differential scanning calorimetry. The hydrated rate of guar gum and oxidized guar gum was estimated through measuring the required time when their solutions (1%, w/v) reached the maximum viscosity. The effects of the salt concentration and pH on viscosity of the resultant product were studied. The mixed paste containing oxidized guar gum and carboxymethyl starch was prepared and its viscosity was determined by the viscometer. The rheological property of the mixed paste was appraised by the printing viscosity index. In addition, the applied effect of mixed paste in reactive dye printing was examined by assessing the fabric stiffness, color yield and sharp edge to the printed image in comparison with sodium alginate. And the results indicated that the mixed paste could partially replace sodium alginate as thickener in reactive dye printing. The study also showed that the method was low cost and eco-friendly and the product would have an extensive application in reactive dye printing. Copyright © 2011 Elsevier B.V. All rights reserved.

Multi‐criteria manufacturability indices for ranking high‐concentration monoclonal antibody formulations

PubMed Central

Velayudhan, Ajoy; Thornhill, Nina F.

2017-01-01

ABSTRACT The need for high‐concentration formulations for subcutaneous delivery of therapeutic monoclonal antibodies (mAbs) can present manufacturability challenges for the final ultrafiltration/diafiltration (UF/DF) step. Viscosity levels and the propensity to aggregate are key considerations for high‐concentration formulations. This work presents novel frameworks for deriving a set of manufacturability indices related to viscosity and thermostability to rank high‐concentration mAb formulation conditions in terms of their ease of manufacture. This is illustrated by analyzing published high‐throughput biophysical screening data that explores the influence of different formulation conditions (pH, ions, and excipients) on the solution viscosity and product thermostability. A decision tree classification method, CART (Classification and Regression Tree) is used to identify the critical formulation conditions that influence the viscosity and thermostability. In this work, three different multi‐criteria data analysis frameworks were investigated to derive manufacturability indices from analysis of the stress maps and the process conditions experienced in the final UF/DF step. Polynomial regression techniques were used to transform the experimental data into a set of stress maps that show viscosity and thermostability as functions of the formulation conditions. A mathematical filtrate flux model was used to capture the time profiles of protein concentration and flux decay behavior during UF/DF. Multi‐criteria decision‐making analysis was used to identify the optimal formulation conditions that minimize the potential for both viscosity and aggregation issues during UF/DF. Biotechnol. Bioeng. 2017;114: 2043–2056. © 2017 The Authors. Biotechnology and Bioengineering Published by Wiley Perodicals, Inc. PMID:28464235

New instrument for on-line viscosity measurement of fermentation media.

PubMed

Picque, D; Corrieu, G

1988-01-01

In an attempt to resolve the difficult problem of on-line determination of the viscosity of non-Newtonian fermentation media, the authors have used a vibrating rod sensor mounted on a bioreactor. The sensor signal decreases nonlinearly with increased apparent viscosity. Electronic filtering of the signal damps the interfering effect of aeration and mechanical agitation. Sensor drift is very low (0.03% of measured value per hour). On the rheological level the sensor is primarily an empirical tool that must be specifically calibrated for each fermentation process. Once this is accomplished, it becomes possible to establish linear or second-degree correlations between the electrical signal from the sensor and the essential parameters of the fermentation process in question (pH of a fermented milk during acidification, concentration of extra cellular polysaccharide). In addition, by applying the power law to describe the rheological behavior of fermentation media, we observe a second-order polynomial correlation between the sensor signal and the behavior index (n).

Influence of processing parameters on pore structure of 3D porous chitosan-alginate polyelectrolyte complex scaffolds.

PubMed

Florczyk, Stephen J; Kim, Dae-Joon; Wood, David L; Zhang, Miqin

2011-09-15

Fabrication of porous polymeric scaffolds with controlled structure can be challenging. In this study, we investigated the influence of key experimental parameters on the structures and mechanical properties of resultant porous chitosan-alginate (CA) polyelectrolyte complex (PEC) scaffolds, and on proliferation of MG-63 osteoblast-like cells, targeted at bone tissue engineering. We demonstrated that the porous structure is largely affected by the solution viscosity, which can be regulated by the acetic acid and alginate concentrations. We found that the CA PEC solutions with viscosity below 300 Pa.s yielded scaffolds of uniform pore structure and that more neutral pH promoted more complete complexation of chitosan and alginate, yielding stiffer scaffolds. CA PEC scaffolds produced from solutions with viscosities below 300 Pa.s also showed enhanced cell proliferation compared with other samples. By controlling the key experimental parameters identified in this study, CA PEC scaffolds of different structures can be made to suit various tissue engineering applications. Copyright © 2011 Wiley Periodicals, Inc.

Traceability of pH measurements by glass electrode cells: performance characteristic of pH electrodes by multi-point calibration.

PubMed

Naumann, R; Alexander-Weber, Ch; Eberhardt, R; Giera, J; Spitzer, P

2002-11-01

Routine pH measurements are carried out with pH meter-glass electrode assemblies. In most cases the glass and reference electrodes are thereby fashioned into a single probe, the so-called 'combination electrode' or simply 'the pH electrode'. The use of these electrodes is subject to various effects, described below, producing uncertainties of unknown magnitude. Therefore, the measurement of pH of a sample requires a suitable calibration by certified standard buffer solutions (CRMs) traceable to primary pH standards. The procedures in use are based on calibrations at one point, at two points bracketing the sample pH and at a series of points, the so-called multi-point calibration. The multi-point calibration (MPC) is recommended if minimum uncertainty and maximum consistency are required over a wide range of unknown pH values. Details of uncertainty computations for the two-point and MPC procedure are given. Furthermore, the multi-point calibration is a useful tool to characterise the performance of pH electrodes. This is demonstrated with different commercial pH electrodes. ELECTRONIC SUPPLEMENTARY MATERIAL is available if you access this article at http://dx.doi.org/10.1007/s00216-002-1506-5. On that page (frame on the left side), a link takes you directly to the supplementary material.

Nutritional evaluation of raw and extruded kidney bean (Phaseolus vulgaris L. var. pinto) in chicken diets.

PubMed

Arija, I; Centeno, C; Viveros, A; Brenes, A; Marzo, F; Illera, J C; Silvan, G

2006-04-01

An experiment was conducted to study the effect of inclusion of different concentrations (0, 100, 200, and 300 g/kg) of raw kidney bean and extruded kidney bean in broiler chick (0 to 21 d of age) diets on performance, digestive organ sizes, protein and amino acid digestibilities, intestinal viscosity, cecal pH, and blood parameters. Data were analyzed as a 3 x 2 factorial arrangement with 3 levels of kidney bean with and without extrusion. Positive control without kidney bean was used. Increasing the kidney bean content in the diet reduced weight gain and consumption, and increased the feed-to-gain ratio. Relative pancreas, liver, and jejunum weights, and intestinal viscosity were increased in response to increasing kidney bean concentration in the diet. The inclusion of different concentrations of kidney bean did not affect the apparent ileal digestibility of essential and nonessential amino acids, except for Met, Phe, and Cys, which were increased. Increasing kidney bean in the diet did not affect blood parameters, except for total protein, which was increased, and for androstenedione and testosterone, which were reduced. Extrusion significantly improved weight gain, feed consumption, and feed conversion. Relative pancreas, liver, and jejunum weights were reduced and spleen weight, cecal and intestinal viscosity were increased by extrusion. Apparent ileal digestibility of crude protein and all essential and nonessential amino acids were improved by extrusion. Like-wise, extrusion increased significantly the concentrations of cholesterol, triglycerides, glucose, and testosterone. We concluded that the inclusion of kidney bean in chicken diets cause a negative effect on performance and CP and amino acid digestibilities, and modified digestive organ sizes, intestinal viscosity, cecal pH, and some blood parameters. These effects were counteracted by the extrusion of kidney bean. However, the inclusion of extruded kidney bean in a chick diet resulted in poorer performance compared with that obtained with a corn-soybean diet.

Characterization of Carbopol® hydrogel rheology for experimental tectonics and geodynamics

NASA Astrophysics Data System (ADS)

Di Giuseppe, E.; Corbi, F.; Funiciello, F.; Massmeyer, A.; Santimano, T. N.; Rosenau, M.; Davaille, A.

2015-02-01

One of the long-standing challenges of modern tectonics and geodynamics is to fully understand the strong strain localization and its effects observed in the lithosphere, which presents viscous, as well as elastic and brittle properties. Recently yield stress-shear thinning hydrogels, such as Carbopol®, have been employed in analog modeling because of its great potential for mimicking the non-Newtonian behavior of rocks. Conversely its use has been limited by the difficulties in assessing its rheology and in preparing uniform samples. Ergo, it is essential to ensure a standard recipe, yielding to a reproducible behavior, no matter which rheometer model is used. We carried out, at four institutions (FAST, GFZ, IPGP and LET), a benchmark for developing a standard preparation and for testing the comparability of results. Then, we conducted a systematical rheological characterization of a wide range of Carbopol® formulas as a function of concentration, composition, pH, temperature and aging. Results show that neutral pH favors higher viscosity. The shear modulus, yield stress, viscosity, and shear thinning behavior increase with concentration. The linear viscoelastic range increases with concentration contrarily to what is observed in gelatins or colloidal suspensions. A weak inverse relationship between temperature and viscosity is found. Similarly, aging reduces both the viscosity and loss modulus, with reduction more evident for low concentration samples. Scaling analysis revealed that low concentration samples, i.e. < 0.1 wt.%, exhibiting shear thinning behavior and low yield stress, are appropriate to model the rising of thermal instabilities. Those at 0.5-1.0 wt.%, showing yield stress in the order of hundreds of Pa and n ranging between 1.6 and 3.4 are good candidates to mimic the non-linear ductile behavior of crustal rocks. We conclude that tuning the visco-elasto-plastic rheology of Carbopol® would make this material a good candidate for modeling of also other geological processes.

New Photochrome Probe Allows Simultaneous pH and Microviscosity Sensing.

PubMed

Wu, Yuanyuan; Papper, Vladislav; Pokholenko, Oleksandr; Kharlanov, Vladimir; Zhou, Yubin; Steele, Terry W J; Marks, Robert S

2015-07-01

4-N,N'-dimethylamino-4'-N'-stilbenemaleamic acid (DASMA), a unique molecular photochrome probe that exhibits solubility and retains trans-cis photoisomerisation in a wide range of organic solvents and aqueous pH environments, was prepared, purified and chemically characterised. Absorption, fluorescence excitation and emission spectra and constant-illumination fluorescence decay were measured in acetonitrile, dimethyl sulfoxide, ethanol, propylene carbonate, and aqueous glycerol mixtures. The pseudo-first-order fluorescence decay rates were found to be strongly dependent on the medium viscosity. In addition, the molecule exhibited the pH-dependent fluorescence and photoisomerisation kinetics.

Confinement in Melts of Chains with Junction Points, but No Ends

NASA Astrophysics Data System (ADS)

Foster, Mark; He, Qiming; Zhou, Yang; Zhang, Fan; Huang, Chongwen; Narayanan, Suresh

Measurements of surface fluctuations of 4-arm star and ''8-shaped'' analogs of the same polystyrene (PS) chain show that elimination of chain ends is much more important in dictating the fragility in a thin film than is the introduction of a branch point in the molecule. Both the viscosities derived from surface fluctuations and rheological measurements for the 8-shaped PS manifest a lower value than the 4-arm star PS analog, with the discrepancy increasing as the temperature approaches the glass transition temperature, Tg , bulk. Comparison among different chain topologies shows the effect of the number of chain ends and junction point on the viscosity. The viscosity behavior of the 8-shaped PS is quite different from that of the star analog, but similar to that of the simple cycle analog. The fragility of the 8-shaped molecule in the thin film is reduced relative to that in the bulk, manifesting a nanoconfinement effect. This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357.

Optimization of physico-chemical properties of gelatin extracted from fish skin of rainbow trout (Onchorhynchus mykiss).

PubMed

Tabarestani, H Shahiri; Maghsoudlou, Y; Motamedzadegan, A; Mahoonak, A R Sadeghi

2010-08-01

Physico-chemical properties of gelatin extracted from rainbow trout (Onchorhynchus mykiss) skin were optimized using response surface methodology (RSM). Central rotatable composite design was applied to study the combined effects of NaOH concentration (0.01-0.21 N), acetic acid concentration (0.01-0.21 N) and pre-treatment time (1-3h) on yield, molecular weight distribution, gel strength, viscosity and melting point of gelatin. Regression models were developed to predict the variables. Predict values of multiple response at optimal condition were that yield=9.36%, alpha(1)/alpha(2) chain ratio=1.76, beta chain percent=32.81, gel strength=459 g, viscosity=3.2 mPa s and melting point=20.4 degrees C. The optimal condition was obtained using 0.19 N NaOH and 0.121 N acetic acid for 3h. The results showed that the concentration of H(+) during pre-treatment had significant effect on molecular weight distribution, melting point and gel strength. The concentration of OH(-) had significant effect on viscosity and for extraction yield, pretreatment time was the critical factor. (c) 2010 Elsevier Ltd. All rights reserved.

Dependence of the Tidal Response on the Internal Structure of the Moon: Geodetic Implication to the Partial Melt Layer at the Lower-Most Part of the Lunar Mantle

NASA Astrophysics Data System (ADS)

Harada, Y.; Goossens, S. J.; Matsumoto, K.; Yan, J.; Ping, J.; Noda, H.

2012-12-01

Generally, internal energy dissipation associated with tidal deformation and physical libration of a planetary body depends on its internal structure, especially viscosity structure. Here magnitude of the tidal dissipation is mainly represented by the quality factor (Q) and the Love number (k2). These values inevitably depend on its viscosity structure, and thus, give us clues of its thermal state and history. Although dependence of the tidal dissipation on the viscosity structure of the Moon has already been demonstrated by previous research, its parameter study unfortunately has certain limitations. First, it assumes the lunar interior as a uniform sphere. Second, only Q has been calculated. Third, in the past, there are no observational values which correspond to the calculation results. By resolving the above issues, we would be able to put a new constraint on the interior structure on the Moon. That is, it allows us to consider what kind of viscosity structure can explain both Q and k2 with no contradiction. Moreover, such consideration further enables us to tell what should be investigated in the framework of the lunar exploration project in the next generation. Therefore, parameter studies on visco-elastic deformation are performed based on more realistic interior structure, and then, these calculation results are compared with pre-existing values derived from selenodetic observation. Concretely speaking, by employing the density and elasticity structures from seismic inversion, and by defining the viscosity as a free parameter, Q and k2 are calculated for both monthly and annual periods. After that, by comparing these numerical results with the observational values, it is examined whether the viscosity value satisfying Q and k2 at the same time is admissible or not. For the sake of simplification, this study only prepares the viscosity structure in which just the viscosity of the lower-most part of the mantle is changed over several orders of magnitude. The viscosity in this part is probably lower than that in the upper portion because the knowledge of seismology also indicates the presence of a high attenuation zone. On the other hand, the viscosity of the upper portion is regarded to be uniform in here, and fixed to the maximum value of the above parameter range. As a result, it is clarified that the viscosity solution consistent with geodetic observations of both rotation and gravity field exists if the interior structure includes the specific low viscosity zone. There is just one narrow range of allowable viscosity with the observed Q, which can only be explained by this low viscosity zone. This viscosity range determines a numerical k2 which is consistent with the observed values. As a conclusion, the strong seismic attenuation zone inside the lunar interior is probably equivalent to the low viscosity zone. Particularly, it is the remarkable point that the value of the viscosity inferred here is too low considering solid rock whereas it is too high considering complete melt. Therefore, as has formerly been pointed out, the partial melting would occur in this lower-most part like that of the ultra-low velocity zone on the Earth. Moreover, this zone is expected to include the fluid phase with a ratio corresponding to the rheologically critical melt fraction.

Characterisation of pectins extracted from banana peels (Musa AAA) under different conditions using an experimental design.

PubMed

Happi Emaga, Thomas; Ronkart, Sébastien N; Robert, Christelle; Wathelet, Bernard; Paquot, Michel

2008-05-15

An experimental design was used to study the influence of pH (1.5 and 2.0), temperature (80 and 90°C) and time (1 and 4h) on extraction of pectin from banana peels (Musa AAA). Yield of extracted pectins, their composition (neutral sugars, galacturonic acid, and degree of esterification) and some macromolecular characteristics (average molecular weight, intrinsic viscosity) were determined. It was found that extraction pH was the most important parameter influencing yield and pectin chemical composition. Lower pH values negatively affected the galacturonic acid content of pectin, but increased the pectin yield. The values of degree of methylation decreased significantly with increasing temperature and time of extraction. The average molecular weight ranged widely from 87 to 248kDa and was mainly influenced by pH and extraction time. Copyright © 2007 Elsevier Ltd. All rights reserved.

Use of an isoelectric solubilization/precipitation process to modify the functional properties of PSE (pale, soft, exudative)-like chicken meat protein: A mechanistic approach.

PubMed

Zhao, Xue; Bai, Yun; Xing, Tong; Xu, Xing-Lian; Zhou, Guanghong

2018-05-15

The functionality of pale, soft, exudative (PSE)-like chicken protein was improved by isoelectric solubilization/precipitation (ISP) treatment. PSE-like chicken proteins were solubilized at an acidic pH 3.5 or an alkaline pH 11.0, followed by precipitating at pH 5.5 and 6.2. PSE-like meat paste was treated as control (CON). Precipitated at pH 6.2 led to a more elastic gel than at pH 5.5. Water distribution of ISP-isolated protein was affected by precipitation pH. More tryptophan residues exposed and -SH was partially oxidized to disulfide bond after ISP treatment, which led to large aggregates formation and higher viscosity of ISP isolated proteins than of CON. Absolute zeta potential of alkali-treated protein was higher than other counterparts, indicating stronger electric repulsion. ISP treatments could convert α-helix structure to relatively irregular structures. Overall, solubilizing at pH 11.0, combined with a precipitation pH 6.2 ISP treatment offers a potential for enhanced functionality of PSE-like chicken protein. Copyright © 2017 Elsevier Ltd. All rights reserved.

Production and Characterization of a Polymer from Arthrobacter sp.

PubMed

Bodie, E A; Schwartz, R D; Catena, A

1985-09-01

An Arthrobacter sp. isolated from a glucose-sucrose agar plate was found to produce a neutral, extremely viscous, opalescent extracellular polymer. Growth, polymer production, and rheological properties and chemical composition of the isolated polymer were examined. The polymer was found to be substantially different from other arthrobacter polymers. Some unusual properties included irreversible loss of viscosity with high temperature and degradation of the polymer during fermentation and upon storage at 4 degrees C. Other characteristics included dependence on sucrose for polymer production, relative pH stability, increased viscosity with increased salt concentration, and pseudoplasticity. The polymer was found to be composed primarily (if not entirely) of d-fructose. The fructose content and other characteristics suggested that the polymer was a levan.

Production and Characterization of a Polymer from Arthrobacter sp

PubMed Central

Bodie, Elizabeth A.; Schwartz, Robert D.; Catena, Anthony

1985-01-01

An Arthrobacter sp. isolated from a glucose-sucrose agar plate was found to produce a neutral, extremely viscous, opalescent extracellular polymer. Growth, polymer production, and rheological properties and chemical composition of the isolated polymer were examined. The polymer was found to be substantially different from other arthrobacter polymers. Some unusual properties included irreversible loss of viscosity with high temperature and degradation of the polymer during fermentation and upon storage at 4°C. Other characteristics included dependence on sucrose for polymer production, relative pH stability, increased viscosity with increased salt concentration, and pseudoplasticity. The polymer was found to be composed primarily (if not entirely) of d-fructose. The fructose content and other characteristics suggested that the polymer was a levan. PMID:16346883

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.

Glass formability in medium-sized molecular systems/pharmaceuticals. I. Thermodynamics vs. kinetics.

PubMed

Tu, Wenkang; Li, Xiangqian; Chen, Zeming; Liu, Ying Dan; Labardi, Massimiliano; Capaccioli, Simone; Paluch, M; Wang, Li-Min

2016-05-07

Scrutinizing critical thermodynamic and kinetic factors for glass formation and the glass stability of materials would benefit the screening of the glass formers for the industry of glassy materials. The present work aims at elucidating the factors that contribute to the glass formation by investigating medium-sized molecules of pharmaceuticals. Glass transition related thermodynamics and kinetics are performed on the pharmaceuticals using calorimetric, dielectric, and viscosity measurements. The characteristic thermodynamic and kinetic parameters of glass transition are found to reproduce the relations established for small-molecule glass formers. The systematic comparison of the thermodynamic and kinetic contributions to glass formation reveals that the melting-point viscosity is the crucial quantity for the glass formation. Of more interest is the finding of a rough correlation between the melting-point viscosity and the entropy of fusion normalized by the number of beads of the pharmaceuticals, suggesting the thermodynamics can partly manifest its contribution to glass formation via kinetics.

Glass formability in medium-sized molecular systems/pharmaceuticals. I. Thermodynamics vs. kinetics

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

Tu, Wenkang; Li, Xiangqian; Chen, Zeming

Scrutinizing critical thermodynamic and kinetic factors for glass formation and the glass stability of materials would benefit the screening of the glass formers for the industry of glassy materials. The present work aims at elucidating the factors that contribute to the glass formation by investigating medium-sized molecules of pharmaceuticals. Glass transition related thermodynamics and kinetics are performed on the pharmaceuticals using calorimetric, dielectric, and viscosity measurements. The characteristic thermodynamic and kinetic parameters of glass transition are found to reproduce the relations established for small-molecule glass formers. The systematic comparison of the thermodynamic and kinetic contributions to glass formation reveals thatmore » the melting-point viscosity is the crucial quantity for the glass formation. Of more interest is the finding of a rough correlation between the melting-point viscosity and the entropy of fusion normalized by the number of beads of the pharmaceuticals, suggesting the thermodynamics can partly manifest its contribution to glass formation via kinetics.« less

Generation of digitized microfluidic filling flow by vent control.

PubMed

Yoon, Junghyo; Lee, Eundoo; Kim, Jaehoon; Han, Sewoon; Chung, Seok

2017-06-15

Quantitative microfluidic point-of-care testing has been translated into clinical applications to support a prompt decision on patient treatment. A nanointerstice-driven filling technique has been developed to realize the fast and robust filling of microfluidic channels with liquid samples, but it has failed to provide a consistent filling time owing to the wide variation in liquid viscosity, resulting in an increase in quantification errors. There is a strong demand for simple and quick flow control to ensure accurate quantification, without a serious increase in system complexity. A new control mechanism employing two-beam refraction and one solenoid valve was developed and found to successfully generate digitized filling flow, completely free from errors due to changes in viscosity. The validity of digitized filling flow was evaluated by the immunoassay, using liquids with a wide range of viscosity. This digitized microfluidic filling flow is a novel approach that could be applied in conventional microfluidic point-of-care testing. Copyright © 2016 Elsevier B.V. All rights reserved.

Corrosion and stability study of Bacillus thuringiensis var. kurstaki starch industry wastewater-derived biopesticide formulation.

PubMed

Gnepe, Jean R; Tyagi, Rajeshwar D; Brar, Satinder K; Valéro, José R; Surampalli, Rao Y

2014-01-01

Biopesticides are usually sprayed on forests by using planes made up of aluminum alloy. Bioval derived from starch industry wastewater (SIW) in suspension form was developed as stable anticorrosive biopesticide formulation. In this context, various anticorrosion agents such as activated charcoal, glycerin, ethylene glycol, phytic acid, castor oil and potassium silicate were tested as anticorrosive agents. There was no corrosion found in Bioval formulation where potassium silicate (0.5% w/v) was added and compared with Foray 76 B, as an industrial standard, when stored over 6 months. In relation to other parameters, the anticorrosion formulation of Bioval+buffer+KSi reported excellent zeta potential (-33.19 ± 4 mV) and the viscosity (319.13 ± 32 mPa.s) proving it's stability over 6 months, compared to the standard biopesticide Foray 76 B (-36.62 ± 4 mV potential zeta, pH 4.14 ± 0.1 and 206 ± 21 mPa.s viscosity). Metal analysis of the different biopesticides showed that Bioval+buffer+KSi has no corrosion (5.11 ± 0.5 mg kg(-1) of Al and 13.53 ± 1.5 mg kg(-1) of Fe) on the aluminum alloy due to the contribution of sodium acetate buffer at pH 5. The bioassays reported excellent results for Bioval+Buffer+KSi (2.95 ± 0.3 × 10(9) CFU mL(-1) spores and 26.6 ± 2.7 × 10(9) IU L(-1) Tx) compared with initial Bioval (2.46 ± 0.3 × 10(9) CFU mL(-1) spores and 23.09 ± 3 × 10(9) IU L(-1) Tx) and Foray 76 B (2.3 ± 0.2 × 10(9) CFU mL(-1) spores and 19.950 ± 2.1 UI L(-1) Tx) which was due to the break-up of the external chitinous membrane due to abrasive action of potassium silicate after ingestion by insects. The contribution of sodium acetate buffer and potassium silicate (0.5% and at pH = 5) as anticorrosion agent in the Bioval allowed production of an efficient biopesticide with a reduced viscosity and favorable pH as compared to Foray 76 B which enhanced the entomotoxic potential against spruce budworm (SB) larvae (Lepidoptera: Choristoneura fumiferana).

Cottonseed protein derivatives as nutritional and functional supplements in food formulations.

PubMed

Cherry, J P; Berardi, L C; Zarins, Z M; Wadsworth, J I; Vinnett, C H

1978-01-01

Cottonseeds contain protein with desirable food functional and nutritional properties. Storage globulins make up most of the protein stored in cottonseed and can be separated into five fractions by gel filtration chromatography. Each fraction is distinguishable from the other by its amino acid and polyacrylamide gel electrophoretic properties. Proteins of cottonseed contribute greatly to the functional properties of emulsions, co-isolates, and texturized derivatives. For example, increasing the amount of high protein cottonseed flour in wheat suspensions from 2% to 10% improved the capacity (54-97 ml of oil) and viscosity (5,000-100,000+ cps) of emulsions. The 10% suspension formed emulsions with increasing oil capacity (84-100 ml) and viscosity (28,000-100,000+ cps) as the pH was adjusted from 4.5 to 9.5. Consistencies of the products ranged from that of salad dressing (low percent suspensions, or acid pH) to that of mayonnaise (high percent, or basic pH). These data were utilized to derive a multiple regression model to predict optimum use of cottonseed proteins in emulsions of varying consistencies. A coprecipitated isolate containing greater than 94% protein was prepared from a blend of cottonseed and peanut flours. Amino acid content of the co-isolate reflected that of the protein in the two flours of the composite. The co-isolate has lower gossypol level and improved color and functional properties than a cottonseed protein isolate. Storage protein isolate of cottonseed suspended in aqueous solution and heated with constant stirring forms a texturized product; the quality of the product depends on heat, pH, salt, and the quantity of nonstorage proteins. Protein and amino acid content of meat products were improved by the addition of the texturized protein of cottonseed.

Nanostructure, hydrogen bonding and rheology in choline chloride deep eutectic solvents as a function of the hydrogen bond donor.

PubMed

Stefanovic, Ryan; Ludwig, Michael; Webber, Grant B; Atkin, Rob; Page, Alister J

2017-01-25

Deep eutectic solvents (DESs) are a mixture of a salt and a molecular hydrogen bond donor, which form a eutectic liquid with a depressed melting point. Quantum mechanical molecular dynamics (QM/MD) simulations have been used to probe the 1 : 2 choline chloride-urea (ChCl : U), choline chloride-ethylene glycol (ChCl : EG) and choline chloride-glycerol (ChCl : Gly) DESs. DES nanostructure and interactions between the ions is used to rationalise differences in DES eutectic point temperatures and viscosity. Simulations show that the structure of the bulk hydrogen bond donor is largely preserved for hydroxyl based hydrogen bond donors (ChCl:Gly and ChCl:EG), resulting in a smaller melting point depression. By contrast, ChCl:U exhibits a well-established hydrogen bond network between the salt and hydrogen bond donor, leading to a larger melting point depression. This extensive hydrogen bond network in ChCl:U also leads to substantially higher viscosity, compared to ChCl:EG and ChCl:Gly. Of the two hydroxyl based DESs, ChCl:Gly also exhibits a higher viscosity than ChCl:EG. This is attributed to the over-saturation of hydrogen bond donor groups in the ChCl:Gly bulk, which leads to more extensive hydrogen bond donor self-interaction and hence higher cohesive forces within the bulk liquid.

Viscous cosmology for early- and late-time universe

NASA Astrophysics Data System (ADS)

Brevik, Iver; Grøn, Øyvind; de Haro, Jaume; Odintsov, Sergei D.; Saridakis, Emmanuel N.

From a hydrodynamicist’s point of view the inclusion of viscosity concepts in the macroscopic theory of the cosmic fluid would appear most natural, as an ideal fluid is after all an abstraction (exluding special cases such as superconductivity). Making use of modern observational results for the Hubble parameter plus standard Friedmann formalism, we may extrapolate the description of the universe back in time up to the inflationary era, or we may go to the opposite extreme and analyze the probable ultimate fate of the universe. In this review, we discuss a variety of topics in cosmology when it is enlarged in order to contain a bulk viscosity. Various forms of this viscosity, when expressed in terms of the fluid density or the Hubble parameter, are discussed. Furthermore, we consider homogeneous as well as inhomogeneous equations of state. We investigate viscous cosmology in the early universe, examining the viscosity effects on the various inflationary observables. Additionally, we study viscous cosmology in the late universe, containing current acceleration and the possible future singularities, and we investigate how one may even unify inflationary and late-time acceleration. Finally, we analyze the viscosity-induced crossing through the quintessence-phantom divide, we examine the realization of viscosity-driven cosmological bounces, and we briefly discuss how the Cardy-Verlinde formula is affected by viscosity.

Constrasting Conductance/Viscosity Relations in Liquid States of Vitreous and Polymer Solid Electrolytes.

DTIC Science & Technology

1987-11-01

State lonics, 9 & 10, 617 (1983). 17. 11. Tweer, N. Laberge , and P.B. Macedo, J. Am. Ceram. Soc., 54, 121 (1971). p 18. R. Weiler, S. Blaser, and P.B...Bressel, Ph.D. Thesis, Purdue University, (1971). 25. S. Schantz, J. Sandahl, L. Borjesson, L.M. Torell and J.R. Stevens . Solid State lonics (in press). 26

Molecular Control.

DTIC Science & Technology

1985-01-01

the equilibrium fluctuations and functional motions in different proteins as function of external parameters (pH, viscosity , temperature, pressure) and...For example, let us consider the perturbation of an integrable non-linear conservative system with N degrees of freedom. In the absence of the field...in integrable systems. If one 9 tries to influence soliton propagation by an external field, for example, is the predominately integrable behavior of

Some further characteristics of the growth of Naegleria fowleri and N. gruberi in axenic culture.

PubMed

Cerva, L

1978-01-01

The effects of pH, various viscosity of the medium, changed ratio between the concentrations of dissolved and corpuscular components in the medium, and dissolved inorganic salts on the growth of axenic cultures of Naegleria fowleri and N. gruberi have been studied. The cultures were grown in liquid CALYG and BCS media. The pH optimum was 6.5 for N. fowleri and 6.0--6.5 for N. gruberi. No negative influence on the growth of N. fowleri was observed even at 0.5% concentration of highly viscous methylcellulose, whereas the growth of N. gruberi was distinctly inhibited by more than 0.2% of methycellulose. N. fowleri preferred the osmotorphic and N. gruberi phagotrophic nutrition in the given system of cultivation. The growth of both Naegleria species was inhibited by 0.1 N concentration of sodium chloride and potassium chloride without any significant difference in the tolerance. The inhibitory effect of these salts correlated primarily with the concentration of chloride anion. The ability to grow in a medium with increased viscosity and the preference for osmotrophic nutrtion are, besides the higher temperature optimum determined earlier, further characteristics of the pathogenic species N. fowleri.

Sheep fed with banana leaf hay reduce ruminal protozoa population.

PubMed

Freitas, Cláudio Eduardo Silva; Duarte, Eduardo Robson; Alves, Dorismar David; Martinele, Isabel; D'Agosto, Marta; Cedrola, Franciane; de Moura Freitas, Angélica Alves; Dos Santos Soares, Franklin Delano; Beltran, Makenzi

2017-04-01

A ciliate protozoa suppression can reduce methane production increasing the energy efficiency utilization by ruminants. The physicochemical characteristics of rumen fluid and the profile of the rumen protozoa populations were evaluated for sheep fed banana leaf hay in replacement of the Cynodon dactylon cv. vaqueiro hay. A total of 30 male sheep were raised in intensive system during 15 days of adaptation and 63 days of experimental period. The animals were distributed in a completely randomized design that included six replicates of five treatments with replacement levels (0, 25, 50, 75, and 100%) of the grass vaquero for the banana leaf hay. Samples of fluid were collected directly from the rumen with sterile catheters. Color, odor, viscosity, and the methylene blue reduction potential (MBRP) were evaluated and pH estimated using a digital potentiometer. After decimal dilutions, counts of genus protozoa were performed in Sedgewick Rafter chambers. The averages of pH, MBRP, color, odor, and viscosity were not influenced by the inclusion of the banana leaf hay. However, the total number of protozoa and Entodinium spp. population significantly decreased at 75 and 100% inclusions of banana leaf hay as roughage.

Polymer-Coated Nanoparticles for Reversible Emulsification and Recovery of Heavy Oil.

PubMed

Qi, Luqing; Song, Chen; Wang, Tianxiao; Li, Qilin; Hirasaki, George J; Verduzco, Rafael

2018-06-05

Heavy crude oil has poor solubility and a high density, making recovery and transport much more difficult and expensive than for light crude oil. Emulsifiers can be used to produce low viscosity oil-in-water emulsions for recovery and transport, but subsequent demulsification can be challenging. Here, we develop and implement interfacially active, pH-responsive polymer-coated nanoparticles (PNPs) to reversibly stabilize, recover, and break oil/water emulsions through variation of solution pH. Silica particles with poly(2-(dimethylamino)ethyl methacrylate) (DMAEMA) chains covalently grafted to the surface are prepared although a reversible addition fragmentation chain transfer grafting-through technique. The resulting DMAEMA PNPs can stabilize emulsions of high viscosity Canadian heavy oil at PNP concentrations as low as 0.1 wt % and at neutral pH. The performance of the DMAEMA PNPs exceeds that of DMAEMA homopolymer additives, which we attribute to the larger size and irreversible adsorption of DMAEMA PNPs to the oil/water interface. After recovery, the emulsion can be destabilized by the addition of acid to reduce pH, resulting in separation and settling of the heavy oil from the aqueous phase. Recovery of more than 10 wt % of the crude heavy oil-in-place is achieved by flooding with aqueous solution of 0.1 wt % DMAEMA PNPs without any additional surfactant or chemical. This work demonstrates the applicability of PNPs as surface active materials for enhanced oil recovery processes and for heavy oil transport.

Quality by design approach for understanding the critical quality attributes of cyclosporine ophthalmic emulsion.

PubMed

Rahman, Ziyaur; Xu, Xiaoming; Katragadda, Usha; Krishnaiah, Yellela S R; Yu, Lawrence; Khan, Mansoor A

2014-03-03

Restasis is an ophthalmic cyclosporine emulsion used for the treatment of dry eye syndrome. There are no generic products for this product, probably because of the limitations on establishing in vivo bioequivalence methods and lack of alternative in vitro bioequivalence testing methods. The present investigation was carried out to understand and identify the appropriate in vitro methods that can discriminate the effect of formulation and process variables on critical quality attributes (CQA) of cyclosporine microemulsion formulations having the same qualitative (Q1) and quantitative (Q2) composition as that of Restasis. Quality by design (QbD) approach was used to understand the effect of formulation and process variables on critical quality attributes (CQA) of cyclosporine microemulsion. The formulation variables chosen were mixing order method, phase volume ratio, and pH adjustment method, while the process variables were temperature of primary and raw emulsion formation, microfluidizer pressure, and number of pressure cycles. The responses selected were particle size, turbidity, zeta potential, viscosity, osmolality, surface tension, contact angle, pH, and drug diffusion. The selected independent variables showed statistically significant (p < 0.05) effect on droplet size, zeta potential, viscosity, turbidity, and osmolality. However, the surface tension, contact angle, pH, and drug diffusion were not significantly affected by independent variables. In summary, in vitro methods can detect formulation and manufacturing changes and would thus be important for quality control or sameness of cyclosporine ophthalmic products.

Proximate composition of Karkadeh (Hibiscus sabdariffa) seeds and some functional properties of seed protein isolate as influenced by pH and NaCl.

PubMed

Salah, E O Mahgoub; Hayat, Z E Elbashir

2009-05-01

Seeds of an inbred line (B-11-90) of Karkadeh (Hibiscus sabdariffa) were investigated for their proximate composition (AOAC methods), nitrogen solubility and protein isolate (Karkadeh seed protein isolates [KSPI]) functional properties (standard methods). The fat and protein contents of the seeds were 22.43% and 32.46%, respectively. Nitrogen solubility was good in both water and 1.0 M NaCl at alkaline pH rather than at acidic pH, with better solubility at higher pH levels in water than in 1.0 M NaCl. The functional properties of the KSPI were as follows: water absorption capacity, 181 ml/100 g; fat absorption capacity, 110 ml/100 g; bulk density, 0.77 g/ml; and apparent viscosity (at 20 degrees C), 13.42 cps. KSPI showed a maximum foaming capacity at pH 12 and 1.6 M NaCl, a maximum emulsification capacity at pH 11 and 1.8 M NaCl, and a weaker foam stability at neutral pH than at acidic or alkaline pH, with a better foam stability at alkaline pH. The foam stability was considerably improved by treatment with 1.6 M NaCl.

An experimental approach to manufacturing technology of historical glass (XIII-XV centuries). Comparison with current glassmaking technology.

NASA Astrophysics Data System (ADS)

Tarrago, Mariona; Gimeno, Domingo; Bazzocchi, Flavia; Garcia-Valles, Maite; Martinez, Salvador

2015-04-01

One of the major and less explored issues in the characterization of historical glasses is the determination of their viscosity as a function of temperature in order to constrain technological aspects of glass production. Until now, assumptions on temperatures have been based on mathematical models based on chemical compositions. Hence, the topic of this work is to explore the technology of stained glass production related to the workability and melting process of the glass by experimental laboratory measurements. This work presents the analysis of viscosity of glasses from different historical sites and chemical compositions: four from Santes Creus (Tarragona, XIII century), two of classical medieval stained glass window from Santa Maria de Pedralbes (Barcelona, mid XIV century), and three of evolved late-medieval type from Santa Maria del Mar (Barcelona first half of XV century), and one sample of soda-lime industrial glass by means of Hot-Stage Microscopy and glass transformation temperature Tg by dilatometry. These data are then compared to the predictions on theoretical viscosity obtained from mathematical models based on chemical composition. These samples are classified according to their major modifier in: Na-rich (12-17% of Na2O, between 65-77% of SiO2 and less than 3 % of K2O); Ca-rich (29% of CaO, 54% of SiO2, 4% of K2O, and 4% of Na2O); K-Ca-rich (17 to 21% of K2O, more than 14% of CaO, 49-55% of SiO2and less than 2% of Na2O); Na-Ca-rich (12-14% of Na2O, 9-15% of CaO, 57-71% of SiO2 and < 6% of K2O). Glass transition temperature (Tg) is correlated to chemical composition: 464-492 °C for Na-rich, 645 °C for Ca-rich, 582-586 °C for K-Ca-rich and 497-542 °C for Na-Ca-rich glasses. Experimental viscosity-temperature curves are traced using Tg and fixed viscosity points measured by Hot-Stage microscopy (according to German standard 51730) in order to provide more accurate insight into the phases of glass production process (melting, working, conditioning and annealing ranges). These results are also compared to mathematical models of glass viscosity based on chemical composition. The annealing range (viscosity between 1013.5 and 1012 Pa-s) is reached at temperatures between 484-633°C (strain point) and 509-664°C (upper limit). The working point (viscosity of 103 Pa-s) has temperature values in the range between 958 and 1097°C.

Viscous fingering of HCI through gastric mucin

NASA Astrophysics Data System (ADS)

Bhaskar, K. Ramakrishnan; Garik, Peter; Turner, Bradley S.; Bradley, James Douglas; Bansil, Rama; Stanley, H. Eugene; Lamont, J. Thomas

1992-12-01

THE HCI in the mammalian stomach is concentrated enough to digest the stomach itself, yet the gastric epithelium remains undamaged. One protective factor is gastric mucus, which forms a protective layer over the surface epithelium1-4 and acts as a diffusion barrier5,6 Bicarbonate ions secreted by the gastric epithelium7 are trapped in the mucus gel, establishing a gradient from pH 1-2 at the lumen to pH 6-7 at the cell surface8-10. How does HCI, secreted at the base of gastric glands by parietal cells, traverse the mucus layer without acidifying it? Here we demonstrate that injection of HCI through solutions of pig gastric mucin produces viscous fingering patterns11-18 dependent on pH, mucin concentration and acid flow rate. Above pH 4, discrete fingers are observed, whereas below pH 4, HCI neither penetrates the mucin solution nor forms fingers. Our in vitro results suggest that HCI secreted by the gastric gland can penetrate the mucus gel layer (pH 5-7) through narrow fingers, whereas HC1 in the lumen (pH 2) is prevented from diffusing back to the epithelium by the high viscosity of gastric mucus gel on the luminal side.

Empty calories and phantom fullness: a randomized trial studying the relative effects of energy density and viscosity on gastric emptying determined by MRI and satiety.

PubMed

Camps, Guido; Mars, Monica; de Graaf, Cees; Smeets, Paul Am

2016-07-01

Stomach fullness is a determinant of satiety. Although both the viscosity and energy content have been shown to delay gastric emptying, their relative importance is not well understood. We compared the relative effects of and interactions between the viscosity and energy density on gastric emptying and perceived satiety. A total of 15 healthy men [mean ± SD age: 22.6 ± 2.4 y; body mass index (in kg/m(2)): 22.6 ± 1.8] participated in an experiment with a randomized 2 × 2 crossover design. Participants received dairy-based shakes (500 mL; 50% carbohydrate, 20% protein, and 30% fat) that differed in viscosity (thin and thick) and energy density [100 kcal (corresponding to 0.2 kcal/mL) compared with 500 kcal (corresponding to 1 kcal/mL)]. After ingestion, participants entered an MRI scanner where abdominal scans and oral appetite ratings on a 100-point scale were obtained every 10 min until 90 min after ingestion. From the scans, gastric content volumes were determined. Overall, the gastric emptying half-time (GE t50) was 54.7 ± 3.8 min. The thin 100-kcal shake had the lowest GE t50 of 26.5 ± 3.0 min, followed by the thick 100-kcal shake with a GE t50 of 41 ± 3.9 min and the thin 500-kcal shake with a GE t50 of 69.5 ± 5.9 min, and the thick 500-kcal shake had the highest GE t50 of 81.9 ± 8.3 min. With respect to appetite, the thick 100-kcal shake led to higher fullness (58 points at 40 min) than the thin 500-kcal shake (48 points at 40 min). Our results show that increasing the viscosity is less effective than increasing the energy density in slowing gastric emptying. However, the viscosity is more important to increase the perceived fullness. These results underscore the lack of the satiating efficiency of empty calories in quickly ingested drinks such as sodas. The increase in perceived fullness that is due solely to the increased viscosity, which is a phenomenon that we refer to as phantom fullness, may be useful in lowering energy intake. This trial was registered at www.trialregister.nl as NTR4573. © 2016 American Society for Nutrition.

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.

Optimization of Fermentation Conditions and Rheological Properties of Exopolysaccharide Produced by Deep-Sea Bacterium Zunongwangia profunda SM-A87

PubMed Central

Liu, Sheng-Bo; Qiao, Li-Ping; He, Hai-Lun; Zhang, Qian; Chen, Xiu-Lan; Zhou, Wei-Zhi; Zhou, Bai-Cheng; Zhang, Yu-Zhong

2011-01-01

Zunongwangia profunda SM-A87 isolated from deep-sea sediment can secrete large quantity of exopolysaccharide (EPS). Response surface methodology was applied to optimize the culture conditions for EPS production. Single-factor experiment showed that lactose was the best carbon source. Based on the Plackett–Burman design, lactose, peptone and temperature were selected as significant variables, which were further optimized by the steepest ascent (descent) method and central composite design. The optimal culture conditions for EPS production and broth viscosity were determined as 32.21 g/L lactose, 8.87 g/L peptone and an incubation temperature of 9.8°C. Under these conditions, the maximum EPS yield and broth viscosity were 8.90 g/L and 6551 mPa•s, respectively, which is the first report of such high yield of EPS from a marine bacterium. The aqueous solution of the EPS displayed high viscosity, interesting shearing thinning property and great tolerance to high temperature, a wide range of pH, and high salinity. PMID:22096500

Quality improvement of a rice-substituted fried noodle by utilizing the protein-polyphenol interaction between a pea protein isolate and green tea (Camellia sinensis) extract.

PubMed

Song, Youngwoon; Yoo, Sang-Ho

2017-11-15

The quality of rice-substituted fried noodles was improved by applying interaction between pea protein isolate (PPI) and green tea extract (GTE). Radical-scavenging activities of GTE were stably maintained when exposed to acidic pH, UV light, and fluorescent light, but decreased by approximately 65% when exposed to 80°C for 168h. The RVA profiles of noodle dough showed that peak viscosity and breakdown increased significantly but that setback and final viscosity remained unchanged with 20% rice flour replacement. PPI significantly decreased the viscosity parameters of rice-supplemented dough, and the addition of GTE recovered these values significantly. The cooking loss and viscoelasticity (R max ) of cooked rice-supplemented noodles were fully restored by combined treatment of PPI and GTE. GTE decreased the peroxide value of fried noodles by 14% after storage at 63°C for 16days. Therefore, PPI+GTE treatment has great potential for use in fried noodles owing to the reinforced network and antioxidant activity. Copyright © 2017 Elsevier Ltd. All rights reserved.

A comparison of the tribological behaviour of Y-TZP in tea and coffee under micro-abrasion conditions

NASA Astrophysics Data System (ADS)

Sharifi, S.; Stack, M. M.

2013-10-01

The micro-abrasion of Y-TZP, a candidate dental restorative material, was investigated in a range of caffeine-containing solutions which included tea and coffee. Additions of sugar and milk were used to test the effects of viscosity and pH on the wear rate. The results indicated a significant increase in wear rate in the various solutions, with some correlation between wear rate and increases in viscosity and this was linked to enhance particle entrainment in the more viscous solutions. The generally lower wear rate in tea compared to coffee was associated with a longer ageing period in this solution before uniform wear was observed. Micro-abrasion maps were used to characterize the differences in performance for the material in the environments studied.

Pharmaceutical applications of in vivo EPR

NASA Astrophysics Data System (ADS)

Mäder, Karsten

1998-07-01

The aim of this article is to discuss the applications of in vivo EPR in the field of pharmacy. In addition to direct detection of free radical metabolites and measurement of oxygen, EPR can be used to characterize the mechanisms of drug release from biodegradable polymers. Unique information about drug concentration, the microenvironment (viscosity, polarity, pH) and biodistribution (by localized measurement or EPR Imaging) can be obtained.

40 CFR 158.2171 - Experimental use permit microbial pesticides product analysis data requirements table.

Code of Federal Regulations, 2010 CFR

2010-07-01

... Characteristics 830.6302 Color R TGAI TGAI -- 830.6303 Physical state R TGAI TGAI -- 830.6304 Odor R TGAI TGAI... Characteristics R MP EP 5 830.7000 pH R TGAI TGAI -- 830.7100 Viscosity R MP EP 6 830.7300 Density/relative... microbial pesticides are packaged in metal, plastic, or paper containers. 6. Only required for liquid forms...

Experimental investigation on CRDI engine using butanol-biodiesel-diesel blends as fuel

NASA Astrophysics Data System (ADS)

Divakar Shetty, A. S.; Dineshkumar, L.; Koundinya, Sandeep; Mane, Swetha K.

2017-07-01

In this research work an experimental investigation of butanol-biodisel-diesel blends on combustion, performance and emission characteristics of a direct injection (DI) diesel engine is carried out. The blends are prepared at different proportions and fuel properties such as calorific value, viscosity, flash point and fire point, cloud point, pour point of butanol (B), biodiesel (B), diesel (D), biodiesel-diesel (BD) blends and butanol-biodiesel-diesel (BBD) blends are determined. The engine test is conducted at different speed and load. From the results obtained for fuel properties we can observe that the flash, fire and pour point, viscosity and density are decreasing by increasing the percentage of butanol in BBD blends. It is also observed that the performance parameters such as brake thermal efficiency (BTE) and exhaust gas temperature increases with increase in the proportion of butanol in BBD blend. However, the brake specific fuel consumption (BFSC) decreases with increase in the proportion of butanol in BBD blend. The increase of butanol in BBD blends also influence to increase on emission characteristic such as carbon monoxide (CO), hydrocarbon (HC) and oxides of nitrogen (NOx).

Connecting Structural and Transport Properties of Ionic Liquids with Cationic Oligoether Chains

DOE PAGES

Lall-Ramnarine, Sharon I.; Zhao, Man; Rodriguez, Chanele; ...

2017-06-01

We used X-ray diffraction and molecular dynamics simulations to probe the structures of two families of ionic liquids containing oligoether tails on the cations. Imidazolium and pyrrolidinium bis(trifluoromethylsulfonyl)amide ILs with side chains ranging from 4 to 10 atoms in length, including both linear alkyl and oligo-ethylene oxide tails, were prepared. Furthermore, their physical properties, such as viscosity, conductivity and thermal profile, were measured and compared for systematic trends. Consistent with earlier literature, a single ether substituent substantially decreases the viscosity of pyrrolidinium and imidazolium ILs compared to their alkyl congeners. Remarkably, as the number of ether units in the pyrrolidiniummore » ILs increases there is hardly any increase in the viscosity, in contrast to alkylpyrrolidinium ILs where the viscosity increases steadily with chain length. Viscosities of imidazolium ether ILs increase with chain length but always remain well below their alkyl congeners. To complement the experimentally determined properties, molecular dynamics simulations were run on the two ILs with the longest ether chains. Our results point to specific aspects that could be useful for researchers designing ILs for specific applications.« less

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

Lall-Ramnarine, Sharon I.; Zhao, Man; Rodriguez, Chanele

We used X-ray diffraction and molecular dynamics simulations to probe the structures of two families of ionic liquids containing oligoether tails on the cations. Imidazolium and pyrrolidinium bis(trifluoromethylsulfonyl)amide ILs with side chains ranging from 4 to 10 atoms in length, including both linear alkyl and oligo-ethylene oxide tails, were prepared. Furthermore, their physical properties, such as viscosity, conductivity and thermal profile, were measured and compared for systematic trends. Consistent with earlier literature, a single ether substituent substantially decreases the viscosity of pyrrolidinium and imidazolium ILs compared to their alkyl congeners. Remarkably, as the number of ether units in the pyrrolidiniummore » ILs increases there is hardly any increase in the viscosity, in contrast to alkylpyrrolidinium ILs where the viscosity increases steadily with chain length. Viscosities of imidazolium ether ILs increase with chain length but always remain well below their alkyl congeners. To complement the experimentally determined properties, molecular dynamics simulations were run on the two ILs with the longest ether chains. Our results point to specific aspects that could be useful for researchers designing ILs for specific applications.« less

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

Lall-Ramnarine, Sharon I.; Zhao, Man; Rodriguez, Chanele

X-ray diffraction and molecular dynamics simulations were used to probe the structures of two families of ionic liquids containing oligoether tails on the cations. Imidazolium and pyrrolidinium bis(trifluoromethylsulfonyl)amide ILs with side chains ranging from 4 to 10 atoms in length, including both linear alkyl and oligo-ethylene oxide tails, were prepared. Their physical properties, such as viscosity, conductivity and thermal profile, were measured and compared for systematic trends. Consistent with earlier literature, a single ether substituent substantially decreases the viscosity of pyrrolidinium and imidazolium ILs compared to their alkyl congeners. Remarkably, as the number of ether units in the pyrrolidinium ILsmore » increases there is hardly any increase in the viscosity, in contrast to alkylpyrrolidinium ILs where the viscosity increases steadily with chain length. Viscosities of imidazolium ether ILs increase with chain length but always remain well below their alkyl congeners. To complement the experimentally determined properties, molecular dynamics simulations were run on the two ILs with the longest ether chains. The results point to specific aspects that could be useful for researchers designing ILs for specific applications.« less

Surface Charge Development on Transition Metal Sulfides: An Electrokinetic Study

NASA Astrophysics Data System (ADS)

Bebie, Joakim; Schoonen, Martin A. A.; Fuhrmann, Mark; Strongin, Daniel R.

1998-02-01

The isoelectric points, pH i.e.p., of ZnS, PbS, CuFeS 2, FeS, FeS 2, NiS 2, CoS 2, and MnS 2 in NaCl supported electrolyte solutions are estimated to be between pH 3.3 and 0.6, with most of the isoelectric points below pH 2. The first electrokinetic measurements on NiS 2, CoS 2, and MnS 2 are reported here. Below pH i.e.p. the metal-sulfide surfaces are positively charged, above pH i.e.p. the surfaces are negatively charged. The addition of Me 2+ ions shifts the pH i.e.p. and changes the pH dependence considerably. The isoelectric points of the measured transition metal sulfides in the absence of metal ions or dissolved sulfide (H 2S or HS -) are in agreement with those found in earlier studies. The pH range of observed isoelectric points for metal sulfides (0.6-3.3) is compared to the considerably wider pH i.e.p. range (2-12) found for oxides. The correlation between pH i.e.p. and the electronegativities of the metal sulfides suggests that all metal sulfides will have an isoelectric point between pH 0.6 and 3.3. Compared to metal oxides, sulfides exhibit an isoelectric point that is largely independent of the nature of the metal cation in the solid.

Effect of extraction condition on properties of pectin from banana peels and its function as fat replacer in salad cream.

PubMed

Maneerat, Nitjaree; Tangsuphoom, Nattapol; Nitithamyong, Anadi

2017-02-01

Banana peels are wasted from banana processing industry. Pectin is a soluble dietary fibre usually prepared from fruit and vegetable processing wastes. Pectin extraction from banana peels thus should be an effective way of waste utilization. This study aimed to determine the effect of extraction condition on the properties of pectin from peels of Nam Wa banana ( Musa (ABB group) 'Kluai Nam Wa') and its role as fat replacer in salad cream. Banana peel pectin (BPP) was extracted with HCl (pH 1.5) and water (pH 6.0) for 30-120 min at 90 ± 5 °C. Acid extraction yielded 7-11% pectin on a dry basis with galacturonic acid content (GalA), degree of methylation (DM), and viscosity-average molecular weight (M v ) of 42-47, 57-61%, and 17-40 kDa, respectively; while water-extracted BPP contained lower DM but higher GalA and M v . Prolonged extraction raised the pectin yield but lowered the M v of BPP and the viscosity of their solutions. Incorporation of BPP obtained from 60 min acid- and water-extraction into salad cream at 30% oil substitution level resulted in the decreases in viscosity and lightness. All reduced-fat samples were stable to cream separation during 3-weeks storage although the formula containing water-extracted BPP had larger oil droplet size and greater extent of droplet flocculation. There was no difference in sensory scores rated by 50 panelists on thickness, smoothness, and overall acceptability of the full- and reduced-fat salad creams. Therefore, Nam Wa banana peels can be an alternative source of pectin with potential application as fat replacer in food products.

Effect of the Duck Skin on Quality Characteristics of Duck Hams

PubMed Central

Kim, Dong-Hyun; Kim, Tae-Kyung; Kim, Young-Boong; Sung, Jung-Min; Jang, YoungJin; Shim, Jae-Yun; Han, Sung-Gu; Choi, Yun-Sang

2017-01-01

This study was conducted to investigate the effect of duck skin on cooking loss, emulsion stability, pH, color, protein solubility, texture profile analysis (TPA), apparent viscosity, and sensory characteristics of press type duck ham with different ratio of duck breast meat and duck skin. Five duck ham formulations were produced with the following compositions: T1 (duck breast 70% + duck skin 30%), T2 (duck breast 60% + duck skin 40%), T3 (duck breast 50% + duck skin 50%), T4 (duck breast 40% + duck skin 60%), and T5 (duck breast 30% + duck skin 70%). The cooking loss and fat separation were lower in T1, and the total expressible fluid separations were lower in T1 and T2 than others. The pH ranged from 6.48 to 6.59, with the highest values in T4 and T5. T5 had the highest CIE L*-value, and T1 and T2 had the highest CIE a*-values; however, CIE b*-values did not differ significantly between the duck ham samples. The protein solubility and TPA (hardness, springiness, cohesiveness, gumminess, and chewiness) were the highest in T1. T1 and T2 had higher scores for color, tenderness, and overall acceptability. T1, T2, and T3 showed significantly higher values, but there were no significant differences for flavor and juiciness. Regarding apparent viscosity properties, T1 and T2 had higher viscosity values than the other formulations. In conclusion, the T1 (duck breast 70% + duck skin 30%) and T2 (duck breast 60% + duck skin 40%) duck hams show the highest quality characteristics. PMID:28747821

Critical Viscosity of Xenon

NASA Technical Reports Server (NTRS)

2001-01-01

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. Shear thirning will cause a normally viscous fluid -- such as pie filling or whipped cream -- to deform and flow more readily under high shear conditions. In shear thinning, a pocket of fluid will deform and move one edge forward, as depicted here.

Modelling droplet collision outcomes for different substances and viscosities

NASA Astrophysics Data System (ADS)

Sommerfeld, Martin; Kuschel, Matthias

2016-12-01

The main objective of the present study is the derivation of models describing the outcome of binary droplet collisions for a wide range of dynamic viscosities in the well-known collision maps (i.e. normalised lateral droplet displacement at collision, called impact parameter, versus collision Weber number). Previous studies by Kuschel and Sommerfeld (Exp Fluids 54:1440, 2013) for different solution droplets having a range of solids contents and hence dynamic viscosities (here between 1 and 60 mPa s) revealed that the locations of the triple point (i.e. coincidence of bouncing, stretching separation and coalescence) and the critical Weber number (i.e. condition for the transition from coalescence to separation for head-on collisions) show a clear dependence on dynamic viscosity. In order to extend these findings also to pure liquids and to provide a broader data basis for modelling the viscosity effect, additional binary collision experiments were conducted for different alcohols (viscosity range 1.2-15.9 mPa s) and the FVA1 reference oil at different temperatures (viscosity range 3.0-28.2 mPa s). The droplet size for the series of alcohols was around 365 and 385 µm for the FVA1 reference oil, in each case with fixed diameter ratio at Δ= 1. The relative velocity between the droplets was varied in the range 0.5-3.5 m/s, yielding maximum Weber numbers of around 180. Individual binary droplet collisions with defined conditions were generated by two droplet chains each produced by vibrating orifice droplet generators. For recording droplet motion and the binary collision process with good spatial and temporal resolution high-speed shadow imaging was employed. The results for varied relative velocity and impact angle were assembled in impact parameter-Weber number maps. With increasing dynamic viscosity a characteristic displacement of the regimes for the different collision scenarios was also observed for pure liquids similar to that observed for solutions. This displacement could be described on a physical basis using the similarity number and structure parameter K which was obtained through flow process evaluation and optimal proportioning of momentum and energy by Naue and Bärwolff (Transportprozesse in Fluiden. Deutscher Verlag für Grundstoffindustrie GmbH, Leipzig 1992). Two correlations including the structure parameter K could be derived which describe the location of the triple point and the critical We number. All fluids considered, pure liquids and solutions, are very well fitted by these physically based correlations. The boundary model of Jiang et al. (J Fluid Mech 234:171-190, 1992) for distinguishing between coalescence and stretching separation could be adapted to go through the triple point by the two involved model parameters C a and C b, which were correlated with the relaxation velocity u_{{relax}} = {σ/μ}. Based on the predicted critical Weber number, denoting the onset of reflexive separation, the model of Ashgriz and Poo (J Fluid Mech 221:183-204, 1990) was adapted accordingly. The proper performance of the new generalised models was validated based on the present and previous measurements for a wide range of dynamic viscosities (i.e. 1-60 mPa s) and liquid properties. Although the model for the lower boundary of bouncing (Estrade et al. in J Heat Fluid Flow 20:486-491, 1999) could be adapted through the shape factor, it was found not suitable for the entire range of Weber numbers and viscosities.

Flow properties of liquid crystal phases of the Gay-Berne fluid

NASA Astrophysics Data System (ADS)

Sarman, Sten

1998-05-01

We have calculated the viscosities of a variant of the Gay-Berne fluid as a function of the temperature by performing molecular dynamics simulations. We have evaluated the Green-Kubo relations for the various viscosity coefficients. The results have been cross-checked by performing shear flow simulations. At high temperatures there is a nematic phase that is transformed to a smectic A phase as the temperature is decreased. The nematic phase is found to be flow stable. Close to the nematic-smectic transition point the liquid crystal model system becomes flow unstable. This is in agreement with the theoretical predictions by Jähnig and Brochard [F. Jähnig and F. Brochard, J. Phys. 35, 301 (1974)]. In a planar Couette flow one can define the three Miesowicz viscosities or effective viscosities η1, η2, and η3. The coefficient η1 is the viscosity when the director is parallel to the streamlines, η2 is the viscosity when the director is perpendicular to the shear plane, and η3 is the viscosity when the director is perpendicular to the vorticity plane. In the smectic phase η1 is undefined because the strain rate field is incommensurate with the smectic layer structure when the director is parallel to the streamlines. The viscosity η3 is found to be fairly independent of the temperature. The coefficient η2 increases with the temperature. This is unusual because the viscosity of most isotropic liquids decreases with the temperature. This anomaly is due to the smectic layer structure that is present at low temperatures. This lowers the friction because the layers can slide past each other fairly easily.

A dynamic jamming point for shear thickening suspensions

NASA Astrophysics Data System (ADS)

Brown, Eric; Jaeger, Heinrich

2008-11-01

Densely packed suspensions can shear thicken, in which the viscosity increases with shear rate. We performed rheometry measurements on two model systems: corn starch in water and glass spheres in oils. In both systems we observed shear thickening up to a critical packing fraction φc (=0.55 for spherical grains) above which the flow abruptly transitions to shear thinning. The viscosity and yield stress diverge as power laws at φc. Extrapolating the dynamic ranges of shear rate and stress in the shear thickening regime up to φc suggests a finite change in shear stress with zero change in shear rate. This is a dynamic analog to the jamming point with a yield stress at zero shear rate.

Utilizing whey protein isolate and polysaccharide complexes to stabilize aerated dairy gels.

PubMed

O'Chiu, Emily; Vardhanabhuti, Bongkosh

2017-05-01

Heated soluble complexes of whey protein isolate (WPI) with polysaccharides may be used to modify the properties of aerated dairy gels, which could be formulated into novel-textured high-protein desserts. The objective of this study was to determine the effect of polysaccharide charge density and concentration within a WPI-polysaccharide complex on the physical properties of aerated gels. Three polysaccharides having different degrees of charge density were chosen: low-methoxyl pectin, high-methoxyl type D pectin, and guar gum. Heated complexes were prepared by heating the mixed dispersions (8% protein, 0 to 1% polysaccharide) at pH 7. To form aerated gels, 2% glucono-δ-lactone was added to the dispersions of skim milk powder and heated complex and foam was generated by whipping with a handheld frother. The foam set into a gel as the glucono-δ-lactone acidified to a final pH of 4.5. The aerated gels were evaluated for overrun, drainage, gel strength, and viscoelastic properties. Without heated complexes, stable aerated gels could not be formed. Overrun of aerated gel decreased (up to 73%) as polysaccharide concentration increased from 0.105 to 0.315% due to increased viscosity, which limited air incorporation. A negative relationship was found between percent drainage and dispersion viscosity. However, plotting of drainage against dispersion viscosity separated by polysaccharide type revealed that drainage decreased most in samples with high-charge-density, low-methoxyl pectin followed by those with low-charge-density, high-methoxyl type D pectin. Aerated gels with guar gum (no charge) did not show improvement to stability. Rheological results showed no significant difference in gelation time among samples; therefore, stronger interactions between WPI and high-charge-density polysaccharide were likely responsible for increased stability. Stable dairy aerated gels can be created from WPI-polysaccharide complexes. High-charge-density polysaccharides, at concentrations that provide adequate viscosity, are needed to achieve stability while also maintaining dispersion overrun capabilities. Copyright © 2017 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Effect of different fat replacers on the physicochemical and instrumental analysis of low-fat cupuassu goat milk yogurts.

PubMed

Costa, Marion P; Frasao, Beatriz S; Rodrigues, Bruna L; Silva, Adriana Co; Conte-Junior, Carlos A

2016-11-01

The aim of this Research Communication was to investigate the changes in physicochemical, colour, apparent viscosity and texture properties in low-fat goat milk yogurts prepared with cupuassu pulp by the addition of inulin (SI), maltodextrin (SM), whey protein (SW) and skim milk powder (SP). Three batches of each cupuassu goat milk yogurt were prepared and analysed on the 1st day of storage by pH, proximate composition, colour, apparent viscosity, and texture. In comparison to yogurts from whole (W) or skimmed milk (S), all of the fat replacers improved the physicochemical properties (P < 0·05). The addition of the carbohydrates (inulin and maltodextrin) and proteins (whey protein and skim milk powder) also influenced the colour of the low-fat cupuassu goat milk yogurt (P < 0·05). All fat replacer treatments (SI, SM, SW and SP) presented a higher (P < 0·05) apparent viscosity than W and S yogurts. However, only the addition of skim milk powder increased the texture parameters (firmness and consistency) (P < 0·05). These results suggest that skim milk powder can be used to improve the texture properties of low-fat cupuassu goat milk. Furthermore, inulin, maltodextrin, and whey protein can potentially be applied in the goat dairy industry to increase the viscosity of yogurts.

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.

Evaluation of the diffusion coefficient for controlled release of oxytetracycline from alginate/chitosan/poly(ethylene glycol) microbeads in simulated gastrointestinal environments.

PubMed

Cruz, Maria C Pinto; Ravagnani, Sergio P; Brogna, Fabio M S; Campana, Sérgio P; Triviño, Galo Cardenas; Lisboa, Antonio C Luz; Mei, Lucia H Innocentini

2004-12-01

Diffusion studies of OTC (oxytetracycline) entrapped in microbeads of calcium alginate, calcium alginate coacervated with chitosan (of high, medium and low viscosity) and calcium alginate coacervated with chitosan of low viscosity, covered with PEG [poly(ethylene glycol) of molecular mass 2, 4.6 and 10 kDa, were carried out at 37+/-0.5 degrees C, in pH 7.4 and pH 1.2 buffer solutions - conditions similar to those found in the gastrointestinal system. The diffusion coefficient, or diffusivity (D), of OTC was calculated by equations provided by Crank [(1975) Mathematics in Diffusion, p. 85, Clarendon Press, Oxford] for diffusion, which follows Fick's [(1855) Ann. Physik (Leipzig) 170, 59] second law, considering the diffusion from the inner parts to the surface of the microbeads. The least-squares and the Newton-Raphson [Carnahan, Luther and Wilkes (1969) Applied Numerical Methods, p. 319, John Wiley & Sons, New York] methods were used to obtain the diffusion coefficients. The microbead swelling at pH 7.4 and OTC diffusion is classically Fickian, suggesting that the OTC transport, in this case, is controlled by the exchange rates of free water and relaxation of calcium alginate chains. In case of acid media, it was observed that the phenomenon did not follow Fick's law, owing, probably, to the high solubility of the OTC in this environment. It was possible to modulate the release rate of OTC in several types of microbeads. The presence of cracks formed during the process of drying the microbeads was observed by scanning electron microscopy.

Sensitivity of Clay Suspension Rheological Properties to pH, Temperature, Salinity, and Smectite-Quartz Ratio

NASA Astrophysics Data System (ADS)

Kameda, Jun; Morisaki, Tomonori

2017-10-01

Understanding the rheological properties of clay suspensions is critical to assessing the behavior of sediment gravity flows such as debris flow or turbidity current. We conducted rheological measurements of composite smectite-quartz suspensions at a temperature of 7°C and a salt concentration of 0.6 M. This is representative of smectite-bearing sediments under conditions on the seafloor. The flow curves obtained were fitted by the Bingham fluid model, from which we determined the Bingham yield stress and dynamic viscosity of each suspension. At a constant smectite-quartz mixing ratio, the yield stress and the dynamic viscosity tend to increase as the solid/water ratio of the suspension is increased. In the case of a constant solid/water ratio, these values increase with increasing smectite content in the smectite-quartz mixture. Additional experiments exploring differing physicochemical conditions (pH 1.0-9.0; temperature 2-30°C; and electrolyte (NaCl) concentration 0.2-0.6 M) revealed that the influence of temperature is negligible, while pH moderately affects the rheology of the suspension. More significantly, the electrolyte concentration greatly affects the flow behavior. These variations can be explained by direct and/or indirect (double-layer) interactions between smectite-smectite particles as well as between smectite-quartz particles in the suspension. Although smectite is known as a frictionally weak material, our experimental results suggest that its occurrence can reduce the likelihood that slope failure initiates. Furthermore, smectite can effectively suppress the spreading distance once the slope has failed.

Formulation development and evaluation of innovative two-polymer (SR-2P) bioadhesive vaginal gel.

PubMed

Podaralla, Satheesh; Alt, Carsten; Shankar, Gita N

2014-08-01

The main objective of this investigation was to study the feasibility of developing a vaginal bioadhesive microbicide using a SRI's proprietary two-polymer gel platform (SR-2P). Several formulations were prepared with different combinations of temperature-sensitive polymer (Pluronic® F-127) and mucoadhesive polymer (Noveon® AA-1), producing gels of different characteristics. Prototype polymeric gels were evaluated for pH, osmolality, buffering capacity, and viscosity under simulated vaginal semen dilutions, and bioadhesivity using ex vivo mini pig vaginal tissues and texture analyzer. The pH of the polymeric gel formulations ranged from 5.1 to 6.4; the osmolality varied from 13 to 173 mOsm. Absolute viscosity ranged from 513 to 3,780 cPs, and was significantly reduced (1.5- to 3-fold) upon incubation with simulated vaginal and semen fluid mixture. Among the tested gels (indicated in the middle row as a molar ratio of a mixture of Noveon vs. Pluronic), only SR-2P retained gel structure upon dilution with simulated fluids and mild simulated coital stress. The pH of the SR-2P gel was maintained at about 4.6 in simulated vaginal fluid and also showed high peak force of adhesion in mini pig vaginal tissue. Furthermore, SR-2P gel caused no or only minimal irritation in a mouse vaginal irritation model. The results of this preliminary study demonstrated the potential application of SR-2P gel as a vaginal microbicide vehicle for delivery of anti-HIV agents.

Coarse-Grain Molecular Dynamics Simulations To Investigate the Bulk Viscosity and Critical Micelle Concentration of the Ionic Surfactant Sodium Dodecyl Sulfate (SDS) in Aqueous Solution.

PubMed

Ruiz-Morales, Yosadara; Romero-Martínez, Ascención

2018-04-12

The first critical micelle concentration (CMC) of the ionic surfactant sodium dodecyl sulfate (SDS) in diluted aqueous solution has been determined at room temperature from the investigation of the bulk viscosity, at several concentrations of SDS, by means of coarse-grain molecular dynamics simulations. The coarse-grained model molecules at the mesoscale level are adopted. The bulk viscosity of SDS was calculated at several millimolar concentrations of SDS in water using the MARTINI force field by means of NVT shear Mesocite molecular dynamics. The definition of each bead in the MARTINI force field is established, as well as their radius, volume, and mass. The effect of the size of the simulation box on the obtained CMC has been investigated, as well as the effect of the number of SDS molecules, in the simulations, on the formation of aggregates. The CMC, which was obtained from a graph of the calculated viscosities versus concentration, is in good agreement with the reported experimental data and does not depend on the size of the box used in the simulation. The formation of a spherical micelle-like aggregate is observed, where the dodecyl sulfate tails point inward and the heads point outward the aggregation micelle, in accordance with experimental observations. The advantage of using coarse-grain molecular dynamics is the possibility of treating explicitly charged beads, applying a shear flow for viscosity calculation, and processing much larger spatial and temporal scales than atomistic molecular dynamics can. Furthermore, the CMC of SDS obtained with the coarse-grained model is in much better agreement with the experimental value than the value obtained with atomistic simulations.

Preparation and characterization of bio-diesels from various bio-oils.

PubMed

Lang, X; Dalai, A K; Bakhshi, N N; Reaney, M J; Hertz, P B

2001-10-01

Methyl, ethyl, 2-propyl and butyl esters were prepared from canola and linseed oils through transesterification using KOH and/ or sodium alkoxides as catalysts. In addition, methyl and ethyl esters were prepared from rapeseed and sunflower oils using the same catalysts. Chemical composition of the esters was determined by HPLC for the class of lipids and by GC for fatty acid compositions. The bio-diesel esters were characterized for their physical and fuel properties including density, viscosity, iodine value, acid value, cloud point, pure point, gross heat of combustion and volatility. Methyl and ethyl esters prepared from a particular vegetable oil had similar viscosities, cloud points and pour points, whereas methyl, ethyl, 2-propyl and butyl esters derived from a particular vegetable oil had similar gross heating values. However, their densities, which were 2 7% higher than those of diesel fuels, statistically decreased in the order of methyl approximately 2-propyl > ethyl > butyl esters. Butyl esters showed reduced cloud points (-6 degrees C to -10 degrees C) and pour points (-13 degrees C to -16 degrees C) similar to those of summer diesel fuel having cloud and pour points of -8 degrees C and -15 degrees C, respectively. The viscosities of bio-diesels (3.3-7.6 x 10(-4) Pa s at 40 degrees C) were much less than those of pure oils (22.4-45.1 x 10(-4) Pa s at 40 degrees C) and were twice those of summer and winter diesel fuels (3.50 and 1.72 x 10(-4) Pa s at 40 degrees C), and their gross heat contents of approximately 40 MJ/kg were 11% less than those of diesel fuels (approximately 45 MJ/kg). For different esters from the same vegetable oil, methyl esters were the most volatile, and the volatility decreased as the alkyl group grew bulkier. However, the bio-diesels were considerably less volatile than the conventional diesel fuels.

Lysozyme encapsulated gold nanoclusters: effects of cluster synthesis on natural protein characteristics.

PubMed

Russell, B A; Jachimska, B; Komorek, P; Mulheran, P A; Chen, Y

2017-03-08

The study of gold nanoclusters (AuNCs) has seen much interest in recent history due to their unique fluorescence properties and environmentally friendly synthesis method using proteins as a growth scaffold. The differences in the physicochemical properties of lysozyme encapsulated AuNCs in comparison to natural lysozyme are characterised in order to determine the effects AuNCs have on natural protein behaviour. The hydrodynamic radius (dynamic light scattering), light absorbance (UV-Vis), electrophoretic mobility, relative density, dynamic viscosity, adsorption (quartz crystal microbalance) and circular dichroism (CD) characteristics of the molecules were studied. It was found that lysozyme forms small dimer/trimer aggregates upon the synthesis of AuNCs within the protein. The diameter of Ly-AuNCs was found to be 8.0 nm across a pH range of 2-11 indicating dimer formation, but larger aggregates with diameters >20 nm were formed between pH 3 and 6. The formation of larger aggregates limits the use of Ly-AuNCs as a fluorescent probe in this pH range. A large shift in the protein's isoelectric point was also observed, shifting from 11.0 to 4.0 upon AuNC synthesis. This resulted in major changes to the adsorption characteristics of lysozyme, observed using a QCM. A monolayer of 8 nm was seen for Ly-AuNCs at pH 4, offering further evidence that the proteins form small aggregates, unlike the natural monomer form of lysozyme. The adsorption of Ly-AuNCs was seen to decrease as pH was increased; this is in major contrast to the lysozyme adsorption behaviour. A decrease in the α-helix content was observed from 25% in natural lysozyme to 1% in Ly-AuNCs. This coincided with an increase in the β-sheet content after AuNC synthesis indicating that the natural structure of lysozyme was lost. The formation of protein dimers, the change in the protein surface charge from positive to negative, and secondary structure alteration caused by the AuNC synthesis must be considered before attempting to utilise Ly-AuNCs as in vivo probes.

Effect of Isopropyl Myristate on Transdermal Permeation of Testosterone From Carbopol Gel.

PubMed

Zidan, Ahmed S; Kamal, Nahid; Alayoubi, Alaadin; Seggel, Mark; Ibrahim, Sarah; Rahman, Ziyaur; Cruz, Celia N; Ashraf, Muhammad

2017-07-01

The objective of the present study was to investigate the effect of isopropyl myristate (IPM) on the in vitro permeation of testosterone through human cadaver skin from carbopol gels. Six testosterone gel formulations were prepared using different IPM contents of 0%, 0.4%, 0.7%, 1%, 2%, and 3%. The gels were characterized for drug permeation, matrix morphology, pH, kinetics of ethanol evaporation, and viscosity. Mass balance studies were performed to estimate testosterone distribution among the compartments of diffusion cells. All formulations exhibited pH values of 5.1 and viscosities of 1.25-1.75 Pa.s depending on IPM contents. Under occlusive condition, testosterone flux was found to increase significantly (p < 0.05) by increasing IPM content. Gels containing 2% IPM exhibited 11-fold increase in flux compared with formulation devoid of IPM. Ethanol was found to have a synergistic effect with IPM in enhancing testosterone flux. Mass balance analysis showed that testosterone was in a saturated state in the skin. Conducting permeation experiments under nonocclusive condition was nondiscriminating because of the evaporation of alcohol and consequent precipitation of drugs. Based on demonstrated effect of IPM on product performance, the final IPM concentration should be controlled with minimal variation during manufacturing and shelf life of drug product. Published by Elsevier Inc.

Effect of fermentation and sterilization on anthocyanins in blueberry.

PubMed

Nie, Qixing; Feng, Lei; Hu, Jielun; Wang, Sunan; Chen, Haihong; Huang, Xiaojun; Nie, Shaoping; Xiong, Tao; Xie, Mingyong

2017-03-01

Blueberry products have various health benefits due to their high content of dietary anthocyanins. The aim of this study was to investigate the impact of fermentation and sterilization on total anthocyanin content, composition and some quality attributes of blueberry puree. The blueberry puree used here was fermented for 40 h at 37 °C by Lactobacillus after sterilization. The method of ultra-performance liquid chromatography-mass spectrometry was optimized for the rapid analysis of anthocyanins. Quality attributes including pH, color, total soluble solids and viscosity were measured. A total of 21 anthocyanins and five anthocyanidins were quantified by ultra-performance liquid chromatography. Fermented blueberry had reduced total anthocyanin content (29%) and levels of individual anthocyanins compared with fresh blueberry. Total anthocyanin content was decreased 46% by sterilization, and different degradation behavior of individual anthocyanin was appeared between fermented and sterilized-fermented blueberry puree. Fermentation and sterilization decreased the total soluble solids and pH and changed color parameters, while minimally influencing viscosity. The loss of total anthocyanin content by fermentation was related to the unstable structure of blueberry anthocyanins. Anthocyanins are sensitive to temperature (>80 °C), and degradation of anthocyanins by sterilization in blueberry should be considered in the fermentation procedure. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

Optimization of Sugar Replacement with Date Syrup in Prebiotic Chocolate Milk Using Response Surface Methodology.

PubMed

Kazemalilou, Sahar; Alizadeh, Ainaz

2017-01-01

Chocolate milk is one of the most commonly used non-fermentative dairy products, which, due to high level of sucrose, could lead to diabetes and tooth decay among children. Therefore, it is important to replace sucrose with other types of sweeteners, especially, natural ones. In this research, response surface methodology (RSM) was used to optimize the ingredients formulation of prebiotic chocolate milk, date syrup as sweetener (4-10%w/w), inulin as prebiotic texturizer (0-0.5%w/w) and carrageenan as thickening agent (0-0.04%w/w) in the formulation of chocolate milk. The fitted models to predict the variables of selected responses such as pH, viscosity, total solid, sedimentation and overall acceptability of chocolate milk showed a high coefficient of determination. The independent effect of carrageenan was the most effective parameter which led to pH and sedimentation decrease but increased viscosity. Moreover, in most treatments, date syrup and inulin variables had significant effects which had a mutual impact. Optimization of the variables, based on the responses surface 3D plots showed that the sample containing 0.48% (w/w) of inulin, 0.04% (w/w) of carrageenan, and 10% of date syrup was selected as the optimum condition.

Refrigerated Shelf Life of a Coconut Water-Oatmeal Mix and the Viability of Lactobacillus Plantarum Lp 115-400B

PubMed Central

Dharmasena, Muthu; Barron, Felix; Fraser, Angela; Jiang, Xiuping

2015-01-01

Non-dairy probiotic products have the advantage of being lactose-free and can be manufactured to sustain the growth of probiotics. In this study, coconut water and oatmeal were used with the probiotic, Lactobacillus plantarum Lp 115-400B (L. plantarum) as a starter culture. Two separate treatments were carried out probiotic (P) and probiotic and prebiotic (PP) added. In both treatments, oatmeal-coconut water matrix was inoculated with 7 log CFU/g of L. plantarum and fermented at 27 °C for 10 h. For the PP treatment, 1 g of inulin/100 mL of the product was added additionally. The fermented products were then refrigerated (4 °C) and the viability of L. plantarum, pH, total acidity, and apparent viscosity of the matrix were monitored at selected time intervals. The shelf life to reach was defined by maintenance of L. plantarum count of 7 log CFU/g product. Refrigerated shelf life was determined to be seven-weeks for the P treatment and five-weeks for PP treatment. A significant reduction of pH was observed at the end of the considered shelf life; conversely, the apparent viscosity of the product did not change significantly. PMID:28231208

Refrigerated Shelf Life of a Coconut Water-Oatmeal Mix and the Viability of Lactobacillus Plantarum Lp 115-400B.

PubMed

Dharmasena, Muthu; Barron, Felix; Fraser, Angela; Jiang, Xiuping

2015-08-10

Non-dairy probiotic products have the advantage of being lactose-free and can be manufactured to sustain the growth of probiotics. In this study, coconut water and oatmeal were used with the probiotic, Lactobacillus plantarum Lp 115-400B ( L. plantarum ) as a starter culture. Two separate treatments were carried out probiotic (P) and probiotic and prebiotic (PP) added. In both treatments, oatmeal-coconut water matrix was inoculated with 7 log CFU/g of L. plantarum and fermented at 27 °C for 10 h. For the PP treatment, 1 g of inulin/100 mL of the product was added additionally. The fermented products were then refrigerated (4 °C) and the viability of L. plantarum , pH, total acidity, and apparent viscosity of the matrix were monitored at selected time intervals. The shelf life to reach was defined by maintenance of L. plantarum count of 7 log CFU/g product. Refrigerated shelf life was determined to be seven-weeks for the P treatment and five-weeks for PP treatment. A significant reduction of pH was observed at the end of the considered shelf life; conversely, the apparent viscosity of the product did not change significantly.

Physicochemical parameters influencing coaggregation between the freshwater bacteria Sphingomonas natatoria 2.1 and Micrococcus luteus 2.13.

PubMed

Min, K R; Zimmer, M N; Rickard, A H

2010-11-01

The aim of this study was to explore the physicochemical parameters that influence coaggregation between the freshwater bacteria Sphingomonas natatoria 2.1 and Micrococcus luteus 2.13. Using visual coaggregation assays, the effect of different buffers, solutions of differing ionic strength, pH, temperature, and viscosity on the degree of coaggregation was assessed. Coaggregation occurred maximally in distilled water but was inhibited when coaggregates were suspended in a commonly-used oral bacterial coaggregation buffer, saline solutions, and Tris-Cl buffers. Coaggregation was weakly expressed in standard laboratory buffers. The ionic strength of inorganic salt solutions required to inhibit coaggregation depended upon the inorganic salt being tested. Coaggregation occurred at a pH of 3-10, between 5 and 80°C and was inhibited in solutions with a viscosity of 22.5 centipoises at 20°C. Inhibition of coaggregation with NaCl impaired biofilm development. When developing buffers to test for coaggregation, the natural liquid environment should be considered. Coaggregation between S. natatoria 2.1 and M. luteus 2.13 is only affected by physicochemical conditions beyond those typically found in natural freshwater ecosystems. Such a robust ability to coaggregate may enhance the ability of S. natatoria 2.1 and M. luteus 2.13 to develop a niche in freshwater biofilms.

High-order centered difference methods with sharp shock resolution

NASA Technical Reports Server (NTRS)

Gustafsson, Bertil; Olsson, Pelle

1994-01-01

In this paper we consider high-order centered finite difference approximations of hyperbolic conservation laws. We propose different ways of adding artificial viscosity to obtain sharp shock resolution. For the Riemann problem we give simple explicit formulas for obtaining stationary one and two-point shocks. This can be done for any order of accuracy. It is shown that the addition of artificial viscosity is equivalent to ensuring the Lax k-shock condition. We also show numerical experiments that verify the theoretical results.

Protonation-induced ultrafast torsional dynamics in 9-anthrylbenzimidazole: a pH activated molecular rotor.

PubMed

Nandi, Amitabha; Kushwaha, Archana; Das, Dipanwita; Ghosh, Rajib

2018-03-07

We report the photophysical properties and excited state dynamics of 9-anthrylbenzimidazole (ANBI) which exhibits protonation-induced molecular rotor properties. In contrast to the highly emissive behavior of neutral ANBI, protonation of the benzimidazole group of ANBI induces efficient nonradiative deactivation by ultrafast torsional motion around the bond connecting the anthracene and benzimidazole units, as revealed by ultrafast transient absorption and fluorescence spectroscopy. Contrary to viscosity-independent fluorescence of neutral dyes, protonated ANBI is shown to display linear variation of emission yield and lifetime with solvent viscosity. The protonation-induced molecular rotor properties in the studied system are shown to be driven by enhanced charge transfer and are corroborated by quantum chemical calculations. Potential application as a microviscosity sensor of acidic regions in a heterogeneous environment by these proton-activated molecular rotor properties of ANBI is discussed.

Human albumin solders for clinical application during laser tissue welding.

PubMed

Poppas, D P; Wright, E J; Guthrie, P D; Shlahet, L T; Retik, A B

1996-01-01

Fifty percent human albumin solder significantly improves weld strength when compared to lower concentrations [Wright et al., ASLMS meeting, April, 1995]. We developed a method for preparing 50% human albumin that may be considered compatible for clinical applications. Fifty percent human albumin solder was prepared from 25% commercially available human albumin using a lyophilization technique. Assessment of sterility, viscosity, pH, and peak absorption wavelength were performed. This report describes the methodology used to prepare a 50% human albumin solder that is compatible with clinical use. Maintenance of the structural integrity of the albumin was confirmed by polyacrylamide gel electrophoresis. This solder preparation can be used alone or with the addition of exogenous chromophores. The final product is sterile, incorporates viral free protocols, maintains high viscosity, and can be applied easily during open or laparoscopic procedures.

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

PubMed

Yao, Xiumin; Tan, Shouhong; Jiang, Dongliang

2005-02-01

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

Fully Fueled TACOM Vehicle Storage Test Program.

DTIC Science & Technology

1981-12-01

Messrs. H. Hobart, T. Wilson, and T. Hinkley , DRSTA-GSP, U.S. Army Tank Automotive Command (TACOM) for providing both liai- son and fuel-sampling...and its characteristics are as follows: Density, g/ml 0.9 Flash point , *F 140 Fire point , *F 145 Pour point , *F -50 Neutralization No., TAN 25 TBN 130...following characteristics: Density, g/ml 1.05 Flash point , *F 144 Pour point , *F -27.5 Viscosity, cSt, @ 70*F 29 Boron content 7.4% Water (free

Biorefinery Demonstration Project Final Progress Report

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

Lee, David

2015-10-20

In this project we focused on various aspects of biorefinery technology development including algal-biorefinery technology, thermochemical conversion of biomass to bio-oils and biochar; we tested characteristics and applications of biochars and evaluated nutrient cycling with wastewater treatment by the coupling of algal culture systems and anaerobic digestion. Key results include a method for reducing water content of bio-oil through atomized alcohol addition. The effect included increasing the pH and reducing the viscosity and cloud point of the bio-oil. Low input biochar production systems were evaluated via literature reviews and direct experimental work. Additionally, emissions were evaluated and three biochar systemsmore » were compared via a life cycle analysis. Attached growth systems for both algal cultivation and algal harvesting were found to be superior to suspended growth cultures. Nutrient requirements for algal cultivation could be obtained by the recycling of anaerobic digester effluents, thus experimentally showing that these two systems could be directly coupled. Twenty-two journal articles and six intellectual property applications resulted from the cumulative work that this project contributed to programmatically.« less

Tidal Interaction among Red Giants Close Binary Systems in APOGEE Database

NASA Astrophysics Data System (ADS)

Sun, Meng; Arras, Phil; Majewski, Steven R.; Troup, Nicholas William; Weinberg, Nevin N.

2017-01-01

Motivated by the newly discovered close binary systems in the Apache Point Observatory Galactic Evolution Experiment (APOGEE-1), the tidal evolution of binaries containing a red giant branch (RGB) star with a stellar or substellar companion was investigated. The tide raised by the companion in the RGB star leads to exchange of angular momentum between the orbit and the stellar spin, causing the orbit to contract. The tidal dissipation rate is computed using turbulent viscosity acting on the equilibrium tidal flow, where careful attention is paid to the effects of reduced viscosity for close-in companions. Evolutionary models for the RGB stars, from the zero-age main sequence to the present, were acquired from the MESA code. "Standard" turbulent viscosity gives rise to such a large orbital decay that many observed systems have decay times much shorter than the RGB evolution time. Several theories for "reduced" turbulent viscosity are investigated, and reduce the number of systems with uncomfortably short decay times.

Effects of Eddy Viscosity on Time Correlations in Large Eddy Simulation

NASA Technical Reports Server (NTRS)

He, Guowei; Rubinstein, R.; Wang, Lian-Ping; Bushnell, Dennis M. (Technical Monitor)

2001-01-01

Subgrid-scale (SGS) models for large. eddy simulation (LES) have generally been evaluated by their ability to predict single-time statistics of turbulent flows such as kinetic energy and Reynolds stresses. Recent application- of large eddy simulation to the evaluation of sound sources in turbulent flows, a problem in which time, correlations determine the frequency distribution of acoustic radiation, suggest that subgrid models should also be evaluated by their ability to predict time correlations in turbulent flows. This paper compares the two-point, two-time Eulerian velocity correlation evaluated from direct numerical simulation (DNS) with that evaluated from LES, using a spectral eddy viscosity, for isotropic homogeneous turbulence. It is found that the LES fields are too coherent, in the sense that their time correlations decay more slowly than the corresponding time. correlations in the DNS fields. This observation is confirmed by theoretical estimates of time correlations using the Taylor expansion technique. Tile reason for the slower decay is that the eddy viscosity does not include the random backscatter, which decorrelates fluid motion at large scales. An effective eddy viscosity associated with time correlations is formulated, to which the eddy viscosity associated with energy transfer is a leading order approximation.

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.

40 CFR 414.91 - Toxic pollutant effluent limitations and standards for direct discharge point sources that use...

Code of Federal Regulations, 2011 CFR

2011-07-01

... AND STANDARDS ORGANIC CHEMICALS, PLASTICS, AND SYNTHETIC FIBERS Direct Discharge Point Sources That...(k)fluoranthene 59 22 Benzo(a)pyrene 61 23 Bis(2-ethylhexyl) phthalate 279 103 Carbon Tetrachloride... Zinc for Rayon Fiber Manufacture that uses the viscose process and Acrylic Fiber Manufacture that uses...

40 CFR 414.91 - Toxic pollutant effluent limitations and standards for direct discharge point sources that use...

Code of Federal Regulations, 2010 CFR

2010-07-01

... AND STANDARDS ORGANIC CHEMICALS, PLASTICS, AND SYNTHETIC FIBERS Direct Discharge Point Sources That...(k)fluoranthene 59 22 Benzo(a)pyrene 61 23 Bis(2-ethylhexyl) phthalate 279 103 Carbon Tetrachloride... Zinc for Rayon Fiber Manufacture that uses the viscose process and Acrylic Fiber Manufacture that uses...

Contribution to modeling the viscosity Arrhenius-type equation for saturated pure fluids

NASA Astrophysics Data System (ADS)

Tian, Jianxiang; Zhang, Laibin

2016-09-01

Recently, Haj-Kacem et al. proposed an equation modeling the relationship between the two parameters of viscosity Arrhenius-type equations [Fluid Phase Equilibria 383, 11 (2014)]. The authors found that the two parameters are dependent upon each other in an exponential function form. In this paper, we reconsidered their ideas and calculated the two parameter values for 49 saturated pure fluids by using the experimental data in the NIST WebBook. Our conclusion is different with the ones of Haj-Kacem et al. We found that (the linearity shown by) the Arrhenius equation stands strongly only in low temperature range and that the two parameters of the Arrhenius equation are independent upon each other in the whole temperature range from the triple point to the critical point.

Characterizing optical polishing pitch

NASA Astrophysics Data System (ADS)

Varshneya, Rupal; DeGroote, Jessica E.; Gregg, Leslie L.; Jacobs, Stephen D.

2003-05-01

Characterization data for five experimental optical polishing pitch products were compared to those for corresponding standard commercial optical polishing pitches. The experimental pitches were tested for three physical properties: hardness, viscosity at 90°C, and softening point. A Shore A Durometer test was used to measure hardness. Viscosity data were collected using a Stony Brook Scientific falling needle viscometer. Softening point was determined using the ASTM D3104-97 method. Results demonstrate that the softest and the hardest batches of the experimental grades of optical pitch are comparable to the industry-accepted standards, while the other grades of pitch are not. The experimental methodology followed in this research may allow opticians to rapidly compare different brands of pitch to help identify batch-to-batch differences and control pitch quality before use.

Characterizing optical polishing pitch

NASA Astrophysics Data System (ADS)

Varshneya, Rupal

2003-05-01

Characterization data for five experimental optical polishing pitch products were compared to those for corresponding standard commercial optical polishing pitches. The experimental pitches were tested for three physical properties: hardness, viscosity at 90°C, and softening point. A Shore A Durometerl test was used to measure hardness. Viscosity data were collected using a Stony Brook Scientific' falling needle viscometer. Softening point was determined using the ASTM D3104-97 method. Results demonstrate that the softest and the hardest batches of the experimental grades of optical pitch are comparable to the industry-accepted standards, while the other grades of pitch are not. The experimental methodology followed in this research may allow opticians to rapidly compare different brands of pitch to help identify batch- to- batch differences and control pitch quality before use.

Monitoring of the Physical and Chemical Properties of a Gasoline Engine Oil during Its Usage

PubMed Central

Rahimi, Behnam; Semnani, Abolfazl; Nezamzadeh-Ejhieh, Alireza; Shakoori Langeroodi, Hamid; Hakim Davood, Massoud

2012-01-01

Physicochemical properties of a mineral-based gasoline engine oil have been monitored at 0, 500, 1000, 2000, 3500, 6000, 8500, and 11500 kilometer of operation. Tracing has been performed by inductively coupled plasma and some other techniques. At each series of measurements, the concentrations of twenty four elements as well as physical properties such as: viscosity at 40 and 100°C; viscosity index; flash point; pour point; specific gravity; color; total acid and base numbers; water content have been determined. The results are indicative of the decreasing trend in concentration of additive elements and increasing in concentration for wear elements. Different trends have been observed for various physical properties. The possible reasons for variations in physical and chemical properties have been discussed. PMID:22567569

Impregnation of Scots pine and beech with tannin solutions: effect of viscosity and wood anatomy in wood infiltration.

PubMed

Tondi, G; Thevenon, M F; Mies, B; Standfest, G; Petutschnigg, A; Wieland, S

The impregnation process of Scots pine and beech samples with tannin solutions was investigated. The two materials involved in the process (impregnation solution and wood samples) are studied in depth. Viscosity of mimosa tannin solutions and the anatomical aspect of beech and Scots pine were analysed and correlated. The viscosity of tannin solutions presents a non-newtonian behaviour when its pH level increases, and in the case of addition of hexamine as a hardener, the crosslinking of the flavonoids turns out to be of great importance. During the impregnation of Scots pine ( Pinus sylvestris L.) and beech ( Fagus sylvatica L.), the liquid and solid uptakes were monitored while taking into consideration the different conditions of the impregnation process. This method allowed to identify the best conditions needed in order to get a successful preservative uptake for each wooden substrate. The penetration mechanism within the wood of both species was revealed with the aid of a microscopic analysis. Scots pine is impregnated through the tracheids in the longitudinal direction and through parenchyma rays in the radial direction, whereas in beech, the penetration occurs almost completely through longitudinal vessels.

Short Communication: Rheological properties of blood serum of rats after irradiation with different gamma radiation doses in vivo.

PubMed

Abdelhalim, Mohamed Anwar K; Moussa, Sherif Aa; Ms, Al-Ayed

2016-01-01

The blood serum rheological properties open the door to find suitable radio-protectors and convenient therapy for many cases of radiation exposure. The present study aimed to investigate the rheological properties of rat blood serum at wide range of shear rates after whole body irradiation with different gamma radiation doses in vivo. Healthy male rats were divided into five groups; one control group and 4 irradiated groups. The irradiation process was carried out using Co60 source with dose rate of 0.883cG/sec. Several rheological parameters were measured using Brookfield LVDV-III Programmable rheometer. A significant increase in viscosity and shear stress was observed with 25 and 50Gy corresponding to each shear rate compared with the control; while a significant decrease observed with 75 and 100Gy. The viscosity exhibited a Non-Newtonian behaviour with the shear rate while shear stress values were linearly related with shear rate. The decrease in blood viscosity might be attributed to changes in molecular weight, pH sensitivity and protein structure. The changes in rheological properties of irradiated rats' blood serum might be attributed to destruction changes in the haematological and dimensional properties of rats' blood products.

Rheological and Performance Research on a Regenerable Polyvinyl Alcohol Fracturing Fluid

PubMed Central

Shang, Xiaosen; Ding, Yunhong; Wang, Yonghui; Yang, Lifeng

2015-01-01

A regenerable polyvinyl alcohol/organic boron fracturing fluid system with 1.6 wt% polyvinyl alcohol (PVOH) and 1.2 wt% organic boron (OBT) was studied, and its main regeneration mechanism is the reversible cross-linking reaction between B(OH)4 - and hydroxyl groups of PVOH as the change of pH. Results of rheology evaluations show that both the apparent viscosity and the thermal stability of the fracturing fluid decreased with the regeneration number of times increasing. In addition, the apparent viscosity of the fluid which was without regeneration was more sensitive to the shear action compared with that of the fluid with regeneration once or twice. When the fracturing fluid was without regeneration, the elasticity was dominating due to the three-dimensional network structure of the formed gel; the viscosity gradually occupied the advantage when the fracturing fluid was regenerated once or twice. The settling velocity of proppant was accelerated by both the regeneration process and the increasing temperature, but it was decelerated when the proppant ratio increased. Results of core damage tests indicate that less permeability damage was caused by the PVOH/OBT fracturing fluid compared with that caused by the guar gum fracturing fluid after gel breaking. PMID:26641857

Rheological and Performance Research on a Regenerable Polyvinyl Alcohol Fracturing Fluid.

PubMed

Shang, Xiaosen; Ding, Yunhong; Wang, Yonghui; Yang, Lifeng

2015-01-01

A regenerable polyvinyl alcohol/organic boron fracturing fluid system with 1.6 wt% polyvinyl alcohol (PVOH) and 1.2 wt% organic boron (OBT) was studied, and its main regeneration mechanism is the reversible cross-linking reaction between B(OH)4- and hydroxyl groups of PVOH as the change of pH. Results of rheology evaluations show that both the apparent viscosity and the thermal stability of the fracturing fluid decreased with the regeneration number of times increasing. In addition, the apparent viscosity of the fluid which was without regeneration was more sensitive to the shear action compared with that of the fluid with regeneration once or twice. When the fracturing fluid was without regeneration, the elasticity was dominating due to the three-dimensional network structure of the formed gel; the viscosity gradually occupied the advantage when the fracturing fluid was regenerated once or twice. The settling velocity of proppant was accelerated by both the regeneration process and the increasing temperature, but it was decelerated when the proppant ratio increased. Results of core damage tests indicate that less permeability damage was caused by the PVOH/OBT fracturing fluid compared with that caused by the guar gum fracturing fluid after gel breaking.

High solid loading aqueous base metal/ceramic feedstock for injection molding

NASA Astrophysics Data System (ADS)

Behi, Mohammad

2001-07-01

Increasing volume fraction of metal powder in feedstock provided lower shrinkage. Reduction of the shrinkage results in better dimensional precision. The rheology of the feedstock material plays an important role to allowing larger volume fractions of the metal powder to be incorporated in the feedstock formulations. The viscosity of the feedstock mainly depends on the binder viscosity, powder volume fraction and characteristics of metal powder. Aqueous polysaccharide agar was used as a baseline binder system for this study. The effect of several gel-strengthening additives on 1.5wt% and 2wt% agar gel was evaluated. A new gel-strengthening additive was found to be the most effective among the others. The effect of other additives such as glucose, sucrose and fructose on viscosity of baseline binder and feedstock was investigated. Two new agar based binder compositions were developed. The use of these new binder formulations significantly improved the volume fraction of the metal powder, the stability of the feedstock, and reduced the final shrinkage of the molded articles. Two types of 17-4PH stainless steel metal powders, one gas atomized and, the other water atomized, were used for this research.

Formulation of multiparticulate systems as lyophilised orally disintegrating tablets.

PubMed

Alhusban, Farhan; Perrie, Yvonne; Mohammed, Afzal R

2011-11-01

The current study aimed to exploit the electrostatic associative interaction between carrageenan and gelatin to optimise a formulation of lyophilised orally disintegrating tablets (ODTs) suitable for multiparticulate delivery. A central composite face centred (CCF) design was applied to study the influence of formulation variables (gelatin, carrageenan and alanine concentrations) on the crucial responses of the formulation (disintegration time, hardness, viscosity and pH). The disintegration time and viscosity were controlled by the associative interaction between gelatin and carrageenan upon hydration which forms a strong complex that increases the viscosity of the stock solution and forms tablet with higher resistant to disintegration in aqueous medium. Therefore, the levels of carrageenan, gelatin and their interaction in the formulation were the significant factors. In terms of hardness, increasing gelatin and alanine concentration was the most effective way to improve tablet hardness. Accordingly, optimum concentrations of these excipients were needed to find the best balance that fulfilled all formulation requirements. The revised model showed high degree of predictability and optimisation reliability and therefore was successful in developing an ODT formulation with optimised properties that were able deliver enteric coated multiparticulates of omeprazole without compromising their functionality. Copyright © 2011 Elsevier B.V. All rights reserved.

Rational design of viscosity reducing mutants of a monoclonal antibody: Hydrophobic versus electrostatic inter-molecular interactions

PubMed Central

Nichols, Pilarin; Li, Li; Kumar, Sandeep; Buck, Patrick M; Singh, Satish K; Goswami, Sumit; Balthazor, Bryan; Conley, Tami R; Sek, David; Allen, Martin J

2015-01-01

High viscosity of monoclonal antibody formulations at concentrations ≥100 mg/mL can impede their development as products suitable for subcutaneous delivery. The effects of hydrophobic and electrostatic intermolecular interactions on the solution behavior of MAB 1, which becomes unacceptably viscous at high concentrations, was studied by testing 5 single point mutants. The mutations were designed to reduce viscosity by disrupting either an aggregation prone region (APR), which also participates in 2 hydrophobic surface patches, or a negatively charged surface patch in the variable region. The disruption of an APR that lies at the interface of light and heavy chain variable domains, VH and VL, via L45K mutation destabilized MAB 1 and abolished antigen binding. However, mutation at the preceding residue (V44K), which also lies in the same APR, increased apparent solubility and reduced viscosity of MAB 1 without sacrificing antigen binding or thermal stability. Neutralizing the negatively charged surface patch (E59Y) also increased apparent solubility and reduced viscosity of MAB 1, but charge reversal at the same position (E59K/R) caused destabilization, decreased solubility and led to difficulties in sample manipulation that precluded their viscosity measurements at high concentrations. Both V44K and E59Y mutations showed similar increase in apparent solubility. However, the viscosity profile of E59Y was considerably better than that of the V44K, providing evidence that inter-molecular interactions in MAB 1 are electrostatically driven. In conclusion, neutralizing negatively charged surface patches may be more beneficial toward reducing viscosity of highly concentrated antibody solutions than charge reversal or aggregation prone motif disruption. PMID:25559441

Experimental study on the pressure and pulse wave propagation in viscoelastic vessel tubes-effects of liquid viscosity and tube stiffness.

PubMed

Ikenaga, Yuki; Nishi, Shohei; Komagata, Yuka; Saito, Masashi; Lagrée, Pierre-Yves; Asada, Takaaki; Matsukawa, Mami

2013-11-01

A pulse wave is the displacement wave which arises because of ejection of blood from the heart and reflection at vascular bed and distal point. The investigation of pressure waves leads to understanding the propagation characteristics of a pulse wave. To investigate the pulse wave behavior, an experimental study was performed using an artificial polymer tube and viscous liquid. A polyurethane tube and glycerin solution were used to simulate a blood vessel and blood, respectively. In the case of the 40 wt% glycerin solution, which corresponds to the viscosity of ordinary blood, the attenuation coefficient of a pressure wave in the tube decreased from 4.3 to 1.6 dB/m because of the tube stiffness (Young's modulus: 60 to 200 kPa). When the viscosity of liquid increased from approximately 4 to 10 mPa·s (the range of human blood viscosity) in the stiff tube, the attenuation coefficient of the pressure wave changed from 1.6 to 3.2 dB/m. The hardening of the blood vessel caused by aging and the increase of blood viscosity caused by illness possibly have opposite effects on the intravascular pressure wave. The effect of the viscosity of a liquid on the amplitude of a pressure wave was then considered using a phantom simulating human blood vessels. As a result, in the typical range of blood viscosity, the amplitude ratio of the waves obtained by the experiments with water and glycerin solution became 1:0.83. In comparison with clinical data, this value is much smaller than that seen from blood vessel hardening. Thus, it can be concluded that the blood viscosity seldom affects the attenuation of a pulse wave.

Rational design of viscosity reducing mutants of a monoclonal antibody: hydrophobic versus electrostatic inter-molecular interactions.

PubMed

Nichols, Pilarin; Li, Li; Kumar, Sandeep; Buck, Patrick M; Singh, Satish K; Goswami, Sumit; Balthazor, Bryan; Conley, Tami R; Sek, David; Allen, Martin J

2015-01-01

High viscosity of monoclonal antibody formulations at concentrations ≥100 mg/mL can impede their development as products suitable for subcutaneous delivery. The effects of hydrophobic and electrostatic intermolecular interactions on the solution behavior of MAB 1, which becomes unacceptably viscous at high concentrations, was studied by testing 5 single point mutants. The mutations were designed to reduce viscosity by disrupting either an aggregation prone region (APR), which also participates in 2 hydrophobic surface patches, or a negatively charged surface patch in the variable region. The disruption of an APR that lies at the interface of light and heavy chain variable domains, VH and VL, via L45K mutation destabilized MAB 1 and abolished antigen binding. However, mutation at the preceding residue (V44K), which also lies in the same APR, increased apparent solubility and reduced viscosity of MAB 1 without sacrificing antigen binding or thermal stability. Neutralizing the negatively charged surface patch (E59Y) also increased apparent solubility and reduced viscosity of MAB 1, but charge reversal at the same position (E59K/R) caused destabilization, decreased solubility and led to difficulties in sample manipulation that precluded their viscosity measurements at high concentrations. Both V44K and E59Y mutations showed similar increase in apparent solubility. However, the viscosity profile of E59Y was considerably better than that of the V44K, providing evidence that inter-molecular interactions in MAB 1 are electrostatically driven. In conclusion, neutralizing negatively charged surface patches may be more beneficial toward reducing viscosity of highly concentrated antibody solutions than charge reversal or aggregation prone motif disruption.

Reinventing Design Principles for Developing Low-Viscosity Carbon Dioxide-Binding Organic Liquids for Flue Gas Clean Up.

PubMed

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

2017-02-08

Anthropogenic CO 2 emissions from point sources (e.g., coal fired-power plants) account for the majority of the greenhouse gases in the atmosphere. Water-lean solvent systems such as CO 2 -binding organic liquids (CO 2 BOLs) are being developed to reduce the energy requirement for CO 2 capture. Many water-lean solvents such as CO 2 BOLs are currently limited by the high viscosities of concentrated electrolyte solvents, thus many of these solvents have yet to move toward commercialization. Conventional standard trial-and-error approaches for viscosity reduction, while effective, are time consuming and economically expensive. We rethink the metrics and design principles of low-viscosity CO 2 -capture solvents using a combined synthesis and computational modeling approach. We critically study the effects of viscosity reducing factors such as orientation of hydrogen bonding, introduction of higher degrees of freedom, and cation or anion charge solvation, and assess whether or how each factor affects viscosity of CO 2 BOL CO 2 capture solvents. Ultimately, we found that hydrogen bond orientation and strength is the predominant factor influencing the viscosity in CO 2 BOL solvents. With this knowledge, a new CO 2 BOL variant, 1-MEIPADM-2-BOL, was synthesized and tested, resulting in a solvent that is approximately 60 % less viscous at 25 mol % CO 2 loading than our base compound 1-IPADM-2-BOL. The insights gained from the current study redefine the fundamental concepts and understanding of what influences viscosity in concentrated organic CO 2 -capture solvents. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Processing effects in production of composite prepreg by hot melt impregnation

NASA Astrophysics Data System (ADS)

Chmielewski, C.; Jayaraman, K.; Petty, C. A.

1993-06-01

The hot melt impregnation process for producing composite prepreg has been studied. The role of the exit die is highlighted by operating without impregnation bars. Experimental results show that when a fiber tow is pulled through a resin bath and then through a wedge shaped die, the total resin mass fraction and the extent of resin impregnation in the tow increase with the processing viscosity. The penetration of resin into a fiber bundle is greater when the resin viscosity is higher. This trend is unchanged over a range of tow speeds up to the breaking point. A theoretical model is developed to describe the effect of processing conditions and die geometry on the degree of impregnation. Calculations with this model indicate that for a given die geometry, the degree of impregnation increases from 58 percent to 90 percent as the ratio of the clearance between the tow and the die wall, to the total die gap is decreased from 0.15 to 0.05. Physical arguments related to the effective viscosity of the prepreg show that the clearance ratio is independent of the tow speed, but decreases as the ratio of the effective shear viscosity of the prepreg to the resin viscosity increases. This provides a connection between the experimental results obtained with varying resin viscosity and the computational results obtained with varying clearance values at the die inlet.

The initial freezing point temperature of beef rises with the rise in pH: a short communication.

PubMed

Farouk, M M; Kemp, R M; Cartwright, S; North, M

2013-05-01

This study tested the hypothesis that the initial freezing point temperature of meat is affected by pH. Sixty four bovine M. longissimus thoracis et lumborum were classified into two ultimate pH groups: low (<5.8) and high pH (>6.2) and their cooling and freezing point temperatures were determined. The initial freezing temperatures for beef ranged from -0.9 to -1.5°C (∆=0.6°C) with the higher and lower temperatures associated with high and low ultimate pH respectively. There was a significant correlation (r=+0.73, P<0.01) between beef pH and freezing point temperature in the present study. The outcome of this study has implications for the meat industry where evidence of freezing (ice formation) in a shipment as a result of high pH meat could result in a container load of valuable chilled product being downgraded to a lower value frozen product. Copyright © 2013 Elsevier Ltd. All rights reserved.

A Simple Model for the Viscosity of Rhyolites as a Function of Temperature, Pressure and Water Content: Implications for Obsidian Flow Emplacement

NASA Astrophysics Data System (ADS)

Whittington, A. G.; Romine, W. L.

2014-12-01

Understanding the dynamics of rhyolitic conduits and lava flows, requires precise knowledge of how viscosity (η) varies with temperature (T), pressure (P) and volatile content (X). In order to address the paucity of viscosity data for high-silica rhyolite at low water contents, which represent water saturation at near-surface conditions, we made 245 viscosity measurements on Mono Craters (California) rhyolites containing between 0.01 and 1.1 wt.% H2O, at temperatures between 796 and 1774 K using parallel plate and concentric cylinder methods at atmospheric pressure. We then developed and calibrated a new empirical model for the log of the viscosity of rhyolitic melts, where non-linear variations due to temperature and water content are nested within a linear dependence of log η on P. The model was fitted to a total of 563 data points: our 245 new data, 255 published data from rhyolites across a wide P-T-X space, and 63 data on haplogranitic and granitic melts under high P-T conditions. Statistically insignificant parameters were eliminated from the model in an effort to increase parsimony and the final model is simple enough for use in numerical models of conduit or lava flow dynamics: log η = -5.142+(13080-2982log⁡(w+0.229))/(T-(98.9-175.9 log⁡(w+0.229)))- P(0.0007-0.76/T ) where η is in Pa s, w is water content in wt.%, P is in MPa and T is in K. The root mean square deviation (rmsd) between the model predictions and the 563 data points used in calibration is 0.39 log units. Experimental constraints have led previously to spurious correlations between P, T, X and η in viscosity data sets, so that predictive models may struggle to correctly resolve the individual effects of P, T and X, and especially their cross-correlations. The increasing water solubility with depth inside a simple isothermal sheet of obsidian suggests that viscosity should decrease by ~1 order of magnitude at ~20m depth and by ~2 orders of magnitude at ~100m depth. If equilibrium water contents are maintained, then deformation in spreading obsidian flows should be strongly partitioned into the deeper parts of the flow. Kinetically inhibited degassing, or recycling of degassed crust into a flow interior (e.g. by caterpillar-tread motion) could lead to strong lateral variations in viscosity within a flow, affecting flow evolution and morphology.

Properties of sugar-based low-melting mixtures

NASA Astrophysics Data System (ADS)

Fischer, Veronika; Kunz, Werner

2014-05-01

Physico-chemical properties of ternary sugar-based low-melting mixtures were determined. Choline chloride, urea and glucose or sorbitol, serving as sugars, were blended in various compositions. The refractive index, density, viscosity, decomposition temperatures and glass transition temperatures were measured. Further, the influence of temperature and water content was investigated. The results show that the mixtures are liquid below room temperature and the viscosity and density are dependent on the temperature and composition. Moreover, the viscosity decreases with increasing water content. These mixtures are biodegradable, low toxic, non-volatile, non-reactive with water and can be accomplished with low-cost materials. In consideration of these advantages and a melting point below room temperature, these low-melting mixtures can be a good alternative to ionic liquids as well as environmentally unfriendly and toxic solvents.

Complexation of sodium caseinate with gum tragacanth: Effect of various species and rheology of coacervates.

PubMed

Ghorbani Gorji, Sara; Ghorbani Gorji, Elham; Mohammadifar, Mohammad Amin; Zargaraan, Azizollaah

2014-06-01

We investigated complex coacervation of sodium caseinate/Astragalus rahensis (A.r) as a function of pH with light scattering, spectrophotometry, and viscosity measurements. Interestingly, sodium caseinate/A.r displayed five structural transitions; pH 7.00 to pH ∼5.40: no interaction occurred, pH ∼5.40 to pH ∼4.80: initiation of the formation of primary soluble complexes, pH ∼4.80 to ∼4.30: formation of interpolymer complexes, pH ∼4.30 to ∼4.02: optimum coacervation and pH ∼4.02 to ∼2.50: suppression of coacervation. In addition, rheological properties of sodium caseinate/A.r coacervates were studied at various pH values. A much higher storage modulus (G') than loss modulus (G″) for all sodium caseinate/A.r coacervates suggests the formation of highly interconnected gel-like network structures with mainly elastic behaviour. Moreover, sodium caseinate/A.r coacervates at all pH values exhibited a shear thinning behaviour across the entire shear rate range investigated. Effects of different species of gum tragacanth on the interactions with sodium caseinate have been scarcely studied. Our study showed that systems containing various species (A.r, soluble fraction of A.r and Astragalus gossypinus (A.g)) had different critical pH values and particle sizes during complex coacervation, which could be due to different ratio of soluble to insoluble fractions and uronic acid content of various species. Copyright © 2014 Elsevier B.V. All rights reserved.

Methyl ester of [Maclura pomifera (Rafin.) Schneider] seed oil: biodiesel production and characterization.

PubMed

Saloua, Fatnassi; Saber, Chatti; Hedi, Zarrouk

2010-05-01

Oil extracted from seeds of Maclura pomifera fruits grown in Tunisia was investigated as an alternative feedstock for the production of biodiesel fuel. Biodiesel was prepared by transesterification of the crude oil with methanol in the presence of NaOH as catalyst. Maximum oil to ester conversion was 90%. The viscosity of the biodiesel oil (4.66 cSt) is similar to that of petroleum diesel (2.5-3.5 cSt). The density (0.889 g/cm(3)), kinematic viscosity (4.66 cSt), flash point (180 degrees Celsius), iodine number (125 degrees Celsius), neutralization number (0.4), pour point (-9 degrees Celsius), cloud point (-5 degrees Celsius), cetane number (48) are very similar to the values set forth by the ASTM and EN biodiesel standards for petroleum diesel (No. 2). The comparison shows that the methyl esters of M. pomifera oil could be possible diesel fuel replacements. Copyright 2009 Elsevier Ltd. All rights reserved.

Changes of Properties of Bitumen Binders by Additives Application

NASA Astrophysics Data System (ADS)

Remišová, Eva; Holý, Michal

2017-10-01

Requirements for properties of bituminous binders are determined in the European standards. The physico-chemical behaviour of bitumen depends on its colloidal structure (asphaltenes dispersed into an oily matrix constituted by saturates, aromatics and resins) that depends primarily on its crude source and processing. Bitumen properties are evaluated by group composition, elementary analysis, but more often conventional or functional tests. Bitumen for road uses is assessed according to the physical characteristics. For the purpose of improving the qualitative properties of bitumen and asphalts the additives are applied e.g. to increase elasticity, improving the heat stability, improving adhesion to aggregate, to decrease viscosity, increasing the resistance to aging, to prevent binder drainage from the aggregate surface, etc. The objective of presented paper is to assess and compare effect of additives on properties of bitumen binders. In paper, the results of bitumen properties, penetration, softening point, and dynamic viscosity of two paving grade bitumen 35/50, 50/70 and polymer modified bitumen PmB 45/80-75 are analyzed and also the changes of these properties by the application of selected additives (Sasobit, Licomont BS100, Wetfix BE and CWM) to improve adhesion to aggregate and improve workability. Measurements of properties have been performed according to the relevant European standards. The laboratory tests showed significantly increasing the softening point of paving grade bitumen 50/70 and 35/50 by 13 to 45°C. The effect of various additives on bitumen softening point is different. Penetration varies according to type of bitumen and type of used additive. The penetration values of modified bitumen PmB 45/80-75 with additives Sasobit and Licomont BS100 show increase of bitumen stiffness of 16 0.1mm and a shift in the gradation. The changes in penetration and in softening point significantly shown when calculating on Penetration index as a parameter of temperature susceptibility. The additives changed the viscosity of bitumen to lower values mostly with modified bitumen. In case of the additive Wetfix BE mix in 35/50caused the viscosity increase. The additive changes the properties of original bituminous binders, and that can affect the properties of asphalt mixtures and asphalt layers.

For Stimul-Responsive Polymers with Enhanced Efficiency in Reservoir Recovery Processes

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

Charles McCormick; Roger Hester

Acrylamide-based hydrophobically modified (HM) polybetaines containing N-butylphenylacrylamide (BPAM) and varying amounts of either sulfobetaine (3-(2-acrylamido-2-methylpropanedimethylammonio)-1-propanesulfonate, AMPDAPS) or carboxybetaine (4-(2-acrylamido-2-methylpropyldimethylammonio) butanoate, AMPDAB) comonomers were synthesized via micellar copolymerization. The terpolymers were characterized via {sup 13}C NMR and UV spectroscopies, classical and dynamic light scattering, and potentiometric titration. The response of aqueous polymer solutions to various external stimuli, including changes in solution pH, electrolyte concentration, and the addition of small molecule surfactants, was investigated using surface tension and rheological measurements. Low charge density terpolymers were found to show greater viscosity enhancement upon the addition of surfactant compared to the high charge densitymore » terpolymers. The addition of sodium dodecyl sulfate (SDS) produced the largest maximum in solution viscosity, while N-dodecyl-N,N,N-trimethylammonium bromide (DTAB), N-dodecyl-N,N-dimethylammonio-1-propanesulfonate (SB3-12), and Triton X-100 tended to show reduced viscosity enhancement. In most cases, the high charge density carboxybetaine terpolymer exhibited diminished solution viscosities upon surfactant addition. In our last report, we discussed solution thermodynamic theory that described changes in polymer coil conformation as a function of solution temperature and polymer molecular weight. These polymers contained no ionic charges. In this report, we expand polymer solution theory to account for the electrostatic interactions present in solutions of charged polymers. Polymers with ionic charges are referred to as polyions or polyelectrolytes.« less

User`s guide for UTCHEM-5.32m a three dimensional chemical flood simulator. Final report, September 30, 1992--December 31, 1995

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

NONE

1996-07-01

UTCHEM is a three-dimensional chemical flooding simulator. The solution scheme is analogous to IMPES, where pressure is solved for implicitly, but concentrations rather than saturations are then solved for explicitly. Phase saturations and concentrations are then solved in a flash routine. An energy balance equation is solved explicitly for reservoir temperature. The energy balance equation includes heat flow between the reservoir and the over-and under-burden rocks. The major physical phenomena modeled in the simulator are: dispersion; dilution effects; adsorption; interfacial tension; relative permeability; capillary trapping; cation exchange; phase density; compositional phase viscosity; phase behavior (pseudoquaternary); aqueous reactions; partitioning of chemicalmore » species between oil and water; dissolution/precipitation; cation exchange reactions involving more than two cations; in-situ generation of surfactant from acidic crude oil; pH dependent adsorption; polymer properties: shear thinning viscosity; inaccessible pore volume; permeability reduction; adsorption; gel properties: viscosity; permeability reduction; adsorption; tracer properties: partitioning; adsorption; radioactive decay; reaction (ester hydrolization); temperature dependent properties: viscosity; tracer reaction; gel reactions The following options are available with UTCHEM: isothermal or non-isothermal conditions, a constant or variable time-step, constant pressure or constant rate well conditions, horizontal and vertical wells, and a radial or Cartesian geometry. Please refer to the dissertation {open_quotes}Field Scale Simulation of Chemical Flooding{close_quotes} by Naji Saad, August, 1989, for a more detailed discussion of the UTCHEM simulator and its formulation.« less

Relationship between blood viscosity and infarct size in patients with ST-segment elevation myocardial infarction undergoing primary percutaneous coronary intervention.

PubMed

Cecchi, Emanuele; Liotta, Agatina Alessandriello; Gori, Anna Maria; Valente, Serafina; Giglioli, Cristina; Lazzeri, Chiara; Sofi, Francesco; Gensini, Gian Franco; Abbate, Rosanna; Mannini, Lucia

2009-05-15

Previous studies explored the association between hemorheological alterations and acute myocardial infarction, pointing out the role of hematological components on microvascular flow. The aim of this study was to evaluate the association between blood viscosity and infarct size, estimated by creatine kinase (CK) peak activity and cardiac Troponin I (cTnI) peak concentration in ST-segment elevation myocardial infarction (STEMI) patients after primary percutaneous coronary intervention (PCI). The study population included 197 patients with diagnosis of STEMI undergoing PCI. Hemorheological studies were performed by assessing whole blood viscosity (measured at shear rates of 0.512 s(-1) and 94.5 s(-1)) and plasma viscosity using the Rotational Viscosimeter LS 30 and erythrocyte deformability index by Myrenne filtrometer. Significant correlations between CK peak activity, cTnI peak concentration, left ventricular ejection fraction and hemorheological variables were observed. At linear regression analysis (adjusted for age, gender, traditional cardiovascular risk factors, renal dysfunction, timeliness of reperfusion, pre-PCI TIMI flow, infarct location, multivessel disease and previous coronary artery disease) leukocytes and whole blood viscosity at 0.512 s(-1) and 94.5 s(-1) were independently and positively associated with infarct size. These results demonstrate a significant and independent association between hemorheology and infarct size in STEMI patients after PCI suggesting that blood viscosity, in a condition of low flow, might worsen myocardial perfusion leading to an increased infarct size. The measurement of whole blood viscosity in STEMI patients could help to identify those who may benefit from new therapeutic strategies.

Viscous driving of global oscillations in accretion discs around black holes

NASA Astrophysics Data System (ADS)

Miranda, Ryan; Horák, Jiří; Lai, Dong

2015-01-01

We examine the role played by viscosity in the excitation of global oscillation modes (both axisymmetric and non-axisymmetric) in accretion discs around black holes using two-dimensional hydrodynamic simulations. The turbulent viscosity is modelled by the α-ansatz, with different equations of state. We consider both discs with transonic radial inflows across the innermost stable circular orbit, and stationary discs truncated by a reflecting wall at their inner edge, representing a magnetosphere. In transonic discs, viscosity can excite several types of global oscillation modes. These modes are either axisymmetric with frequencies close to multiples of the maximum radial epicyclic frequency κmax, non-axisymmetric with frequencies close to multiples of the innermost stable orbit frequency ΩISCO, or hybrid modes whose frequencies are linear combinations of these two frequencies. Small values of the viscosity parameter α primarily produce non-axisymmetric modes, while axisymmetric modes become dominant for large α. The excitation of these modes may be related to an instability of the sonic point, at which the radial infall speed is equal to the sound speed of the gas. In discs with a reflective inner boundary, we explore the effect of viscosity on trapped p modes which are intrinsically overstable due to the corotation resonance effect. The effect of viscosity is either to reduce the growth rates of these modes, or to completely suppress them and excite a new class of higher frequency modes. The latter requires that the dynamic viscosity scales positively with the disc surface density, indicating that it is a result of the classic viscous overstability effect.

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

PubMed Central

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

2016-01-01

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

Adequacy of human milk viscosity to respond to infants with dysphagia: experimental study

PubMed Central

de ALMEIDA, Mariangela Bartha de Mattos; de ALMEIDA, João Aprígio Guerra; MOREIRA, Maria Elisabeth Lopes; NOVAK, Franz Reis

2011-01-01

Neonatal nutrition is an important subject in health in the short, medium and long term. In preterm newborns, nutrition assumes a predominant role for the child's overall development. Babies with uncoordinated swallowing or respiration may not have the necessary oral abilities to suck the mother's breast and will need to implement different feeding practices; one of them is changing the consistency of the milk offered. Objectives Determine viscosity variations of untreated human and pasteurized milk without and with thickening to adapt the diet to the needs of dysphagic infants hospitalized in the Neonatal Intensive Cara Unit (NICU). Material and Methods The authors altered the viscosity of natural infant powdered milk and, after thickening, determined and adopted a thickening standard for human milk. Untreated human and pasteurized milk was thickened in concentrations of 2%, 3%, 5% and 7% and the viscosity were determined every 20 minutes for a period of 60 minutes at a temperature of 37ºC. Results The infant lactose formula thickened at concentrations of 2% and 3% produced viscosities of 8.97cP and 27.73 cP, respectively. The increases were significantly different after 1 hour. Inversely, untreated human milk at 2%, 3%, 5% and 7% produced diminished viscosity over time; the changes were more accentuated in the first 20 minutes. In pasteurized human milk, the 2% concentration had no variation in viscosity, but with the 3%, 5% and 7% concentrations, there was a significant decrease in the first 20 minutes with stability observed in the subsequent times. Conclusion In powdered milk, the viscosity increases over time; the viscosity in human milk diminishes. The results point out the importance not only of considering the concentration of the thickener but also the time being administered after its addition to effectively treat dysphagic infants. PMID:22230987

Comparative study of acetazolamide and spironolactone on body fluid compartments on induction to high altitude

NASA Astrophysics Data System (ADS)

Singh, M. V.; Jain, S. C.; Rawal, S. B.; Divekar, H. M.; Parshad, Rajinder; Tyagi, A. K.; Sinha, K. C.

1986-03-01

Studies were conducted on 29 male healthy subjects having no previous experience of living at high altitude. These subjects were divided into three groups, i.e., subjects treated with placebo, acetazolamide and spironolactone. These subjects were first studied in Delhi. The drug schedule was started 24 hour prior to the airlift of these subjects to an altitude of 3,500 m and was continued for 48 hour after arrival at high altitude. Total body water, extra cellular water, plasma volume, blood electrolytes, pH, pO2, pCO2 and blood viscosity were determined on 3rd and 12th day of their stay at high altitude. Total body water, extra cellular water intracellular water and plasma volume decreased on high altitude exposure. There was a further slight decrease in these compartments with acetazolamide and spironolactone. It was also observed that spironolactone drives out more water from the extracellular compartment. Loss of plasma water was also confirmed by increased plasma osmolality. Increase in arterial blood pH was noticed on hypoxic exposure but the increase was found less in acetazolamide and spironolactone cases. This decrease in pH is expected to result in better oxygen delivery to the tissues at the low oxygen tension. It was also confirmed because blood pO2 increased in both the groups. No significant change in plasma electrolytes was observed in subjects of various groups. Blood viscosity slightly increased on exposure to high altitude. The degree of rise was found less in the group treated with spironolactone. This study suggests that both the drugs are likely to be beneficial in ameliorating/prevention of AMS syndrome.

Ozone treatment of shell eggs to preserve functional quality and enhance shelf life during storage.

PubMed

Yüceer, Muhammed; Aday, Mehmet Seçkin; Caner, Cengiz

2016-06-01

Eggs have long been recognised as a source of high-quality proteins. Many methods exist to extend shelf life of food and one of them is ozone treatment, which is an emerging technology for disinfecting surfaces in the food industry. This study aimed to extend the shelf life of fresh eggs using gaseous ozone treatments at concentrations of 2, 4 and 6 ppm with exposure times of 2 and 5 min during storage for 6 weeks at 24 °C. The effect of the treatments on interior quality and functional properties of eggs is also reported. Ozone concentration and exposure time significantly affected the Haugh unit (HU), yolk index, albumen pH, relative whipping capacity (RWC), and albumen viscosity of eggs during the storage. Control eggs had the highest albumen pH and lowest albumen viscosity. Attributes such as albumen pH and RWC of eggs exposed to ozone treatments were better than the control samples. The measurement results showed that ozone concentration at 6 ppm and exposure time of 5 min can be applied to fresh eggs and extend shelf life up to 6 weeks at 24 °C storage period. Ozone treatments helped to maintain egg quality for a longer time. Ozone concentrations at 2 and 4 ppm showed promising results in maintaining internal quality and functional properties of fresh eggs during storage. Ozone at high concentration (6 ppm) caused a detrimental effect on eggshell quality. As a result, this study demonstrated that ozone treatments of 2, and especially 4 and 6 ppm concentration maintained eggshell quality during the storage. © 2015 Society of Chemical Industry. © 2015 Society of Chemical Industry.

Optimization of replacing pork back fat with grape seed oil and rice bran fiber for reduced-fat meat emulsion systems.

PubMed

Choi, Yun-Sang; Choi, Ji-Hun; Han, Doo-Jeong; Kim, Hack-Youn; Lee, Mi-Ai; Kim, Hyun-Wook; Lee, Ju-Woon; Chung, Hai-Jung; Kim, Cheon-Jei

2010-01-01

The effects of reducing pork fat levels from 30% to 20% and partially substituting the pork fat with a mix of grape seed oil (0%, 5%, 10% and 15%) and 2% rice bran fiber were investigated based on chemical composition, cooking characteristics, physicochemical and textural properties, and viscosity of reduced-fat meat batters. For reduced-fat meat batters containing grape seed oil and rice bran fiber the moisture and ash contents, uncooked and cooked pH values, yellowness, cohesiveness, gumminess, chewiness, and sarcoplasmic protein solubility were higher than in the control samples. The reduced-fat samples with increasing grape seed oil concentrations had lower cooking loss, emulsion stability, and apparent viscosity. The incorporation of grape seed oil and rice bran fiber successfully reduced the animal fat content in the final products while improving other characteristics.

Particle size and interfacial effects on heat transfer characteristics of water and {alpha}-SiC nanofluids.

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

Timofeeva, E.; Smith, D. S.; Yu, W.

2010-01-01

The effect of average particle sizes on basic macroscopic properties and heat transfer performance of {alpha}-SiC/water nanofluids was investigated. The average particle sizes, calculated from the specific surface area of nanoparticles, were varied from 16 to 90 nm. Nanofluids with larger particles of the same material and volume concentration provide higher thermal conductivity and lower viscosity increases than those with smaller particles because of the smaller solid/liquid interfacial area of larger particles. It was also demonstrated that the viscosity of water-based nanofluids can be significantly decreased by pH of the suspension independently from the thermal conductivity. Heat transfer coefficients weremore » measured and compared to the performance of base fluids as well as to nanofluids reported in the literature. Criteria for evaluation of the heat transfer performance of nanofluids are discussed and optimum directions in nanofluid development are suggested.« less

Internal Waves in CVX

NASA Technical Reports Server (NTRS)

Berg, Robert F.

1996-01-01

Near the liquid-vapor critical point, density stratification supports internal gravity waves which affect 1-g viscosity measurements in the CVX (Critical Viscosity of Xenon) experiment. Two internal-wave modes were seen in the horizontal viscometer. The frequencies of the two modes had different temperature dependences: with decreasing temperature, the higher frequency increased monotonically from 0.7 to 2.8 Hz, but the lower frequency varied non-monotonically, with a maximum of 1.0 Hz at 20 mK above the critical temperature. The measured frequencies agree with independently calculated frequencies to within 15%.

Critical Viscosity of Xenon team

NASA Technical Reports Server (NTRS)

2001-01-01

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. The thermostat for CVX sits inside the white cylinder on a support structure (at left) that is placed inside a pressure canister. A similar canister (right) holds the electronics and control systems. The CVX-2 arrangement is identical. The principal investigator is Dr. Robert F. Berg (left) of the National Institutes of Standards and Technology, Gaithersburg, MD.

Critical Viscosity of Xenon team

NASA Technical Reports Server (NTRS)

2001-01-01

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. The thermostat for CVX sits inside the white cylinder on a support structure (at left) that is placed inside a pressure canister. A similar canister (right) holds the electronics and control systems. The CVX-2 arrangement is identical. The principal investigator is Dr. Robert F. Berg (not shown) of the National Institutes of Standards and Technology, Gaithersburg, MD.

Viscosity and thermal conductivity coefficients of gaseous and liquid oxygen

NASA Technical Reports Server (NTRS)

Hanley, H. J. M.; Mccarty, R. D.; Sengers, J. V.

1974-01-01

Equations and tables are presented for the viscosity and thermal conductivity coefficients of gaseous and liquid oxygen at temperatures between 80 K and 400 K for pressures up to 200 atm. and at temperatures between 80 K and 2000 K for the dilute gas. A description of the anomalous behavior of the thermal conductivity in the critical region is included. The tabulated coefficients are reliable to within about 15% except for a region in the immediate vicinity of the critical point. Some possibilities for future improvements of this reliability are discussed.

40 CFR 414.101 - Toxic pollutant effluent limitations and standards for direct discharge point sources that do not...

Code of Federal Regulations, 2011 CFR

2011-07-01

... GUIDELINES AND STANDARDS ORGANIC CHEMICALS, PLASTICS, AND SYNTHETIC FIBERS Direct Discharge Point Sources...(k)fluoranthene 47 19 Benzo(a)pyrene 48 20 Bis(2-ethylhexyl) phthalate 258 95 Carbon Tetrachloride... micrograms per liter. 2 Total Zinc for Rayon Fiber Manufacture that uses the viscose process and Acrylic...

40 CFR 414.101 - Toxic pollutant effluent limitations and standards for direct discharge point sources that do not...

Code of Federal Regulations, 2010 CFR

2010-07-01

... GUIDELINES AND STANDARDS ORGANIC CHEMICALS, PLASTICS, AND SYNTHETIC FIBERS Direct Discharge Point Sources...(k)fluoranthene 47 19 Benzo(a)pyrene 48 20 Bis(2-ethylhexyl) phthalate 258 95 Carbon Tetrachloride... micrograms per liter. 2 Total Zinc for Rayon Fiber Manufacture that uses the viscose process and Acrylic...

Fluid property measurements study

NASA Technical Reports Server (NTRS)

Devaney, W. E.

1976-01-01

Fluid properties of refrigerant-21 were investigated at temperatures from the freezing point to 423 Kelvin and at pressures to 1.38 x 10 to the 8th power N/sq m (20,000 psia). The fluid properties included were: density, vapor pressure, viscosity, specific heat, thermal conductivity, thermal expansion coefficient, freezing point and bulk modulus. Tables of smooth values are reported.

Cupuassu (Theobroma grandiflorum) pulp, probiotic, and prebiotic: Influence on color, apparent viscosity, and texture of goat milk yogurts.

PubMed

Costa, Marion P; Frasao, Beatriz S; Silva, Adriana Cristina O; Freitas, Mônica Q; Franco, Robson M; Conte-Junior, Carlos A

2015-09-01

Cupuassu is an acidic fruit that has a characteristic aroma, flavor, and texture; its fiber-rich pulp can provide a different consistency than other fruit pulps. Goat milk is an excellent source of amino acids, fatty acids, and minerals, and is widely used for processing fermented milks, such as yogurt. However, compared with cow milk yogurts, it is difficult to make goat milk yogurts with a good consistency. Therefore, it is necessary to use certain technological strategies. This study was carried out to investigate the possibility of adding cupuassu pulp, probiotic (Lactobacillus acidophilus LA-5), and prebiotic (inulin) to improve the texture of goat milk yogurt. A total of 6 treatments were performed: natural (N), probiotic (Pro), prebiotic (Pre), synbiotic (S), cupuassu (C), and probiotic with cupuassu (PC). The viability of probiotic in yogurts (Pro, S, and PC) was evaluated. In addition, instrumental analyses (pH, color, apparent viscosity, and texture) were performed to evaluate the influence of these different ingredients on goat milk yogurts. The probiotic bacteria remained viable (≥7 log cfu·mL(-1)) throughout the 28d of refrigerated storage, which exceeded the minimum count required to confer probiotic physiological benefits. The pH levels of the yogurts inoculated with L. acidophilus (Pro, S, and PC) were lower than others yogurts (N, Pre, and C). However, all yogurt samples underwent gradual decreases in pH until 7 to 14d of storage. The lightness (L*) was affected initially by addition of all ingredients (cupuassu pulp, probiotic, and prebiotic). The addition of cupuassu pulp (C and PC) increased the L* during the period of storage. Apparent viscosity and firmness decreased in the PC yogurt. The consistency was highest in the yogurts with added prebiotic (Pre and S) than the other yogurts (N, Pro, C, and PC) at the end of the storage period (d 28). The cohesiveness remained constant in all yogurts (N, Pro, Pre, S, C, and PC). Based on the results obtained from the current study, it was concluded that cupuassu pulp addition improves the texture of goat milk yogurts. Therefore, this pulp could be an important technological strategy for the dairy goat industry. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

The Concept of Solid Solvent as Processing Aid.

DTIC Science & Technology

1984-09-20

3 presents the DSC results of acetanilide . Acetanilide shows a sharp melting peak at 116C, very close to the melting point (Tm) reported by Fisher...should become compatible with a polymer and act as a solvent in the liquid state above its melting point , significantly reducing the viscosity of the...polymer, but should become incompatible and crystallize out of the polymer as discrete domains below its melting point without adversely affecting

Chemical analyses of geothermal waters from a South Louisiana well

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

Hankins, B.E.; Chavanne, R.E.; Ham, R.A.

1977-11-16

The abandoned Edna Delcambre No. 1 gas well, about 8 miles south of Delcambre, Louisiana was reopened and bottom-hole and flowing samples were collected. McNeese State University was responsible for the analyses of the products of the well. Typical values from the analyses are shown for such quantities as: pH, turbidity, conductance, density, total dissolved solids, hardness, viscosity, dissolved silicates, chlorides, bicarbonates, etc. Some observations on these values are made. (MHR)

Evaluation of an Interdigitated Gate Electrode Field-Effect Transistor (IGEFET) for In Situ Resin Cure Monitoring

DTIC Science & Technology

1991-12-01

School of Engineering, Air Force Institute of Technology, Wright-Patterson AFB OH, October 1988. 8. Billmeyer, Fred W., Jr. Textbook of Polymer Science...448-453 (April 1989). 10. Sheppard, Norman Fred , Jr. Dielectric Analysis of the Cure of Thermosetting Epoxy/Amine Systems. PhD Dissertation...Viscosity and Chemical Changes During Polymerization," American Chemical Society Symposium Series on Photophysics of Polymers, edited by C. E. Hoyle and J. M

Shear viscosity in monatomic liquids: a simple mode-coupling approach

NASA Astrophysics Data System (ADS)

Balucani, Umberto

The value of the shear-viscosity coefficient in fluids is controlled by the dynamical processes affecting the time decay of the associated Green-Kubo integrand, the stress autocorrelation function (SACF). These processes are investigated in monatomic liquids by means of a microscopic approach with a minimum use of phenomenological assumptions. In particular, mode-coupling effects (responsible for the presence in the SACF of a long-lasting 'tail') are accounted for by a simplified approach where the only requirement is knowledge of the structural properties. The theory readily yields quantitative predictions in its domain of validity, which comprises ordinary and moderately supercooled 'simple' liquids. The framework is applied to liquid Ar and Rb near their melting points, and quite satisfactory agreement with the simulation data is found for both the details of the SACF and the value of the shear-viscosity coefficient.

Anatomy of a laminar starting thermal plume at high Prandtl number

NASA Astrophysics Data System (ADS)

Davaille, Anne; Limare, Angela; Touitou, Floriane; Kumagai, Ichiro; Vatteville, Judith

2011-02-01

We present an experimental study of the dynamics of a plume generated from a small heat source in a high Prandtl number fluid with a strongly temperature-dependent viscosity. The velocity field was determined with particle image velocimetry, while the temperature field was measured using differential interferometry and thermochromic liquid crystals. The combination of these different techniques run simultaneously allows us to identify the different stages of plume development, and to compare the positions of key-features of the velocity field (centers of rotation, maximum vorticity locations, stagnation points) respective to the plume thermal anomaly, for Prandtl numbers greater than 103. We further show that the thermal structure of the plume stem is well predicted by the constant viscosity model of Batchelor (Q J R Met Soc 80: 339-358, 1954) for viscosity ratios up to 50.

The effect of viscosity on steady transonic flow with a nodal solution topology

NASA Technical Reports Server (NTRS)

Owocki, Stanley P.; Zank, Gary P.

1991-01-01

The effect of viscosity on a steady, transonic flow for which the inviscid limit has a nodal solution topology near the critical point is investigated. For the accelerating case, viscous solutions tend to repel each other, so that a very delicate choice of initial conditions is required to prevent them from diverging. Only the two critical solutions extend to arbitrarily large distances into both the subsonic and supersonic flows. For the decelerating case, the solutions tend to attract, and so an entire two-parameter family of solutions now extends over large distances. The general effect of viscosity on the solution degeneracy of a nodal topology is thus to reduce or limit it for the accelerating case and to enhance it for the decelerating case. The astrophysical implications of these findings are addressed.

Microbial spoilage, instability risk of antacid suspension in the presence of commonly used preservative system.

PubMed

Khan, Jamshaid Ali; Khan, Imran Ullah; Iqbal, Zafar; Nasir, Fazli; Muhammad, Salar; Hannan, Peer Abdul; Ullah, Irfan

2015-09-01

Manifestation of microbial spoilage of any product by bacteria and to assess the effectiveness of the anti-microbial preservatives (parabens) used for the prevention and stability purpose. The aim of the present work is to study the effectiveness of preservatives used in the antacid suspensions and to analyze the effect of microbial growth on the quality of respective antacid suspensions. Samples of various antacid suspensions were randomly collected from local market and Government hospital pharmacies. Three different antacid formulations were prepared in the laboratory. All the formulations were preliminarily evaluated on the basis of organoleptic characteristics, pH, viscosity and assay. Efficacy of the preservative system in suspension formulation was determined by inoculating the samples in its final container, with specific strains of bacteria i.e. Escherichia coli ATCC 8739, Pseudomonas aeruginosa ATCC 9027 and Staphylococcus aureus ATCC 6538, taking samples from the inoculated preparation at specified intervals of time i.e. 0 time, 07 days, 14 days and 28 days, growing it on nutrient agar medium and colony forming units (CFUs) were scored by plate count. At the same time the samples were also subjected to qualitative and quantitative testing. The decrease in CFU and alteration in assay, pH and viscosity was observed in all the formulations except formulation M2 and F3 that showed stability throughout the study period.

Preparation and in vitro evaluation of a pluronic lecithin organogel containing ricinoleic acid for transdermal delivery.

PubMed

Boddu, Sai Hs; Bonam, Sindhu Prabha; Wei, Yangjie; Alexander, Kenneth

2014-01-01

The present study deals with the preparation and in vitro evaluation of a Pluronic lecithin organogel gel containing ricinoleic acid for transdermal delivery. Blank Pluronic lecithin organogel gels were prepared using ricinoleic acid as the oil phase and characterized for pH, viscosity, gelation temperature, and microscopic structure. The optimized Pluronic lecithin organogel gel formulation was further evaluated using ketoprofen (10%) and dexamethasone (0.5%) as model drugs. The stability and in vitro permeability of ketoprofen and dexamethasone was evaluated and compared with the corresponding control formulation (Pluronic lecithin organogel gel made with isopropyl palmitate as the oil phase). The pH and viscosity of blank Pluronic lecithin organogel gel prepared with ricinoleic acid was comparable with the isopropyl palmitate Pluronic lecithin organogel gel. The thixotropic property of ricinoleic acid Pluronic lecithin organogel gel was found to be better than the control. Drug-loaded Pluronic lecithin organogel gels behaved in a similar manner and all formulations were found to be stable at 25 degrees C, 35 degrees C, and 40 degrees C for up to 35 days. The penetration profile of dexamethasone was similar from both the Pluronic lecithin organogel gels, while the permeability for ketoprofen from Pluronic lecithin organogel gel containing ricinoleic acid was found to be three times higher as compared to the control formulation.

Germination conditions affect physicochemical properties of germinated brown rice flour.

PubMed

Charoenthaikij, Phantipha; Jangchud, Kamolwan; Jangchud, Anuvat; Piyachomkwan, Kuakoon; Tungtrakul, Patcharee; Prinyawiwatkul, Witoon

2009-01-01

Germinated brown rice has been reported to be nutritious due to increased free gamma-aminobutyric acid (GABA). The physicochemical properties of brown rice (BR) and glutinous brown rice (GNBR) after germination as affected by different steeping times (24, 36, 48, and 72 h depending on the rice variety) and pHs of steeping water (3, 5, 7, and as-is) were determined and compared to those of the nongerminated one (control). As the steeping time increased or pH of steeping water decreased, germinated brown rice flours (GBRF) from both BR and GNBR had greater reducing sugar, free GABA and alpha-amylase activity; while the total starch and viscosity were lower than their respective controls. GBRFs from both BR and GNBR prepared after 24-h steeping time at pH 3 contained a high content of free GABA at 32.70 and 30.69 mg/100 g flour, respectively. The peak viscosity of GBRF obtained from both BR and GNBR (7.42 to 228.22 and 4.42 to 58.67 RVU, respectively) was significantly lower than that of their controls (255.46 and 190.17 RVU, respectively). The principal component analysis indicated that the important variables for discriminating among GBRFs, explained by the first 2 components at 89.82% of total explained variance, were the pasting profiles, alpha-amylase activity, and free GABA.

Nanostructured DPA-MPC-DPA triblock copolymer gel for controlled drug release of ketoprofen and spironolactone.

PubMed

Azmy, Bahaa; Standen, Guy; Kristova, Petra; Flint, Andrew; Lewis, Andrew L; Salvage, Jonathan P

2017-08-01

Uncontrolled rapid release of drugs can reduce their therapeutic efficacy and cause undesirable toxicity; however, controlled release from reservoir materials helps overcome this issue. The aims of this study were to determine the release profiles of ketoprofen and spironolactone from a pH-responsive self-assembling DPA-MPC-DPA triblock copolymer gel and elucidate underlying physiochemical properties. Drug release profiles from DPA 50 -MPC 250 -DPA 50 gel (pH 7.5), over 32 h (37 °C), were determined using UV-Vis spectroscopy. Nanoparticle size was measured by dynamic light scattering (DLS) and critical micelle concentration (CMC) by pyrene fluorescence. Polymer gel viscosity was examined via rheology, nanoparticle morphology investigated using scanning transmission electron microscopy (STEM) and the gel matrix observed using cryo-scanning electron microscopy (Cryo-SEM). DPA 50 -MPC 250 -DPA 50 copolymer (15% w/v) formed a free-standing gel (pH 7.5) that controlled drug release relative to free drugs. The copolymer possessed a low CMC, nanoparticle size increased with copolymer concentration, and DLS data were consistent with STEM. The gel displayed thermostable viscosity at physiological temperatures, and the gel matrix was a nanostructured aggregation of smaller nanoparticles. The DPA 50 -MPC 250 -DPA 50 copolymer gel could be used as a drug delivery system to provide the controlled drug release of ketoprofen and spironolactone. © 2017 Royal Pharmaceutical Society.

Rock inhabiting potassium solubilizing bacteria from Kerala, India: characterization and possibility in chemical K fertilizer substitution.

PubMed

Anjanadevi, Indira Parameswaran; John, Neetha Soma; John, Kuzhivilayil Susan; Jeeva, Muthulekshmi Lajapathy; Misra, Raj Shekhar

2016-01-01

The role of rock inhabiting bacteria in potassium (K) solubilization from feldspar and their application in crop nutrition through substitution of fertilizer K was explored through the isolation of 36 different bacteria from rocks of a major hill station at Ponmudi in Thiruvananthapuram, Kerala, India. A comprehensive characterization of K solubilization from feldspar was achieved with these isolates which indicated that the K solubilizing efficiency increases with decrease in pH and increase in viscosity and viable cell count. Based on the level of K solubilization, two potent isolates were selected and identified as Bacillus subtilis ANctcri3 and Bacillus megaterium ANctcri7. Exopolysaccharide production, scanning electron microscopic and fourier transform infrared spectroscopic studies with these efficient strains conclusively depicted the role of low pH, increase in viscosity, and bacterial attachment in K solubilization. They were also found to be efficient in phosphorus (P) solubilization, indole acetic acid production as well as tolerant to wide range of physiological conditions. Moreover, the applicability of K containing rock powder as a carrier for K solubilizing bacteria was demonstrated. A field level evaluation on the yield of a high K demanding tuberous vegetable crop, elephant foot yam (Amorphophallus paeoniifolius (dennst.) nicolson) established the possibility of substituting chemical K fertilizer with these biofertilizer candidates successfully. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Formulation and Characterization of Aceclofenac -Aloe vera Transemulgel.

PubMed

Raju, Y Prasanna; Haritha, K; Satyanarayana, Rao P; Vandana, K R; Bindu, D Thushara; Vinesha, V; Chowdary, V Harini

2015-01-01

The present research was aimed to formulate aceclofenac transemulgel using Aloe vera as gel base. The prepared formulations were subjected to physical characterization, in-vitro and in-vivo assessment. Aceclofenac, a hydrophobic potential non steroidal anti inflammatory drug, causes ulceration upon chronic oral administration, could be formulated into transemulgel to enhance therapeutic efficacy and to lower the unwanted side effects. The transemulgel was prepared from aqueous Aloe vera gel and aceclofenac emulsion. The prepared transemulgel was evaluated for its pH, viscosity, drug content, skin irritation, in-vitro diffusion and accelerated stability studies. The prepared aceclofenac-Aloe vera tranemulgel and commercial aceclofenac gel were subjected to pharmacodynamic studies in albino rats of Wistar strain employing carrageenan induced left hind paw edema method to assess the anti-inflammatory effect. The transemulgel showed a pH of 6.78 and viscosity of 18 cps. In-vitro diffusion data revealed better permeation characteristics. Topical application of formulation found no skin irritation. Stability study has proved the integrity of the formulation. The prepared aceclofenac Aloe vera transemulgel showed better in-vitro drug release when compared with the commercial aceclofenac gel formulation. Anti-inflammatory activity in treated rats showed the significant paw volume reduction at p<0.05 compared with that of control. Thus, it is concluded that aceclofenac, a potential non steroidal anti inflammatory drug, showed high therapeutic efficiency when formulated into transemulgel using aqueous Aloe vera as gel base.

Understanding and modulating opalescence and viscosity in a monoclonal antibody formulation

PubMed Central

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

2014-01-01

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

Total internal reflection and dynamic light scattering microscopy of gels

NASA Astrophysics Data System (ADS)

Gregor, Brian F.

Two different techniques which apply optical microscopy in novel ways to the study of biological systems and materials were built and applied to several samples. The first is a system for adapting the well-known technique of dynamic light scattering (DLS) to an optical microscope. This can detect and scatter light from very small volumes, as compared to standard DLS which studies light scattering from volumes 1000x larger. The small scattering volume also allows for the observation of nonergodic dynamics in appropriate samples. Porcine gastric mucin (PGM) forms a gel at low pH which lines the epithelial cell layer and acts as a protective barrier against the acidic stomach environment. The dynamics and microscopic viscosity of PGM at different pH levels is studied using polystyrene microspheres as tracer particles. The microscopic viscosity and microrheological properties of the commercial basement membrane Matrigel are also studied with this instrument. Matrigel is frequently used to culture cells and its properties remain poorly determined. Well-characterized and purely synthetic Matrigel substitutes will need to have the correct rheological and morphological characteristics. The second instrument designed and built is a microscope which uses an interferometry technique to achieve an improvement in resolution 2.5x better in one dimension than the Abbe diffraction limit. The technique is based upon the interference of the evanescent field generated on the surface of a prism by a laser in a total internal reflection geometry. The enhanced resolution is demonstrated with fluorescent samples. Additionally. Raman imaging microscopy is demonstrated using the evanescent field in resonant and non-resonant samples, although attempts at applying the enhanced resolution technique to the Raman images were ultimately unsuccessful. Applications of this instrument include high resolution imaging of cell membranes and macroscopic structures in gels and proteins. Finally, a third section incorporating previous research on simulations of complex fluids is included. Two dimensional simulations of oil, water, and surfactant mixtures were computed with a lattice gas method. The simulated systems were randomly mixed and then the temperature was quenched to a predetermined point. Spontaneous micellization is observed for a narrow range of temperature quenches, and the overall growth rate of macroscopic structure is found to follow a Vogel-Fulcher growth law.

Topological Ordering and Viscosity in the Glassy Ge-Se System: The Search for a Structural or Dynamical Signature of the Intermediate Phase

NASA Astrophysics Data System (ADS)

Zeidler, Anita; Salmon, Philip S.; Whittaker, Dean A. J.; Pizzey, Keiron J.; Hannon, Alex C.

2017-11-01

The topological ordering of the network structure in vitreous Ge_xSe_{1-x} was investigated across most of the glass-forming region (0 ≤ x ≤ 0.4) by using high-resolution neutron diffraction to measure the Bhatia-Thornton number-number partial structure factor. This approach gives access to the composition dependence of the mean coordination number \\bar{n} and correlation lengths associated with the network ordering. The thermal properties of the samples were also measured by using temperature-modulated differential scanning calorimetry. The results do not point to a structural origin of the so-called intermediate phase, which in our work is indicated for the composition range 0.175(8) ≤ x ≤ 0.235(8) by a vanishingly-small non-reversing enthalpy near the glass transition. The midpoint of this range coincides with the mean-field expectation of a floppy-to-rigid transition at x = 0.20. The composition dependence of the liquid viscosity, as taken from the literature, was also investigated to look for a dynamical origin of the intermediate phase, using the Mauro-Yue-Ellison-Gupta-Allan (MYEGA) model to estimate the viscosity at the liquidus temperature. The evidence points to a maximum in the viscosity at the liquidus temperature, and a minimum in the fragility index, for the range 0.20 ≤ x ≤ 0.22. The utility of the intermediate phase as a predictor of the material properties in network glass-forming systems is discussed.

A compositional tipping point governing the mobilization and eruption style of rhyolitic magma

NASA Astrophysics Data System (ADS)

di Genova, D.; Kolzenburg, S.; Wiesmaier, S.; Dallanave, E.; Neuville, D. R.; Hess, K. U.; Dingwell, D. B.

2017-12-01

The most viscous volcanic melts and the largest explosive eruptions on our planet consist of calcalkaline rhyolites. These eruptions have the potential to influence global climate. The eruptive products are commonly very crystal-poor and highly degassed, yet the magma is mostly stored as crystal mushes containing small amounts of interstitial melt with elevated water content. It is unclear how magma mushes are mobilized to create large batches of eruptible crystal-free magma. Further, rhyolitic eruptions can switch repeatedly between effusive and explosive eruption styles and this transition is difficult to attribute to the rheological effects of water content or crystallinity. Here we measure the viscosity of a series of melts spanning the compositional range of the Yellowstone volcanic system and find that in a narrow compositional zone, melt viscosity increases by up to two orders of magnitude. These viscosity variations are not predicted by current viscosity models and result from melt structure reorganization, as confirmed by Raman spectroscopy. We identify a critical compositional tipping point, independently documented in the global geochemical record of rhyolites, at which rhyolitic melts fluidize or stiffen and that clearly separates effusive from explosive deposits worldwide. This correlation between melt structure, viscosity and eruptive behaviour holds despite the variable water content and other parameters, such as temperature, that are inherent in natural eruptions. Thermodynamic modelling demonstrates how the observed subtle compositional changes that result in fluidization or stiffening of the melt can be induced by crystal growth from the melt or variation in oxygen fugacity. However, the rheological effects of water and crystal content alone cannot explain the correlation between composition and eruptive style. We conclude that the composition of calcalkaline rhyolites is decisive in determining the mobilization and eruption dynamics of Earth’s largest volcanic systems, resulting in a better understanding of how the melt structure controls volcanic processes.

A compositional tipping point governing the mobilization and eruption style of rhyolitic magma.

PubMed

Di Genova, D; Kolzenburg, S; Wiesmaier, S; Dallanave, E; Neuville, D R; Hess, K U; Dingwell, D B

2017-12-13

The most viscous volcanic melts and the largest explosive eruptions on our planet consist of calcalkaline rhyolites. These eruptions have the potential to influence global climate. The eruptive products are commonly very crystal-poor and highly degassed, yet the magma is mostly stored as crystal mushes containing small amounts of interstitial melt with elevated water content. It is unclear how magma mushes are mobilized to create large batches of eruptible crystal-free magma. Further, rhyolitic eruptions can switch repeatedly between effusive and explosive eruption styles and this transition is difficult to attribute to the rheological effects of water content or crystallinity. Here we measure the viscosity of a series of melts spanning the compositional range of the Yellowstone volcanic system and find that in a narrow compositional zone, melt viscosity increases by up to two orders of magnitude. These viscosity variations are not predicted by current viscosity models and result from melt structure reorganization, as confirmed by Raman spectroscopy. We identify a critical compositional tipping point, independently documented in the global geochemical record of rhyolites, at which rhyolitic melts fluidize or stiffen and that clearly separates effusive from explosive deposits worldwide. This correlation between melt structure, viscosity and eruptive behaviour holds despite the variable water content and other parameters, such as temperature, that are inherent in natural eruptions. Thermodynamic modelling demonstrates how the observed subtle compositional changes that result in fluidization or stiffening of the melt can be induced by crystal growth from the melt or variation in oxygen fugacity. However, the rheological effects of water and crystal content alone cannot explain the correlation between composition and eruptive style. We conclude that the composition of calcalkaline rhyolites is decisive in determining the mobilization and eruption dynamics of Earth's largest volcanic systems, resulting in a better understanding of how the melt structure controls volcanic processes.

Calibration of the Oscillating Screen Viscometer

NASA Technical Reports Server (NTRS)

Berg, Robert F.; Moldover, Michael R.

1993-01-01

We have devised a calibration procedure for the oscillating screen viscometer which can provide the accuracy needed for the flight measurement of viscosity near the liquid-vapor critical point of xenon. The procedure, which makes use of the viscometer's wide bandwidth and hydrodynamic similarity, allows the viscometer to be self-calibrating. To demonstrate the validity of this procedure we measured the oscillator's transfer function under a wide variety of conditions. We obtained data using CO2 at temperatures spanning a temperature range of 35 K and densities varying by a factor of 165, thereby encountering viscosity variations as great as 50%. In contrast the flight experiment will be performed over a temperature range of 29 K and at only a single density, and the viscosity is expected to change by less than 40%. The measurements show that, after excluding data above 10 Hz (where frequency-dependent corrections are poorly modeled) and making a plausible adjustment to the viscosity value used at high density, the viscometer's behavior is fully consistent with the use of hydrodynamic similarity for calibration. Achieving this agreement required understanding a 1% anelastic effect present in the oscillator's torsion fiber.

Stability of Clindamycin Hydrochloride in PCCA Base SuspendIt.

PubMed

Pramar, Yashoda V; Graves, Richard A; Ledet, Grace A; Phan, Kelly V; Bostanian, Levon A; Mandal, Tarun K

2016-01-01

Clindamycin is an effective antibiotic in the treatment of infections caused by certain gram-positive and gram-negative anaerobic microorganisms. While manufactured forms of the drug for pediatric use are available, there are instances when a compounded liquid dosage form is essential to meet unique patient needs. The purpose of this study was to determine the chemical stability of clindamycin hydrochloride in the PCCA base SuspendIt, a sugar-free, paraben- free, dye-free, and gluten-free thixotropic vehicle containing a natural sweetener obtained from the monk fruit. It thickens upon standing to minimize settling of any insoluble drug particles and becomes fluid upon shaking to allow convenient pouring during administration to the patient. A robust stability-indicating high-performance liquid chromatographic assay for the determination of clindamycin hydrochloride in SuspendIt was developed and validated. This assay was used to determine the chemical stability of the drug in SuspendIt. Samples were prepared and stored under three different temperature conditions (5°C, 25°C, and 40°C), and assayed using the high-performance liquid chromatographic assay at pre-determined intervals over an extended period of time as follows: 7, 14, 30, 45, 60, 91, 120, and 182 days at each designated temperature. Physical data such as pH, viscosity, and appearance were also monitored. The study showed that drug concentration did not go below 90% of the label claim (initial drug concentration) at all three temperatures studied, barring isolated experimental errors. Viscosity and pH values also did not change significantly. Some variations in viscosity were attributed to the thixotropic nature of the vehicle. This study demonstrates that clindamycin hydrochloride is physically and chemically stable in SuspendIt for 182 days in the refrigerator and at room temperature, thus providing a viable, compounded alternative for clindamycin hydrochloride in a liquid dosage form, with an extended beyond-use date to meet patient needs. Copyright© by International Journal of Pharmaceutical Compounding, Inc.

Chemistry Notes.

ERIC Educational Resources Information Center

School Science Review, 1978

1978-01-01

Describes some laboratory apparatus, chemistry experiments and demonstrations, such as a Kofler block melting point apparatus, chromatographic investigation of the phosphoric acid, x-ray diffraction, the fountain experiment, endothermic sherbet, the measurement of viscosity, ionization energies and electronic configurations. (GA)

Analysis of Alcohols.

ERIC Educational Resources Information Center

McCullough, Brother Thomas

1984-01-01

Presents a novel approach to identification of unknown alcohols using experimental measurements of boiling point and viscosity which are easily obtained without expensive equipment of instrumentation. Provides instructions for preparing capillary viscometer, listing special hints for obtaining good results. (JM)

Correlation of physical properties with molecular structure for some dicyclic hydrocarbons having high thermal-energy release per unit volume

NASA Technical Reports Server (NTRS)

Wise, P H; Serijan, K T; Goodman, I A

1951-01-01

As part of a program to study the correlation between molecular structure and physical properties of high-density hydrocarbons, the net heats of combustion, melting points, boiling points, densities, and kinematic viscosities of some hydrocarbons in the 2-n-alkylbiphenyl, 1,1-diphenylalkane, diphenylalkane, 1,1-dicyclohexylalkane, and dicyclohexylalkane series are presented.

Numerical simulation of hot-melt extrusion processes for amorphous solid dispersions using model-based melt viscosity.

PubMed

Bochmann, Esther S; Steffens, Kristina E; Gryczke, Andreas; Wagner, Karl G

2018-03-01

Simulation of HME processes is a valuable tool for increased process understanding and ease of scale-up. However, the experimental determination of all required input parameters is tedious, namely the melt rheology of the amorphous solid dispersion (ASD) in question. Hence, a procedure to simplify the application of hot-melt extrusion (HME) simulation for forming amorphous solid dispersions (ASD) is presented. The commercial 1D simulation software Ludovic ® was used to conduct (i) simulations using a full experimental data set of all input variables including melt rheology and (ii) simulations using model-based melt viscosity data based on the ASDs glass transition and the physical properties of polymeric matrix only. Both types of HME computation were further compared to experimental HME results. Variation in physical properties (e.g. heat capacity, density) and several process characteristics of HME (residence time distribution, energy consumption) among the simulations and experiments were evaluated. The model-based melt viscosity was calculated by using the glass transition temperature (T g ) of the investigated blend and the melt viscosity of the polymeric matrix by means of a T g -viscosity correlation. The results of measured melt viscosity and model-based melt viscosity were similar with only few exceptions, leading to similar HME simulation outcomes. At the end, the experimental effort prior to HME simulation could be minimized and the procedure enables a good starting point for rational development of ASDs by means of HME. As model excipients, Vinylpyrrolidone-vinyl acetate copolymer (COP) in combination with various APIs (carbamazepine, dipyridamole, indomethacin, and ibuprofen) or polyethylene glycol (PEG 1500) as plasticizer were used to form the ASDs. Copyright © 2017 Elsevier B.V. All rights reserved.

Stereoisomeric effects on dynamic viscosity versus pressure and temperature for the system cis- + trans-decalin

NASA Astrophysics Data System (ADS)

Miyake, Yasufumi; Boned, Christian; Baylaucq, Antoine; Bessières, David; Zéberg-Mikkelsen, Claus K.; Galliéro, Guillaume; Ushiki, Hideharu

2007-07-01

In order to study the influence of stereoisomeric effects on the dynamic viscosity, an extensive experimental study of the viscosity of the binary system composed of the two stereoisomeric molecular forms of decalin - cis and trans - has been carried out for five different mixtures at three temperatures (303.15, 323.15 and 343.15) K and six isobars up to 100 MPa with a falling-body viscometer (a total of 90 points). The experimental relative uncertainty is estimated to be 2%. The variations of dynamic viscosity versus composition are discussed with respect to their behavior due to stereoisomerism. Four different models with a physical and theoretical background are studied in order to investigate how they take the stereoisomeric effect into account through their required model parameters. The evaluated models are based on the hard-sphere scheme, the concepts of the free-volume and the friction theory, and a model derived from molecular dynamics. Overall, a satisfactory representation of the viscosity of this binary system is found for the different models within the considered ( T, p) range taken into account their simplicity. All the models are able to distinguish between the two stereoisomeric decalin compounds. Further, based on the analysis of the model parameters performed on the pure compounds, it has been found that the use of simple mixing rules without introducing any binary interaction parameters are sufficient in order to predict the viscosity of cis + trans-decalin mixtures with the same accuracy in comparison with the experimental values as obtained for the pure compounds. In addition to these models, a semi-empirical self-referencing model and the simple mixing laws of Grunberg-Nissan and Katti-Chaudhri are also applied in the representation of the viscosity behavior of these systems.

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

PubMed

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

2016-07-08

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

Welding of Pyroclastic Deposits: Questions Arising from Experiments (Invited)

NASA Astrophysics Data System (ADS)

Russell, K.; Quane, S.; Robert, G.; Andrews, G. D.; Kennedy, B. M.

2009-12-01

Ultimately, all natural magmas vesiculate near the Earth’s surface to produce bubble-rich melts, that commonly foam to the point of fragmentation producing pyroclastic deposits. Vesiculation processes increase porosity and create permeability thereby increasing the efficacy of fluid escape and suppressing explosivity. Conversely, processes that destroy porosity and permeability, including bubble collapse, compaction, and welding, inhibit the escape of fluids and can produce overpressures leading to explosive behavior. Compaction and welding processes are pervasive in volcanic deposits and pertinent to: i) formation of spatter-fed clastogenic lava flows, ii) sintering of fragmental material in volcanic conduits, and to iii) welding of pyroclastic flow and fall deposits. The rate at which porous pyroclastic deposits compact and sinter (i.e., welding; cf. Grunder and Russell, 2005) governs the efficacy with which porosity (and ultimately permeability) is lost (Sparks et al., 1999). Ultimately, rates of welding reflect the aggregate rheological properties of the deposit. Here, we present an ensemble of experimental results used to investigate the rheology of hot, porous, pyroclastic materials during compaction. We have used a GEOCOMP Loadtrac II device modified to perform constant displacement rate or constant load deformation experiments on large (7 x 4.5 cm) unconfined cores of pumice, lava, or sintered ash. The experiments are at temperatures (T ~ 800-900°C), load stresses (< 150 MPa), and strain rates (10-6 to -2 s-1) consistent with the emplacement of pyroclastic flows. The effects of fluid pressure have also been studied experimentally by using a steel cell and piston system that permits high-T deformation experiments at controlled PH2O (Robert et al. 2008). Our experiments simulate compaction of natural pyroclastic deposits and provide the data to parameterize a relationship between the effective viscosity of the hot, porous deposit of ash (η), the viscosity of the melt fragments (ηo) and porosity (Φ) of the deposit (Quane et al. 2009): log η = log ηo - 2.5Φ/(1-Φ). This relationship is used to model compaction and welding of processes in ignimbrites and in volcanic conduits as a function of load, temperature and porosity. Our analysis shows that compaction operates very rapidly at high-T such that welding in ignimbrites is fully decoupled from cooling history and may even rival the depositional timescales of pyroclastic density currents. Experiments performed at PH2O values of ~1-3 MPa recover lower values of effective viscosity (109.2 - 9.4 Pa s), despite being run at substantially lower temperature (640-665°C). The presence of the H2O fluid expands the window of viscous (vs. brittle) deformation and prevents the strain hardening that normally accompanies porosity reduction allowing for the continuous accumulation of strain. These results apply to welding of rheomorphic ignimbrites and the compaction, annealing and eventual sealing of volcanic conduits.

Nitric Oxide Measurement Study. Volume II. Probe Methods,

DTIC Science & Technology

1980-05-01

case of the Task I study, it should be pointed out that at lower gas temperatures where much of the study was performed, the mass flow through the...third body as pointed out by Matthews, et al. (1977) but also dependent on the viscosity of the sampled gas for standard commercial units (Folsom and...substantially above the dew point (based on the maximum pressure in the sampling system and the initial water concentration) or (2) sample line and

Cloud-point detection using a portable thickness shear mode crystal resonator

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

Mansure, A.J.; Spates, J.J.; Germer, J.W.

1997-08-01

The Thickness Shear Mode (TSM) crystal resonator monitors the crude oil by propagating a shear wave into the oil. The coupling of the shear wave and the crystal vibrations is a function of the viscosity of the oil. By driving the crystal with circuitry that incorporates feedback, it is possible to determine the change from Newtonian to non-Newtonian viscosity at the cloud point. A portable prototype TSM Cloud Point Detector (CPD) has performed flawlessly during field and lab tests proving the technique is less subjective or operator dependent than the ASTM standard. The TSM CPD, in contrast to standard viscositymore » techniques, makes the measurement in a closed container capable of maintaining up to 100 psi. The closed container minimizes losses of low molecular weight volatiles, allowing samples (25 ml) to be retested with the addition of chemicals. By cycling/thermal soaking the sample, the effects of thermal history can be investigated and eliminated as a source of confusion. The CPD is portable, suitable for shipping the field offices for use by personnel without special training or experience in cloud point measurements. As such, it can make cloud point data available without the delays and inconvenience of sending samples to special labs. The crystal resonator technology can be adapted to in-line monitoring of cloud point and deposition detection.« less

Rheological and electrical properties used to investigate the coagulation process during sludge treatment.

PubMed

Mortadi, A; El Melouky, A; Chahid, E; Nasrellah, H; Bakasse, M; Zradba, A; Cherkaoui, O; El Moznine, R

2018-01-01

Analyses of rheological properties and electrical conductivity (σ dc ) at direct current have been employed in order to investigate the effects of calcium oxide on the coagulation process during sludge treatment in the textile industry. In this context, rheological and electrical measurements were performed on five samples - one that contained raw sludge and the other four that were prepared from the raw sludge and different amounts of calcium oxide: 2, 3, 4, 5% (w/w). Rheological behavior of these samples was analyzed using the Herschel-Bulkley modified model. The influence of calcium oxide content on the rheological parameters such as infinite viscosity, the yield stress, the consistency coefficient, and the consistency index, are presented and discussed. The impact of the calcium oxide content on pH and conductivity were also examined. Similar behaviors have been seen in the evolution of conductivity and infinite viscosity as a function of the calcium oxide content. These latter characteristics were modeled by an equation using two power laws. This equation was able to fit very well the evolution of electrical conductivity and also the viscosity versus the percentage of calcium oxide to predict the optimal amount of calcium oxide (3%) to achieve the coagulation step during sludge treatment.

Effects of surfactant micelles on viscosity and conductivity of poly(ethylene glycol) solutions

NASA Astrophysics Data System (ADS)

Wang, Shun-Cheng; Wei, Tzu-Chien; Chen, Wun-Bin; Tsao, Heng-Kwong

2004-03-01

The neutral polymer-micelle interaction is investigated for various surfactants by viscometry and electrical conductometry. In order to exclude the well-known necklace scenario, we consider aqueous solutions of low molecular weight poly(ethylene glycol) (2-20)×103, whose radial size is comparable to or smaller than micelles. The single-tail surfactants consist of anionic, cationic, and nonionic head groups. It is found that the viscosity of the polymer solution may be increased several times by micelles if weak attraction between a polymer segment and a surfactant exists, ɛ

Environmentally friendly and biobased lubricants

USDA-ARS?s Scientific Manuscript database

Biobased and environmentally friendly lubricants are finding applications in many areas ranging from hydraulic fluids to grease. They offer excellent biodegradability and very low ecotoxicity; high viscosity index; improved tribological properties; lower volatility and flash points relative to petro...

Polar symmetric flow of a viscous compressible atmosphere; an application to Mars

NASA Technical Reports Server (NTRS)

Pirraglia, J. A.

1974-01-01

The atmosphere is assumed to be driven by a polar symmetric temperature field and the equations of motion in pressure ratio coordinates are linearized by considering the zero order in terms of a thermal Rossby number R delta I/(2a omega) sq where delta T is a measure of the latitudinal temperature gradient. When the eddy viscosity is greater than 1 million sq cm/sec, the boundary layer extends far up into the atmosphere, making the geostrophic approximation invalid for the bulk of the atmosphere. A temperature model for Mars was used which was based on Mariner 9 infrared spectral data with a 30% increase in the depth averaged temperature from the winter pole to the subsolar point. The results obtained for the increase in surface pressure from the subsolar point to the winter pole, as a function of eddy viscosity and with no-slip conditions imposed at the surface, are given.

Extracting of yellowfin tuna (Thunnus albacares) fish skin gelatin as influenced by alkaline concentration and extraction times

NASA Astrophysics Data System (ADS)

Mafazah, E. M.; Pranoto, Y.; Rohman, A.

2018-03-01

Yellowfin tuna (Thunnus albacares) skin is a by-product of the fish processing industry. Yellowfin tuna skin was used as materials for gelatin because it contains collagen. This study was conducted to determine the characteristics of yellowfin tuna skin gelatin (YSG). In this study, YSG was obtained by the extraction process in 0.01 M NaOH solution for 12 h. The results show that the yield of YSG was 12.49 % dry basis, with the gel strength of 291.73 g Bloom, viscosity of 8.6 cPs and melting point of 35 °C. The gel strength and melting point of YSG were lower than commercial bovine gelatin (CBG), which was 309.7401 g Bloom and 36.33 °C, respectively. However, the viscosity of YSG was higher than the CBG which was 5.6 cPs.

Critical Viscosity of Xenon

NASA Technical Reports Server (NTRS)

2001-01-01

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. The sample cell at the heart of CVX-2 will sit inside a thermostat providing three layers of insulation. The cell itself comprises a copper body that conducts heat efficiently and smoothes out thermal variations that that would destroy the xenon's uniformity. Inside the cell, the oscillating screen viscometer element is supported between two pairs of electrodes that deflect the screen and then measure screen motion.

What causes the buoyancy reversal in compressible convection?

NASA Technical Reports Server (NTRS)

Chan, K. L.

1983-01-01

The problem posed by the existence of a negative buoyancy work region at the top of cellular type convection in a deeply stratified superadiabatic layer (Massaguer and Zahn, 1980) is addressed. It is approached by studying two-dimensional cellular compressible convection with different physical parameters. The results suggest that a large viscosity, together with density stratification, is responsible for the buoyancy reversal. The numerical results obtained are analyzed. It is pointed out, however, that in an astrophysical situation a fluid involved in convection will generally have very small viscosity. It is therefore thought unlikely that buoyancy reversal occurs in this way.

Critical Viscosity of Xenon

NASA Technical Reports Server (NTRS)

2001-01-01

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

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° C. Measured values range between ~2 and 20 mPa sec. The results point out that the viscosity of synthetic samples is inversely related to the cations radius, being Li2CO3 melt the more viscous. Viscosity measurements on natural samples (carbonatitic lava from Lengai volcano, Tanzania), reveal a higher viscosity (~1000 mPa s) and a dramatic higher activation energy than the synthetic samples. Our results have been compared with literature data in order to determine the effect of chemical composition and oxygen fugacity conditions on the liquid viscosity of carbonatitic melts.

New correlation for the temperature-dependent viscosity for saturated liquids

NASA Astrophysics Data System (ADS)

Tian, Jianxiang; Zhang, Laibin

2016-11-01

Based on the recent progress on both the temperature dependence of surface tension [H. L. Yi, J. X. Tian, A. Mulero and I. Cachading, J. Therm. Anal. Calorim. 126 (2016) 1603, and the correlation between surface tension and viscosity of liquids [J. X. Tian and A. Mulero, Ind. Eng. Chem. Res. 53 (2014) 9499], we derived a new multiple parameter correlation to describe the temperature-dependent viscosity of liquids. This correlation is verified by comparing with data from NIST Webbook for 35 saturated liquids including refrigerants, hydrocarbons and others, in a wide temperature range from the triple point temperature to the one very near to the critical temperature. Results show that this correlation predicts the NIST data with high accuracy with absolute average deviation (AAD) less than 1% for 21 liquids and more than 3% for only four liquids, and is clearly better than the popularly used Vogel-Fulcher-Tamman (VFT) correlation.

Screening for High Conductivity/Low Viscosity Ionic Liquids Using Product Descriptors.

PubMed

Martin, Shawn; Pratt, Harry D; Anderson, Travis M

2017-07-01

We seek to optimize Ionic liquids (ILs) for application to redox flow batteries. As part of this effort, we have developed a computational method for suggesting ILs with high conductivity and low viscosity. Since ILs consist of cation-anion pairs, we consider a method for treating ILs as pairs using product descriptors for QSPRs, a concept borrowed from the prediction of protein-protein interactions in bioinformatics. We demonstrate the method by predicting electrical conductivity, viscosity, and melting point on a dataset taken from the ILThermo database on June 18 th , 2014. The dataset consists of 4,329 measurements taken from 165 ILs made up of 72 cations and 34 anions. We benchmark our QSPRs on the known values in the dataset then extend our predictions to screen all 2,448 possible cation-anion pairs in the dataset. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

The viscosity of the refrigerant 1,1-difluoroethane along the saturation line

NASA Astrophysics Data System (ADS)

van der Gulik, P. S.

1993-07-01

The viscosity coefficient of the refrigerant R152a (1,1-difluoroethane) has been measured along the saturation line both in the saturated liquid and in the saturated vapor. The data have been obtained every 10 K from 243 up to 393 K by means of a vibrating-wire viscometer using the free damped oscillation method. The density along the saturation line was calculated from the equation of state given by Tamatsu et al. with application of the saturated vapor-pressure correlation given by Higashi et al. An interesting result is that in the neighborhood of the critical point, the kinematic viscosity of the saturated liquid seems to coincide with that of the saturated vapor. The results for the saturated liquid are in satisfying agreement with those of Kumagai and Takahashi and of Phillips and Murphy. A comparison of the saturatedvaport data with the unsaturated-vapor data of Takahashi et al. shows some discrepancies.

Glycerol, trehalose and glycerol-trehalose mixture effects on thermal stabilization of OCT

NASA Astrophysics Data System (ADS)

Barreca, D.; Laganà, G.; Magazù, S.; Migliardo, F.; Bellocco, E.

2013-10-01

The stabilization effects of trehalose, glycerol and their mixtures on ornithine carbamoyltransferase catalytic activity has been studied as a function of temperature by complementary techniques. The obtained results show that the kinematic viscosities of trehalose (1.0 M) and protein mixture are higher than the one of glycerol plus protein. Changing the trehalose/glycerol ratio, we notice a decrease of the kinematic viscosity values at almost all the analyzed ratio. In particular, the solution composed of 95% trehalose-5% glycerol shows a peculiar behavior. Moreover the trehalose (1.0 M) solution shows the higher OCT thermal stabilization at 343 K, while all the other solutions show minor effects. The smallest stabilizing effect is revealed for the solution that shows the maximum kinematic viscosity. These results support Inelastic Neutron Scattering (INS) and Quasi Elastic Neutron Scattering (QENS) findings, which pointed out a slowing down of the relaxation and diffusive dynamics in some investigated samples.

High Accuracy Fuel Flowmeter, Phase 1

NASA Technical Reports Server (NTRS)

Mayer, C.; Rose, L.; Chan, A.; Chin, B.; Gregory, W.

1983-01-01

Technology related to aircraft fuel mass - flowmeters was reviewed to determine what flowmeter types could provide 0.25%-of-point accuracy over a 50 to one range in flowrates. Three types were selected and were further analyzed to determine what problem areas prevented them from meeting the high accuracy requirement, and what the further development needs were for each. A dual-turbine volumetric flowmeter with densi-viscometer and microprocessor compensation was selected for its relative simplicity and fast response time. An angular momentum type with a motor-driven, spring-restrained turbine and viscosity shroud was selected for its direct mass-flow output. This concept also employed a turbine for fast response and a microcomputer for accurate viscosity compensation. The third concept employed a vortex precession volumetric flowmeter and was selected for its unobtrusive design. Like the turbine flowmeter, it uses a densi-viscometer and microprocessor for density correction and accurate viscosity compensation.

Screening for High Conductivity/Low Viscosity Ionic Liquids Using Product Descriptors

DOE PAGES

Martin, Shawn; Pratt, III, Harry D.; Anderson, Travis M.

2017-02-21

We seek to optimize Ionic liquids (ILs) for application to redox flow batteries. As part of this effort, we have developed a computational method for suggesting ILs with high conductivity and low viscosity. Since ILs consist of cation-anion pairs, we consider a method for treating ILs as pairs using product descriptors for QSPRs, a concept borrowed from the prediction of protein-protein interactions in bioinformatics. We demonstrate the method by predicting electrical conductivity, viscosity, and melting point on a dataset taken from the ILThermo database on June 18th, 2014. The dataset consists of 4,329 measurements taken from 165 ILs made upmore » of 72 cations and 34 anions. In conclusion, we benchmark our QSPRs on the known values in the dataset then extend our predictions to screen all 2,448 possible cation-anion pairs in the dataset.« less

Screening for High Conductivity/Low Viscosity Ionic Liquids Using Product Descriptors

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

Martin, Shawn; Pratt, III, Harry D.; Anderson, Travis M.

We seek to optimize Ionic liquids (ILs) for application to redox flow batteries. As part of this effort, we have developed a computational method for suggesting ILs with high conductivity and low viscosity. Since ILs consist of cation-anion pairs, we consider a method for treating ILs as pairs using product descriptors for QSPRs, a concept borrowed from the prediction of protein-protein interactions in bioinformatics. We demonstrate the method by predicting electrical conductivity, viscosity, and melting point on a dataset taken from the ILThermo database on June 18th, 2014. The dataset consists of 4,329 measurements taken from 165 ILs made upmore » of 72 cations and 34 anions. In conclusion, we benchmark our QSPRs on the known values in the dataset then extend our predictions to screen all 2,448 possible cation-anion pairs in the dataset.« less

A Novel Methodology for the Synthesis of Acyloxy Castor Polyol Esters: Low Pour Point Lubricant Base Stocks.

PubMed

Kamalakar, Kotte; Mahesh, Goli; Prasad, Rachapudi B N; Karuna, Mallampalli S L

2015-01-01

Castor oil, a non-edible oil containing hydroxyl fatty acid, ricinoleic acid (89.3 %) was chemically modified employing a two step procedure. The first step involved acylation (C(2)-C(6) alkanoic anhydrides) of -OH functionality employing a green catalyst, Kieselguhr-G and solvent free medium. The catalyst after reaction was filtered and reused several times without loss in activity. The second step is esterification of acylated castor fatty acids with branched mono alcohol, 2-ethylhexanol and polyols namely neopentyl glycol (NPG), trimethylolpropane (TMP) and pentaerythritol (PE) to obtain 16 novel base stocks. The base stocks when evaluated for different lubricant properties have shown very low pour points (-30 to -45°C) and broad viscosity ranges 20.27 cSt to 370.73 cSt, higher viscosity indices (144-171), good thermal and oxidative stabilities, and high weld load capacities suitable for multi-range industrial applications such as hydraulic fluids, metal working fluids, gear oil, forging and aviation applications. The study revealed that acylated branched mono- and polyol esters rich in monounsaturation is desirable for developing low pour point base stocks.

Quantifying mixing and age variations of heterogeneities in models of mantle convection: Role of depth-dependent viscosity

NASA Astrophysics Data System (ADS)

Hunt, D. L.; Kellogg, L. H.

2001-04-01

Using a two-dimensional finite element model of mantle convection containing over a million tracer particles, we examine the effects of depth-dependent viscosity on the rates and patterns of mixing. We simulate the processes of recycling crust at subduction zones and the homogenization of recycled material (by dispersion and by melting at mid-ocean ridges). Particles are continually introduced at downwellings and destroyed when they either are so thoroughly dispersed that it would be impossible to measure their presence in the geochemical signature of mid-ocean ridges or oceanic islands, or when they are close to spreading centers, at which point melting would "reset" the geochemical clock. A large number of factors influence the flow pattern and thus the rate at which heterogeneities are dispersed by convection. We examine the effect of increasing the viscosity with depth, and determine how both the residence time of heterogeneities and the extent of lateral mixing and exchange between the upper and lower mantle vary with the viscosity profile of the mantle. We determine the particle distribution resulting from convection models with three viscosity profiles: uniform viscosity, a smooth increase of viscosity with depth, and an abrupt jump in viscosity between the upper and lower mantle. We characterize the resulting distribution of heterogeneities in space and time by examining the age distribution of particles and their locations relative to others introduced into the flow at separate downwellings. Mixing rates in the three models are calculated as a function of the number of particles removed from the flow through time. We found that an increase of viscosity at depth does not induce age stratification in which older particles stagnate in the lover mantle, and it does not produce an upper layer (the source of mid-ocean ridge basalt) that is well-mixed compared to the deeper regions. However, pronounced lateral heterogeneity is evident in the distribution of particles of different ages and starting locations that is not apparent from the particle positions alone.

Effects of variable properties on MHD heat and mass transfer flow near a stagnation point towards a stretching sheet in a porous medium with thermal radiation

NASA Astrophysics Data System (ADS)

M. Salem, A.; Rania, Fathy

2012-05-01

The effect of variable viscosity and thermal conductivity on steady magnetohydrodynamic (MHD) heat and mass transfer flow of viscous and incompressible fluid near a stagnation point towards a permeable stretching sheet embedded in a porous medium are presented, taking into account thermal radiation and internal heat genberation/absorbtion. The stretching velocity and the ambient fluid velocity are assumed to vary linearly with the distance from the stagnation point. The Rosseland approximation is used to describe the radiative heat flux in the energy equation. The governing fundamental equations are first transformed into a system of ordinary differential equations using a scaling group of transformations and are solved numerically by using the fourth-order Rung—Kutta method with the shooting technique. A comparison with previously published work has been carried out and the results are found to be in good agreement. The results are analyzed for the effect of different physical parameters, such as the variable viscosity and thermal conductivity, the ratio of free stream velocity to stretching velocity, the magnetic field, the porosity, the radiation and suction/injection on the flow, and the heat and mass transfer characteristics. The results indicate that the inclusion of variable viscosity and thermal conductivity into the fluids of light and medium molecular weight is able to change the boundary-layer behavior for all values of the velocity ratio parameter λ except for λ = 1. In addition, the imposition of fluid suction increases both the rate of heat and mass transfer, whereas fluid injection shows the opposite effect.

Selected Thermophysical Properties of 2,2 Dimethylcyclopentyl Methylphosphonofluoridate (GP) and 2,2 Dimethylcyclopentanol (DMCP)

DTIC Science & Technology

2016-09-01

Thermophysical properties, including vapor pressure, density, viscosity, surface tension, and flash point, are reported for 2,2-dimethylcyclopentyl...methylphosphonofluoridate (GP; Chemical Abstracts Service [CAS] no. 453574-97-5). Density data above the melting point, and vapor pressure of the liquid and solid...experimental vapor pressure data and were used to calculate the temperature-dependent enthalpy of vaporization , volatility, and entropy of

The Formation of Novel Thermoplastic Composites from Liquid Crystalline Polymers and Their Blends

DTIC Science & Technology

1991-07-01

melting point of the Vectra. This is due to the long relaxation time of the LCPs ccjzIed with the much higher viscosity of the matrix polymer. Ultem...the LCP reinforcing characteristics i.e. orientation and morphology can be retained upon post-processing provided that the melting point of the LCP is...isothermal compression molding and involves deforming the composites in a cold press after heating the blends at temperatures below the melting point of

Microgravity

NASA Image and Video Library

2001-01-24

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. Because xenon near the critical point will collapse under its own weight, experiments on Earth (green line) are limited as they get closer (toward the left) to the critical point. CVX in the microgravity of space (red line) moved into unmeasured territory that scientists had not been able to reach.

Effect of atmosphere on the surface tension and viscosity of molten LiNbO 3 measured using the surface laser-light scattering method

NASA Astrophysics Data System (ADS)

Nagasaka, Yuji; Kobayashi, Yusuke

2007-09-01

The surface tension and the viscosity of molten LiNbO 3 (LN) having the congruent composition have been measured simultaneously in a temperature range from 1537 to 1756 K under argon gas and dry-air atmospheres. The present measurement technique involves surface laser-light scattering (SLLS) that detects nanometer-order-amplitude surface waves usually regarded as ripplons excited by thermal fluctuations. This technique's non-invasive nature allows it to avoid the experimental difficulties of conventional techniques resulting from the insertion of an actuator in the melt. The results of surface tension measurement obtained under a dry-air atmosphere are about 5% smaller than those obtained under an argon atmosphere near the melting temperature, and the temperature dependence of the surface tension under a dry-air atmosphere is twice that under an argon atmosphere. The uncertainty of surface tension measurement is estimated to be ±2.6% under argon and ±1.9% under dry air. The temperature dependence of viscosity can be well correlated with the results of Arrhenius-type equations without any anomalous behavior near the melting point. The viscosities obtained under a dry-air atmosphere were slightly smaller than those obtained under an argon atmosphere. The uncertainty of viscosity measurement is estimated to be ±11.1% for argon and ±14.3% for dry air. Moreover, we observed the real-time dynamic behavior of the surface tension and the viscosity of molten LN in response to argon and dry-air atmospheres.

Analysis of Bacterial and Archaeal Communities along a High-Molecular-Weight Polyacrylamide Transportation Pipeline System in an Oil Field

PubMed Central

Li, Cai-Yun; Li, Jing-Yan; Mbadinga, Serge Maurice; Liu, Jin-Feng; Gu, Ji-Dong; Mu, Bo-Zhong

2015-01-01

Viscosity loss of high-molecular-weight partially hydrolyzed polyacrylamide (HPAM) solution was observed in a water injection pipeline before being injected into subterranean oil wells. In order to investigate the possible involvement of microorganisms in HPAM viscosity loss, both bacterial and archaeal community compositions of four samples collected from different points of the transportation pipeline were analyzed using PCR-amplification of the 16S rRNA gene and clone library construction method together with the analysis of physicochemical properties of HPAM solution and environmental factors. Further, the relationship between environmental factors and HPAM properties with microorganisms were delineated by canonical correspondence analysis (CCA). Diverse bacterial and archaeal groups were detected in the four samples. The microbial community of initial solution S1 gathered from the make-up tank is similar to solution S2 gathered from the first filter, and that of solution S3 obtained between the first and the second filter is similar to that of solution S4 obtained between the second filter and the injection well. Members of the genus Acinetobacter sp. were detected with high abundance in S3 and S4 in which HPAM viscosity was considerably reduced, suggesting that they likely played a considerable role in HPAM viscosity loss. This study presents information on microbial community diversity in the HPAM transportation pipeline and the possible involvement of microorganisms in HPAM viscosity loss and biodegradation. The results will help to understand the microbial community contribution made to viscosity change and are beneficial for providing information for microbial control in oil fields. PMID:25849654

Analysis of bacterial and archaeal communities along a high-molecular-weight polyacrylamide transportation pipeline system in an oil field.

PubMed

Li, Cai-Yun; Li, Jing-Yan; Mbadinga, Serge Maurice; Liu, Jin-Feng; Gu, Ji-Dong; Mu, Bo-Zhong

2015-04-02

Viscosity loss of high-molecular-weight partially hydrolyzed polyacrylamide (HPAM) solution was observed in a water injection pipeline before being injected into subterranean oil wells. In order to investigate the possible involvement of microorganisms in HPAM viscosity loss, both bacterial and archaeal community compositions of four samples collected from different points of the transportation pipeline were analyzed using PCR-amplification of the 16S rRNA gene and clone library construction method together with the analysis of physicochemical properties of HPAM solution and environmental factors. Further, the relationship between environmental factors and HPAM properties with microorganisms were delineated by canonical correspondence analysis (CCA). Diverse bacterial and archaeal groups were detected in the four samples. The microbial community of initial solution S1 gathered from the make-up tank is similar to solution S2 gathered from the first filter, and that of solution S3 obtained between the first and the second filter is similar to that of solution S4 obtained between the second filter and the injection well. Members of the genus Acinetobacter sp. were detected with high abundance in S3 and S4 in which HPAM viscosity was considerably reduced, suggesting that they likely played a considerable role in HPAM viscosity loss. This study presents information on microbial community diversity in the HPAM transportation pipeline and the possible involvement of microorganisms in HPAM viscosity loss and biodegradation. The results will help to understand the microbial community contribution made to viscosity change and are beneficial for providing information for microbial control in oil fields.

Effect of two viscosity models on lethality estimation in sterilization of liquid canned foods.

PubMed

Calderón-Alvarado, M P; Alvarado-Orozco, J M; Herrera-Hernández, E C; Martínez-González, G M; Miranda-López, R; Jiménez-Islas, H

2016-09-01

A numerical study on 2D natural convection in cylindrical cavities during the sterilization of liquid foods was performed. The mathematical model was established on momentum and energy balances and predicts both the heating dynamics of the slowest heating zone (SHZ) and the lethal rate achieved in homogeneous liquid canned foods. Two sophistication levels were proposed in viscosity modelling: 1) considering average viscosity and 2) using an Arrhenius-type model to include the effect of temperature on viscosity. The remaining thermodynamic properties were kept constant. The governing equations were spatially discretized via orthogonal collocation (OC) with mesh size of 25 × 25. Computational simulations were performed using proximate and thermodynamic data for carrot-orange soup, broccoli-cheddar soup, tomato puree, and cream-style corn. Flow patterns, isothermals, heating dynamics of the SHZ, and the sterilization rate achieved for the cases studied were compared for both viscosity models. The dynamics of coldest point and the lethal rate F0 in all food fluids studied were approximately equal in both cases, although the second sophistication level is closer to physical behavior. The model accuracy was compared favorably with reported sterilization time for cream-style corn packed at 303 × 406 can size, predicting 66 min versus an experimental time of 68 min at retort temperature of 121.1 ℃. © The Author(s) 2016.

Jet-mixing of initially-stratified liquid-liquid pipe flows: experiments and numerical simulations

NASA Astrophysics Data System (ADS)

Wright, Stuart; Ibarra-Hernandes, Roberto; Xie, Zhihua; Markides, Christos; Matar, Omar

2016-11-01

Low pipeline velocities lead to stratification and so-called 'phase slip' in horizontal liquid-liquid flows due to differences in liquid densities and viscosities. Stratified flows have no suitable single point for sampling, from which average phase properties (e.g. fractions) can be established. Inline mixing, achieved by static mixers or jets in cross-flow (JICF), is often used to overcome liquid-liquid stratification by establishing unstable two-phase dispersions for sampling. Achieving dispersions in liquid-liquid pipeline flows using JICF is the subject of this experimental and modelling work. The experimental facility involves a matched refractive index liquid-liquid-solid system, featuring an ETFE test section, and experimental liquids which are silicone oil and a 51-wt% glycerol solution. The matching then allows the dispersed fluid phase fractions and velocity fields to be established through advanced optical techniques, namely PLIF (for phase) and PTV or PIV (for velocity fields). CFD codes using the volume of a fluid (VOF) method are then used to demonstrate JICF breakup and dispersion in stratified pipeline flows. A number of simple jet configurations are described and their dispersion effectiveness is compared with the experimental results. Funding from Cameron for Ph.D. studentship (SW) gratefully acknowledged.

Approximate factorization for incompressible flow. Ph.D. Thesis; [Navier-Stokes equation

NASA Technical Reports Server (NTRS)

Bernard, R. S.

1981-01-01

For computational solution of the incompressible Navier-Stokes equations, the approximate factorization (AF) algorithm is used to solve the vectorized momentum equation in delta form based on the pressure calculated in the previous time step. The newly calculated velocities are substituted into the pressure equation (obtained from a linear combination of the continuity and momentum equation), which is then solved by means of line SOR. Computational results are presented for the NACA 66 sub 3 018 airfoil at Reynolds numbers of 1000 and 40,000 and attack angles of 0 and 6 degrees. Comparison with wind tunnel data for Re = 40,000 indicates good qualitative agreement between measured and calculated pressure distributions. Quantitative agreement is only fair, however, with the calculations somewhat displaced from the measurements. Furthermore, the computed velocity profiles are unrealistically thick around the airfoil, due to the excessive amount of artificial viscosity needed for stability. Based on the performance of the algorithm with regard to stability, it is concluded that AF/SOR is suitable for calculations at Reynolds numbers less than 10,000. Speedwise, the method is faster than point SOR by at least a factor of two.

Development of clay liquid detergent for Islamic cleansing and the stability study.

PubMed

Angkatavanich, J; Dahlan, W; Nimmannit, U; Sriprasert, V; Sulongkood, N

2009-04-01

Clay liquid detergents (CLDs) were developed for cleansing religiously-prohibited dirt ('najis') according to Islamic law. Four types of clay were selected: marl, kaolin, bentonite and veegum. After product development trials, five CLD formulations with varying combinations of clays were qualified for stability testing. Three exaggerated temperature conditions were considered: 4 degrees C for 24 h, 50 degrees C for 7 days, and 40 degrees C for 1 month. The CLDs were also evaluated at 30, 60 and 90 days after production, while being stored at room temperature (RT30, RT60 and RT90). Physical and chemical characteristics including pH, colour, viscosity, surface tension, foam tests and sensory liking scores were evaluated. Our results showed that the kaolin-based formula, F2, had an optimal pH (closest to skin pH) of 5.08. The other formulas ranged from pH 6 to 8. Colour shades of the CLDs ranged from white, to creamy white, to mildly greenish-white. The foaming properties of the CLDs, the means +/- SD of foam heights at 0 and 5 min, using the Ross-Miles test, were 19.13 +/- 0.25 to 20.88 +/- 0.45 cm at RT90 and were comparable with those of commercial detergents. Foam stability of all CLDs was high, as shown from the foam heights between 0 and 5 min being not significantly different (P > 0.05). The surface tensions, means +/- SD, of CLD solutions were between 27.94 +/- 0.08 and 28.72 +/- 0.04 mN m(-1), which were slightly better than the surface tension of 29.08 +/- 0.04 mN m(-1) for sodium lauryl sulphate. There was a weak negative relationship between surface activity and foam height, based on the pooled data of the CLDs (R(2) = 0.209, P < 0.01). The viscosity of four CLDs ranged from 16 317 to 49 036 mPa s. In conclusion, CLDs can be formulated with good stability. F2 (kaolin-based, with a white, creamy texture) was the best CLD formula. It had the highest surface activity, moderate lathering and pleasant physical appearance.

Investigation of the erosive potential of sour novelty sweets.

PubMed

Aljawad, A; Morgan, M Z; Fairchild, R; Rees, J S

2017-04-21

Background The expansion of the novelty sweets market in the UK has major potential public health implications in children and young adults as they may cause dental erosion.Objective To investigate the erosive potential of the novelty sweets in term of their physiochemical properties and amount of enamel loss.Subjects and methods The pH of a variety of novelty sweets was tested in vitro using a pH meter and the neutralisable acidity was assessed by titrating the sweets against 0.1M NaOH. The viscosity of the novelty sweets was measured using a rotational viscometer. The wettability of enamel by each sweet was measured using dynamic contact angle analyser. Enamel loss was assessed using contact profilometry.Results The pH ranged from 1.8-3.2, the neutralisable acidity ranged from 9-201 ml of 0.1 NaOH. The viscosity of the novelty sweets that come in liquid form ranged from 2-594 mPa s. The surface enamel erosion ranged from 1.95-15.77 μm and from 2.5-17.6 μm with and without immersing in saliva for 1 hour before immersing in acidic solution respectively. The amount of subsurface enamel loss was ranged from 0.75 to 2.3 μm following ultrasonication at 0 min of acidic attack and from 0.23 to 0.85 μm at 60 minutes of acidic attack while immersed in saliva. The contact angle between enamel surface and four sweet was less than the angle formed between the orange juice and the enamel which caused more wettability of enamel.Conclusion The pH is lower than the critical value for enamel erosion (5.5), high neutralisable acidity and high sugar content strongly suggest that these sweets may cause significant amount of dental erosion clinically. In addition, the degree of wettability of enamel by solution is an important factor to consider in determining the enamel loss caused by acidic solution. Immediate tooth brushing would cause further enamel loss as a result of the mechanical removal of softened enamel. However, it has been suggested that postponing brushing after erosive attack should be reconsidered.

Upper Limit of the Viscosity Parameter in Accretion Flows around a Black Hole with Shock Waves

NASA Astrophysics Data System (ADS)

Nagarkoti, Shreeram; Chakrabarti, Sandip K.

2016-01-01

Black hole accretion is necessarily transonic; thus, flows must become supersonic and, therefore, sub-Keplerian before they enter into the black hole. The viscous timescale is much longer than the infall timescale close to a black hole. Hence, the angular momentum remains almost constant and the centrifugal force ˜ {l}2/{r}3 becomes increasingly dominant over the gravitational force ˜ 1/{r}2. The slowed down matter piles creating an accretion shock. The flow between shock and inner sonic point is puffed up and behaves like a boundary layer. This so-called Comptonizing cloud/corona produces hard X-rays and jets/outflows and, therefore, is an important component of black hole astrophysics. In this paper, we study steady state viscous, axisymmetric, transonic accretion flows around a Schwarzschild black hole. We adopt a viscosity parameter α and compute the highest possible value of α (namely, {α }{cr}) for each pair of two inner boundary parameters (namely, specific angular momentum carried to horizon, lin and specific energy at inner sonic point, E({x}{in})) which is still capable of producing a standing or oscillating shock. We find that while such possibilities exist for α as high as {α }{cr}=0.3 in very small regions of the flow parameter space, typical {α }{cr} appears to be about ˜0.05-0.1. Coincidentally, this also happens to be the typical viscosity parameter achieved by simulations of magnetorotational instabilities in accretion flows. We therefore believe that all realistic accretion flows are likely to have centrifugal pressure supported shocks unless the viscosity parameter everywhere is higher than {α }{cr}.

Effects of local thermodynamics and of stellar mass ratio on accretion disc stability in close binaries

NASA Astrophysics Data System (ADS)

Lanzafame, G.

2009-08-01

Inflow kinematics at the inner Lagrangian point L1, gas compressibility, and physical turbulent viscosity play a fundamental role on accretion disc dynamics and structure in a close binary (CB). Physical viscosity supports the accretion disc development inside the primary gravitational potential well, developing the gas radial transport, converting mechanical energy into heat. The Stellar-Mass-Ratio (SMR) between the compact primary and the secondary star (M1/M2) is also effective, not only in the location of the inner Lagrangian point, but also in the angular kinematics of the mass transfer and in the geometry of the gravitational potential wells. In this work we pay attention in particular to the role of the SMR, evaluating boundaries, separating theoretical domains in compressibility-viscosity graphs where physical conditions allow a well-bound disc development, as a function of mass transfer kinematic conditions. In such domains, the lower is the gas compressibility (the higher the polytropic index γ), the higher is the physical viscosity (α) requested. In this work, we show how the boundaries of such domains vary as a function of M1/M2. Conclusions as far as dwarf novae outbursts are concerned, induced by mass transfer rate variations, are also reported. The smaller M1/M2, the shorter the duration of the active-to-quiet and vice-versa transitional phases. Time-scales are of the order of outburst duration of SU Uma, OY Car, Z Cha and SS Cyg-like objects. Moreover, conclusions as far as active-quiet-active phenomena in a CB, according to viscous-thermal instabilities, in accordance to such domains, are also reported.

A protease-resistant exo-polygalacturonase from Klebsiella sp. Y1 with good activity and stability over a wide pH range in the digestive tract.

PubMed

Yuan, Peng; Meng, Kun; Wang, Yaru; Luo, Huiying; Shi, Pengjun; Huang, Huoqing; Bai, Yingguo; Yang, Peilong; Yao, Bin

2012-11-01

Polygalacturonases are important feed and food additives. In the present study an exo-polygalacturonase gene (pgu B) was cloned from Klebsiella sp. Y1 CGMCC 4433 and expressed in Escherichia coli BL21 (DE3). pgu B encodes a 658-amino acid polypeptide belonging to Glycoside Hydrolase Family 28. The optimal pH and temperature of exo-PGU B activity were 6.0 and 40-50°C, respectively. The enzyme exhibited >35% of maximum activity within the pH range of 2.0-12.0. Exo-PGU B or an exo-PGU B/ endo-polygalacturonase mixture reduced the viscosity of polygalacturonic acid (1.0%, w/v) by 15.6 and 39.4%, respectively. Under simulated alimentary tract conditions, exo-PGU B was very stable (>25% activity from pH 1.5 to 6.8) and active, releasing 53.7 and 109.6μg of galacturonic acid from 400 to 800μg of polygalacturonic acid, respectively. These properties make exo-PGU B a potentially valuable additive for applications in feed and food. Copyright © 2012 Elsevier Ltd. All rights reserved.

A transition in the viscous fingering instability in miscible fluids

NASA Astrophysics Data System (ADS)

Videbaek, Thomas; Nagel, Sidney R.

2017-11-01

The viscous fingering instability in a quasi-two dimensional Hele-Shaw cell is an example of complex structure formation from benign initial conditions. When the invading fluid has the lesser viscosity, the interface between the two fluids is unstable to finger formation. Here, we study the instability between pairs of miscible fluids in a circular cell with fluid injected at its center. As the injection rate is decreased, diffusion will smooth out the discontinuity in the gap-averaged viscosity at the interface between the fluids. At high injection rates (i.e., high Péclet number, Pe), fingering is associated with three-dimensional structure within the gap between the confining plates. On lowering Pe, we find a sharp transition in the finger morphology at a critical value, Pec (ηi /ηo) 1 / 2 , with ηi (ηo) being the viscosity of the inner (outer) fluid; at this point, the width of the fingers jumps, the length of the fingers shrinks towards zero and the three-dimensional structure goes from half filling to fully filling the gap. Thus, by controlling the viscosity contrast at the interface, one can alter and even completely suppress the instability.

Effect of thermal modification on rheological properties of polyethylene blends

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

Siriprumpoonthum, Monchai; Nobukawa, Shogo; Yamaguchi, Masayuki, E-mail: m-yama@jaist.ac.jp

2014-03-15

We examined the effects of thermal modification under flow field on the rheological properties of linear low-density polyethylene (LLDPE) with high molecular weight, low-density polyethylene (LDPE), and their blends, without thermal stabilizer. Although structural changes during processing are not detected by size extrusion chromatography or nuclear magnetic resonance spectroscopy, linear viscoelastic properties changed greatly, especially for the LLDPE. A cross-linking reaction took place, leading to, presumably, star-shaped long-chain branches. Consequently, the modified LLDPE, having high zero-shear viscosity, became a thermorheologically complex melt. Moreover, it should be noted that the drawdown force, defined as the uniaxial elongational force at a constantmore » draw ratio, was significantly enhanced for the blends. Enhancement of elongational viscosity was also detected. The drawdown force and elongational viscosity are marked for the thermally modified blend as compared with those for the blend of thermally modified pure components. Intermolecular cross-linking reactions between LDPE and LLDPE, yielding polymers with more than two branch points per chain, result in marked strain-hardening in the elongational viscosity behavior even at small strain. The recovery curve of the oscillatory modulus after the shear modification is further evidence of a branched structure.« less

Suitability of E-tongue Sensors to Assess Taste-Masking of Pediatric Liquids by Different Beverages Considering Their Physico-chemical Properties.

PubMed

Immohr, Laura Isabell; Hedfeld, Claas; Lang, Artur; Pein-Hackelbusch, Miriam

2017-02-01

Manipulation of liquid oral drugs by mixing them into foodstuff is a common procedure for taste-masking of OTC pharmaceuticals when administered to children. However, the taste-masking capability of such application media is not systematically evaluated, and recommendations for suitable media are hardly published. In this study, a sensor array of commercially available and self-developed electronic tongue sensors was employed to assess the taste-masking efficiency of eight different beverages (tap water, apple juice, carrot juice, fennel tea, fruit tea, milk, cocoa, and Alete meal to drink) on the OTC pharmaceuticals Ambroxol-ratiopharm®, Cetirizin AL, and Laxoberal® by multivariate data analysis. The Euclidean distances between each pure application medium and its corresponding drug mixture were used as an indicator for the taste-masking efficiency and correlated to the physico-chemical properties of the beverages. Thus, the pH value, the viscosity, as well as the fat and sugar content of the beverages were included, whereas only the viscosity appeared to be insignificant in all cases. The sugar content as well as the fat content and pH value emerged to be a significant variable in taste-masking efficiency for some of the tested drug products. It was shown that the applied electronic tongue sensors were capable to demonstrate the impact of the physico-chemical properties of the application media on their taste-masking capacity regardless of their non-selectivity towards these characteristics.

Accelerated Stability Testing of a Clobetasol Propionate-Loaded Nanoemulsion as per ICH Guidelines.

PubMed

Ali, Mohammad Sajid; Alam, Mohammad Sarfaraz; Alam, Nawazish; Anwer, Tarique; Safhi, Mohammed Mohsen A

2013-01-01

The physical and chemical degradation of drugs may result in altered therapeutic efficacy and even toxic effects. Therefore, the objective of this work was to study the stability of clobetasol propionate (CP) in a nanoemulsion. The nanoemulsion formulation containing CP was prepared by the spontaneous emulsification method. For the formulation of the nanoemulsion, Safsol, Tween 20, ethanol, and distilled water were used. The drug was incorporated into an oil phase in 0.05% w/v. The lipophilic nature of the drug led to the O/W nanoemulsion formulation. This was characterized by droplet size, pH, viscosity, conductivity, and refractive index. Stability studies were performed as per ICH guidelines for a period of three months. The shelf life of the nanoemulsion formulation was also determined after performing accelerated stability testing (40°C ± 2°C and 75% ± 5% RH). We also performed an intermediate stability study (30°C ± 2°C/65% RH ± 5% RH). It was found that the droplet size, conductivity, and refractive index were slightly increased, while the viscosity and pH slightly decreased at all storage conditions during the 3-month period. However, the changes in these parameters were not statistically significant (p≥0.05). The degradation (%) of the optimized nanoemulsion of CP was determined and the shelf life was found to be 2.18 years at room temperature. These studies confirmed that the physical and chemical stability of CP were enhanced in the nanoemulsion formulation.

Effects of fat content, pasteurization method, homogenization pressure, and storage time on the mechanical and sensory properties of bovine milk.

PubMed

Li, Y; Joyner, H S; Carter, B G; Drake, M A

2018-04-01

Fluid milk may be pasteurized by high-temperature short-time pasteurization (HTST) or ultrapasteurization (UP). Literature suggests that UP increases milk astringency, but definitive studies have not demonstrated this effect. Thus, the objective of this study was to determine the effects of pasteurization method, fat content, homogenization pressure, and storage time on milk sensory and mechanical behaviors. Raw skim (<0.2% fat), 2%, and 5% fat milk was pasteurized in duplicate by indirect UP (140°C, 2.3 s) or by HTST pasteurization (78°C, 15 s), homogenized at 20.7 MPa, and stored at 4°C for 8 wk. Additionally, 2% fat milk was processed by indirect UP and homogenized at 13.8, 20.7, and 27.6 MPa and stored at 4°C for 8 wk. Sensory profiling, instrumental viscosity, and friction profiles of all milk were evaluated at 25°C after storage times of 1, 4, and 8 wk. Sodium dodecyl sulfate PAGE and confocal laser scanning microscopy were used to determine protein structural changes in milk at these time points. Fresh HTST milk was processed at wk 7 for wk 8 evaluations. Ultrapasteurization increased milk sensory and instrumental viscosity compared with HTST pasteurization. Increased fat content increased sensory and instrumental viscosity, and decreased astringency and friction profiles. Astringency, mixed regimen friction profiles, and sensory viscosity also increased for UP versus HTST. Increased storage time showed no effect on sensory viscosity or mechanical viscosity. However, increased storage time generally resulted in increased friction profiles and astringency. Sodium dodecyl sulfate PAGE and confocal laser scanning microscopy showed increased denatured whey protein in UP milk compared with HTST milk. The aggregates or network formed by these proteins and casein micelles likely caused the increase in viscosity and friction profiles during storage. Homogenization pressure did not significantly affect friction behaviors, mechanical viscosity, or astringency; however, samples homogenized at 13.8 MPa versus 20.7 and 27.6 MPa showed higher sensory viscosity. Astringency was positively correlated with the friction coefficient at 100 m/s sliding speed (R 2 = 0.71 for HTST milk and R 2 = 0.74 for UP milk), and sensory viscosity was positively correlated with the mechanical viscosity at a shear rate of 50 s -1 (R 2 = 0.90). Thus, instrumental testing can be used to indicate certain sensory behaviors of milk. Copyright © 2018 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Fluid Mechanical Properties of Silkworm Fibroin Solutions

NASA Astrophysics Data System (ADS)

Matsumoto, Akira

2005-11-01

The aqueous solution behavior of silk fibroin is of interest due to the assembly and processing of this protein related to the spinning of protein fibers that exhibit remarkable mechanical properties. To gain insight into the origins of this functional feature, it is desired to determine how the protein behaves under a range of solution conditions. Pure fibroin at different concentrations in water was studied for surface tension, as a measure of surfactancy. In addition, shear induced changes on these solutions in terms of structure and morphology was also determined. Fibroin solutions exhibited shear rate-sensitive viscosity changes and precipitated at a critical shear rate where a dramatic increase of 75-150% of the initial value was observed along with a decrease in viscosity. In surface tension measurements, critical micelle concentrations were in the range of 3-4% w/v. The influence of additional factors, such as sericin protein, divalent and monovalent cations, and pH on the solution behavior in relation to structural and morphological features will also be described.

Formulation development of physiological environment responsive periodontal drug delivery system for local delviery of metronidazole benzoate.

PubMed

Dabhi, Mahesh R; Sheth, Navin R

2013-03-01

The objective of the present investigation was to develop and evaluate physiological environment responsive periodontal drug delivery system (PERPDDS) for local delivery of metronidazole benzoate. Poly-ϵ-caprolactone an in situ precipitating polymer was used in combination with, carbopol 934P, a pH simulative polymer to develop PERPDDS. The prepared PERPDDS was evaluated for various parameters such as in vitro gelling capacity, viscosity, rheology, compatibility study, and in vitro diffusion study. A 3(2) full factorial design was used to investigate the influence of formulation variables. Drug release data from all formulations were fitted to different kinetic models and the korsemeyer-peppas model was found the best fit model. The value of diffusional exponent (n) was in between 0.3283 and 0.3979 indicating purely fickian diffusion release mechanism. Increasing the concentration of each polymeric component increases viscosity, and time for 50% and 90% drug release was observed and graphically represented by the surface response and contour plots.

Spectroscopic studies on the interaction of sodium benzoate, a food preservative, with calf thymus DNA.

PubMed

Zhang, Guowen; Ma, Yadi

2013-11-01

The interaction between sodium benzoate (SB) and calf thymus DNA in simulated physiological buffer (pH 7.4) using acridine orange (AO) dye as a fluorescence probe, was investigated by UV-Vis absorption, fluorescence and circular dichroism (CD) spectroscopy along with DNA melting studies and viscosity measurements. An expanded UV-Vis spectral data matrix was resolved by multivariate curve resolution-alternating least squares (MCR-ALS) approach. The equilibrium concentration profiles and the pure spectra for SB, DNA and DNA-SB complex from the high overlapping composite response were simultaneously obtained. The results indicated that SB could bind to DNA, and hydrophobic interactions and hydrogen bonds played a vital role in the binding process. Moreover, SB was able to quench the fluorescence of DNA-AO complex through a static procedure. The quenching observed was indicative of an intercalative mode of interaction between SB and DNA, which was supported by melting studies, viscosity measurements and CD analysis. Copyright © 2013 Elsevier Ltd. All rights reserved.

Optimisation of low temperature extraction of banana juice using commercial pectinase.

PubMed

Sagu, Sorel Tchewonpi; Nso, Emmanuel Jong; Karmakar, Sankha; De, Sirshendu

2014-05-15

The objective of this work was to develop a process with optimum conditions for banana juice. The procedure involves hydrolyzing the banana pulp by commercial pectinase followed by cloth filtration. Response surface methodology with Doehlert design was utilised to optimize the process parameters. The temperature of incubation (30-60 °C), time of reaction (20-120 min) and concentration of pectinase (0.01-0.05% v/w) were the independent variables and viscosity, clarity, alcohol insoluble solids (AIS), total polyphenol and protein concentration were the responses. Total soluble sugar, pH, conductivity, calcium, sodium and potassium concentration in the juice were also evaluated. The results showed reduction of AIS and viscosity with reaction time and pectinase concentration and reduction of polyphenol and protein concentration with temperature. Using numerical optimization, the optimum conditions for the enzymatic extraction of banana juice were estimated. Depectinization kinetics was also studied at optimum temperature and variation of kinetic constants with enzyme dose was evaluated. Copyright © 2013 Elsevier Ltd. All rights reserved.

The tetrapeptide N-acetyl-Pro-Pro-Tyr-Leu in skin care formulations-Physicochemical and release studies.

PubMed

Olejnik, Anna; Schroeder, Grzegorz; Nowak, Izabela

2015-08-15

Recently there has been a growth of interest in the novel skin care formulations containing active ingredients such as low molecular weight peptides. In this paper we present new skincare formulations such as hydrogels, oil-in-water emulsions and water-in-oil emulsion containing a tetrapeptide (N-acetyl-Pro-Pro-Tyr-Leu). These formulations were characterized in terms of physicochemical parameters (pH, viscosity), stability and particle size distribution. Additionally, the diffusion parameters of the peptide in the obtained formulations were calculated based on the Einstein-Smoluchowski equation. Furthermore, in order to determine the penetration of the tetrapeptide through membranes its release kinetics were investigated. On the basis of release curves, the release rate constants were determined. The results proved that the properties of the formulations strongly determined the release rate of the tetrapeptide. The higher viscosity of the semisolid, the slower was the permeation through the membrane. Copyright © 2015 Elsevier B.V. All rights reserved.

Alkyltributylphosphonium chloride ionic liquids: synthesis, physicochemical properties and crystal structure.

PubMed

Adamová, Gabriela; Gardas, Ramesh L; Nieuwenhuyzen, Mark; Puga, Alberto V; Rebelo, Luís Paulo N; Robertson, Allan J; Seddon, Kenneth R

2012-07-21

A series of alkyltributylphosphonium chloride ionic liquids, prepared from tributylphosphine and the respective 1-chloroalkane, C(n)H(2n+1)Cl (where n = 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12 or 14), is reported. This work is a continuation of an extended series of tetraalkylphosphonium ionic liquids, where the focus is on the variability of n and its impact on the physical properties, such as melting points/glass transitions, thermal stability, density and viscosity. Experimental density and viscosity data were interpreted using QPSR and group contribution methods and the crystal structure of propyl(tributyl)phosphonium chloride is detailed.

Viscous flow of the Pd43Ni10Cu27P20 bulk metallic glass-forming liquid

NASA Astrophysics Data System (ADS)

Fan, G. J.; Fecht, H.-J.; Lavernia, E. J.

2004-01-01

The equilibrium viscosity of the Pd43Ni10Cu27P20 bulk metallic glass-forming liquid was measured over a wide temperature range from the equilibrium supercooled liquid state to the glass transition region using parallel-plate rheometry and three-point beam bending. Based on the measured viscosity data, the fragility of this liquid was quantitatively determined. The Pd43Ni10Cu27P20 alloy, despite exhibiting the best glass-forming ability reported thus far, is relatively fragile compared with other bulk glass-forming liquids, such as Vit 1 and Vit 4.

Study of drug concentration effects on in vitro lipolysis kinetics in medium-chain triglycerides by considering oil viscosity and surface tension.

PubMed

Arnold, Yvonne Elisabeth; Imanidis, Georgios; Kuentz, Martin

2011-10-09

Simple oil formulations are widely used in oral drug delivery and the fate of these systems is governed mainly by the dispersion and digestion process. The current work aimed to study concentration effects of six poorly water-soluble drugs on the in vitro lipolysis rate of medium-chain triglycerides. The results were compared with drug effects on oil viscosity and surface tension. First the different drugs were characterized by molecular modeling and their influence on physical oil properties was assessed. Herein capillary viscosimetry was employed as well as dynamic surface tensiometry. Subsequently, an apparent in vitro lipolysis rate was determined in biorelevant medium using an automated pH stat titrator linked to a thermo-controlled vessel. The different drugs exhibited varying effects on oil viscosity and surface tension. However, all drugs significantly lowered the apparent lipolysis rate of the oil. This effect was very similar among the different compounds with exception of orlistat, which practically blocked lipolysis because of a potent direct inhibition. The other drugs affected lipolysis kinetics most likely by different mechanism(s). In light of the obtained results, a drug effect on oil viscosity or surface tension appeared to play a minor role in reducing the lipolysis rate. The lipolysis kinetics was further not affected by the drug load, which was deemed advantageous from a pharmaceutical viewpoint. Different dose strengths are therefore not assumed to alter lipolysis kinetics, which is beneficial for limiting the variability of in vivo drug release. Further studies of drug solubility kinetics in the evolving digestion phases are, however, needed to finally assess potential effects of dosage strength in simple oil formulations. Copyright © 2011. Published by Elsevier B.V.

Improvement of flavor and viscosity in hot and cold break tomato juice and sauce by peel removal.

PubMed

Mirondo, Rita; Barringer, Sheryl

2015-01-01

Tomatoes are typically not peeled before being made into juice but the peels contain enzymes that affect the odor, flavor, and viscosity of the juice. The peels are removed in the finisher, but their presence during the break process may affect quality. Juice was processed from peeled and unpeeled tomatoes using hot or cold break. The juices were pasteurized by high temperature short time (HTST), low temperature long time (LTLT), or with a retort. The control samples were treated with 10% calcium chloride to stop enzymatic activity in the juice. Sauce was made from juice and the tomato products were analyzed for volatiles, color, viscosity, and by sensory. Cold break juice made with peel contained higher levels of some lipoxygenase-, carotenoid-, and amino acid-derived volatiles, than the juice made without peel. Because of the lack of enzyme activity, hot break juices had lower levels of these volatiles and there was no significant difference between hot break juices made with and without peel. CaCl2 -treated and HTST juice had higher levels of most of the volatiles than LTLT, including the lipoxygenase-derived volatiles. The presence of peel produced a significant decrease in the viscosity of the cold break juice and sauce. There was no significant difference in the hue angle, total soluble solids, pH, titratable acidity, and vitamin C for most of the treatments. The texture, flavor, and overall liking of cold break juice made without peel were preferred over cold break juice made with peel whereas the color was less preferred. Between the sauces no significant differences in preference were obtained. © 2014 Institute of Food Technologists®

Point-to-plane and plane-to-plane electrostatic charge injection atomization for insulating liquids

NASA Astrophysics Data System (ADS)

Malkawi, Ghazi

An electrostatic charge injection atomizer was fabricated and used to introduce and study the electrostatic charge injection atomization methods for highly viscous vegetable oils and high conductivity low viscosity aviation fuel, JP8. The total, spray and leakage currents and spray breakup characteristics for these liquids were investigated and compared with Diesel fuel data. Jet breakup and spray atomization mechanism showed differences for vegetable oils and lower viscosity hydrocarbon fuels. For vegetable oils, a bending/spinning instability phenomenon was observed similar to the phenomenon found in liquid jets of high viscosity polymer solutions. The spray tip lengths and cone angles were presented qualitatively and quantitatively and correlated with the appropriate empirical formulas. The different stages of the breakup mechanisms for such oils, as a function of specific charges and flow rates, were discussed. In order to make this method of atomization more suitable for practical use in high flow rate applications, a blunt face electrode (plane-to-plane) was used as the charge emitter in place of a single pointed electrode (point-to-plane). This allowed the use of a multi-orifice emitter that maintained a specific charge with the flow rate increase which could not be achieved with the needle electrode. The effect of the nozzle geometry, liquid physical properties and applied bulk flow on the spray charge, total charge, maximum critical spray specific charge and electrical efficiency compared with the needle point-to-plane atomizer results was presented. Our investigation revealed that the electrical efficiency of the atomizer is dominated by the charge forced convection rate rather than charge transport by ion motilities and liquid motion by the electric field. As a result of the electric coulomb forces between the electrified jets, the multi-orifice atomizer provided a unique means of dispersing the fuel in a hollow cone with wide angles making the new method suitable for variety of combustion applications.

Gamma irradiation of sorghum flour: Effects on microbial inactivation, amylase activity, fermentability, viscosity and starch granule structure

NASA Astrophysics Data System (ADS)

Mukisa, Ivan M.; Muyanja, Charles M. B. K.; Byaruhanga, Yusuf B.; Schüller, Reidar B.; Langsrud, Thor; Narvhus, Judith A.

2012-03-01

Malted and un-malted sorghum ( Sorghum bicolor (L.) Moench) flour was gamma irradiated with a dose of 10 kGy and then re-irradiated with 25 kGy. The effects of irradiation on microbial decontamination, amylase activity, fermentability (using an amylolytic L. plantarum MNC 21 strain), starch granule structure and viscosity were determined. Standard methods were used during determinations. The 10 kGy dose had no effect on microbial load of un-malted flour but reduced that of malted flour by 3 log cycles. Re-irradiation resulted in complete decontamination. Irradiation of malt caused a significant ( p<0.05) reduction in alpha and beta amylase activity (22% and 32%, respectively). Irradiation of un-malted flour increased the rates of utilization of glucose and maltose by 53% and 100%, respectively, during fermentation. However, microbial growth, rate of lactic acid production, final lactic acid concentration and pH were not affected. Starch granules appeared normal externally even after re-irradiation, however, granules ruptured and dissolved easily after hydration and gelatinization. Production of high dry matter density porridge (200 g dry matter/L) with a viscosity of 3500 cP was achieved by irradiation of un-malted flout at 10 kGy. Gamma irradiation can be used to decontaminate flours and could be utilized to produce weaning porridge from sorghum.

The Mechanisms and Biomedical Applications of an NIR BODIPY-Based Switchable Fluorescent Probe

PubMed Central

Cheng, Bingbing; Bandi, Venugopal; Yu, Shuai; D’Souza, Francis; Nguyen, Kytai T.; Hong, Yi; Tang, Liping; Yuan, Baohong

2017-01-01

Highly environment-sensitive fluorophores have been desired for many biomedical applications. Because of the noninvasive operation, high sensitivity, and high specificity to the microenvironment change, they can be used as excellent probes for fluorescence sensing/imaging, cell tracking/imaging, molecular imaging for cancer, and so on (i.e., polarity, viscosity, temperature, or pH measurement). In this work, investigations of the switching mechanism of a recently reported near-infrared environment-sensitive fluorophore, ADP(CA)2, were conducted. Besides, multiple potential biomedical applications of this switchable fluorescent probe have been demonstrated, including wash-free live-cell fluorescence imaging, in vivo tissue fluorescence imaging, temperature sensing, and ultrasound-switchable fluorescence (USF) imaging. The fluorescence of the ADP(CA)2 is extremely sensitive to the microenvironment, especially polarity and viscosity. Our investigations showed that the fluorescence of ADP(CA)2 can be switched on by low polarity, high viscosity, or the presence of protein and surfactants. In wash-free live-cell imaging, the fluorescence of ADP(CA)2 inside cells was found much brighter than the dye-containing medium and was retained for at least two days. In all of the fluorescence imaging applications conducted in this study, high target-to-noise (>5-fold) was achieved. In addition, a high temperature sensitivity (73-fold per Celsius degree) of ADP(CA)2-based temperature probes was found in temperature sensing. PMID:28208666

Abiotic versus biotic drivers of ocean pH variation under fast sea ice in McMurdo Sound, Antarctica.

PubMed

Matson, Paul G; Washburn, Libe; Martz, Todd R; Hofmann, Gretchen E

2014-01-01

Ocean acidification is expected to have a major effect on the marine carbonate system over the next century, particularly in high latitude seas. Less appreciated is natural environmental variation within these systems, particularly in terms of pH, and how this natural variation may inform laboratory experiments. In this study, we deployed sensor-equipped moorings at 20 m depths at three locations in McMurdo Sound, comprising deep (bottom depth>200 m: Hut Point Peninsula) and shallow environments (bottom depth ∼25 m: Cape Evans and New Harbor). Our sensors recorded high-frequency variation in pH (Hut Point and Cape Evans only), tide (Cape Evans and New Harbor), and water mass properties (temperature and salinity) during spring and early summer 2011. These collective observations showed that (1) pH differed spatially both in terms of mean pH (Cape Evans: 8.009±0.015; Hut Point: 8.020±0.007) and range of pH (Cape Evans: 0.090; Hut Point: 0.036), and (2) pH was not related to the mixing of two water masses, suggesting that the observed pH variation is likely not driven by this abiotic process. Given the large daily fluctuation in pH at Cape Evans, we developed a simple mechanistic model to explore the potential for biotic processes--in this case algal photosynthesis--to increase pH by fixing carbon from the water column. For this model, we incorporated published photosynthetic parameters for the three dominant algal functional groups found at Cape Evans (benthic fleshy red macroalgae, crustose coralline algae, and sea ice algal communities) to estimate oxygen produced/carbon fixed from the water column underneath fast sea ice and the resulting pH change. These results suggest that biotic processes may be a primary driver of pH variation observed under fast sea ice at Cape Evans and potentially at other shallow sites in McMurdo Sound.

Abiotic versus Biotic Drivers of Ocean pH Variation under Fast Sea Ice in McMurdo Sound, Antarctica

PubMed Central

Matson, Paul G.; Washburn, Libe; Martz, Todd R.; Hofmann, Gretchen E.

2014-01-01

Ocean acidification is expected to have a major effect on the marine carbonate system over the next century, particularly in high latitude seas. Less appreciated is natural environmental variation within these systems, particularly in terms of pH, and how this natural variation may inform laboratory experiments. In this study, we deployed sensor-equipped moorings at 20 m depths at three locations in McMurdo Sound, comprising deep (bottom depth>200 m: Hut Point Peninsula) and shallow environments (bottom depth ∼25 m: Cape Evans and New Harbor). Our sensors recorded high-frequency variation in pH (Hut Point and Cape Evans only), tide (Cape Evans and New Harbor), and water mass properties (temperature and salinity) during spring and early summer 2011. These collective observations showed that (1) pH differed spatially both in terms of mean pH (Cape Evans: 8.009±0.015; Hut Point: 8.020±0.007) and range of pH (Cape Evans: 0.090; Hut Point: 0.036), and (2) pH was not related to the mixing of two water masses, suggesting that the observed pH variation is likely not driven by this abiotic process. Given the large daily fluctuation in pH at Cape Evans, we developed a simple mechanistic model to explore the potential for biotic processes – in this case algal photosynthesis – to increase pH by fixing carbon from the water column. For this model, we incorporated published photosynthetic parameters for the three dominant algal functional groups found at Cape Evans (benthic fleshy red macroalgae, crustose coralline algae, and sea ice algal communities) to estimate oxygen produced/carbon fixed from the water column underneath fast sea ice and the resulting pH change. These results suggest that biotic processes may be a primary driver of pH variation observed under fast sea ice at Cape Evans and potentially at other shallow sites in McMurdo Sound. PMID:25221950

A Novel Acid-Stable Endo-Polygalacturonase from Penicillium oxalicum CZ1028: Purification, Characterization, and Application in the Beverage Industry.

PubMed

Cheng, Zhong; Chen, Dong; Lu, Bo; Wei, Yutuo; Xian, Liang; Li, Yi; Luo, Zhenzhen; Huang, Ribo

2016-06-28

Acidic endo-polygalacturonases are the major part of pectinase preparations and extensively applied in the clarification of fruits juice, vegetables extracts, and wines. However, most of the reported fungal endo-polygalacturonases are active and stable under narrow pH range and low temperatures. In this study, an acidic endo-polygalacturonase (EPG4) was purified and characterized from a mutant strain of Penicillium oxalicum. The N-terminal amino acid sequence of EPG4 (ATTCTFSGSNGAASASKSQT) was different from those of reported endopolygalacturonases. EPG4 displayed optimal pH and temperature at 5.0 and 60-70°C towards polygalacturonic acid (PGA), respectively, and was notably stable at pH 2.2-7.0. When tested against pectins, EPG4 showed enzyme activity over a broad acidic pH range (>15.0% activity at pH 2.2-6.0 towards citrus pectin; and >26.6% activity at pH 2.2-7.0 towards apple pectin). The Km and Vmax values were determined as 1.27 mg/ml and 5,504.6 U/mg, respectively. The enzyme hydrolyzed PGA in endo-manner, releasing oligo-galacturonates from PGA, as determined by TLC. Addition of EPG4 (3.6 U/ml) significantly reduced the viscosity (by 42.4%) and increased the light transmittance (by 29.5%) of the papaya pulp, and increased the recovery (by 24.4%) of the papaya extraction. All of these properties make the enzyme a potential application in the beverage industry.

Routine Testing of Bitumen Binders

NASA Astrophysics Data System (ADS)

Holý, Michal; Remišová, Eva

2017-12-01

The quality of bituminous binders used in the construction and maintenance of road surfaces is currently assessed by empirical testing based on obtaining one value for specific boundary conditions, which were designed about 100 years ago. Basic empirical tests include the softening point and penetration, but the practice shows that these tests appear to be inadequate. The evaluation of changes of bitumen properties during the production and paving process of bituminous mixture is also important. The paper points out how the "traditional" tests as softening point and penetration and viscosity are sufficient to evaluate properties of bitumen binders.

A Novel GH7 Endo-β-1,4-Glucanase from Neosartorya fischeri P1 with Good Thermostability, Broad Substrate Specificity and Potential Application in the Brewing Industry.

PubMed

Liu, Yun; Dun, Baoqing; Shi, Pengjun; Ma, Rui; Luo, Huiying; Bai, Yingguo; Xie, Xiangming; Yao, Bin

2015-01-01

An endo-β-1,4-glucanase gene, cel7A, was cloned from the thermophilic cellulase-producing fungus Neosartorya fischeri P1 and expressed in Pichia pastoris. The 1,410-bp full-length gene encodes a polypeptide of 469 amino acids consisting of a putative signal peptide at residues 1-20, a catalytic domain of glycoside hydrolase family 7 (GH7), a short Thr/Ser-rich linker and a family 1 carbohydrate-binding module (CBM 1). The purified recombinant Cel7A had pH and temperature optima of pH 5.0 and 60°C, respectively, and showed broad pH adaptability (pH 3.0-6.0) and excellent stability at pH3.0-8.0 and 60°C. Belonging to the group of nonspecific endoglucanases, Cel7A exhibited the highest activity on barley β-glucan (2020 ± 9 U mg-1), moderate on lichenan and CMC-Na, and weak on laminarin, locust bean galactomannan, Avicel, and filter paper. Under simulated mashing conditions, addition of Cel7A (99 μg) reduced the mash viscosity by 9.1% and filtration time by 24.6%. These favorable enzymatic properties make Cel7A as a good candidate for applications in the brewing industry.

Separation of switchgrass bio-oil by water/organic solvent addition and pH adjustment

DOE PAGES

Park, Lydia Kyoung-Eun; Ren, Shoujie; Yiacoumi, Sotira; ...

2016-01-29

Applications of bio-oil are limited by its challenging properties including high moisture content, low pH, high viscosity, high oxygen content, and low heating value. Separation of switchgrass bio-oil components by adding water, organic solvents (hexadecane and octane), and sodium hydroxide may help to overcome these issues. Acetic acid and phenolic compounds were extracted in aqueous and organic phases, respectively. Polar chemicals, such as acetic acid, did not partition in the organic solvent phase. Acetic acid in the aqueous phase after extraction is beneficial for a microbial-electrolysis-cell application to produce hydrogen as an energy source for further hydrodeoxygenation of bio-oil. Organicmore » solvents extracted more chemicals from bio-oil in combined than in sequential extraction; however, organic solvents partitioned into the aqueous phase in combined extraction. When sodium hydroxide was added to adjust the pH of aqueous bio-oil, organic-phase precipitation occurred. As the pH was increased, a biphasic aqueous/organic dispersion was formed, and phase separation was optimized at approximately pH 6. The neutralized organic bio-oil had approximately 37% less oxygen and 100% increased heating value than the initial centrifuged bio-oil. In conclusion, the less oxygen content and increased heating value indicated a significant improvement of the bio-oil quality through neutralization.« less

Separation of switchgrass bio-oil by water/organic solvent addition and pH adjustment

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

Park, Lydia Kyoung-Eun; Ren, Shoujie; Yiacoumi, Sotira

Applications of bio-oil are limited by its challenging properties including high moisture content, low pH, high viscosity, high oxygen content, and low heating value. Separation of switchgrass bio-oil components by adding water, organic solvents (hexadecane and octane), and sodium hydroxide may help to overcome these issues. Acetic acid and phenolic compounds were extracted in aqueous and organic phases, respectively. Polar chemicals, such as acetic acid, did not partition in the organic solvent phase. Acetic acid in the aqueous phase after extraction is beneficial for a microbial-electrolysis-cell application to produce hydrogen as an energy source for further hydrodeoxygenation of bio-oil. Organicmore » solvents extracted more chemicals from bio-oil in combined than in sequential extraction; however, organic solvents partitioned into the aqueous phase in combined extraction. When sodium hydroxide was added to adjust the pH of aqueous bio-oil, organic-phase precipitation occurred. As the pH was increased, a biphasic aqueous/organic dispersion was formed, and phase separation was optimized at approximately pH 6. The neutralized organic bio-oil had approximately 37% less oxygen and 100% increased heating value than the initial centrifuged bio-oil. In conclusion, the less oxygen content and increased heating value indicated a significant improvement of the bio-oil quality through neutralization.« less

Palmyra palm (Borassus aethiopum Mart.) fruits: novel raw materials for the pectin industry.

PubMed

Assoi, Sylvie; Konan, Koffi; Agbo, Georges N; Dodo, Hortense; Holser, Ron; Wicker, Louise

2017-05-01

Preventing post-harvest waste of Palmyra palm (Borassus aethiopum Mart.) fruits is possible by recovery of pectin as a value-added ingredient. Extraction conditions on yield and functionality of Palmyra palm pectin was determined at different temperatures and pH values with 30 min extraction time. Palmyra palm fruits contain more than 650 g kg -1 galacturonic acid and produce soft gels with sucrose in acidic media despite a high degree of acetylation (∼5%). Mechanical deformation of pectin gel was similar when extracted at pH 2.5 and 70 °C or under natural pH at room temperature or 70 °C. Pectins isolated at pH 7 exhibited comparable gel softness (G'/G″) with commercial pectin. Palm pectins also showed emulsifying activity greater than 50%, attributed to high protein content of 8 g 100 g -1 . For pectins extracted at pH near 5.2-5.5, molar mass ranged from 3.00 to 3.38 × 10 5 g mol -1 ; intrinsic viscosity ranged from 218 to 297 mL g -1 ; arabinose was the main neutral sugar; ζ-potential ranged from -23 to -25 mV. Palm fruit offers an inexpensive raw material to extract pectin in environmentally friendly and economical way and yield a pectin with unique gelling, viscosifying and emulsifying properties. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

Shear thinning behaviors in magmas

NASA Astrophysics Data System (ADS)

Vetere, F. P.; Cassetta, M.; Perugini, D.

2017-12-01

Studies on magma rheology are of fundamental importance to understanding magmatic processes from depth to surface. Since viscosity is one of the most important parameter controlling eruption mechanisms, as well as lava flow emplacement, a comprehensive knowledge on the evolution of magma viscosities during crystallization is required. We present new viscosity data on partly crystalized basalt, andesite and analogue lavas comparable to those erupted on Mercury's northern volcanic plains. High-temperature viscosity measurements were performed using a rotational Anton Paar RheolabQC viscometer head at the PVRG labs, in Perugia (Italy) (http://pvrg.unipg.it). The relative proportion of phases in each experimental run were determined by image analysis on BS-SEM images at different magnifications; phases are glasses, clinopyroxene, spinel, plagioclase for the basalt, plagioclase and spinel for the andesite and pure enstatite and clinopyroxenes, for the analogue Mercury's composition. Glass and crystalline fractions determined by image analysis well correlate with compositions of residual melts. In order to constrain the viscosity (η) variations as a function of crystallinity, shear rate (γ) was varied from 0.1 to 5 s-1. Viscosity vs. time at constant temperature shows a typical S-shape curve. In particular, for basaltic composition η vary from 3.1-3.8 Pa s [log η] at 1493 K and crystallinity of 19 area % as γ vary from 1.0 to 0.1 s-1; the andesite viscosity evolution is 3.2 and 3.7 Pa s [log η] as γ varies from 1 to 0.1 at 1493 K and crystal content of 17 area %; finally, Mercury's analogue composition was investigated at different temperature ranging from 1533 to 1502 K (Vetere et al., 2017). Results, for γ = 0.1, 1.0 and 5.0 s-1, show viscosity variation between 2.7-4.0, 2.5-3.4 and 2.0-3.0 [log η inPa s] respectively while crystallinity vary from 9 to 27 (area %). As viscosity decreases as shear rate increases, these data points to a shear thinning behaviour of the partly crystallized melt. This new dataset can be used to model the behaviour of lavas during magma rise in conduits and lava flow on Earth surface and other planetary bodies. F. Vetere et al., (2017) Experimental constraints on the rheology, eruption and emplacement dynamics of lavas from Mercury Northern Volcanic Plains". JGR-Planets DOI: 10.1002/2016JE005181

40 CFR 430.45 - New source performance standards (NSPS).

Code of Federal Regulations, 2011 CFR

2011-07-01

... GUIDELINES AND STANDARDS THE PULP, PAPER, AND PAPERBOARD POINT SOURCE CATEGORY Dissolving Sulfite Subcategory... dissolving sulfite pulp facilities where nitration grade pulp is produced] Pollutant or pollutant property Kg... dissolving sulfite pulp facilities where viscose grade pulp is produced] Pollutant or pollutant property Kg...

Correlations for the Viscosity of 2,3,3,3-Tetrafluoroprop-1-ene (R1234yf) and trans-1,3,3,3-Tetrafluoropropene (R1234ze(E))†

PubMed Central

Huber, Marcia L.; Assael, Marc J.

2016-01-01

Due to concerns about global warming, there is interest in 2,3,3,3-Tetrafluoroprop-1-ene (R1234yf) and trans-1,3,3,3-Tetrafluoropropene (R1234ze(E)) as potential replacements for refrigerants with high global warming potential (GWP). In this manuscript we survey available data and provide viscosity correlations that cover the entire fluid range including vapor, liquid, and supercritical regions. The correlation for R1234yf is valid from the triple point (220 K) to 410 K at pressures up to 30 MPa, and the correlation for R1234ze(E) is valid from the triple point (169 K) to 420 K at pressures up to 100 MPa. The estimated uncertainty for both correlations at a 95 % confidence level is 2 % for the liquid phase over the temperature range 243 K to 363 K at pressures to 30 MPa, and 3 % for the gas phase at atmospheric pressure. PMID:27840461

Effects of pre-cooked cheeses of different emulsifying conditions on mechanical properties and microstructure of processed cheese.

PubMed

Fu, Wei; Watanabe, Yurika; Inoue, Keita; Moriguchi, Natsumi; Fusa, Kazunao; Yanagisawa, Yuya; Mutoh, Takaaki; Nakamura, Takashi

2018-04-15

The effect of pre-cooked cheeses of different emulsifying conditions on the viscosities, mechanical properties, fat globules, and microstructure of processed cheese was investigated, and changes in protein network relating to the creaming effect and the occurrence of yielding point were discussed. The addition of pre-cooked cheeses with a short stirring time had no obvious impact on the fat globules and protein network. The random network brought low viscosities and a gradual increase in the fracture stress/strain curve. The addition of pre-cooked cheeses with the long stirring time caused protein network to become fine-stranded. The fine-stranded network caused creaming effect, and brought yielding points in the mechanical properties. The pre-cooked cheese with the small fat globules also caused fat globules to become smaller, and give the processed cheese more firmness. This study provides a potential solution to control the functional properties of processed cheese by using a variety of pre-cooked cheeses. Copyright © 2017 Elsevier Ltd. All rights reserved.

Bio-lubricants derived from waste cooking oil with improved oxidation stability and low-temperature properties.

PubMed

Li, Weimin; Wang, Xiaobo

2015-01-01

Waste cooking oil (WCO) was chemically modified via epoxidation using H2O2 followed by transesterification with methanol and branched alcohols (isooctanol, isotridecanol and isooctadecanol) to produce bio-lubricants with improved oxidative stability and low temperature properties. Physicochemical properties of synthesized bio-lubricants such as pour point (PP), cloud point (CP), viscosity, viscosity index (VI), oxidative stability, and corrosion resistant property were determined according to standard methods. The synthesized bio-lubricants showed improved low temperature flow performances compared with WCO, which can be attributing to the introduction of branched chains in their molecular structures. What's more, the oxidation stability of the WCO showed more than 10 folds improvement due to the elimination of -C=C-bonds in the WCO molecule. Tribological performances of these bio-lubricants were also investigated using four-ball friction and wear tester. Experimental results showed that derivatives of WCO exhibited favorable physicochemical properties and tribological performances which making them good candidates in formulating eco-friendly lubricants.

Connecting thermodynamic and dynamical anomalies of water-like liquid-liquid phase transition in the Fermi-Jagla model

NASA Astrophysics Data System (ADS)

Higuchi, Saki; Kato, Daiki; Awaji, Daisuke; Kim, Kang

2018-03-01

We present a study using molecular dynamics simulations based on the Fermi-Jagla potential model, which is the continuous version of the mono-atomic core-softened Jagla model [J. Y. Abraham, S. V. Buldyrev, and N. Giovambattista, J. Phys. Chem. B 115, 14229 (2011)]. This model shows the water-like liquid-liquid phase transition between high-density and low-density liquids at the liquid-liquid critical point. In particular, the slope of the coexistence line becomes weakly negative, which is expected to represent one of the anomalies of liquid polyamorphism. In this study, we examined the density, dynamic, and thermodynamic anomalies in the vicinity of the liquid-liquid critical point. The boundaries of density, self-diffusion, shear viscosity, and excess entropy anomalies were characterized. Furthermore, these anomalies are connected according to Rosenfeld's scaling relationship between the excess entropy and the transport coefficients such as diffusion and viscosity. The results demonstrate the hierarchical and nested structures regarding the thermodynamic and dynamic anomalies of the Fermi-Jagla model.

Synergistic enhancement in the co-gelation of salt-soluble pea proteins and whey proteins.

PubMed

Wong, Douglas; Vasanthan, Thava; Ozimek, Lech

2013-12-15

This paper investigated the enhancement of thermal gelation properties when salt-soluble pea proteins were co-gelated with whey proteins in NaCl solutions, using different blend ratios, total protein concentrations, pH, and salt concentrations. Results showed that the thermal co-gelation of pea/whey proteins blended in ratio of 2:8 in NaCl solutions showed synergistic enhancement in storage modulus, gel hardness, paste viscosity and minimum gelation concentrations. The highest synergistic enhancement was observed at pH 6.0 as compared with pH 4.0 and 8.0, and at the lower total protein concentration of 10% as compared with 16% and 22% (w/v), as well as in lower NaCl concentrations of 0.5% and 1.0% as compared with 1.5%, 2.0%, 2.5%, and 3.0% (w/v). The least gelation concentrations were also lower in the different pea/whey protein blend ratios than in pure pea or whey proteins, when dissolved in 1.0% or 2.5% (w/v) NaCl aqueous solutions. Copyright © 2013 Elsevier Ltd. All rights reserved.

Membrane-mediated extractive fermentation for lactic acid production from cellulosic biomass.

PubMed

Chen, R; Lee, Y Y

1997-01-01

Lactic acid production from cellulosic biomass by cellulase and Lactobacillus delbrueckii was studied in a fermenter-extractor employing a microporous hollow fiber membrane (MHF). This bioreactor system was operated under a fed-batch mode with continuous removal of lactic acid by anin situ extraction. A tertiary amine (Alamine 336) was used as an extractant for lactic acid. The extraction capacity of Alamine 336 is greatly enhanced by addition of alcohol. Long-chain alcohols serve well for this purpose since they are less toxic to micro-organism. Addition of kerosene, a diluent, was necessary to reduce the solvent viscosity. A solvent mixture of 20% Alamine 336, 40% oleyl alcohol, and 40% kerosene was found to be most effective in the extraction of lactic acid. Progressive change of pH from an initial value of 5.0 down to 4.3 has significantly improved the overall performance of the simultaneous saccharification and extractive fermentation over that of constant pH operation. The change of pH was applied to promote cell growth in the early phase, and extraction in the latter phase.

High-yield production of a low-temperature-active polygalacturonase for papaya juice clarification.

PubMed

Tu, Tao; Meng, Kun; Bai, Yingguo; Shi, Pengjun; Luo, Huiying; Wang, Yaru; Yang, Peilong; Zhang, Yuhong; Zhang, Wei; Yao, Bin

2013-12-01

A novel endo-polygalacturonase (endo-PG I) from Achaetomium sp. Xz8 was identified, overexpressed in Pichia pastoris, and characterized in this report. Recombinant endo-PG I is distinguished from other enzyme counterparts by its high activity towards polygalacturonic acid (49,934 U/ml) and high yield in the 15-l fermentor (2.13 g/l). It exhibits optimal activity at 45 °C and remained active over a broad temperature range of 0-80 °C. Distinct from most fungal polygalacturonases that have acidic pH optima, endo-PG I is optimally active at pH 6, similar to the pH of fresh papaya juice (5.7). Endo-PG I alone reduced the viscosity of papaya juice by 17.6%, and increased its transmittance by 59.1%. When combined with a commercial pectin methylesterase, it showed much higher efficiency with a synergy degree of more than 1.25. All these favourable enzymatic properties make endo-PG I attractive for potential applications in the juice industry. Copyright © 2013 Elsevier Ltd. All rights reserved.

Solution of magnetohydrodynamic flow and heat transfer of radiative viscoelastic fluid with temperature dependent viscosity in wire coating analysis

PubMed Central

Khan, Muhammad Altaf; Siddiqui, Nasir; Ullah, Murad; Shah, Qayyum

2018-01-01

Wire coating process is a continuous extrusion process for primary insulation of conducting wires with molten polymers for mechanical strength and protection in aggressive environments. In the present study, radiative melt polymer satisfying third grade fluid model is used for wire coating process. The effect of magnetic parameter, thermal radiation parameter and temperature dependent viscosity on wire coating analysis has been investigated. Reynolds model and Vogel’s models have been incorporated for variable viscosity. The governing equations characterizing the flow and heat transfer phenomena are solved analytically by utilizing homotopy analysis method (HAM). The computed results are also verified by ND-Solve method (Numerical technique) and Adomian Decomposition Method (ADM). The effect of pertinent parameters is shown graphically. In addition, the instability of the flow in the flows of the wall of the extrusion die is well marked in the case of the Vogel model as pointed by Nhan-Phan-Thien. PMID:29596448

40 CFR 434.22 - Effluent limitation guidelines representing the degree of effluent reduction attainable by the...

Code of Federal Regulations, 2014 CFR

2014-07-01

... consecutive days Concentration in mg/l Iron, total 7.0 3.5 Manganese, total 4.0 2.0 TSS 70 35 pH 1 1 1 Within... if discharges from such point sources normally exhibit a pH of less than 6.0 prior to treatment: BPT... practicable control technology currently available if discharges from such point sources normally exhibit a pH...

40 CFR 434.22 - Effluent limitation guidelines representing the degree of effluent reduction attainable by the...

Code of Federal Regulations, 2010 CFR

2010-07-01

... consecutive days Concentration in mg/l Iron, total 7.0 3.5 Manganese, total 4.0 2.0 TSS 70 35 pH 1 1 1 Within... if discharges from such point sources normally exhibit a pH of less than 6.0 prior to treatment: BPT... practicable control technology currently available if discharges from such point sources normally exhibit a pH...

40 CFR 434.22 - Effluent limitation guidelines representing the degree of effluent reduction attainable by the...

Code of Federal Regulations, 2011 CFR

2011-07-01

... consecutive days Concentration in mg/l Iron, total 7.0 3.5 Manganese, total 4.0 2.0 TSS 70 35 pH 1 1 1 Within... if discharges from such point sources normally exhibit a pH of less than 6.0 prior to treatment: BPT... practicable control technology currently available if discharges from such point sources normally exhibit a pH...

40 CFR 434.22 - Effluent limitation guidelines representing the degree of effluent reduction attainable by the...

Code of Federal Regulations, 2013 CFR

2013-07-01

... consecutive days Concentration in mg/l Iron, total 7.0 3.5 Manganese, total 4.0 2.0 TSS 70 35 pH 1 1 1 Within... if discharges from such point sources normally exhibit a pH of less than 6.0 prior to treatment: BPT... practicable control technology currently available if discharges from such point sources normally exhibit a pH...

40 CFR 434.22 - Effluent limitation guidelines representing the degree of effluent reduction attainable by the...

Code of Federal Regulations, 2012 CFR

2012-07-01

... consecutive days Concentration in mg/l Iron, total 7.0 3.5 Manganese, total 4.0 2.0 TSS 70 35 pH 1 1 1 Within... if discharges from such point sources normally exhibit a pH of less than 6.0 prior to treatment: BPT... practicable control technology currently available if discharges from such point sources normally exhibit a pH...

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

Predota, Milan; Machesky, Michael L.; Wesolowski, David J.

The zeta potential (ZP) is an oft-reported measure of the macroscopic charge state of solid surfaces and colloidal particles in contact with solvents. However, the origin of this readily measurable parameter has remained divorced from the molecular-level processes governing the underlying electrokinetic phenomena, which limits its usefulness. Here, we connect the macroscopic measure to the microscopic realm through nonequilibrium molecular dynamics simulations of electroosmotic flow between parallel slabs of the hydroxylated (110) rutile (TiO 2) surface. These simulations provided streaming mobilities, which were converted to ZP via the commonly used Helmholtz-Smoluchowski equation. A range of rutile surface charge densities (0.1more » to –0.4 C/m 2), corresponding to pH values between about 2.8 and 9.4, in RbCl, NaCl, and SrCl 2 aqueous solutions, were modeled and compared to experimental ZPs for TiO 2 particle suspensions. Simulated ZPs qualitatively agree with experiment and show that “anomalous” ZP values and inequalities between the point of zero charge derived from electrokinetic versus pH titration measurements both arise from differing co- and counterion sorption affinities. We show that at the molecular level the ZP arises from the delicate interplay of spatially varying dynamics, structure, and electrostatics in a narrow interfacial region within about 15 Å of the surface, even in dilute salt solutions. This contrasts fundamentally with continuum descriptions of such interfaces, which predict the ZP response region to be inversely related to ionic strength. In reality the properties of this interfacial region are dominated by relatively immobile and structured water. Furthermore, viscosity values are substantially greater than in the bulk, and electrostatic potential profiles are oscillatory in nature.« less

Molecular origins of the zeta potential

DOE PAGES

Predota, Milan; Machesky, Michael L.; Wesolowski, David J.

2016-09-19

The zeta potential (ZP) is an oft-reported measure of the macroscopic charge state of solid surfaces and colloidal particles in contact with solvents. However, the origin of this readily measurable parameter has remained divorced from the molecular-level processes governing the underlying electrokinetic phenomena, which limits its usefulness. Here, we connect the macroscopic measure to the microscopic realm through nonequilibrium molecular dynamics simulations of electroosmotic flow between parallel slabs of the hydroxylated (110) rutile (TiO 2) surface. These simulations provided streaming mobilities, which were converted to ZP via the commonly used Helmholtz-Smoluchowski equation. A range of rutile surface charge densities (0.1more » to –0.4 C/m 2), corresponding to pH values between about 2.8 and 9.4, in RbCl, NaCl, and SrCl 2 aqueous solutions, were modeled and compared to experimental ZPs for TiO 2 particle suspensions. Simulated ZPs qualitatively agree with experiment and show that “anomalous” ZP values and inequalities between the point of zero charge derived from electrokinetic versus pH titration measurements both arise from differing co- and counterion sorption affinities. We show that at the molecular level the ZP arises from the delicate interplay of spatially varying dynamics, structure, and electrostatics in a narrow interfacial region within about 15 Å of the surface, even in dilute salt solutions. This contrasts fundamentally with continuum descriptions of such interfaces, which predict the ZP response region to be inversely related to ionic strength. In reality the properties of this interfacial region are dominated by relatively immobile and structured water. Furthermore, viscosity values are substantially greater than in the bulk, and electrostatic potential profiles are oscillatory in nature.« less

Gradient-free determination of isoelectric points of proteins on chip.

PubMed

Łapińska, Urszula; Saar, Kadi L; Yates, Emma V; Herling, Therese W; Müller, Thomas; Challa, Pavan K; Dobson, Christopher M; Knowles, Tuomas P J

2017-08-30

The isoelectric point (pI) of a protein is a key characteristic that influences its overall electrostatic behaviour. The majority of conventional methods for the determination of the isoelectric point of a molecule rely on the use of spatial gradients in pH, although significant practical challenges are associated with such techniques, notably the difficulty in generating a stable and well controlled pH gradient. Here, we introduce a gradient-free approach, exploiting a microfluidic platform which allows us to perform rapid pH change on chip and probe the electrophoretic mobility of species in a controlled field. In particular, in this approach, the pH of the electrolyte solution is modulated in time rather than in space, as in the case for conventional determinations of the isoelectric point. To demonstrate the general approachability of this platform, we have measured the isoelectric points of representative set of seven proteins, bovine serum albumin, β-lactoglobulin, ribonuclease A, ovalbumin, human transferrin, ubiquitin and myoglobin in microlitre sample volumes. The ability to conduct measurements in free solution thus provides the basis for the rapid determination of isoelectric points of proteins under a wide variety of solution conditions and in small volumes.

Adsorption of bovine serum albumin on silicon dioxide nanoparticles: Impact of pH on nanoparticle-protein interactions.

PubMed

Givens, Brittany E; Diklich, Nina D; Fiegel, Jennifer; Grassian, Vicki H

2017-05-03

Bovine serum albumin (BSA) adsorbed on amorphous silicon dioxide (SiO 2 ) nanoparticles was studied as a function of pH across the range of 2 to 8. Aggregation, surface charge, surface coverage, and protein structure were investigated over this entire pH range. SiO 2 nanoparticle aggregation is found to depend upon pH and differs in the presence of adsorbed BSA. For SiO 2 nanoparticles truncated with hydroxyl groups, the largest aggregates were observed at pH 3, close to the isoelectric point of SiO 2 nanoparticles, whereas for SiO 2 nanoparticles with adsorbed BSA, the aggregate size was the greatest at pH 3.7, close to the isoelectric point of the BSA-SiO 2 complex. Surface coverage of BSA was also the greatest at the isoelectric point of the BSA-SiO 2 complex with a value of ca. 3 ±   1 × 10 11 molecules cm -2 . Furthermore, the secondary protein structure was modified when compared to the solution phase at all pH values, but the most significant differences were seen at pH 7.4 and below. It is concluded that protein-nanoparticle interactions vary with solution pH, which may have implications for nanoparticles in different biological fluids (e.g., blood, stomach, and lungs).

Transport and dielectric properties of water and the influence of coarse-graining: Comparing BMW, SPC/E, and TIP3P models

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

Braun, Daniel; Boresch, Stefan; Steinhauser, Othmar

Long-term molecular dynamics simulations are used to compare the single particle dipole reorientation time, the diffusion constant, the viscosity, and the frequency-dependent dielectric constant of the coarse-grained big multipole water (BMW) model to two common atomistic three-point water models, SPC/E and TIP3P. In particular, the agreement between the calculated viscosity of BMW and the experimental viscosity of water is satisfactory. We also discuss contradictory values for the static dielectric properties reported in the literature. Employing molecular hydrodynamics, we show that the viscosity can be computed from single particle dynamics, circumventing the slow convergence of the standard approaches. Furthermore, our datamore » indicate that the Kivelson relation connecting single particle and collective reorientation time holds true for all systems investigated. Since simulations with coarse-grained force fields often employ extremely large time steps, we also investigate the influence of time step on dynamical properties. We observe a systematic acceleration of system dynamics when increasing the time step. Carefully monitoring energy/temperature conservation is found to be a sufficient criterion for the reliable calculation of dynamical properties. By contrast, recommended criteria based on the ratio of fluctuations of total vs. kinetic energy are not sensitive enough.« less

The volume-viscosity swallow test for clinical screening of dysphagia and aspiration.

PubMed

Rofes, Laia; Arreola, Viridiana; Clavé, Pere

2012-01-01

Oropharyngeal dysphagia (OD) is a major complaint among many patients with neurological diseases and in the elderly, but is often underdiagnosed. The volume-viscosity swallow test (V-VST) is a bedside method to screen patients for dysphagia. The V-VST was designed to identify clinical signs of impaired efficacy (labial seal, oral and pharyngeal residue, and piecemeal deglutition) and impaired safety of swallow (voice changes, cough and decrease in oxygen saturation ≥3%). It starts with nectar viscosity and increasing bolus volume, then liquid and finally pudding viscosity in a progression of increasing difficulty to protect patients from aspiration. The V-VST allows quick, safe and accurate screening for OD in hospitalized and independently living patients with multiple etiologies. The V-VST presents a sensitivity of 88.2% and a specificity of 64.7% to detect clinical signs of impaired safety of swallow (aspiration or penetration). The test takes 5-10 min to complete. The V-VST is an excellent tool to screen patients for OD. It combines good psychometric properties, a detailed and easy protocol designed to protect safety of patients, and valid end points to evaluate safety and efficacy of swallowing and detect silent aspirations. Copyright © 2012 S. Karger AG, Basel.

Sonic Estimation of Elasticity via Resonance: A New Method of Assessing Hemostasis

PubMed Central

Corey, F. Scott; Walker, William F.

2015-01-01

Uncontrolled bleeding threatens patients undergoing major surgery and in care for traumatic injury. This paper describes a novel method of diagnosing coagulation dysfunction by repeatedly measuring the shear modulus of a blood sample as it clots in vitro. Each measurement applies a high-energy ultrasound pulse to induce a shear wave within a rigid walled chamber, and then uses low energy ultrasound pulses to measure displacements associated with the resonance of that shear wave. Measured displacements are correlated with predictions from Finite Difference Time Domain (FDTD) models, with the best fit corresponding to the modulus estimate. In our current implementation each measurement requires 62.4 ms. Experimental data was analyzed using a fixed-viscosity algorithm and a free-viscosity algorithm. In experiments utilizing human blood induced to clot by exposure to kaolin, the free-viscosity algorithm quantified the shear modulus of formed clots with a worst-case precision of 2.5%. Precision was improved to 1.8% by utilizing the fixed-viscosity algorithm. Repeated measurements showed a smooth evolution from liquid blood to a firm clot with a shear modulus between 1.4 kPa and 3.3 kPa. These results show the promise of this technique for rapid, point of care assessment of coagulation. PMID:26399992

40 CFR 430.45 - New source performance standards (NSPS).

Code of Federal Regulations, 2012 CFR

2012-07-01

... GUIDELINES AND STANDARDS (CONTINUED) THE PULP, PAPER, AND PAPERBOARD POINT SOURCE CATEGORY Dissolving Sulfite... biocides: Subpart D [NSPS for dissolving sulfite pulp facilities where nitration grade pulp is produced... all times. Subpart D [NSPS for dissolving sulfite pulp facilities where viscose grade pulp is produced...

Using Molecular Dynamics Simulation to Reinforce Student Understanding of Intermolecular Forces

ERIC Educational Resources Information Center

Burkholder, Phillip R.; Purser, Gordon H.; Cole, Renee S.

2008-01-01

Intermolecular forces play an important role in many aspects of chemistry ranging from inorganic to biological chemistry. These forces dictate molecular conformation, species aggregation (including self-assembly), trends in solubility and boiling points, adsorption characteristics, viscosity, phase changes, surface tension, capillary action, vapor…

Thermal cracking of poly α-olefin aviation lubricating base oil

NASA Astrophysics Data System (ADS)

Fei, Yiwei; Wu, Nan; Ma, Jun; Hao, Jingtuan

2018-02-01

Thermal cracking of poly α-olefin (PAO) was conducted under different temperatures among 190 °C to 300 °C. The reacted mixtures were sequentially detected by gas chromatography-mass spectrometer (GC/MS). A series of small molecular normal alkanes, branched alkanes and olefins were identified. PAO perfect structure of aligned comb-likely side-chains has been seriously cracked under high temperatures. Property changes about kinematic viscosity and pour point of PAO samples reacted under high temperatures were also investigated. The appearance of small molecular compounds weakened the thermal stability, viscosity temperature performance and low temperature fluidity of PAO samples. Property of PAO samples was deteriorated due to thermal cracking under high temperatures.

Numerical study of drop spreading on a flat surface

NASA Astrophysics Data System (ADS)

Wang, Sheng; Desjardins, Olivier

2017-11-01

In this talk, we perform a numerical study of a droplet on a flat surface with special emphasis on capturing the spreading dynamics. The computational methodology employed is tailored for simulating large-scale two-phase flows within complex geometries. It combines a conservative level-set method to capture the liquid-gas interface, a conservative immersed boundary method to represent the solid-fluid interface, and a sub-grid curvature model at the triple-point to implicitly impose the contact angle of the liquid-gas interface. The performance of the approach is assessed in the inertial droplet spreading regime, the viscous spreading regime of high viscosity drops, and with the capillary oscillation of low viscosity droplets.

Critical Viscosity of Xenon

NASA Technical Reports Server (NTRS)

2001-01-01

The Critical Viscosity of Xenon Experiment (CVX-2) on the STS-107 Research 1 mission in 2002 will measure the viscous behavior of liquid xenon, a heavy inert gas used in flash lamps and ion rocket engines, at its critical point. Resembling a tiny bit of window screen, the oscillator at the heart of CVX-2 will vibrate between two pairs of paddle-like electrodes. The slight bend in the shape of the mesh has no effect on the data. What counts are the mesh's displacement in the xenon fluid and the rate at which the displacement dampens. The unit shown here is encased in a small test cell and capped with a sapphire windown to contain the xenon at high pressure.

The influence of carbon nanotubes on the properties of water solutions and fresh cement pastes

NASA Astrophysics Data System (ADS)

Leonavičius, D.; Pundienė, I.; Girskas, G.; Pranckevičienė, J.; Kligys, M.; Sinica, M.

2017-10-01

It is known, that the properties of cement-based materials can be significantly improved by addition of carbon nanotubes (CNTs). The dispersion of CNTs is an important process due to an extremely high specific surface area. This aspect is very relevant and is one of the main factors for the successful use of CNTs in cement-based materials. The influence of CNTs in different amounts (from 0 to 0.5 percent) on the pH values of water solutions and fresh cement pastes, and also on rheological properties, flow characteristics, setting time and EXO reaction of the fresh cement pastes was analyzed in this work. It was found that the increment of the amount of CNTs leads to decreased pH values of water solutions and fresh cement pastes, and also increases viscosity, setting times and EXO peak times of fresh cement pastes.

Cacao pod husks as a source of low-methoxyl, highly acetylated pectins able to gel in acidic media.

PubMed

Vriesmann, Lúcia Cristina; de Oliveira Petkowicz, Carmen Lúcia

2017-08-01

Cacao pod husks, the main by-product from cocoa production, have been investigated for pectin isolation. In the present study, the rheological properties of two low-methoxyl (LM) pectins isolated from cacao pod husks using different extraction conditions were evaluated. One pectin was obtained from optimized conditions employing aqueous nitric acid as an extractant, and the other one was extracted with boiling water. Pectin gels (0.99% galacturonic acid equivalent, w/w) were prepared at pH 2.5-3.0 in the presence of 60% sucrose (w/w) and subjected to rheological analysis. Dynamic oscillatory experiments at 25°C indicated that better gels were obtained at the lowest pH (2.5). Steady shear measurements revealed a shear-thinning behavior. The apparent viscosities of the samples increased as pH decreased. Gelation with calcium ions was not observed for either of the highly acetylated LM pectins analyzed. The rheological analysis results showed that despite their high acetyl content, LM pectins extracted by different methods from cacao pod husks were able to form gels at low pH under reduced water activity, suggesting a possible application in acidic products. Copyright © 2017 Elsevier B.V. All rights reserved.

Physical and mechanical properties of gelatin-CMC composite films under the influence of electrostatic interactions.

PubMed

Esteghlal, Sara; Niakousari, Mehrdad; Hosseini, Seyed Mohammad Hashem

2018-07-15

The objective of current study was to examine the electrostatic interactions between gelatin and carboxymethyl cellulose (CMC) as a function of pH and mixing ratio (MR) and to observe how the physical and mechanical properties of gelatin-CMC composite films are affected by these interactions. The interaction between biopolymers was studied using turbidometric analysis at different gelatin: CMC MRs and pH values. A reduction in pH and MR enhanced the electrostatic interactions; while, decreased the relative viscosity of mixed system. Physical and mechanical properties of resultant composite films were examined and compared with those of control gelatin films. Changes in the intensity of interactions between the two biopolymers resulted in films with different properties. Polymer complexation led to formation of resistant film networks of less solubility and swellability. Water vapor permeability (WVP) was not significantly (P≤0.05) influenced by incorporating CMC into continuous gelatin films. Composite films prepared at MR of 9:1 and pH opt (corresponding to the maximum amount of interaction) revealed different characteristics such as maximum amounts of WVP and swelling and minimum amounts of tensile strength and solubility. FTIR spectra of composite films confirmed that gelatin and CMC were not covalently bonded. Copyright © 2018 Elsevier B.V. All rights reserved.

Effects of CO2 injection and Kerogen Maturation on Low-Field Nuclear Magnetic Resonance Response

NASA Astrophysics Data System (ADS)

Prasad, M.; Livo, K.

2017-12-01

Low-field Nuclear Magnetic Resonance (NMR) is commonly used in petrophysical analysis of petroleum reservoir rocks. NMR experiments record the relaxation and polarization of in-situ hydrogen protons present in gaseous phases such as free-gas intervals and solution gas fluids, bulk fluid phases such as oil and aquifer intervals, and immovable fractions of kerogen and bitumen. Analysis of NMR relaxation spectra is performed to record how fluid composition, maturity, and viscosity change NMR experimental results. We present T1-T2 maps as thermal maturity of a water-saturated, sub-mature Woodford shale is increased at temperatures from 125 to 400 degrees Celsius. Experiments with applied fluid pressure in paraffinic mineral oil and DI water with varying fluid pH have been performed to mimic reservoir conditions in analysis of the relaxation of bulk fluid phases. We have recorded NMR spectra, T1-T2 maps, and fluid diffusion coefficients using a low-field (2 MHz) MagritekTM NMR. CO2 was injected at a pressure of 900 psi in an in house developed NMR pressure vessel made of torlon plastic. Observable 2D NMR shifts in immature kerogen formations as thermal maturity is increased show generation of lighter oils with increased maturity. CO2 injection leads to a decrease in bulk fluid relaxation time that is attributed to viscosity modification with gas presence. pH variation with increased CO2 presence were shown to not effect NMR spectra. From this, fluid properties have been shown to greatly affect NMR readings and must be taken into account for more accurate NMR reservoir characterization.

Investigation of microemulsion system for transdermal delivery of itraconazole

PubMed Central

Chudasama, Arpan; Patel, Vineetkumar; Nivsarkar, Manish; Vasu, Kamala; Shishoo, Chamanlal

2011-01-01

A new oil-in-water microemulsion-based (ME) gel containing 1% itraconazole (ITZ) was developed for topical delivery. The solubility of ITZ in oils and surfactants was evaluated to identify potential excipients. The microemulsion existence ranges were defined through the construction of the pseudoternary phase diagrams. The optimized microemulsion was characterized for its morphology and particle size distribution. The optimized microemulsion was incorporated into polymeric gels of Lutrol F127, Xanthan gum, and Carbopol 934 for convenient application and evaluated for pH, drug content, viscosity, and spreadability. In vitro drug permeation of ME gels was determined across excised rat skins. Furthermore, in vitro antimycotic inhibitory activity of the gels was conducted using agar-cup method and Candida albicans as a test organism. The droplet size of the optimized microemulsion was found to be <100 nm. The optimized Lutrol F 127 ME gel showed pH in the range of 5.68±0.02 and spreadability of 5.75±1.396 gcm/s. The viscosity of ME gel was found to be 1805.535±542.4 mPa s. The permeation rate (flux) of ITZ from prepared ME gel was found to be 4.234 μg/cm/h. The release profile exhibited diffusion controlled mechanism of drug release from ME ITZ gel. The developed ME gels were nonirritant and there was no erythema or edema. The antifungal activity of ITZ showed the widest zone of inhibition with Lutrol F127 ME gel. These results indicate that the studied ME gel may be a promising vehicle for topical delivery of ITZ. PMID:22171289

Designing Solvent Exchange-Induced In Situ Forming Gel from Aqueous Insoluble Polymers as Matrix Base for Periodontitis Treatment.

PubMed

Srichan, Tharatree; Phaechamud, Thawatchai

2017-01-01

An in situ forming gel is a dosage form which is promised for site-specific therapy such as periodontal pocket of periodontitis treatment. Ethylcellulose, bleached shellac, and Eudragit RS were applied in this study as a polymeric matrix for in situ forming gel employing N-methyl pyrrolidone (NMP) as solvent. Solutions comprising ethylcellulose, bleached shellac, and Eudragit RS in NMP were evaluated for viscosity, rheology, and rate of water penetration. Ease of administration by injection was determined as the force required to expel polymeric solutions through a needle using texture analyzer. In vitro gel formation and in vitro gel degradation were conducted after injection into phosphate buffer solution pH 6.8. Ethylcellulose, bleached shellac, and Eudragit RS could form the in situ gel, in vitro. Gel viscosity and pH value depended on percentage amount of the polymer, whereas the water diffusion at early period likely relied on types of polymer. Furthermore, the solutions containing higher polymer concentration exhibited the lower degree of degradation. All the preparations were acceptable as injectable dosage forms because the applied force was lower than 50 N. All of them inhibited Staphylococcus aureus, Escherichia coli, Candida albicans, Streptococcus mutans, and Porphyrommonas gingivalis growth owing to antimicrobial activity of NMP which exhibited a potential use for periodontitis treatment. Moreover, the developed systems presented as the solvent exchange induced in situ forming gel and showed capability to be incorporated with the suitable antimicrobial active compounds for periodontitis treatment which should be further studied.

Microrheology and microstructure of water-in-water emulsions containing sodium caseinate and locust bean gum.

PubMed

Moschakis, Thomas; Chantzos, Nikos; Biliaderis, Costas G; Dickinson, Eric

2018-05-23

The mechanical response on the microscale of phase-separated water-in-water emulsions containing sodium caseinate (SCN) and locust bean gum (LBG) has been monitored by confocal laser scanning microscopy and particle tracking microrheology. Mixed biopolymer systems exhibiting phase-separated micro-regions were enriched in either protein or polysaccharide in the continuous or dispersed phase, depending on the weight ratio of the two biopolymers. Measurements of the tracking of charged probe particles revealed that the local rheological properties of protein-rich regions were considerably lower than that of LBG-rich domains for all the biopolymer ratios examined. At pH 7 in the absence of added salt, the viscosity of the protein-rich regions was little affected by an increase in overall LBG concentration, which is consistent with the phase separation mechanism in the mixed solution of charged (SCN) and uncharged (LBG) biopolymers being dominated by the relative entropy of the counter-ions associated with the charged protein molecules. Addition of salt was found to produce an enhancement in the level of thermodynamic incompatibility, leading to faster and more pronounced phase separation, and altering the micro-viscosity of protein-rich regions. At high ionic strength, it was also noted that there was a pronounced accumulation of incorporated probe particles at the liquid-liquid interface. The microrheological properties of the SCN-rich regions were found to be substantially pH-dependent in the range 7 > pH > 5.4. By adjusting the acidification conditions and the biopolymer ratio, discrete protein-based microspheres were generated with potential applications as a functional food ingredient.

Field measurement of alkalinity and pH

USGS Publications Warehouse

Barnes, Ivan

1964-01-01

The behavior of electrometric pH equipment under field conditions departs from the behavior predicted from Nernst's law. The response is a linear function of pH, and hence measured pH values may be corrected to true pH if the instrument is calibrated with two reference solutions for each measurement. Alkalinity titrations may also be made in terms of true pH. Standard methods, such as colorimetric titrations, were rejected as unreliable or too cumbersome for rapid field use. The true pH of the end point of the alkalinity titration as a function of temperature, ionic strength, and total alkalinity has been calculated. Total alkalinity in potable waters is the most important factor influencing the end point pH, which varies from 5.38 (0 ? C, 5 ppm (parts per million) HC0a-) to 4.32 (300 ppm HC0a-,35 ? C), for the ranges of variables considered. With proper precautions, the pH may be determined to =i:0.02 pH and the alkalinity to =i:0.6 ppm HCO3- for many naturally occurring bodies of fresh water.

40 CFR 430.44 - Effluent limitations representing the degree of effluent reduction attainable by the application...

Code of Federal Regulations, 2011 CFR

2011-07-01

...) EFFLUENT GUIDELINES AND STANDARDS THE PULP, PAPER, AND PAPERBOARD POINT SOURCE CATEGORY Dissolving Sulfite... dissolving sulfite pulp facilities where nitration, viscose, or cellophane pulps are produced] Pollutant or... ton of product. Subpart D [BAT effluent limitations for dissolving sulfite pulp facilities where...

Teaching Process Engineering Principles Using an Ice Cream Maker

ERIC Educational Resources Information Center

Kaletunc, Gonul; Duemmel, Kevin; Gecik, Christopher

2007-01-01

The ice cream laboratory experiment is designed to illustrate and promote discussion of several engineering and science topics including material and energy balances, heat transfer, freezing, mass transfer, mixing, viscosity, and freezing point depression in a sophomore level engineering class. A pre-lab assignment requires the students to develop…

Effects of Blending Alcohols with Poultry Fat Methyl Esters on Cold Flow Properties

USDA-ARS?s Scientific Manuscript database

The low temperature operability, kinematic viscosity, and acid value of poultry fat methyl esters were improved with addition of ethanol, isopropanol, and butanol in a linear fashion with increasing alcohol content. The flash point decreased and moisture content increased upon addition of alcohols t...

Effects of monoacylglycerols on kinematic viscosity and cold filter plugging point of methyl soyate

USDA-ARS?s Scientific Manuscript database

Biodiesel is an alternative fuel composed of mono-alkyl fatty acid esters made from the transesterification of plant oils or animal fats with methanol or ethanol. After conversion, biodiesel may contain trace concentrations of unconverted monoacylglycerols (MAG). These MAG have low solubility in bio...

Branching, Chain Scission, and Solution Stability of Worm-Like Micelles

NASA Astrophysics Data System (ADS)

Beaucage, Greg; Vogtt, Karsten; Jiang, Hanqui

As salt is added to a simple micelle solution such as SDS or SLES, the zero shear rate specific viscosity rises rapidly followed by a maximum and decay. The rapid rise in viscosity is associated with formation of elliptical and extended chain worm-like micelles, WLMs. Entanglement of these long chain micelles leads to the viscoelastic behavior we associate with shampoo and body wash. The plateau and drop in viscosity at high salt concentrations is caused by a special type of topological branching where the branch points have no energy penalty to motion along the chain according to Cates theory. These have some similarity to catenane crosslinks. Predictive dynamic theories for WLMs rely on structural details; the diameter, persistence length, contour length, branch length, segment length between branch points, and mesh size. Further, since the contour length and other large scale features are in kinetic equilibrium, with frequent chain breakage and formation, the thermodynamics of these long chain structures are of interest both in terms of chain scission as well as in terms of the stability of the colloidal solution as a whole. Recent structural studies of WLMs using static neutron scattering based on new scattering models will be presented demonstrating that these input parameters for dynamic models of complex topological systems are quantitatively and directly available. In this context it is important to consider a comparison between dynamic features, for instance entanglement, and their static analogs, chain overlap.

Evaluation of machine learning algorithms for prediction of regions of high Reynolds averaged Navier Stokes uncertainty

DOE PAGES

Ling, Julia; Templeton, Jeremy Alan

2015-08-04

Reynolds Averaged Navier Stokes (RANS) models are widely used in industry to predict fluid flows, despite their acknowledged deficiencies. Not only do RANS models often produce inaccurate flow predictions, but there are very limited diagnostics available to assess RANS accuracy for a given flow configuration. If experimental or higher fidelity simulation results are not available for RANS validation, there is no reliable method to evaluate RANS accuracy. This paper explores the potential of utilizing machine learning algorithms to identify regions of high RANS uncertainty. Three different machine learning algorithms were evaluated: support vector machines, Adaboost decision trees, and random forests.more » The algorithms were trained on a database of canonical flow configurations for which validated direct numerical simulation or large eddy simulation results were available, and were used to classify RANS results on a point-by-point basis as having either high or low uncertainty, based on the breakdown of specific RANS modeling assumptions. Classifiers were developed for three different basic RANS eddy viscosity model assumptions: the isotropy of the eddy viscosity, the linearity of the Boussinesq hypothesis, and the non-negativity of the eddy viscosity. It is shown that these classifiers are able to generalize to flows substantially different from those on which they were trained. As a result, feature selection techniques, model evaluation, and extrapolation detection are discussed in the context of turbulence modeling applications.« less

Atomic structure of the sweet-tasting protein thaumatin I at pH 8.0 reveals the large disulfide-rich region in domain II to be sensitive to a pH change

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

Masuda, Tetsuya, E-mail: t2masuda@kais.kyoto-u.ac.jp; Department of Natural Resources, Graduate School of Global Environmental Studies, Kyoto University, Gokasho, Uji, Kyoto 611-0011; Ohta, Keisuke

2012-03-02

Highlights: Black-Right-Pointing-Pointer Structure of a recombinant thaumatin at pH 8.0 determined at a resolution of 1.0 A. Black-Right-Pointing-Pointer Substantial fluctuations of a loop in domain II was found in the structure at pH 8.0. Black-Right-Pointing-Pointer B-factors for Lys137, Lys163, and Lys187 were significantly affected by pH change. Black-Right-Pointing-Pointer An increase in mobility might play an important role in the heat-induced aggregation. -- Abstract: Thaumatin, an intensely sweet-tasting plant protein, elicits a sweet taste at 50 nM. Although the sweetness remains when thaumatin is heated at 80 Degree-Sign C for 4 h under acid conditions, it rapidly declines when heating atmore » a pH above 6.5. To clarify the structural difference at high pH, the atomic structure of a recombinant thaumatin I at pH 8.0 was determined at a resolution of 1.0 A. Comparison to the crystal structure of thaumatin at pH 7.3 and 7.0 revealed the root-mean square deviation value of a C{alpha} atom to be substantially greater in the large disulfide-rich region of domain II, especially residues 154-164, suggesting that a loop region in domain II to be affected by solvent conditions. Furthermore, B-factors of Lys137, Lys163, and Lys187 were significantly affected by pH change, suggesting that a striking increase in the mobility of these lysine residues, which could facilitate a reaction with a free sulfhydryl residue produced via the {beta}-elimination of disulfide bonds by heating at a pH above 7.0. The increase in mobility of lysine residues as well as a loop region in domain II might play an important role in the heat-induced aggregation of thaumatin above pH 7.0.« less

Rheological changes of polyamide 12 under oscillatory shear

NASA Astrophysics Data System (ADS)

Mielicki, C.; Gronhoff, B.; Wortberg, J.

2014-05-01

Changes in material properties as well as process deviation prevent Laser Sintering (LS) technology from manufacturing of quality assured parts in a series production. In this context, the viscosity of Polyamide 12 (PA12) is assumed to possess the most significant influence, as it determines the sintering velocity, the resistance towards melt formation and the bonding strength of sintered layers. Moreover, the viscosity is directly related to the structure of the molten polymer. In particular, it has been recently reported that LS process conditions lead to structural changes of PA12 affecting viscosity and coalescence of adjacent polymer particles, i.e. melt formation significantly. Structural change of PA12 was understood as a post condensation. Its influence on viscosity was described by a time and temperature depending rheological model whereas time dependence was considered by a novel structural change shift factor which was derived from melt volume rate data. In combination with process data that was recorded using online thermal imaging, the model is suitable to control the viscosity (processability of the material) as result of material and process properties. However, as soon as laser energy is exposed to the powder bed PA12 undergoes a phase transition from solid to molten state. Above the melting point, structural change is expected to occur faster due to a higher kinetic energy and free volume of the molten polymer. Oscillatory shear results were used to study the influence of aging time and for validation of the novel structural change shift factor and its model parameters which were calibrated based on LS processing condition.

Soymilk residue (okara) as a natural immobilization carrier for Lactobacillus plantarum cells enhances soymilk fermentation, glucosidic isoflavone bioconversion, and cell survival under simulated gastric and intestinal conditions

PubMed Central

Xiudong, Xia; Ying, Wang; Xiaoli, Liu; Ying, Li

2016-01-01

Cell immobilization is an alternative to microencapsulation for the maintenance of cells in a liquid medium. However, artificial immobilization carriers are expensive and pose a high safety risk. Okara, a food-grade byproduct from soymilk production, is rich in prebiotics. Lactobacilli could provide health enhancing effects to the host. This study aimed to evaluate the potential of okara as a natural immobilizer for L. plantarum 70810 cells. The study also aimed to evaluate the effects of okara-immobilized L. plantarum 70810 cells (IL) on soymilk fermentation, glucosidic isoflavone bioconversion, and cell resistance to simulated gastric and intestinal stresses. Scanning electron microscopy (SEM) was used to show cells adherence to the surface of okara. Lactic acid, acetic acid and isoflavone analyses in unfermented and fermented soymilk were performed by HPLC with UV detection. Viability and growth kinetics of immobilized and free L. plantarum 70810 cells (FL) were followed during soymilk fermentation. Moreover, changes in pH, titrable acidity and viscosity were measured by conventional methods. For in vitro testing of simulated gastrointestinal resistance, fermented soymilk was inoculated with FL or IL and an aliquot incubated into acidic MRS broth which was conveniently prepared to simulate gastric, pancreatic juices and bile salts. Survival to simulated gastric and intestinal stresses was evaluated by plate count of colony forming units on MRS agar. SEM revealed that the lactobacilli cells attached and bound to the surface of okara. Compared with FL, IL exhibited a significantly higher specific growth rate, shorter lag phase of growth, higher productions of lactic and acetic acids, a faster decrease in pH and increase in titrable acidity, and a higher soymilk viscosity. Similarly, IL in soymilk showed higher productions of daizein and genistein compared with the control. Compared with FL, IL showed reinforced resistance to simulatedgastric and intestinal stresses in vitro that included low pH, low pH plus pepsin, pancreatin, and bile salt. Our results indicate that okara is a new potential immobilization carrier to enhance the growth and glucosidic isoflavone bioconversion activities of L. plantarum in soymilk and improve cell survivability following simulated gastric and intestinal conditions. PMID:27867770

Soymilk residue (okara) as a natural immobilization carrier for Lactobacillus plantarum cells enhances soymilk fermentation, glucosidic isoflavone bioconversion, and cell survival under simulated gastric and intestinal conditions.

PubMed

Xiudong, Xia; Ying, Wang; Xiaoli, Liu; Ying, Li; Jianzhong, Zhou

2016-01-01

Cell immobilization is an alternative to microencapsulation for the maintenance of cells in a liquid medium. However, artificial immobilization carriers are expensive and pose a high safety risk. Okara, a food-grade byproduct from soymilk production, is rich in prebiotics. Lactobacilli could provide health enhancing effects to the host. This study aimed to evaluate the potential of okara as a natural immobilizer for L. plantarum 70810 cells. The study also aimed to evaluate the effects of okara-immobilized L. plantarum 70810 cells (IL) on soymilk fermentation, glucosidic isoflavone bioconversion, and cell resistance to simulated gastric and intestinal stresses. Scanning electron microscopy (SEM) was used to show cells adherence to the surface of okara. Lactic acid, acetic acid and isoflavone analyses in unfermented and fermented soymilk were performed by HPLC with UV detection. Viability and growth kinetics of immobilized and free L. plantarum 70810 cells (FL) were followed during soymilk fermentation. Moreover, changes in pH, titrable acidity and viscosity were measured by conventional methods. For in vitro testing of simulated gastrointestinal resistance, fermented soymilk was inoculated with FL or IL and an aliquot incubated into acidic MRS broth which was conveniently prepared to simulate gastric, pancreatic juices and bile salts. Survival to simulated gastric and intestinal stresses was evaluated by plate count of colony forming units on MRS agar. SEM revealed that the lactobacilli cells attached and bound to the surface of okara. Compared with FL, IL exhibited a significantly higher specific growth rate, shorter lag phase of growth, higher productions of lactic and acetic acids, a faster decrease in pH and increase in titrable acidity, and a higher soymilk viscosity. Similarly, IL in soymilk showed higher productions of daizein and genistein compared with the control. Compared with FL, IL showed reinforced resistance to simulatedgastric and intestinal stresses in vitro that included low pH, low pH plus pepsin, pancreatin, and bile salt. Our results indicate that okara is a new potential immobilization carrier to enhance the growth and glucosidic isoflavone bioconversion activities of L. plantarum in soymilk and improve cell survivability following simulated gastric and intestinal conditions.

Adsorption of superplasticizer admixtures on alkali-activated slag pastes

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

Palacios, M.; Houst, Y.F.; Bowen, P.

2009-08-15

Alkali-activated slag (AAS) binders are obtained by a manufacturing process less energy-intensive than ordinary Portland cement (OPC) and involves lower greenhouse gasses emission. These alkaline cements allow the production of high mechanical strength and durable concretes. In the present work, the adsorption of different superplasticizer admixtures (naphthalene-based, melamine-based and a vinyl copolymer) on the slag particles in AAS pastes using alkaline solutions with different pH values have been studied in detail. The effect of the superplasticizers on the yield stress and plastic viscosity of the AAS and OPC pastes have been also evaluated. The results obtained allowed us to concludemore » that the adsorption of the superplasticizers on AAS pastes is independent of the pH of the alkaline solutions used and lower than on OPC pastes. However, the effect of the admixtures on the rheological parameters depends directly on the type and dosage of the superplasticizer as well as of the binder used and, in the case of the AAS, on the pH of the alkaline activator solution. In 11.7-pH NaOH-AAS pastes the dosages of the superplasticizers required to attain similar reduction in the yield stress are ten-fold lower than for Portland cement. In this case the superplasticizers studied show a fluidizing effect considerably higher in 11.7-pH NaOH-AAS pastes than in OPC pastes. In 13.6-pH NaOH-AAS pastes, the only admixture observed to affect the rheological parameters is the naphthalene-based admixture due to its higher chemical stability in such extremely alkaline media.« less

Minimising alkalinity and pH spikes from Portland cement-bound Bauxsol (seawater-neutralized red mud) pellets for pH circum-neutral waters.

PubMed

Despland, Laure M; Clark, Malcolm W; Aragno, Michel; Vancov, Tony

2010-03-15

Bauxsol reagents (powder, slurry, or pellet forms) are powerful tools in environmental remediation and water and sewage treatment However, when used in circum-neutral water treatments, cement-bound Bauxsol pellets produce a sustained pH and alkalinity spike due to the presence of unreacted CaO in the cement binder. This study developed a pellet treatment system to minimize the alkalinity/pH spike. The recipe for pelletization consisted of Bauxsol powder, ordinary Portland cement (OPC), hydrophilic fumed silica, aluminum powder, a viscosity modifier, and water. Several batches (including different ratios and sizes) were run using modified makeup waters (H(2)0 + CO(2) or NaHCO(3)) or curing brines (CO(2), NaHCO(3), or Mg/CaCl(2)). Alkalinity, pH stability, and slake durability tests were performed on pellets before and/or after curing. The best result for reducing the alkalinity/pH spike was obtained from a MgCl(2), CaCl(2) bath treatment using a Bauxsol:cement ratio of 2.8:1 (pH 8.28; alkalinity 75.1 mg/L) for a 100 g batch or 245:1 (pH 8.05; alkalinity 35.4 mg/L) for a 1 kg batch. Although brine curing does provide a control on pH/alkalinity release, the pellets may still contain unreacted CaO. Therefore, a freshwater rinse of pellets before treating circum-neutral waters is recommended as is the continued investigation of alternative pellet binders.

Evaluation of the 5 and 8 pH point titration methods for monitoring anaerobic digesters treating solid waste.

PubMed

Vannecke, T P W; Lampens, D R A; Ekama, G A; Volcke, E I P

2015-01-01

Simple titration methods certainly deserve consideration for on-site routine monitoring of volatile fatty acid (VFA) concentration and alkalinity during anaerobic digestion (AD), because of their simplicity, speed and cost-effectiveness. In this study, the 5 and 8 pH point titration methods for measuring the VFA concentration and carbonate system alkalinity (H2CO3*-alkalinity) were assessed and compared. For this purpose, synthetic solutions with known H2CO3*-alkalinity and VFA concentration as well as samples from anaerobic digesters treating three different kind of solid wastes were analysed. The results of these two related titration methods were verified with photometric and high-pressure liquid chromatography measurements. It was shown that photometric measurements lead to overestimations of the VFA concentration in the case of coloured samples. In contrast, the 5 pH point titration method provides an accurate estimation of the VFA concentration, clearly corresponding with the true value. Concerning the H2CO3*-alkalinity, the most accurate and precise estimations, showing very similar results for repeated measurements, were obtained using the 8 pH point titration. Overall, it was concluded that the 5 pH point titration method is the preferred method for the practical monitoring of AD of solid wastes due to its robustness, cost efficiency and user-friendliness.

Lubrication of nonconformal contacts. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Jeng, Y. R.

1985-01-01

Minimum film thickness results for piezoviscous-rigid regime of lubrication are developed for a compressible Newtonian fluid with Roelands viscosity. The results provide a basis for the analysis and design of a wide range of machine elements operating in the piezoviscous-rigid regime of lubrication. A new numerical method of calculating elastic deformation in contact stresses is developed using a biquadratic polynomial to approximate the pressure distribution on the whole domain analyzed. The deformation of every node is expressed as a linear combination of the nodal pressures whose coefficients can be combined into an influence coefficient matrix. This approach has the advantages of improved numerical accuracy, less computing time and smaller storage size required for influence matrix. The ideal elastohydrodynamic lubrication is extended to real bearing systems in order to gain an understanding of failure mechanisms in machine elements. The improved elastic deformation calculation is successfully incorporated into the EHL numerical scheme. Using this revised numerical technique and the flow factor model developed by Patir and Cheng (1978) the surface roughness effects on the elastohydrodynamic lubrication of point contact is considered. Conditions typical of an EHL contact in the piezoviscous-elastic regime entrained in pure rolling are investigated. Results are compared with the smooth surface solutions. Experiments are conducted to study the transient EHL effects in instrument ball bearings.

Smart wormlike micelles.

PubMed

Chu, Zonglin; Dreiss, Cécile A; Feng, Yujun

2013-09-07

A major scientific challenge of the past decade pertaining to the field of soft matter has been to craft 'adaptable' materials, inspired by nature, which can dynamically alter their structure and functionality on demand, in response to triggers produced by environmental changes. Amongst these, 'smart' surfactant wormlike micelles, responsive to external stimuli, are a particularly recent area of development, yet highly promising, given the versatility of the materials but simplicity of the design-relying on small amphiphilic molecules and their spontaneous self-assembly. The switching 'on' and 'off' of the micellar assembly structures has been reported using electrical, optical, thermal or pH triggers and is now envisaged for multiple stimuli. The structural changes, in turn, can induce major variations in the macroscopic characteristics, affecting properties such as viscosity and elasticity and sometimes even leading to a spontaneous and effective 'sol-gel' transition. These original smart materials based on wormlike micelles have been successfully used in the oil industry, and offer a significant potential in a wide range of other technological applications, including biomedicine, cleaning processes, drag reduction, template synthesis, to name but a few. This review will report results in this field published over the last few years, describe the potential and practical applications of stimuli-responsive wormlike micelles and point out future challenges.

Evaluation of the simultaneous effects of processing parameters on the iron and zinc solubility of infant sorghum porridge by response surface methodology.

PubMed

Kayodé, A P Polycarpe; Nout, Martinus J R; Bakker, Evert J; Van Boekel, Martinus A J S

2006-06-14

The purpose of this study was to improve the micronutrient quality of indigenous African infant flour using traditional techniques available in the region. Response surface methodology was used to study the effect of duration of soaking, germination, and fermentation on phytate and phenolic compounds (PC), pH, viscosity, and the in vitro solubility (IVS) of iron and zinc in infant sorghum flour. The phytate and the PC concentrations of the flour were significantly modified as a result of the duration of germination and fermentation and their mutual interaction. These modifications were accompanied by a significant increase in % IVS Zn after 24 h of sprouting. Except for the interaction of soaking and fermentation, none of the processing parameters exerted a significant effect on the % IVS Fe. The viscosity of the porridge prepared with the flour decreased significantly with the duration of germination, making it possible to produce a porridge with high energy and nutrient density. The use of germination in combination with fermentation is recommended in the processing of cereals for infant feeding in developing countries.

Influence of sodium polyacrylate on the rheology of aqueous Laponite dispersions.

PubMed

Labanda, Jordi; Llorens, Joan

2005-09-01

Aqueous Laponite dispersions containing a sodium polyacrylate were analyzed, at fixed ionic strength and pH, by rheometric and electroacoustic (for zeta-potential determinations) techniques at 7 days after their preparation. The rheological behavior of these dispersions was determined by oscillatory and flow experiments. Addition of sodium polyacrylate modifies the interactions between Laponite particles and therefore the physical state of the dispersion. The phase diagram of Laponite dispersion as a function of sodium polyacrylate concentration shows different sol-gel transitions for a specific Laponite concentration as a function of the polyacrylate concentration. Under equilibrium flow conditions the Laponite dispersions fit the pseudoplastic Oswald-de Waele power law model. At the same time, these dispersions show thixotropy, which was analyzed using a second-order kinetic equation. The kinetic processes were characterized by breakdown and build-up parameters, which were found to depend on shear rate. This kinetic equation was modified by a power law exponent of viscosity with shear rate that takes into account the viscosity variations when the shear rates are suddenly changed, in order to fit the hysteresis loops.

Contribution of the net charge to the regulatory effects of amino acids and epsilon-poly(L-lysine) on the gelatinization behavior of potato starch granules.

PubMed

Ito, Azusa; Hattori, Makoto; Yoshida, Tadashi; Takahashi, Koji

2006-01-01

The effects of lysine (Lys), monosodium glutamate (GluNa), glycine, alanine and epsilon-poly(L-lysine) (PL) with different degrees of polymerization on the gelatinization behavior of potato starch granules were investigated by DSC, viscosity and swelling measurements, microscopic observation, and measurement of the retained amino acid amount to clarify the contribution of the net charge to their regulatory effects on the gelatinization behavior. The amino acids and PL each contributed to an increase in the gelatinization temperature, and a decrease in the peak viscosity and swelling. These effects strongly depended on the absolute value of their net charge. The disappearance of a negative or positive net charge by adjusting the pH value weakened the contribution. The swelling index and size of the potato starch granules changed according to replacement of the swelling medium. The amino acids and PL were easily retained by the swollen potato starch granules according to replacement of the outer solution of the starch granules.

Systematic parameter study of hadron spectra and elliptic flow from viscous hydrodynamic simulations of Au+Au collisions at sNN=200 GeV

NASA Astrophysics Data System (ADS)

Shen, Chun; Heinz, Ulrich; Huovinen, Pasi; Song, Huichao

2010-11-01

Using the (2+1)-dimensional viscous hydrodynamic code vish2+1 [H. Song and U. Heinz, Phys. Lett. BPYLBAJ0370-269310.1016/j.physletb.2007.11.019 658, 279 (2008); H. Song and U. Heinz, Phys. Rev. CPRVCAN0556-281310.1103/PhysRevC.77.064901 77, 064901 (2008); H. Song, Ph. D. thesis, The Ohio State University, 2009], we present systematic studies of the dependence of pion and proton transverse-momentum spectra and their elliptic flow in 200A GeV Au+Au collisions on the parameters of the hydrodynamic model (thermalization time, initial entropy density distribution, decoupling temperature, equation of state, and specific shear viscosity η/s). We identify a tension between the slope of the proton spectra, which (within hydrodynamic simulations that assume a constant shear viscosity to entropy density ratio) prefer larger η/s values, and the slope of the pT dependence of charged hadron elliptic flow, which prefers smaller values of η/s. Changing other model parameters does not appear to permit dissolution of this tension.

An environmentally friendly organosolv (ethanol-water) pulping of poplar wood.

PubMed

Akgul, Mehmet; Kirci, Huseyin

2009-09-01

In this study pulp production from the fast growing plant, poplar; was examined for organosolv pulping with or without catalysts. In order to find the optimum cooking conditions, 18 different cooking experiments were carried out. The effect of ethanol ratio, cooking time as well as catalyst was studied. It was observed that even at lower temperature (90 degrees C), cooking without catalyst was able to cause sufficient defiberization. It was seen that the increasing proportion of catalyst and cooking temperature resulted in an increased delignification. However in the case of using 0.02% acid catalyst pulp yield and viscosity were lowered to an unacceptable level. The most important cooking factors were found to be the proportion of acid catalyst. Furthermore, the delignification performance was found to be depending on the pH of the black liquor. In a result, the optimum pulp properties were obtained by cooking at 180 degrees C for 90 min with 50% ethanol mixture without catalyst. The pulp yield was noted as 44.49%, viscosity was 892 cm2 g(-1) and the kappa number was 67.

Systematic parameter study of hadron spectra and elliptic flow from viscous hydrodynamic simulations of Au+Au collisions at {radical}(s{sub NN})=200 GeV

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

Shen Chun; Heinz, Ulrich; Huovinen, Pasi

2010-11-15

Using the (2+1)-dimensional viscous hydrodynamic code vish2+1[H. Song and U. Heinz, Phys. Lett. B 658, 279 (2008); H. Song and U. Heinz, Phys. Rev. C 77, 064901 (2008); H. Song, Ph. D. thesis, The Ohio State University, 2009], we present systematic studies of the dependence of pion and proton transverse-momentum spectra and their elliptic flow in 200A GeV Au+Au collisions on the parameters of the hydrodynamic model (thermalization time, initial entropy density distribution, decoupling temperature, equation of state, and specific shear viscosity {eta}/s). We identify a tension between the slope of the proton spectra, which (within hydrodynamic simulations that assumemore » a constant shear viscosity to entropy density ratio) prefer larger {eta}/s values, and the slope of the p{sub T} dependence of charged hadron elliptic flow, which prefers smaller values of {eta}/s. Changing other model parameters does not appear to permit dissolution of this tension.« less

Protective effect of total flavonoids of seabuckthorn (Hippophae rhamnoides) in simulated high-altitude polycythemia in rats.

PubMed

Zhou, Ji-Yin; Zhou, Shi-Wen; Du, Xiao-Huang; Zeng, Sheng-Ya

2012-09-28

Seabuckthorn (Hippophae rhamnoides L.) has been used to treat high altitude diseases. The effects of five-week treatment with total flavonoids of seabuckthorn (35, 70, 140 mg/kg, ig) on cobalt chloride (5.5 mg/kg, ip)- and hypobaric chamber (simulating 5,000 m)-induced high-altitude polycythemia in rats were measured. Total flavonoids decreased red blood cell number, hemoglobin, hematocrit, mean corpuscular hemoglobin levels, span of red blood cell electrophoretic mobility, aggregation index of red blood cell, plasma viscosity, whole blood viscosity, and increased deformation index of red blood cell, erythropoietin level in serum. Total flavonoids increased pH, pO₂, Sp(O₂), pCO₂ levels in arterial blood, and increased Na⁺, HCO₃⁻, Cl⁻, but decreased K⁺ concentrations. Total flavonoids increased mean arterial pressure, left ventricular systolic pressure, end-diastolic pressure, maximal rate of rise and decrease, decreased heart rate and protected right ventricle morphology. Changes in hemodynamic, hematologic parameters, and erythropoietin content suggest that administration of total flavonoids from seabuckthorn may be useful in the prevention of high altitude polycythaemia in rats.

Effects of Dietary Fiber Extracted from Pumpkin (Cucurbita maxima Duch.) on the Physico-Chemical and Sensory Characteristics of Reduced-Fat Frankfurters.

PubMed

Kim, Cheon-Jei; Kim, Hyun-Wook; Hwang, Ko-Eun; Song, Dong-Heon; Ham, Youn-Kyung; Choi, Ji-Hun; Kim, Young-Boong; Choi, Yun-Sang

2016-01-01

In this study, we investigated the effects of reducing fat levels from 30% to 25, 20, and 15% by substituting pork fat with water and pumpkin fiber (2%) on the quality of frankfurters compared with control. Decreasing the fat concentration from 30% to 15% significantly increased moisture content, redness of meat batter and frankfurter, cooking loss, and water exudation, and decreased fat content, energy value, pH, and lightness of meat batter and frankfurter, hardness, cohesiveness, gumminess, chewiness, and apparent viscosity. The addition of 2% pumpkin fiber was significantly increased moisture content, yellowness of meat batter and frankfurter, hardness, cohesiveness, gumminess, chewiness, and apparent viscosity, whereas reduced cooking loss and emulsion stability. The treatment of reduced-fat frankfurters formulated with 20 and 25% fat levels and with pumpkin fiber had sensory properties similar to the high-fat control frankfurters. The results demonstrate that when the reduced-fat frankfurter with 2% added pumpkin fiber and water replaces fat levels can be readily made with high quality and acceptable sensory properties.

Effects of Dietary Fiber Extracted from Pumpkin (Cucurbita maxima Duch.) on the Physico-Chemical and Sensory Characteristics of Reduced-Fat Frankfurters

PubMed Central

Kim, Cheon-Jei; Kim, Hyun-Wook; Hwang, Ko-Eun; Song, Dong-Heon; Ham, Youn-Kyung; Choi, Ji-Hun

2016-01-01

In this study, we investigated the effects of reducing fat levels from 30% to 25, 20, and 15% by substituting pork fat with water and pumpkin fiber (2%) on the quality of frankfurters compared with control. Decreasing the fat concentration from 30% to 15% significantly increased moisture content, redness of meat batter and frankfurter, cooking loss, and water exudation, and decreased fat content, energy value, pH, and lightness of meat batter and frankfurter, hardness, cohesiveness, gumminess, chewiness, and apparent viscosity. The addition of 2% pumpkin fiber was significantly increased moisture content, yellowness of meat batter and frankfurter, hardness, cohesiveness, gumminess, chewiness, and apparent viscosity, whereas reduced cooking loss and emulsion stability. The treatment of reduced-fat frankfurters formulated with 20 and 25% fat levels and with pumpkin fiber had sensory properties similar to the high-fat control frankfurters. The results demonstrate that when the reduced-fat frankfurter with 2% added pumpkin fiber and water replaces fat levels can be readily made with high quality and acceptable sensory properties. PMID:27433101

Evaluation of feed and feeding regime on growth performance, flesh quality and fecal viscosity of Atlantic salmon ( Salmo salar L.) in recirculating aquaculture systems

NASA Astrophysics Data System (ADS)

Sun, Guoxiang; Liu, Ying; Li, Yong; Li, Xian; Wang, Shunkui

2015-10-01

The effects of different feeds and feeding regimes on growth performance, flesh quality and fecal viscosity of Atlantic salmon ( Salmo salar L.) in recirculating aquaculture systems (RAS) were investigated. Fish (initial body weight of 1677 g ± 157 g) were fed with four commercial feeds (Nosan salmon-NS, Aller gold-AG, Skretting salmon-SS and Han ye-HY) in two feeding regimes (80% and 100% satiation) for 78 d. The results showed that salmon specific growth ratio (SGR) and weight gain ratio (WGR) were significantly affected by feed type and feeding regime ( P < 0.05). Feed conversion ratio (FCR) varied between 0.93 and 3.40, which was significantly affected by feed type ( P < 0.05), and slightly improved with increased satiation degree. The activities of digestive enzymes including protease, lipase and amylase were also significantly affected by feed type and feeding regime ( P < 0.05), increasing with satiation degree. Flesh qualities for vitamin E, hydroxyproline (HYP), liquid loss and muscle pH among all groups showed significant differences ( P < 0.05), ranging from 26.67 to 29.67, while no obvious difference was found in flesh color. Fecal viscosity for different treatments showed no significant difference, though improvement was found in 100% satiation group. From present experiment, it was concluded that both feed type and feeding regime can affect the important quality attributes of Atlantic salmon.

Characterization of PVA/glutaraldehyde hydrogels obtained using Central Composite Rotatable Design (CCRD).

PubMed

Morandim-Giannetti, Andreia de Araújo; Rubio, Samantha Regina; Nogueira, Regina Freitas; Ortega, Fernando Dos Santos; Magalhães Junior, Octaviano; Schor, Paulo; Bersanetti, Patrícia Alessandra

2018-05-01

Hydrogels are made from natural or synthetic polymers and, currently, they have many biomedical applications. In this work, the conditions for obtaining a hydrogel with similar physicochemical characteristics to the vitreous humor were defined using polyvinyl alcohol (PVA) and glutaraldehyde (GLUT) as cross-linker. The concentration of PVA and GLUT were modified, and their effect was analyzed in terms of the refractive index, density, and dynamic viscosity. The hydrogel which was obtained using 3.98% (w/V) of PVA, 3.13 mL (1.57 g) of GLUT in 100 mL, and the initial pH of 7.2 showed similar characteristics to the vitreous humor (density = 1.0174 ± 0.0050 g mL -1 , dynamic viscosity = 3.7425 ± 0.1800 mPa s and refractive index = 1.3410 ± 0.0010). The hydrogels were further investigated by rheological measurements, infrared spectroscopy, differential scanning calorimetry, X-ray diffraction and determination of swelling degree. The reticulation with GLUT promoted an increase in viscosity and glass transition temperature. On the other hand, it stimulated a decrease in the swelling degree, crystallinity, melting temperature, and intensity of the band related to the -OH bond, compared with the PVA without reticulation. The reticulated hydrogel displayed Newtonian behavior and a higher apparent viscosity than the PVA. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1558-1566, 2018. © 2017 Wiley Periodicals, Inc.

Investigation of a new pH-responsive nanoparticulate pore former for controlled release enteric coating with improved processability and stability.

PubMed

Chen, Kuan; Chang, Hao Han R; Shalviri, Alireza; Li, Jason; Lugtu-Pe, Jamie Anne; Kane, Anil; Wu, Xiao Yu

2017-11-01

Water-soluble polymers are often used as pore formers to tailor permeability of film-forming hydrophobic polymers on coated dosage forms. However, their addition to a coating formulation could significantly increase the viscosity thus making the coating process difficult. Moreover, the dissolution of pore formers after oral administration could compromise film integrity resulting in undesirable, inconsistent release profiles. Therefore, a non-leaching, pH-responsive nanoparticulate pore former is proposed herein to preserve film integrity and maintain pH-dependent permeability. Poly(methacrylic acid)-polysorbate 80-grafted-starch terpolymer nanoparticles (TPNs) were incorporated within an ethylcellulose (EC) film (TPN-EC) by casting or spray coating. TPNs at 10%wt (pore former level) only increased viscosity of EC coating suspension slightly while conventional pore formers increased the viscosity by 490-11,700%. Negligible leaching of TPNs led to superior mechanical properties of TPN-EC films compared to Eudragit® L-EC films. As pH increased from 1.2 to 6.8, TPN-EC films with 10% pore former level exhibited an 8-fold higher diltiazem permeability compared to Eudragit® L-EC films. The pH-dependent drug release kinetics of diltiazem HCl beads coated with TPN-EC films was tunable by adjusting the pore former level. These results suggest that the TPNs are promising pH-sensitive nanoparticulate pore formers in EC-coated dosage forms. Copyright © 2017 Elsevier B.V. All rights reserved.

Dynamic Nucleation of Supercooled Melts and Measurement of the Surface Tension and Viscosity

NASA Technical Reports Server (NTRS)

Trinh, E. H.; Ohsaka, K.

1999-01-01

We investigate the phenomenon of acoustic pressure-induced nucleation by using a novel approach involving the large amplitude resonant radial oscillations and collapse of a single bubble intentionally injected into a supercooled liquid. Using a combination of previously developed and proven techniques, the bubble is suspended in a fluid host by an ultrasonic field which supplies both the levitation capability as well as the forcing of the radial oscillations. We observe the effects of an increase in pressure (due to bubble collapse) in a region no larger than 100 microns within the supercooled melt to rigorously probe the hypothesis of pressure-induced nucleation of the solid phase. The use of single bubbles operating in narrow temporal and spatial scales will allow the direct and unambiguous correlation between the origin and location of the generation of the disturbance and the location and timing of the nucleation event. In a companion research effort, we are developing novel techniques for the non-contact measurements of the surface tension and viscosity of highly viscous supercooled liquids. Currently used non-invasive methods of surface tension measurement for the case of undercooled liquids generally rely of the quantitative determination of the resonance frequencies of drop shape oscillations, of the dynamics of surface capillary waves, or of the velocity of streaming flows. These methods become quickly ineffective when the liquid viscosity rises to a significant value. An alternate and accurate method which would be applicable to liquids of significant viscosity is therefore needed. We plan to develop such a capability by measuring the equilibrium shape of levitated undercooled melt droplets as they undergo solid-body rotation. The experimental measurement of the characteristic point of transition (bifurcation point) between axisymmetric and two-lobed shapes will be used to calculate the surface tension of the liquid. Such an approach has already been validated through the experimental verification of numerical modeling results. The experimental approach involves levitation, melting, and solidification of undercooled droplets using a hybrid ultrasonic-electrostatic technique in both a gaseous as well as a vacuum environment. A shape relaxation method will be investigated in order to derive a reliable method to measure the viscosity of undercooled melts. The analysis of the monotonic relaxation to equilibrium shape of a drastically deformed and super-critically damped free drop has been used to derive interfacial tension of immiscible liquid combinations where one of the component has high viscosity. A standard approach uses the initial elongation of a droplet through shear flows, but an equivalent method could involve the initial deformation of a drop levitated in a gas by ultrasonic radiation pressure, electric stresses, or even solid body rotation. The dynamic behavior of the free drop relaxing back to equilibrium shape will be modeled, and its characteristic time dependence should provide a quantitative means to evaluate the liquid viscosity.

Grid Effect on Spherical Shallow Water Jets Using Continuous and Discontinuous Galerkin Methods

DTIC Science & Technology

2013-01-01

The high-order Legendre -Gauss-Lobatto (LGL) points are added to the linear grid by projecting the linear elements onto the auxiliary gnomonic space...mapping, the triangles are subdivided into smaller ones by a Lagrange polynomial of order nI . The number of quadrilateral elements and grid points of...of the acceleration of gravity and the vertical height of the fluid), ν∇2 is the artificial viscosity term of viscous coefficient ν = 1× 105 m2 s−1

Transport Properties of Ionic Liquid Mixtures Containing Heterodications

DOE PAGES

Lall-Ramnarine, S.; Fernandez, E.; Rodriguez, C.; ...

2016-08-30

This report discusses the transport properties of ionic liquid mixtures that incorporate a series of asymmetrical dications, including heterodications. The dicationic ILs combine either triphenylphosphonium and trimethylammonium cationic sites that are bridged to methylimidazolium or methylpyrrolidinium cationic sites. Mixtures were made of the dicationic bis(trifluoromethylsulfonyl)amide ionic liquids with N-ethoxyethyl-N-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide. The IL mixtures were characterized for their transport properties (temperature dependent conductivity and viscosity) and thermal properties (melting point and glass transition point).

Alternative Fuels Data Center: Biodiesel Fuel Basics

Science.gov Websites

gravity 0.88 Kinematic viscosity at 40°C 4.0 to 6.0 Cetane number 47 to 65 Higher heating value, Btu/gal ~127,960 Lower heating value, Btu/gal ~119,550 Density, lb/gal at 15.5°C 7.3 Carbon, wt% 77 Hydrogen, wt % 12 Oxygen, by dif. wt% 11 Boiling point, °C 315-350 Flash point, °C 100-170 Sulfur, wt% 0.0 to

Low-melting point inorganic nitrate salt heat transfer fluid

DOEpatents

Bradshaw, Robert W [Livermore, CA; Brosseau, Douglas A [Albuquerque, NM

2009-09-15

A low-melting point, heat transfer fluid made of a mixture of four inorganic nitrate salts: 9-18 wt % NaNO.sub.3, 40-52 wt % KNO.sub.3, 13-21 wt % LiNO.sub.3, and 20-27 wt % Ca(NO.sub.3).sub.2. These compositions can have liquidus temperatures less than 100 C; thermal stability limits greater than 500 C; and viscosity in the range of 5-6 cP at 300 C; and 2-3 cP at 400 C.

Transition of basaltic lava from pahoehoe to aa, Kilauea Volcano, Hawaii: Field observations and key factors

USGS Publications Warehouse

Peterson, Donald W.; Tilling, Robert I.

1980-01-01

Nearly all Hawaiian basaltic lava erupts as pahoehoe, and some changes to aa during flowage and cooling; factors governing the transition involve certain critical relations between viscosity and rate of shear strain. If the lava slows, cools, and stops in direct response to concomitant increase in viscosity before these critical relations are reached, it remains pahoehoe. But, if flow mechanics (flow rate, flow dimensions, slope, momentum, etc.) impel the lava to continue to move and deform even after it has become highly viscous, the critical relations may be reached and the lava changes to aa.Typical modes of transition from pahoehoe to aa include: (1) spontaneous formation of relatively stiff clots in parts of the flowing lava where shear rate is highest; these clots grow into discrete, rough, sticky masses to which the remaining fluid lava incrementally adheres; (2) fragmentation and immersion of solid or semi-solid surface crusts of pahoehoe by roiling movements of the flow, forming cores of discrete, tacky masses; (3) sudden renewed movement of lava stored and cooled within surface reservoirs to form clots. The masses, fragments, and clots in these transition modes are characterized by spinose, granulated surfaces; as flow movement continues, the masses and fragments aggregate, fracture, and grind together, completing the transition to aa.Observations show that the critical relation between viscosity and rate of shear strain is inverse: if viscosity is low, a high rate of shear is required to begin the transition to aa; conversely, if viscosity is high, a much lower rate of shear will induce the transition. These relations can be demonstrated qualitatively with simple graphs, which can be used to examine the flow history of any selected finite lava element by tracing the path represented by its changing viscosity and shear rate. A broad, diffuse “transition threshold zone” in these graphs portrays the inverse critical relation between viscosity and shear rate; the transition to aa is represented by the path of the lava element crossing this zone.Moving lava flows can be regarded as natural viscometers, by which shear stress and rate of shear strain at selected points can be determined and viscosity can be computed. By making such determinations under a wide range of conditions on pahoehoe, aa, and transitional flow types, the critical relations that control the pahoehoe-aa transition can be quantified.

Transport properties of gases and binary liquids near the critical point

NASA Technical Reports Server (NTRS)

Sengers, J. V.

1972-01-01

A status report is presented on the anomalies observed in the behavior of transport properties near the critical point of gases and binary liquids. The shear viscosity exhibits a weak singularity near the critical point. An analysis is made of the experimental data for those transport properties, thermal conductivity and thermal diffusivity near the gas-liquid critical point and binary diffusion coefficient near the critical mixing point, that determine the critical slowing down of the thermodynamic fluctuations in the order parameter. The asymptotic behavior of the thermal conductivity appears to be closely related to the asymptotic behavior of the correlation length. The experimental data for the thermal conductivity and diffusivity are shown to be in substantial agreement with current theoretical predictions.

Reinventing Design Principles for Developing Low-Viscosity Carbon Dioxide-Binding Organic Liquids for Flue Gas Clean Up

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

None, None

2017-01-11

Anthropogenic carbon dioxide (CO 2) emission from point sources, such as coal fired-power plants, account for the majority of the green houses gasses in the atmosphere. Capture, storage and utilization are required to mitigate adverse environmental effects. Aqueous amine-based CO 2 capture solvents are currently considered the industry standard, but deployment to market is limited by their high regeneration energy demand. In that context, energy efficient and less-viscous water-lean transformational solvent systems known as CO 2 Binding Organic Liquids (CO 2BOLs) are being developed in our group to advance this technology to commercialization. Herein, we present a logical design approachmore » based on fundamental concepts of organic chemistry and computer simulations aimed at lowering solvent viscosity. Conceptually, viscosity reduction would be achieved by systemmatic methods such as introduction of steric hindrance on the anion to minimize the intermolecular cation-anion interactions, fine tuning the electronics, hydrogen bonding orientation and strength, and charge solvation. Conventional standard trial-and-error approaches while effective, are time consuming and economically expensive. Herein, we rethink the metrics and design principles of low-viscosity CO 2 capture solvents using a combined synthesis and computational modeling approach. We critically study the impacts of modyfying factors such as as orientation of hydrogen bonding, introduction of higher degrees of freedom and cation or anion charge solvation and assess if or how each factor impacts viscosity of CO 2BOL CO 2 capture solvents. Ultimately, we found that hydrogen bond orientation and strength is predominantly influencing the viscosity in CO 2BOL solvents. With this knowledge, a new 1-MEIPADM-2-BOL CO 2BOL variant was synthesized and tested, resulting in a solvent that is approximately 60% less viscous at 25 mol% CO 2 loading with respect to our base compound 1-IPADM-2-BOL. The insights gained from the current study redefines the fundamental concepts and understanding of what influences viscosity in concentrated organic CO 2 capture solvents.« less

Implicit marching solution of compressible viscous subsonic flow in planar and axisymmetric ducts. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Towne, C. E.; Hoffman, J. D.

1982-01-01

A new streamwise marching procedure was developed and coded for compressible viscous subsonic flow in planar or axisymmetric ducts with or without centerbodies. The continuity, streamwise momentum, cross-flow momentum, and energy equations are written in generalized orthogonal curvilinear coordinates. To allow the use of a marching procedure, second derivatives in the streamwise momentum equation are written as the sum of a known two dimensional imposed pressure field and an unknown one dimensional viscous correction. For turbulent flow, the Reynolds stress and heat flux terms are modeled using two-layer eddy viscosity turbulence models.

A summary report on the search for current technologies and developers to develop depth profiling/physical parameter end effectors

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

Nguyen, Q.H.

1994-09-12

This report documents the search strategies and results for available technologies and developers to develop tank waste depth profiling/physical parameter sensors. Sources searched include worldwide research reports, technical papers, journals, private industries, and work at Westinghouse Hanford Company (WHC) at Richland site. Tank waste physical parameters of interest are: abrasiveness, compressive strength, corrosiveness, density, pH, particle size/shape, porosity, radiation, settling velocity, shear strength, shear wave velocity, tensile strength, temperature, viscosity, and viscoelasticity. A list of related articles or sources for each physical parameters is provided.

Constraints on lateral variations in upper mantle viscosity from Lake Bonneville shorelines

NASA Astrophysics Data System (ADS)

Austermann, Jacqueline; Chen, Christine; Lau, Harriet C. P.

2017-04-01

Lake Bonneville is an extinct pluvial lake that formed and catastrophically drained at the onset of the last deglaciation (˜ 20 - 18ka). With a volume of just over 10 000 km3 this lake was comparable in size to present-day Lake Michigan. During its existence the excess load of water stored in Lake Bonneville depressed the crust and upper mantle. After the drainage of the lake this area rebounded by up to 75 m, which is recorded in the paleoshorelines around the lake periphery and on islands within the lake. The rebound pattern has been used to infer the lithospheric thickness and upper mantle viscosity structure of the area (e.g. Bill et al., 1994). In agreement with the tectonic history of the Basin and Range area, the deformed shorelines point to a thin lithosphere (< 30km) and low upper mantle viscosity (˜ 1019 Pa s). This differs from the upper mantle viscosity inferred from post-glacial data in cratonic regions (e.g., Hudson Bay, Fennoscandia), which is one to two orders of magnitude larger (˜ 5 × 1020 Pa s). Direct constraints on the lateral variability of mantle viscosity are invaluable but in order to utilize such constraints it is important to consider the sensitivity range of different observations before comparing the inferred viscosities. In this study we revisit the earlier inversions of shoreline elevations for mantle and lithospheric structure with an updated dataset of paleoshoreline elevations by Chen and Maloof (2017). We construct depth-dependent sensitivity kernels for the lake rebound and compare them to kernels associated with the rebound from glacial ice sheets over Canada and Scandinavia. This comparison along with the inferred viscosities allows us to evaluate the degree to which lateral viscosity variations are required. We additionally compare our results to estimates of lateral viscosity variations based on perturbations in seismic shear wave speed in the respective areas in order to assess the consistency of our results with independent data. The paleoshorelines of Lake Bonneville have been deflected by not only rebound post-drainage, but also the longer-term subsidence of the Laurentide peripheral bulge. The lake was located on the distal flank of the peripheral bulge of the Laurentide Ice Sheet and after its collapse the peripheral bulge subsided leading to an additional northeast trending tilt in shoreline elevations. We show that the degree of tilt is not only sensitive to shallow mantle structure but has also sensitivity in the upper half of the lower mantle, in contrast to the lake rebound pattern. We independently invert the degree of tilt for mantle viscosity and examine its trade-off with uncertainties in the ice history.

Effect of Silk Protein Processing on Drug Delivery from Silk Films

PubMed Central

Pritchard, Eleanor M.; Hu, Xiao; Finley, Violet; Kuo, Catherine K.; Kaplan, David L.

2013-01-01

Sericin removal from the core fibroin protein of silkworm silk is a critical first step in the use of silk for biomaterial-related applications, but degumming can affect silk biomaterial properties, including molecular weight, viscosity, diffusivity and degradation behavior. Increasing the degumming time (10, 30, 60 and 90 min) decreases the average molecular weight of silk protein in solution, silk solution viscosity, and silk film glass transition temperature, and increases the rate of degradation of silk film by protease. Model compounds spanning a range of physical-chemical properties generally showed an inverse relationship between degumming time and release rate through a varied degumming time silk coating. Degumming provides a useful control point to manipulate silk’s material properties. PMID:23349062

Dynamical properties and transport coefficients of one-dimensional Lennard-Jones fluids: A molecular dynamics study

NASA Astrophysics Data System (ADS)

Bazhenov, Alexiev M.; Heyes, David M.

1990-01-01

The thermodynamics, structure, and transport coefficients, as defined by the Green-Kubo integrals, of the one-dimensional Lennard-Jones fluid are evaluated for a wide range of state points by molecular dynamics computer simulation. These calculations are performed for the first time for thermal conductivity and the viscosity. We observe a transition from hard-rod behavior at low number density to harmonic-spring fluid behavior in the close-packed limit. The self-diffusion coefficient decays with increasing density to a finite limiting value. The thermal conductivity increases with density, tending to ∞ in the close-packed limit. The viscosity in contrast maximizes at intermediate density, tending to zero in the zero density and close-packed limits.

An Interpretation of the Laminar-Turbulent Transition Startup against the Consideration of the Transverse Viscosity Factor

NASA Astrophysics Data System (ADS)

Kolodezhnov, V. N.

2018-03-01

This paper proposes a rheological model of a fluid having the Newtonian model applicability limit and a potential for further “addition” of the transverse viscosity factor. The dynamic equations for a fluid that has such rheological model are discussed, the analysis of which demonstrates the possibility of “generating” the cross stream velocity components. The transition to the dimensionless notation introduces four dimensionless complexes of local characterization for the transition conditions in the neighborhood of the flow region point in question. Based on such dimensionless complexes and using the known experimental data, the empiric conditions of “generating” the cross stream velocity components and starting the laminar-turbulent transition are proposed.

A new method for the continuous production of single dosed controlled release matrix systems based on hot-melt extruded starch: analysis of relevant process parameters and implementation of an in-process control.

PubMed

Kipping, Thomas; Rein, Hubert

2013-05-01

In the present study, we evaluated a novel processing technique for the continuous production of hot-melt extruded controlled release matrix systems. A cutting technique derived from plastics industry, where it is widely used for cutting of cables and wires was adapted into the production line. Extruded strands were shaped by a rotary fly cutter. Special focus is laid on the development of a process analytical technology by evaluating signals obtained from the servo control of the rotary fly cutter. The intention is to provide a better insight into the production process and to offer the ability to detect small variations in process-variables. A co-rotating twin-screw extruder ZSE 27 HP-PH from Leistritz (Nürnberg, Germany) was used to plasticize the starch; critical extrusion parameters were recorded. Still elastic strands were shaped by a rotary fly-cutter type Dynamat 20 from Metzner (Neu-Ulm, Germany). Properties of the final products were analyzed via digital image analysis to point out critical parameters influencing the quality. Important aspects were uniformity of diameter, height, roundness, weight, and variations in the cutting angle. Stability of the products was measured by friability tests and by determining the crushing strength of the final products. Drug loading studies up to 70% were performed to evaluate the capacity of the matrix and to prove the technological feasibility. Changes in viscosities during API addition were analyzed by a Haake Minilab capillary rheometer. X-ray studies were performed to investigate molecular structures of the matrices. External shapes of the products were highly affected by die-swelling of the melt. Reliable reproducibility concerning uniformity of mass could be achieved even for high production rates (>2500cuts/min). Both mechanical strength and die-swelling of the products could be linked to the ratio of amylose to amylopectin. Formulations containing up to 70% of API could still be processed. Viscosity measurements revealed the plasticizing effect caused by API addition. Dissolution data proved the suitability of extruded starch matrices as a sustained release dosage form. Monitoring of consumed energies during the cutting process could be linked to changes in viscosity. The established PAT system enables the detection of small variations in material properties and can be an important tool to further improve process stability. Copyright © 2013 Elsevier B.V. All rights reserved.

An adjoint-based simultaneous estimation method of the asthenosphere's viscosity and afterslip using a fast and scalable finite-element adjoint solver

NASA Astrophysics Data System (ADS)

Agata, Ryoichiro; Ichimura, Tsuyoshi; Hori, Takane; Hirahara, Kazuro; Hashimoto, Chihiro; Hori, Muneo

2018-04-01

The simultaneous estimation of the asthenosphere's viscosity and coseismic slip/afterslip is expected to improve largely the consistency of the estimation results to observation data of crustal deformation collected in widely spread observation points, compared to estimations of slips only. Such an estimate can be formulated as a non-linear inverse problem of material properties of viscosity and input force that is equivalent to fault slips based on large-scale finite-element (FE) modeling of crustal deformation, in which the degree of freedom is in the order of 109. We formulated and developed a computationally efficient adjoint-based estimation method for this inverse problem, together with a fast and scalable FE solver for the associated forward and adjoint problems. In a numerical experiment that imitates the 2011 Tohoku-Oki earthquake, the advantage of the proposed method is confirmed by comparing the estimated results with those obtained using simplified estimation methods. The computational cost required for the optimization shows that the proposed method enabled the targeted estimation to be completed with moderate amount of computational resources.

Thermophysical Properties of Liquid Te: Density, Electrical Conductivity, and Viscosity

NASA Technical Reports Server (NTRS)

Li, C.; Su, C.; Lehoczky, S. L.; Scripa, R. N.; Ban, H.; Lin, B.

2004-01-01

The thermophysical properties of liquid Te, namely, density, electrical conductivity, and viscosity, were determined using the pycnometric and transient torque methods from the melting point of Te (723 K) to approximately 1150 K. A maximum was observed in the density of liquid Te as the temperature was increased. The electrical conductivity of liquid Te increased to a constant value of 2.89 x 10(exp 5 OMEGA-1m-1) as the temperature was raised above 1000 K. The viscosity decreased rapidly upon heating the liquid to elevated temperatures. The anomalous behaviors of the measured properties are explained as caused by the structural transitions in the liquid and discussed in terms of Eyring's and Bachiskii's predicted behaviors for homogeneous liquids. The Properties were also measured as a function of time after the liquid was coded from approximately 1173 or 1123 to 823 K. No relaxation phenomena were observed in the properties after the temperature of liquid Te was decreased to 823 K, in contrast to the relaxation behavior observed for some of the Te compounds.

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.

Computational Study of Chaotic and Ordered Solutions of the Kuramoto-Sivashinsky Equation

NASA Technical Reports Server (NTRS)

Smyrlis, Yiorgos S.; Papageorgiou, Demetrios T.

1996-01-01

We report the results of extensive numerical experiments on the Kuramoto-Sivashinsky equation in the strongly chaotic regime as the viscosity parameter is decreased and increasingly more linearly unstable modes enter the dynamics. General initial conditions are used and evolving states do not assume odd-parity. A large number of numerical experiments are employed in order to obtain quantitative characteristics of the dynamics. We report on different routes to chaos and provide numerical evidence and construction of strange attractors with self-similar characteristics. As the 'viscosity' parameter decreases the dynamics becomes increasingly more complicated and chaotic. In particular it is found that regular behavior in the form of steady state or steady state traveling waves is supported amidst the time-dependent and irregular motions. We show that multimodal steady states emerge and are supported on decreasing windows in parameter space. In addition we invoke a self-similarity property of the equation, to show that these profiles are obtainable from global fixed point attractors of the Kuramoto-Sivashinsky equation at much larger values of the viscosity.

Comparative simulations of microjetting using atomistic and continuous approaches in presence of viscosity and surface tension

NASA Astrophysics Data System (ADS)

Durand, Olivier; Soulard, Laurent; Jaouen, Stephane; Heuze, Olivier; Colombet, Laurent; Cieren, Emmanuel

2017-06-01

We compare, at similar scales, the processes of microjetting and ejecta production from shocked roughened metal surfaces by using atomistic and continuous approaches. The atomistic approach is based on very large scale molecular dynamics (MD) simulations. The continuous approach is based on Eulerian hydrodynamics simulations with adaptive mesh refinement; the simulations take into account the effects of viscosity and surface tension, and they use an equation of state calculated from the MD simulations. The microjetting is generated by shock-loading above its fusion point a three-dimensional tin crystal with an initial sinusoidal free surface perturbation, the crystal being set in contact with a vacuum. Several samples with homothetic wavelengths and amplitudes of defect are simulated in order to investigate the influence of the viscosity and surface tension of the metal. The simulations show that the hydrodynamic code reproduces with a very good agreement the distributions, calculated from the MD simulations, of the ejected mass and velocity along the jet. Both codes exhibit also a similar phenomenology of fragmentation of the metallic liquid sheets ejected.

Differential genotoxicity of diphenyl diselenide (PhSe)2 and diphenyl ditelluride (PhTe)2

PubMed Central

Meinerz, Daiane Francine; Allebrandt, Josiane; Mariano, Douglas O.C.; Waczuk, Emily P.; Soares, Felix Antunes

2014-01-01

Organoselenium compounds have been pointed out as therapeutic agents. In contrast, the potential therapeutic aspects of tellurides have not yet been demonstrated. The present study evaluated the comparative toxicological effects of diphenyl diselenide (PhSe)2 and diphenyl ditelluride (PhTe)2 in mice after in vivo administration. Genotoxicity (as determined by comet assay) and mutagenicicity were used as end-points of toxicity. Subcutaneous administration of high doses of (PhSe)2 or (PhTe)2 (500 µmol/kg) caused distinct genotoxicity in mice. (PhSe)2 significantly decreased the DNA damage index after 48 and 96 h of its injection (p < 0.05). In contrast, (PhTe) caused a significant increase in DNA damage (p < 0.05) after 48 and 96 h of intoxication. (PhSe)2 did not cause mutagenicity but (PhTe)2 increased the micronuclei frequency, indicating its mutagenic potential. The present study demonstrated that acute in vivo exposure to ditelluride caused genotoxicity in mice, which may be associated with pro-oxidant effects of diphenyl ditelluride. In addition, the use of this compound and possibly other related tellurides must be carefully controlled. PMID:24711962

Effects of monoacylglycerols on low-temperature viscosity and cold filter plugging point of biodiesel

USDA-ARS?s Scientific Manuscript database

Biodiesel is composed of mono-alkyl fatty acid esters made from the transesterification of vegetable oil or animal fat with methanol or ethanol. Biodiesel must meet rigorous standard fuel specifications (ASTM D 6751; CEN EN 14214) to be classified as an alternative fuel. Nevertheless, biodiesel that...

Concentration Dependent Speciation and Mass Transport Properties of Switchable Polarity Solvents

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

Aaron D. Wilson; Christopher J. Orme

2014-12-01

Tertiary amine switchable polarity solvents (SPS) consisting of predominantly water, tertiary amine, and tertiary ammonium and bicarbonate ions were produced at various concentrations for three different amines: N,N-dimethylcyclohexylamine, N,N-dimethyloctylamine, and 1 cyclohexylpiperidine. For all concentrations, physical properties were measured including viscosity, molecular diffusion coefficients, freezing point depression, and density. Based on these measurements a variation on the Mark Houwink equation was developed to predict the viscosity of any tertiary amine SPS as a function of concentration using the amine’s molecular mass. The observed physical properties allowed the identification of solution state speciation of non-osmotic SPS, where the amine to carbonicmore » acid ratio is significantly greater than one. These results indicate that at most concentrations the stoichiometric excess amine is involved in solvating a proton with two amines. The physical properties of osmotic SPS have consistent concentration dependence behavior over a wide range of concentrations; this consistence suggests osmotic pressures based on low concentrations freezing point studies can be reliably extrapolated to higher concentrations.« less

Modelling the detachment dependence on strike point location in the small angle slot divertor (SAS) with SOLPS

NASA Astrophysics Data System (ADS)

Casali, Livia; Covele, Brent; Guo, Houyang

2017-10-01

The new Small Angle Slot (SAS) divertor in DIII-D is characterized by a shallow-angle target enclosed by a slot structure about the strike point (SP). SOLPS modelling results of SAS have demonstrated divertor closure's utility in widening the range of acceptable densities for adequate heat handling. An extensive database of runs has been built to study the detachment dependence on SP location in SAS. Density scans show that lower Te at lower upstream density occur when the SP is at the critical location in the slot. The cooling front spreads across the entire target at higher densities, in agreement with experimental Langmuir probe measurements. A localized increase of the atomic and molecular density takes place near the SP, which reduces the target incident power density and facilitates detachment at lower upstream density. Systematic scans of variables such as power, transport, and viscosity have been carried out to assess the detachment sensitivity. Therein, a positive role of the viscosity is found. This work supported by DOE Contract Number DE-FC02-04ER54698.

Effects of Waste Plastic on the Physical and Rheological Properties of Bitumen

NASA Astrophysics Data System (ADS)

Ezree Abdullah, Mohd; Asyiqin Ahmad, Nurul; Putra Jaya, Ramadhansyah; Hassan, Norhidayah Abdul; Yaacob, Haryati; Rosli Hainin, Mohd

2017-05-01

Plastic disposal is one of the major problems for developing countries like Malaysia, at the same time Malaysia needs a large network of roads for its smooth economic and social development. The limited source of bitumen needs a deep thinking to ensure fast road construction. Therefore, the use of plastic waste in road construction not only can help to protect environment but also able to help the road construction industry. The aims of this research are to study the effects of waste plastic on rheological properties of bitumen. Modified bitumen was prepared by using blending techniques. Bitumen was heated and plastic waste was slowly added. Rheological properties of bitumen were performance by penetration, softening point, viscosity and direct shear rheometer test. The results showed that when content of plastic waste increase, the penetration value, softening point and viscosity of bitumen also increase. Generally, plastic waste improves the performance of bitumen when it was added into bitumen. It can be said that the usage helps to improve the performance of the road pavement which also reduces the rutting effect.

Effect of fast pyrolysis bio-oil from palm oil empty fruit bunch on bitumen properties

NASA Astrophysics Data System (ADS)

Poh, Chia Chin; Hassan, Norhidayah Abdul; Raman, Noor Azah Abdul; Shukry, Nurul Athma Mohd; Warid, Muhammad Naqiuddin Mohd; Satar, Mohd Khairul Idham Mohd; Ros Ismail, Che; Asmah Hassan, Sitti; Mashros, Nordiana

2018-04-01

Bitumen shortage has triggered the exploration of another alternative waste material that can be blended with conventional bitumen. This study presents the performance of pyrolysis bio-oil from palm oil empty fruit bunch (EFB) as an alternative binder in modified bitumen mixtures. The palm oil EFB was first pyrolyzed using auger pyrolyzer to extract the bio-oil. Conventional bitumen 80/100 penetration grade was used as a control sample and compared with samples that were modified with different percentages, i.e., 5% and 10%, of pyrolysis EFB bio-oil. The physical and rheological properties of the control and modified bitumen samples were investigated using penetration, softening point, viscosity and dynamic shear rheometer (DSR) tests. Results showed that the addition of EFB bio-oil softened the bitumen with high penetration and a reduction in softening point, penetration index, and viscosity. However, the DSR results showed a comparable rutting resistance between the bitumen samples containing EFB bio-oil and virgin bitumen with a failure temperature achieved greater than 64°C.

On radiative heat transfer in stagnation point flow of MHD Carreau fluid over a stretched surface

NASA Astrophysics Data System (ADS)

Khan, Masood; Sardar, Humara; Mudassar Gulzar, M.

2018-03-01

This paper investigates the behavior of MHD stagnation point flow of Carreau fluid in the presence of infinite shear rate viscosity. Additionally heat transfer analysis in the existence of non-linear radiation with convective boundary condition is performed. Moreover effects of Joule heating is observed and mathematical analysis is presented in the presence of viscous dissipation. The suitable transformations are employed to alter the leading partial differential equations to a set of ordinary differential equations. The subsequent non-straight common ordinary differential equations are solved numerically by an effective numerical approach specifically Runge-Kutta Fehlberg method alongside shooting technique. It is found that the higher values of Hartmann number (M) correspond to thickening of the thermal and thinning of momentum boundary layer thickness. The analysis further reveals that the fluid velocity is diminished by increasing the viscosity ratio parameter (β∗) and opposite trend is observed for temperature profile for both hydrodynamic and hydromagnetic flows. In addition the momentum boundary layer thickness is increased with velocity ratio parameter (α) and opposite is true for thermal boundary layer thickness.

Holocene relative sea-level changes from North America and the Caribbean

NASA Astrophysics Data System (ADS)

Horton, Benjamin; Engelhart, Simon; Vacchi, Matteo; Khan, Nicole; Peltier, Dick; Roy, Keven

2014-05-01

Reconstructions of Holocene relative sea level (RSL) are important for identifying the ice equivalent meltwater contribution to sea-level change during deglaciation. Holocene RSL reconstructions from near, intermediate and far field regions enable the assessment of earth and ice parameters of Glacial Isostatic Adjustment (GIA) models. RSL reconstructions provide data for estimating rates of spatially variable and ongoing vertical land motion; a requirement for understanding the variation in modern and late Holocene sea level as recorded by instrumental and proxy records. Here we explain the methodology employed to reconstruct former sea levels, which follows the practice of the International Geoscience Programme (IGCP). We produce sea level index points from the Pacific and Atlantic coasts of North America and the Caribbean. Index points are defined as the most reliable observations of former sea levels. They consist of an estimate of X (age) and Y (the position of former RSL). Where a suite of index points are developed for a locality or region, they describe changes in RSL through time and estimate rates of change. A valid index point must meet the following four criteria; (1) location of the sample is known; (2) the altitude of the sample (and the error associated with measuring that altitude) is known; (3) the indicative meaning (the relationship between the sample and a tide level) is estimated; and (4) the age of the sample, which is commonly radiocarbon dated is calibrated to sidereal years using the latest calibration curves. In total databases have over 2000 sea-level index points from formerly ice covered, uplifting regions of Canada, to the region of forebulge collapse along the subsiding mid-Atlantic and mid-Pacific coastlines of the United States, to the tropical regions of the Caribbean. Recent analyses of these new published databases have led to a further refinement of the most recent of the ICE-NG (VMX) series of global models of GIA. The records from the region of forebulge collapse turn out to be especially sensitive to the mantle viscosity profile in the upper mantle, transition zone and uppermost lower mantle. Relatively minor adjustments to the depth dependence of viscosity characteristic of the VM5a profile employed to construct the newest ICE-6G model of deglaciation history lead to the definition of the refined viscosity structure VM6. This new viscosity model suffices to eliminate the majority of the misfits to the new U.S. Atlantic coast database. The west coast data were held back in the iterative procedure employed to define VM6; but this model is nevertheless found to be equally successful in fitting data from the U.S. Pacific coast. The ICE-6G (VM6) global model continues to provide good fits to all of the North American data from the ice-covered portion of the continent.

Long period grating-based fiber-optic PH sensor for ocean monitoring

NASA Astrophysics Data System (ADS)

Wang, Ke; Klimov, Denis; Kolber, Zbigniew

2007-09-01

A fiber-optic PH sensor is developed based-on the long period grating (LPG). The LPG is fabricated by using CO II laser with a point-by-point technique. Then the grating portion is coated with PH sensitive hydrogel. The hydrogel, made of PVA/PAA, swells its volume in response to the PH change in the surrounding environment and results in a change in the refractive index. As a result, the LPG can response to the refractive index change in the coating by shifting its wavelength. Therefore, change in refractive index can be measured by tracking the wavelength shift using an optical spectrum analyzer (OSA). In this research, the LPG is dip-coated by the hydrogel. A chemostat is designed to simulate the marine environment. The PH in the chemostat is varied by controlling the CO II concentration in the sea water. A PH resolution 0.046/nm using the OSA has been obtained. This sensor is designed to monitor the sea water PH change in a long term basis.

Screening and Characterization of Polygalacturonase as Potential Enzyme for Keprok Garut Orange (Citrus nobilis var. chrysocarpa) Juice Clarification

NASA Astrophysics Data System (ADS)

Widowati, E.; Utami, R.; Kalistyatika, K.

2017-11-01

Use of thermostable enzyme from bacilli for industrial application is significant. This research aimed to isolate thermophilic pectinolytic bacteria from orange peel and vegetable waste which produced thermostable polygalacturonase, to investigate the polygalacturonase ability in clarifying keprok Garut orange juice, and to characterize polygalacturonase based on pH optimum, temperature optimum, enzyme stability, enzyme kinetics KM, and Vmax. Obtained, 14 isolates that further selected to 4 best isolates based on highest polygalacturonase activity and keprok Garut orange juice clarification ability. Four selected enzyme isolates were AR 2, AR 4, KK 4, and KK 5 had ability to increase juice transmittance, decrease juice viscosity and also reduce total soluble solid. Furthermore 4 selected isolates were partially purified by ammonium sulphate precipitation and dialysis method. Four partially purified enzymes were known that enzyme character of AR 2 optimum at pH 6; AR 4 optimum at pH 5.5; KK 4 optimum at pH 6; and KK 5 optimum at pH 4.5. Four enzymes were optimum at temperature 60°C thus stable at temperature 50-60°C, this characteristic indicate that enzymes were thermostable. AR 2 showed active activity stable at pH 4-7; AR 4 showed active activity stable at pH 6-7; KK 4 showed active activity stable at pH 4-6; however KK 5 stable at pH 4-5. Enzyme AR 2 and KK 4 was getting inactive at pH 11, thus AR 4 and KK 5 inactive at pH 12. KM value of AR 2, AR 4, KK 4, and KK 5 was 0.0959; 0.0974; 0.0966; and 0.178 mg/ml respectively. Vmax of AR 2, AR 4, KK 4, and KK 5 was 0.0203; 0.0202; 0.0185; and 0.0229 U/ml respectively. Enzyme AR 2 was the most compatible enzyme to be applied in keprok Garut orange juice clarification for it had the lowest KM value.

Membrane-mediated extractive fermentation for lactic acid production from cellulosic biomass

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

Chen, Rongfu; Lee, Y.Y.

1997-12-31

Lactic acid production from cellulosic biomass by cellulose and Lactobacillus delbrueckii was studied in a fermenter-extractor employing a microporous hollow fiber membrane (NIHF). This bioreactor system was operated under a fed-batch mode with continuous removal of lactic acid by an in situ extraction. A tertiary amine (Alamine 336) was used as an extractant for lactic acid. The extraction capacity of Alamine 336 is greatly enhanced by addition of alcohol. Long-chain alcohols serve well for this purpose since they are less toxic to micro-organism. Addition of kerosene, a diluent, was necessary to reduce the solvent viscosity. A solvent mixture of 20%more » Alamine 336,40% oleyl alcohol, and 40% kerosene was found to be most effective in the extraction of lactic acid. Progressive change of pH from an initial value of 5.0 down to 4.3 has significantly improved the overall performance of the simultaneous saccharification and extractive fermentation over that of constant pH operation. The change of pH was applied to promote cell growth in the early phase, and extraction in the latter phase. 20 refs., 10 figs., 1 tab.« less

Pinhão starch and coat extract as new natural cosmetic ingredients: Topical formulation stability and sensory analysis.

PubMed

Daudt, Renata Moschini; Back, Patrícia Inês; Cardozo, Nilo Sérgio Medeiros; Marczak, Ligia Damasceno Ferreira; Külkamp-Guerreiro, Irene Clemes

2015-12-10

The objective of this study was to use pinhão derivatives, starch and coat extract, as new natural ingredients to develop cosmetic formulations. Two types of formulation, gel and emulgel, and their controls were developed. The formulations were characterized by stability studies using thermal stress. The parameters analyzed were resistance to centrifugation, pH, spreadability, rheology, content of phenolic compounds and antioxidant activity. Sensory analysis was also performed to verify the acceptability of the ingredients to potential consumers. The pH was kept the same after heating/freezing cycles for all formulations, and the formulations showed stability by resistance to centrifugation. The formulations did not induce any skin irritation or cutaneous pH alteration. The pinhão starch addition improved spreadability stability and increased viscosity when compared with control formulations. The pinhão coat extract used in these formulations is a good source of phenolic compounds and antioxidant activity. Moreover, sensory analysis indicates that the emulgel formulation is the best vehicle for adding pinhão starch and pinhão coat extract. Copyright © 2015 Elsevier Ltd. All rights reserved.

Neutralization of acidic drainage by Cryptococcus sp. T1 immobilized in alginate beads.

PubMed

Okai, Masahiko; Suwa, Chisato; Nagaoka, Shintaro; Obara, Nobuo; Mitsuya, Daisuke; Kurihara, Ayako; Ishida, Masami; Urano, Naoto

2017-11-01

We isolated Cryptococcus sp. T1 from Lake Tazawa's acidic water in Japan. Cryptococcus sp. T1 neutralized an acidic casamino acid solution (pH 3.0) and released ammonia from the casamino acids to aid the neutralization. The neutralization volume was estimated to be approximately 0.4 mL/h. The casamino acids' amino acids decreased (1.24→0.15 mM); ammonia increased (0.22→0.99 mM). We neutralized acidic drainage water (1 L) from a Tamagawa River neutralization plant, which was run through the column with the T1-immobilized alginate beads at a flow rate of 0.5 mL/min, and observed that the viscosity, particle size and amounts of the alginate beads affected the acidic drainage neutralization with an increase of the pH value from 5.26 to 6.61 in the last fraction. An increase in the Al concentration decreased Cryptococcus sp. T1's neutralization ability. After 48 h, the pH of acidic water with 50 mg/L Al was apparently lower than that without Al. Almost no pH increase was observed at 75 mg/L.

Evaluation of calcium ion, hydroxyl ion release and pH levels in various calcium hydroxide based intracanal medicaments: An in vitro study

PubMed Central

Fulzele, Punit; Baliga, Sudhindra; Thosar, Nilima; Pradhan, Debaprya

2011-01-01

Aims: Evaluation of calcium ion and hydroxyl ion release and pH levels in various calcium hydroxide based intracanal medicaments. Objective: The purpose of this study was to evaluate calcium and hydroxyl ion release and pH levels of calcium hydroxide based products, namely, RC Cal, Metapex, calcium hydroxide with distilled water, along with the new gutta-percha points with calcium hydroxide. Materials and Methods: The materials were inserted in polyethylene tubes and immersed in deionized water. The pH variation, Ca++ and OH- release were monitored periodically for 1 week. Statistical Analysis Used: Statistical analysis was carried out using one-way analysis of variance and Tukey's post hoc tests with PASW Statistics version 18 software to compare the statistical difference. Results: After 1 week, calcium hydroxide with distilled water and RC Cal raised the pH to 12.7 and 11.8, respectively, while a small change was observed for Metapex, calcium hydroxide gutta-percha points. The calcium released after 1 week was 15.36 mg/dL from RC Cal, followed by 13.04, 1.296, 3.064 mg/dL from calcium hydroxide with sterile water, Metapex and calcium hydroxide gutta-percha points, respectively. Conclusions: Calcium hydroxide with sterile water and RC Cal pastes liberate significantly more calcium and hydroxyl ions and raise the pH higher than Metapex and calcium hydroxidegutta-percha points. PMID:22346155

Influence of extracellular pH on growth, viability, cell size, acidification activity, and intracellular pH of Lactococcus lactis in batch fermentations.

PubMed

Hansen, Gunda; Johansen, Claus Lindvald; Marten, Gunvor; Wilmes, Jacqueline; Jespersen, Lene; Arneborg, Nils

2016-07-01

In this study, we investigated the influence of three extracellular pH (pHex) values (i.e., 5.5, 6.5, and 7.5) on the growth, viability, cell size, acidification activity in milk, and intracellular pH (pHi) of Lactococcus lactis subsp. lactis DGCC1212 during pH-controlled batch fermentations. A universal parameter (e.g., linked to pHi) for the description or prediction of viability, specific acidification activity, or growth behavior at a given pHex was not identified. We found viability as determined by flow cytometry to remain high during all growth phases and irrespectively of the pH set point. Furthermore, regardless of the pHex, the acidification activity per cell decreased over time which seemed to be linked to cell shrinkage. Flow cytometric pHi determination demonstrated an increase of the averaged pHi level for higher pH set points, while the pH gradient (pHi-pHex) and the extent of pHi heterogeneity decreased. Cells maintained positive pH gradients at a low pHex of 5.5 and even during substrate limitation at the more widely used pHex 6.5. Moreover, the strain proved able to grow despite small negative or even absent pH gradients at a high pHex of 7.5. The larger pHi heterogeneity at pHex 5.5 and 6.5 was associated with more stressful conditions resulting, e.g., from higher concentrations of non-dissociated lactic acid, while the low pHi heterogeneity at pHex 7.5 most probably corresponded to lower concentrations of non-dissociated lactic acid which facilitated the cells to reach the highest maximum active cell counts of the three pH set points.

Influence of Cofermentation by Amylolytic Lactobacillus plantarum and Lactococcus lactis Strains on the Fermentation Process and Rheology of Sorghum Porridge

PubMed Central

Byaruhanga, Yusuf B.; Muyanja, Charles M. B. K.; Aijuka, Matthew; Schüller, Reidar B.; Sahlstrøm, Stefan; Langsrud, Thor; Narvhus, Judith A.

2012-01-01

Amylolytic lactic acid bacteria (ALAB) can potentially replace malt in reducing the viscosity of starchy porridges. However, the drawback of using ALAB is their low and delayed amylolytic activity. This necessitates searching for efficient ALAB and strategies to improve their amylolytic activity. Two ALAB, Lactobacillus plantarum MNC 21 and Lactococcus lactis MNC 24, isolated from Obushera, were used to ferment starches in MRS broth: sorghum, millet, sweet potato, and commercial soluble starch. The amylolytic activity of MNC 21 was comparable to that of the ALAB collection strain Lb. plantarum A6, while that of MNC 24 was extremely low. MNC 21, MNC 24, and their coculture were compared to A6 and sorghum malt for ability to ferment and reduce the viscosity of sorghum porridge (11.6% dry matter). ALAB and the coculture lowered the pH from 6.2 to <4.5 within 12 h, while malt as a carrier of wild starter took about 20 h. Coculturing increased lactic acid yield by 46% and 76.8% compared to the yields of MNC 21 and MNC 24 monocultures, respectively. The coculture accumulated significantly larger (P < 0.05) amounts of maltose and diacetyl than the monocultures. Sorghum malt control and the coculture hydrolyzed more starch in sorghum porridge than the monocultures. The coculture initiated changes in the rheological parameters storage modulus (G′), loss modulus (G″), phase angle (δ), and complex viscosity (η*) earlier than its constituent monocultures. The shear viscosity of sorghum porridge was reduced significantly (P < 0.05) from 1950 cP to 110 cP (malt), 281 cP (coculture), 382 cP (MNC 21), 713 cP (MNC 24), and 722 cP (A6). Coculturing strong ALAB with weak ALAB or non-ALAB can be exploited for preparation of nutrient-dense weaning foods and increasing lactic acid yield from starchy materials. PMID:22610432

Influence of cofermentation by amylolytic Lactobacillus plantarum and Lactococcus lactis strains on the fermentation process and rheology of sorghum porridge.

PubMed

Mukisa, Ivan M; Byaruhanga, Yusuf B; Muyanja, Charles M B K; Aijuka, Matthew; Schüller, Reidar B; Sahlstrøm, Stefan; Langsrud, Thor; Narvhus, Judith A

2012-08-01

Amylolytic lactic acid bacteria (ALAB) can potentially replace malt in reducing the viscosity of starchy porridges. However, the drawback of using ALAB is their low and delayed amylolytic activity. This necessitates searching for efficient ALAB and strategies to improve their amylolytic activity. Two ALAB, Lactobacillus plantarum MNC 21 and Lactococcus lactis MNC 24, isolated from Obushera, were used to ferment starches in MRS broth: sorghum, millet, sweet potato, and commercial soluble starch. The amylolytic activity of MNC 21 was comparable to that of the ALAB collection strain Lb. plantarum A6, while that of MNC 24 was extremely low. MNC 21, MNC 24, and their coculture were compared to A6 and sorghum malt for ability to ferment and reduce the viscosity of sorghum porridge (11.6% dry matter). ALAB and the coculture lowered the pH from 6.2 to <4.5 within 12 h, while malt as a carrier of wild starter took about 20 h. Coculturing increased lactic acid yield by 46% and 76.8% compared to the yields of MNC 21 and MNC 24 monocultures, respectively. The coculture accumulated significantly larger (P < 0.05) amounts of maltose and diacetyl than the monocultures. Sorghum malt control and the coculture hydrolyzed more starch in sorghum porridge than the monocultures. The coculture initiated changes in the rheological parameters storage modulus (G'), loss modulus (G″), phase angle (δ), and complex viscosity (η*) earlier than its constituent monocultures. The shear viscosity of sorghum porridge was reduced significantly (P < 0.05) from 1950 cP to 110 cP (malt), 281 cP (coculture), 382 cP (MNC 21), 713 cP (MNC 24), and 722 cP (A6). Coculturing strong ALAB with weak ALAB or non-ALAB can be exploited for preparation of nutrient-dense weaning foods and increasing lactic acid yield from starchy materials.

Rate of deoxygenation modulates rheologic behavior of sickle red blood cells at a given mean corpuscular hemoglobin concentration.

PubMed

Kaul, D K; Liu, X D

1999-01-01

Although the mean corpuscular hemoglobin concentration (MCHC) plays a dominant role in the rheologic behavior of deoxygenated density-defined sickle red blood cells (SS RBCs), previous studies have not explored the relationship between the rate of deoxygenation and the bulk viscosity of SS RBCs at a given MCHC. In the present study, we have subjected density-defined SS classes (i.e., medium-density SS4 and dense SS5 discocytes) to varying deoxygenation rates. This approach has allowed us to minimize the effects of SS RBC heterogeneity and investigate the effect of deoxygenation rates at a given MCHC. The results show that the percentages of granular cells, classic sickle cells and holly leaf forms in deoxygenated samples are significantly influenced by the rate of deoxygenation and the MCHC of a given discocyte subpopulation. Increasing the deoxygenation rate using high K+ medium (pH 6.8), results in a greater percentage of granular cells in SS4 suspensions, accompanied by a pronounced increase in the bulk viscosity of these cells compared with gradually deoxygenated samples (mainly classic sickle cells and holly leaf forms). The effect of MCHC becomes apparent when SS5 dense cells are subjected to varying deoxygenation rates. At a given deoxygenation rate, SS5 dense discocytes show a greater increase in the percentage of granular cells than that observed for SS4 RBCs. Also, at a given deoxygenation rate, SS5 suspensions exhibit a higher viscosity than SS4 suspensions with fast deoxygenation resulting in maximal increase in viscosity. Although MCHC is the main determinant of SS RBC rheologic behavior, these studies demonstrate for the first time that at a given MCHC, the rate of deoxygenation (hence HbS polymerization rates) further modulates the rheologic behavior of SS RBCs. Thus, both MCHC and the deoxygenation rate may contribute to microcirculatory flow behavior of SS RBCs.

Experimental investigation of the influence of nanoparticles on water-based mud

NASA Astrophysics Data System (ADS)

Dhiman, Paritosh; Cheng, Yaoze; Zhang, Yin; Patil, Shirish

2018-03-01

This study has investigated the influence of nanoparticles including nanoparticle concentration, size, and type on water-based mud (WBM) properties including rheology, filtration, and lubricity through experimental tests, while the influence of temperature and aging on these properties have been investigated. It has been found that adding SiO2 nanoparticles increase the plastic viscosity and decrease the yield points and gel strengths with the increase of nanoparticle concentration. At fixed 0.5 wt%, the plastic viscosity decreases with the increase of TiO2 nanoparticle size, but the influence of TiO2 nanoparticle size on yield points and gel strengths is not monotonous. In general, adding negative charged SiO2 nanoparticles reduce the yield points and gel strengths, while adding positively charged TiO2, Al2O3, and Fe3O4 nanoparticles increase yield points and gel strengths. Adding lower concentrations (< 0.05 wt%) of SiO2 nanoparticles improved mud filtration and lubricity properties, but higher concentrations are adverse to these properties and adding 0.5 wt% TiO2, Al2O3 and Fe3O4 nanoparticles impaired these properties. Besides, it is found that there is no consistent influence of aging on mud properties and adding nanoparticles cannot improve aging resistance of mud. Although adding nanoparticles can significantly affect WBM properties, their influences are not consistency, depending on the integrated impact of the nanoparticle properties, such as surface electrical property, specific surface area, concentration, and size.

Rheological behavior of oxide nanopowder suspensions

NASA Astrophysics Data System (ADS)

Cinar, Simge

Ceramic nanopowders offer great potential in advanced ceramic materials and many other technologically important applications. Because a material's rheological properties are crucial for most processing routes, control of the rheological behavior has drawn significant attention in the recent past. The control of rheological behavior relies on an understanding of how different parameters affect the suspension viscosities. Even though the suspension stabilization mechanisms are relatively well understood for sub-micron and micron size particle systems, this knowledge cannot be directly transferred to nanopowder suspensions. Nanopowder suspensions exhibit unexpectedly high viscosities that cannot be explained with conventional mechanisms and are still a topic of investigation. This dissertation aims to establish the critical parameters governing the rheological behavior of concentrated oxide nanopowder suspensions, and to elucidate the mechanisms by which these parameters control the rheology of these suspensions. Aqueous alumina nanopowders were chosen as a model system, and the findings were extrapolated to other oxide nanopowder systems such as zirconia, yttria stabilized zirconia, and titania. Processing additives such as fructose, NaCl, HCl, NaOH, and ascorbic acid were used in this study. The effect of solids content and addition of fructose on the viscosity of alumina nanopowder suspensions was investigated by low temperature differential scanning calorimetry (LT-DSC), rheological, and zeta potential measurements. The analysis of bound water events observed in LT-DSC revealed useful information regarding the rheological behavior of nanopowder suspensions. Because of the significance of interparticle interactions in nanopowder suspensions, the electrostatic stabilization was investigated using indifferent and potential determining ions. Different mechanisms, e.g., the effect of the change in effective volume fraction caused by fructose addition and electrostatic stabilization, were combined to optimize the viscosities and the ability to control the suspension viscosity. The intrinsic viscosities of nanopowder systems were estimated using the Krieger-Dougherty relation. Both the individual and the combined effects were evaluated using slip casting of green bodies. Also, ascorbic acid was used to disperse the alumina nanopowders (described here for the first time in the open literature). The mechanism of viscosity reduction was investigated by in situ Attenuated Total Reflectance Fourier Infrared Spectroscopy (ATR-FTIR), rheological, suspension pH, and zeta potential measurements. Lastly, the findings were extrapolated to several other oxide systems. The rheological behavior of zirconia, yttria stabilized zirconia, and titania nanopowder systems was investigated as a function of solids content, bound water, and intrinsic viscosity. The results indicated that nanopowder suspensions differ from sub-micron powder suspensions because of the higher bound water content and the short separation distances between particles causing increased interparticle interactions. The bound water event was associated with the powder surface. This layer differed from the electrostatic double layer in that it was modified by fructose molecules as well as by specifically adsorbed ions such as H+ and OH but not by indifferent electrolytes, such as NaCl. Because of the large surface area of nanopowders, this additional layer increased the effective solids content and led to higher viscosities. While the alumina suspensions were studied in detail, it was also shown that the bound water was not unique to the alumina nanopowder suspensions, but also present in other oxide systems. However, the bound water content was unique for each system and provided information about its origin. The presence of bound water resulted in lower the maximum achievable solids fractions for nanopowder systems. In order to achieve higher solids contents, the bound water layer had to be modified. Because of the limited separation distances and large surface areas of nanopowders, the electrostatic double layer has an amplified effect on the viscosity of the suspensions. The addition of NaCl decreased the viscosity of alumina nanopowder suspensions significantly by compressing the double layer hence limiting the repulsion length. We also discovered that ascorbic acid can be used to disperse the alumina nanopowder suspensions. By adding only 1 wt% of ascorbic acid, the viscosity of the suspensions decreased significantly. It was shown that ascorbic acid molecules adsorbed to the alumina surfaces and when the adsorption reached equilibrium, the lowest viscosities were observed. By lowering the viscosities, the maximum achievable solids content (where viscosity = 1 Pa at a shear rate of 100 s-1) could be increased up to about 0.35, which is the highest solids content achieved with readily available processing additives reported in the open literature. Even though it is almost impossible to isolate the individual effects, three dominant mechanisms were observed in nanopowder suspensions: (i) increase in effective volume fraction (bound water), (ii) interparticle interactions (electrostatic), and (iii) adsorption of organic molecules. It was shown that the understanding of the system's parameters enables the optimization of the rheological behavior of the suspensions and the prediction of the green body quality.

The effect of antioxidants on quantitative changes of lysine and methionine in linoleic acid emulsions at different pH conditions.

PubMed

Hęś, Marzanna; Gliszczyńska-Świgło, Anna; Gramza-Michałowska, Anna

2017-01-01

Plants are an important source of phenolic compounds. The antioxidant capacities of green tea, thyme and rosemary extracts that contain these compounds have been reported earlier. However, there is a lack of accessible information about their activity against lipid oxidation in emulsions and inhibit the interaction of lipid oxidation products with amino acids. Therefore, the influence of green tea, thyme and rosemary extracts and BHT (butylated hydroxytoluene) on quantitative changes in lysine and methionine in linoleic acid emulsions at a pH of isoelectric point and a pH lower than the isoelectric point of amino acids was investigated. Total phenolic contents in plant extracts were determined spectrophotometrically by using Folin-Ciocalteu's reagent, and individual phenols by using HPLC. The level of oxidation of emulsion was determined using the measurement of peroxides and TBARS (thiobarbituric acid reactive substances). Methionine and lysine in the system were reacted with sodium nitroprusside and trinitrobenzenesulphonic acid respectively, and the absorbance of the complexes was measured. Extract of green tea had the highest total polyphenol content. The system containing antioxidants and amino acid protected linoleic acid more efficiently than by the addition of antioxidants only. Lysine and methionine losses in samples without the addition of antioxidants were lower in their isoelectric points than below these points. Antioxidants decrease the loss of amino acids. The protective properties of antioxidants towards methionine were higher in a pH of isoelectric point whereas towards lysine in pH below this point. Green tea, thyme and rosemary extracts exhibit antioxidant activity in linoleic acid emulsions. Moreover, they can be utilized to inhibit quantitative changes in amino acids in lipid emulsions. However, the antioxidant efficiency of these extracts seems to depend on pH conditions. Further investigations should be carried out to clarify this issue.

Measurements of pH and redox potential distributions in TNT-contaminated plant-soil systems using microelectrode techniques

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

Pang, H.; Zhang, T.C.

1997-12-31

The pH and redox potential profiles in TNT-contaminated soils with and without plants were investigated using microelectrode techniques. The new pH cocktail and double-barreled structure greatly improved the performance of the pH microelectrode. For soil without plants, there is almost no pH difference at different locations with different heights; while for the TNT-contaminated soils with plants there exist pH profiles. The soil immediately near the root of the plant has the lowest pH value. The pH value increases as the distance between the measuring point and the plant roots increases. The pH gradient (the increased pH value over the unitmore » distance) decreases with an increase of the distance between the measuring point and the plant roots. These results show that the plant presence can greatly affect the pH distribution. In vegetated soil, the redox potentials in the layer nearest the plant roots are higher than those in the bulk soil without plants. The redox potentials in the central part of the plant are lower than those in the soil around the plant and soil without the plant. The redox potentials in the soil without plants decrease with an increase of depth.« less

New Formulation for the Viscosity of n-Butane

NASA Astrophysics Data System (ADS)

Herrmann, Sebastian; Vogel, Eckhard

2018-03-01

A new viscosity formulation for n-butane, based on the residual quantity concept, uses the reference equation of state by Bücker and Wagner [J. Phys. Chem. Ref. Data 35, 929 (2006)] and is valid in the fluid region from the triple point to 650 K and to 100 MPa. The contributions for the zero-density viscosity and for the initial-density dependence were separately developed, whereas those for the critical enhancement and for the higher-density terms were pretreated. All contributions were given as a function of the reciprocal reduced temperature τ, while the last two contributions were correlated as a function of τ and of the reduced density δ. The different contributions were based on specific primary data sets, whose evaluation and choice were discussed in detail. The final formulation incorporates 13 coefficients derived employing a state-of-the-art linear optimization algorithm. The viscosity at low pressures p ≤ 0.2 MPa is described with an expanded uncertainty of 0.5% (coverage factor k = 2) for temperatures 293 ≤ T/K ≤ 626. The expanded uncertainty in the vapor phase at subcritical temperatures T ≥ 298 K as well as in the supercritical thermodynamic region T ≤ 448 K at pressures p ≤ 30 MPa is estimated to be 1.5%. It is raised to 4.0% in regions where only less reliable primary data sets are available and to 6.0% in ranges without any primary data, but in which the equation of state is valid. A weakness of the reference equation of state in the near-critical region prevents estimation of the expanded uncertainty in this region. Viscosity tables for the new formulation are presented in Appendix B for the single-phase region, for the vapor-liquid phase boundary, and for the near-critical region.

Glass transition and viscosity of P/sub 2/O/sub 5/

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

Martin, S.W.; Angell, C.A.

1986-12-04

The calorimetric glass transition temperature T/sub g/ for pure anhydrous P/sub 2/O/sub 5/ melted in sealed SiO/sub 2/ ampules at 1000 /sup 0/C has been obtained directly for the first time with differential scanning calorimetry, and the increase in heat capacity at T/sub g/ has been determined. T/sub g/ measured in this way is 57 K higher than the value quoted in the literature, which is probably based on an Arrhenius law extrapolation of viscosity data to eta = 10/sup 13/ P. Combining the high-temperature viscosity data with the common observation that, for oxide glasses, eta = 10/sup 12/ Pmore » at the DSC T/sub g/, the authors find that the P/sub 2/O/sub 5/ viscosity obeys an Arrhenius law over at least 6 decades of eta. Furthermore, the intercept at 1/T = 0 coincides with the common point of T/sub g/ - reduced viscosity plots for a wide variety of liquids recently used in establishing the strong vs. fragile classification of glass-forming liquids. On this basis, P/sub 2/O/sub 5/ behaves as the archetypal strong liquid. However, the value of C/sub p/(liquid)/C/sub p/(glass) at T/sub g/, 1.27, is larger than expected on this basis since other strong liquids show smaller values, e.g., GeO/sub 2/ (1.09) and BeF/sub 2/ (no ..delta..C/sub p/ detected). The dependence of T/sub g/ on heating rate has been determined and shows that enthalpy relaxation in the transition region has, within error, the same activation energy (43.9 kcal/mol) as for viscous flow.« less

Interaction Gaps in PhD Education and ICT as a Way Forward: Results from a Study in Sweden

ERIC Educational Resources Information Center

Aghaee, Naghmeh; Jobe, William Byron; Karunaratne, Thashmee; Smedberg, Åsa; Hansson, Henrik; Tedre, Matti

2016-01-01

Many research studies have highlighted the low completion rate and slow progress in PhD education. Universities strive to improve throughput and quality in their PhD education programs. In this study, the perceived problems of PhD education are investigated from PhD students' points of view, and how an Information and Communication Technology…

Nanofiltration of Mine Water: Impact of Feed pH and Membrane Charge on Resource Recovery and Water Discharge

PubMed Central

Mullett, Mark; Fornarelli, Roberta; Ralph, David

2014-01-01

Two nanofiltration membranes, a Dow NF 270 polyamide thin film and a TriSep TS 80 polyamide thin film, were investigated for their retention of ionic species when filtering mine influenced water streams at a range of acidic pH values. The functional iso-electric point of the membranes, characterized by changes in retention over a small pH range, were examined by filtering solutions of sodium sulphate. Both membranes showed changes in retention at pH 3, suggesting a zero net charge on the membranes at this pH. Copper mine drainage and synthetic solutions of mine influenced water were filtered using the same membranes. These solutions were characterized by pH values within 2 and 5, thus crossing the iso-electric point of both membranes. Retention of cations was maximized when the feed solution pH was less than the iso-electric point of the membrane. In these conditions, the membrane has a net positive charge, reducing the transmission rate of cations. From the recoveries of a range of cations, the suitability of nanofiltration was discussed relative to the compliance with mine water discharge criteria and the recovery of valuable commodity metals. The nanofiltration process was demonstrated to offer advantages in metal recovery from mine waste streams, concomitantly enabling discharge criteria for the filtrate disposal to be met. PMID:24957170

Rheology of surface granular flows

NASA Astrophysics Data System (ADS)

Orpe, Ashish V.; Khakhar, D. V.

Surface granular flow, comprising granular material flowing on the surface of a heap of the same material, occurs in several industrial and natural systems. The rheology of such a flow was investigated by means of measurements of velocity and number-density profiles in a quasi-two-dimensional rotating cylinder, half-filled with a model granular material monosize spherical stainless-steel particles. The measurements were made at the centre of the cylinder, where the flow is fully developed, using streakline photography and image analysis. The stress profile was computed from the number-density profile using a force balance which takes into account wall friction. Mean-velocity and root-mean-square (r.m.s.)-velocity profiles are reported for different particle sizes and cylinder rotation speeds. The profiles for the mean velocity superimpose when distance is scaled by the particle diameter d and velocity by a characteristic shear rate dot{gamma}_C = [gsin(beta_m-beta_s)/dcosbeta_s](1/2) and the particle diameter, where beta_m is the maximum dynamic angle of repose and beta_s is the static angle of repose. The maximum dynamic angle of repose is found to vary with the local flow rate. The scaling is also found to work for the r.m.s. velocity profiles. The mean velocity is found to decay exponentially with depth in the bed, with decay length lambda=1.1d. The r.m.s. velocity shows similar behaviour but with lambda=1.7d. The r.m.s. velocity profile shows two regimes: near the free surface the r.m.s. velocity is nearly constant and below a transition point it decays linearly with depth. The shear rate, obtained by numerical differentiation of the velocity profile, is not constant anywhere in the layer and has a maximum which occurs at the same depth as the transition in the r.m.s. velocity profile. Above the transition point the velocity distributions are Gaussian and below the transition point the velocity distributions gradually approach a Poisson distribution. The shear stress increases roughly linearly with depth. The variation in the apparent viscosity eta with r.m.s. velocity u shows a relatively sharp transition at the shear-rate maximum, and in the region below this point the apparent viscosity eta˜ u(-1.5) . The measurements indicate that the flow comprises two layers: an upper low-viscosity layer with a nearly constant r.m.s. velocity and a lower layer of increasing viscosity with a decreasing r.m.s. velocity. The thickness of the upper layer depends on the local flow rate and is independent of particle diameter while the reverse is found to hold for the lower-layer thickness. The experimental data is compared with the predictions of three models for granular flow.

THE CONSISTENCY OF AMEBA CYTOPLASM AND ITS BEARING ON THE MECHANISM OF AMEBOID MOVEMENT

PubMed Central

Allen, Robert D.

1960-01-01

Three species of common, free-living amebae, Amoeba proteus, Amoeba dubia, and Chaos chaos were directly observed and photographed while exposed to a range of centrifugal accelerations in two types of centrifuge microscopes. Cytoplasmic inclusions in all three species are displaced discontinuously (at a variable velocity) in apparently all parts of the cell, suggesting non-Newtonian behavior and/or heterogeneous consistency. The ectoplasm of all species shows the highest yield point of any region in the cell; the posterior ectoplasm is less rigid than that in the anterior part of the cell. The axial part of the endoplasm shows evidence of structure (a sharp viscosity transition if not a true yield point) by its: (a) resistance to the displacement of particles carried in that region of the cell, (b) hindrance to the passage through the cell of inclusions displaced from other regions, and its (c) support without visible back-slip of inclusion being resuspended in the axial endoplasm in a centripetal direction at accelerations as high as 170 g. At this acceleration, each crystal "weighs" the equivalent reduced weight of seven times its volume in gold at 1 g. The only regions of the normal, moving cell which show clear evidence of low apparent viscosity are the "shear zone" (see Fig. 8) and the "recruitment zone." Possible reasons for low apparent viscosity in these regions are discussed. A new scheme of ameba "structure" is presented on the basis of the combined results of velocity profile analysis and the present centrifugation study. PMID:13682546

Characterization of highly concentrated antibody solution - A toolbox for the description of protein long-term solution stability

PubMed Central

Schermeyer, Marie-Therese; Wöll, Anna K.; Eppink, Michel; Hubbuch, Jürgen

2017-01-01

ABSTRACT High protein titers are gaining importance in biopharmaceutical industry. A major challenge in the development of highly concentrated mAb solutions is their long-term stability and often incalculable viscosity. The complexity of the molecule itself, as well as the various molecular interactions, make it difficult to describe their solution behavior. To study the formulation stability, long- and short-range interactions and the formation of complex network structures have to be taken into account. For a better understanding of highly concentrated solutions, we combined established and novel analytical tools to characterize the effect of solution properties on the stability of highly concentrated mAb formulations. In this study, monoclonal antibody solutions in a concentration range of 50–200 mg/ml at pH 5–9 with and without glycine, PEG4000, and Na2SO4 were analyzed. To determine the monomer content, analytical size-exclusion chromatography runs were performed. ζ-potential measurements were conducted to analyze the electrophoretic properties in different solutions. The melting and aggregation temperatures were determined with the help of fluorescence and static light scattering measurements. Additionally, rheological measurements were conducted to study the solution viscosity and viscoelastic behavior of the mAb solutions. The so-determined analytical parameters were scored and merged in an analytical toolbox. The resulting scoring was then successfully correlated with long-term storage (40 d of incubation) experiments. Our results indicate that the sensitivity of complex rheological measurements, in combination with the applied techniques, allows reliable statements to be made with respect to the effect of solution properties, such as protein concentration, ionic strength, and pH shift, on the strength of protein-protein interaction and solution colloidal stability. PMID:28617076

Solid Loss of Carrots During Simulated Gastric Digestion.

PubMed

Kong, Fanbin; Singh, R Paul

2011-03-01

The knowledge of solid loss kinetics of foods during digestion is crucial for understanding the factors that constrain the release of nutrients from the food matrix and their fate of digestion. The objective of this study was to investigate the solid loss of carrots during simulated gastric digestion as affected by pH, temperature, viscosity of gastric fluids, mechanical force present in stomach, and cooking. Cylindrical carrot samples were tested by static soaking method and using a model stomach system. The weight retention, moisture, and loss of dry mass were determined. The results indicated that acid hydrolysis is critical for an efficient mass transfer and carrot digestion. Internal resistance rather than external resistance is dominant in the transfer of soluble solids from carrot to gastric fluid. Increase in viscosity of gastric fluid by adding 0.5% gum (w/w) significantly increased the external resistance and decreased mass transfer rate of carrots in static soaking. When mechanical force was not present, 61% of the solids in the raw carrot samples were released into gastric fluid after 4 h of static soaking in simulated gastric juice. Mechanical force significantly increased solid loss by causing surface erosion. Boiling increased the disintegration of carrot during digestion that may favor the loss of solids meanwhile reducing the amount of solids available for loss in gastric juice. Weibull function was successfully used to describe the solid loss of carrot during simulated digestion. The effective diffusion coefficients of solids were calculated using the Fick's second law of diffusion for an infinite cylinder, which are between 0.75 × 10(-11) and 8.72 × 10(-11) m(2)/s, depending on the pH of the gastric fluid.

Chitosan-magnesium aluminum silicate composite dispersions: characterization of rheology, flocculate size and zeta potential.

PubMed

Khunawattanakul, Wanwisa; Puttipipatkhachorn, Satit; Rades, Thomas; Pongjanyakul, Thaned

2008-03-03

Composite dispersions of chitosan (CS), a positively charged polymer, and magnesium aluminum silicate (MAS), a negatively charged clay, were prepared and rheology, flocculate size and zeta potential of the CS-MAS dispersions were investigated. High and low molecular weights of CS (HCS and LCS, respectively) were used in this study. Moreover, the effects of heat treatment at 60 degrees C on the characteristics of the CS-MAS dispersions and the zeta potential of MAS upon addition of CS at different pHs were examined. Incorporation of MAS into CS dispersions caused an increase in viscosity and a shift of CS flow type from Newtonian to pseudoplastic flow with thixotropic properties. Heat treatment brought about a significant decrease in viscosity and hysteresis area of the composite dispersions. Microscopic studies showed that flocculation of MAS occurred after mixing with CS. The size and polydispersity index of the HCS-MAS flocculate were greater than those of the LCS-MAS flocculate. However, a narrower size distribution and the smaller size of the HCS-MAS flocculate were found after heating at 60 degrees C. Zeta potentials of the CS-MAS flocculates were positive and slightly increased with increasing MAS content. In the zeta potential studies, the negative charge of the MAS could be neutralized by the addition of CS. Increasing the pH and molecular weight of CS resulted in higher CS concentrations required to neutralize the charge of MAS. These findings suggest that the electrostatic interaction between CS and MAS caused a change in flow behavior and flocculation of the composite dispersions, depending on the molecular weight of CS. Heat treatment affected the rheological properties and the flocculate size of the composite dispersions. Moreover, pH of medium and molecular weight of CS influence the zeta potential of MAS.

Combined effects of high pressure homogenization treatment and citral on microbiological quality of apricot juice.

PubMed

Patrignani, Francesca; Tabanelli, Giulia; Siroli, Lorenzo; Gardini, Fausto; Lanciotti, Rosalba

2013-01-01

High pressure homogenization (HPH) technique is able to significantly reduce spoilage microbiota in fruit juice. On the other hand, aroma compounds and essential oils can have a key role in the microbial stability of these products. For this reason, the aim of this work was to evaluate the combined effects of an aroma compound (citral, used at a concentration of 50 mg/l) and HPH treatments (performed at 100 MPa for 1-8 successive passes) on the inactivation dynamics of Saccharomyces cerevisiae SPA strain inoculated in apricot juices at level of about 4.5 log CFU/ml. Moreover, growth of surviving yeast cells was measured during the storage of the treated juice at 10°C and pH, water activity, viscosity and volatile molecule profile of apricot juice were studied. Since citral had been diluted in ethanol before the addition to juice, also samples with only ethanol added at the same volume used to dissolve citral were considered. The results showed that yeast cell viability decreased with the increases of passes at 100 MPa and the relationship between yeast cell loads and number of passes at 100 MPa followed a linear trend. In addition, the effect of HPH treatment can be notably potentiated throughout the presence of citral and ethanol, increasing the time necessary to reach a spoilage threshold during storage. The volatile profiles of the juices added with citral showed a substitution by yeast metabolism of this aldehyde with molecule characterized by a lower antimicrobial activity such as alcohols. The HPH treatments had also a significant effect on pH and viscosity of apricot juices while did not affect a(w). Copyright © 2012 Elsevier B.V. All rights reserved.

Synthesis and in vitro characterization of entirely S-protected thiolated pectin for drug delivery.

PubMed

Hintzen, Fabian; Hauptstein, Sabine; Perera, Glen; Bernkop-Schnürch, Andreas

2013-11-01

The study was aimed to synthesize a thiolated polymer (thiomer) that is resistant to oxidation in solutions above pH 5. In order to protect a pectin-cysteine conjugate against premature oxidation, the thiomer was S-protected by a disulfide connected leaving group. Therefore, 2-mercaptonicotinic acid was first coupled to L-cysteine by a disulfide exchange reaction and the purified product was subsequently attached to pectin by a carbodiimide mediated amid bond formation. The obtained fully S-protected thiolated pectin was in vitro characterized with respect to co- and mucoadhesive properties and stability toward oxidation. The results indicated a 1.8-fold and 2.3-fold enhanced disintegration time at pH 6.8 of the S-protected thiolated pectin (Pec-Cys-MNA) compared to thiolated pectin (Pec-Cys) and unmodified pectin (Pec). Moreover, rheological measurements of polymer/mucus mixtures showed a 1.6-fold (compared to Pec-Cys) and 6.7-fold (compared to Pec) increased dynamic viscosity of Pec-Cys-MNA. On the other hand, in the presence of a strong oxidizing agent such as H2O2 (0.3% v/v), no increase in viscosity of Pec-Cys-MNA could be observed. A 6-month experiment also demonstrated the long-term stability of a liquid formulation based on Pec-Cys-MNA. Further investigations proved that the first time all thiol groups on a thiolated polymer could be protected owing to the novel synthesis. Accordingly, these features may help to develop thiomer based liquid or gel formulations targeting mucosal surfaces such as nasal, ocular or vaginal drug delivery systems. Copyright © 2013 Elsevier B.V. All rights reserved.