Effect of asphaltenes on crude oil wax crystallization

DEFF Research Database (Denmark)

Kriz, Pavel; Andersen, Simon Ivar

2005-01-01

The paper summarizes the experimental work done on asphaltene influenced wax crystallization. Three different asphaltenes (from stable oil, instable oil, and deposit) were mixed at several concentrations or dispersions into the waxy crude oil. These blends were evaluated by viscometry and yield s...

Haemorheological parameters in hypertensive Nigerians compared ...

African Journals Online (AJOL)

Hct was determined by Hawksley micro capillary centrifugation, Hbc by the cyanmethaemoglobin method, FC by the clot weight method, ESR by the Westergren method, while both RPV and WBRV were determined by capillary viscometry. Systolic and diastolic blood pressures were measured by standard clinical ...

A route to anionic hydrophilic films of copolymers of l-leucine, l-aspartic acid and l-aspartic acid esters

NARCIS (Netherlands)

Sederel, W.L.; Bantjes, A.; Feijen, Jan

1975-01-01

A series of copolymers of l-leucine and β-benzyl-l-aspartate [Leu/Asp(OBz)] covering the range 30–70 mol % of l-leucine, was synthesized by the N-carboxyanhydride (NCA) method. The copolymers were characterized by elemental analysis, infra-red spectroscopy and viscometry. For all compositions high

Regularities in the association of polymethacrylic acid with benzethonium chloride in aqueous solutions

Science.gov (United States)

Tugay, A. V.; Zakordonskiy, V. P.

2006-06-01

The association of cationogenic benzethonium chloride with polymethacrylic acid in aqueous solutions was studied by nephelometry, conductometry, tensiometry, viscometry, and pH-metry. The critical concentrations of aggregation and polymer saturation with the surface-active substance were determined. A model describing processes in such systems step by step was suggested.

The mechanism of interaction of polymethacrylic acid with sodium dodecylbenzenesulfonate in aqueous solutions

Science.gov (United States)

Sachko, A. V.; Zakordonskii, V. P.; Voloshinovskii, A. S.; Golod, T. Yu.

2009-07-01

A complex of physicochemical methods (light scattering, potentiometry, conductometry, viscometry, tensiometry, and fluorescence spectroscopy) were used to show the possibility of formation of intermolecular associates/complexes in systems with likely charged components. The driving forces of such interactions were analyzed and a possible scheme of complex formation between polymethacrylic acid and sodium dodecylbenzenesulfonate was suggested.

Bulk Fluidity and Apparent Wall Slip of Aqueous Kaolin Suspensions Studied Using the Cone-Cone (KK) Sensor: Effect of the Sensor Surface Quality.

Czech Academy of Sciences Publication Activity Database

Pěnkavová, Věra; Tihon, Jaroslav; Wein, Ondřej

2017-01-01

Roč. 533, NOV 20 (2017), s. 338-346 ISSN 0927-7757 EU Projects: Foundation for Science and Technology(XE) MP1305 Institutional support: RVO:67985858 Keywords : aqueous kaolin suspensions * rotational AWS viscometry * apparent wall slip Subject RIV: CI - Industrial Chemistry, Chemical Engineering OBOR OECD: Chemical process engineering Impact factor: 2.714, year: 2016

Stability and Rheology of Dilute TiO2 – Water Nanofluids

Czech Academy of Sciences Publication Activity Database

Pěnkavová, Věra; Tihon, Jaroslav; Wein, Ondřej

2011-01-01

Roč. 6, č. 1 (2011), s. 273 ISSN 1931-7573 R&D Projects: GA ČR GA104/08/0428; GA ČR GA104/09/0972 Institutional research plan: CEZ:AV0Z40720504 Keywords : nanofluids * zeta potential * aws viscometry Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 2.726, year: 2011 http://www.nanoscalereslett.com/content/6/1/273

Complexation of anionic copolymers of acrylamide and N-(2-hydroxypropyl)methacrylamide with aminoglycoside antibiotics

Science.gov (United States)

Solovskii, M. V.; Tarabukina, E. B.; Amirova, A. I.; Zakharova, N. V.; Smirnova, M. Yu.; Gavrilova, I. I.

2014-03-01

The complexation of aminoglycoside antibiotics neomycin, gentamicin, kanamycin, and amikacin in the form of free bases with carboxyl- and sulfo-containing copolymers of acrylamide and N-(2-hydroxypropyl)methacrylamide (HPMA) in water and water-salt solutions is studied by means of viscometry, equilibrium dialysis, potentiometric titration, and molecular hydrodynamics. Factors influencing the stability of formed copolymer-antibiotic complexes and determinations of their toxicity are established.

Development of detection methods for irradiated foods

International Nuclear Information System (INIS)

Yang, Jae Seung; Nam, Hye Seon; Oh, Kyong Nam; Woo, Si Ho; Kim, Kyeung Eun; Yi, Sang Duk; Park, Jun Young; Kim, Kyong Su; Hwang, Keum Taek

2000-04-01

In 1999, we have been studied (1) on the detection of irradiated foods by ESR spectroscopy, by thermoluminescence, and by viscometry for physical measurements, (2) on the detection of hydrocarbons and 2-alkylcyclobutanones derived from fatty foods by GC/MS for chemical measurements, (3) on the screening and detection of irradiated foods by Comet assay and immunochemical (ELISA) technique for biological or biochemical measurements

Development of detection methods for irradiated foods

Energy Technology Data Exchange (ETDEWEB)

Yang, Jae Seung; Nam, Hye Seon; Oh, Kyong Nam; Woo, Si Ho; Kim, Kyeung Eun; Yi, Sang Duk; Park, Jun Young; Kim, Kyong Su; Hwang, Keum Taek

2000-04-01

In 1999, we have been studied (1) on the detection of irradiated foods by ESR spectroscopy, by thermoluminescence, and by viscometry for physical measurements, (2) on the detection of hydrocarbons and 2-alkylcyclobutanones derived from fatty foods by GC/MS for chemical measurements, (3) on the screening and detection of irradiated foods by Comet assay and immunochemical (ELISA) technique for biological or biochemical measurements.

Measurement of Flow Properties of Mammalian Blood with Different Hematocrit Values Using Falling Needle Rheometer

Directory of Open Access Journals (Sweden)

Takamasa Suzuki

2014-08-01

Full Text Available The development of viscometry with high accuracy and quick operation, as well as the establishment of a data evaluation method by pathology are largely required. Especially, the flow properties of human blood are an important factor in the evaluation of blood disease on the medicine, but the method of viscometry and the data collection are not so easy. This study has been described on the viscosity measurement and their evaluations for mammalian blood (rabbit, pig and horse including human blood. A compact-sized falling needle rheometer (FNR and a flow analysis method using this device for blood have been developed, and the relationship between the apparent viscosity and physical properties (density, hematocrit value of blood have also been evaluated. Measured flow properties of blood are evaluated as a flow curve showing the relationship between the shear stress and shear rate. Observed flow curves of mammalian bloods show three typical fluid regions, these are, the Non-newtonian fluid region for a low shear rate range, the transition region and the Newtonian fluid region for a high shear rate range. Flow properties of blood in the Casson fluid region and the apparent viscosity (μ in the Newtonian fluid region are measured, and they are compared between mammals.

Size-exclusion chromatography of perfluorosulfonated ionomers.

Science.gov (United States)

Mourey, T H; Slater, L A; Galipo, R C; Koestner, R J

2011-08-26

A size-exclusion chromatography (SEC) method in N,N-dimethylformamide containing 0.1 M LiNO(3) is shown to be suitable for the determination of molar mass distributions of three classes of perfluorosulfonated ionomers, including Nafion(®). Autoclaving sample preparation is optimized to prepare molecular solutions free of aggregates, and a solvent exchange method concentrates the autoclaved samples to enable the use of molar-mass-sensitive detection. Calibration curves obtained from light scattering and viscometry detection suggest minor variation in the specific refractive index increment across the molecular size distributions, which introduces inaccuracies in the calculation of local absolute molar masses and intrinsic viscosities. Conformation plots that combine apparent molar masses from light scattering detection with apparent intrinsic viscosities from viscometry detection partially compensate for the variations in refractive index increment. The conformation plots are consistent with compact polymer conformations, and they provide Mark-Houwink-Sakurada constants that can be used to calculate molar mass distributions without molar-mass-sensitive detection. Unperturbed dimensions and characteristic ratios calculated from viscosity-molar mass relationships indicate unusually free rotation of the perfluoroalkane backbones and may suggest limitations to applying two-parameter excluded volume theories for these ionomers. Copyright © 2011 Elsevier B.V. All rights reserved.

Rheological Studies of Komatiite Liquids by In-Situ Falling Sphere Viscometry

Science.gov (United States)

O Dwyer, L.; Lesher, C. E.; Baxter, G.; Clark, A.; Fuss, T.; Tangeman, J.; Wang, Y.

2005-12-01

The rheological properties of komatiite liquids at high pressures and temperatures are being investigated by the in situ falling sphere technique, using the T-25 multianvil apparatus at the GSECARS 13 ID-D-D beamline at the Advanced Photon Source, ANL. The refractory and fluid nature of komatiite and other ultramafic liquids relevant to the Earth's deep interior, presents unique challenges for this approach. To reduce the density contrast between the melt and the marker sphere, and thus increase the Stoke's travel time, we have begun testing various composite spheres composed of refractory silicates and metals. Two successful custom designs are zirconia silicate mantled by Pt and Pt mantled by forsterite. These custom spheres contain sufficient Pt to absorb x-rays, while containing sufficient low-density refractory silicate so that marker sphere densities are in the range of 4-6 g/cc. These relatively more buoyant spheres increase travel time. These custom spheres, together with Re or Pt marker spheres, have been used to determine the viscosity of Gorgona anhydrous komatiite around 1600 ° C between 3.5 and 6 GPa. Initial experiments yield viscosities of 2.8 Pa s at 3.5 GPa, 5.3 Pa s at 4.6 GPa and 7.6 Pa s at 6 GPa. The observed positive pressure dependence of viscosity is consistent with recent results on pyrolite composition liquids and suggests that the activation volume for highly depolymerized melts will be positive for at least upper mantle conditions. The development of low-density, x-ray detectable marker spheres has applications in studies of melt density, whereby in situ detection of sink-float behavior during heating and compression cycles may be possible.

The influence of temperature and reaction time in the degradation of natural rubber latex

International Nuclear Information System (INIS)

Siti Zaleha Isa; Rosiyah Yahya; Aziz Hassan; Mohd Tahir

2007-01-01

Liquid natural rubber (LNR /LENR) should be considered as a new material instead of a new type of rubber though they have the same configuration as the rubber used. In this work, thermal degradation of natural rubber latex was carried out to obtain LNR/LENR by varying the reaction time at different temperatures. The degraded polymers were characterized structurally using FTIR and NMR spectroscopies and the average molecular weights were determined by membrane-osmometry and viscometry. (author)

National Standards Laboratory biennial report, 1971--1973

Energy Technology Data Exchange (ETDEWEB)

None

1974-02-28

This report describes the activities of the laboratory in: length interferometry; engineering metrology; photogrammetry; mass, volume, density, and pressure measurement: force, hardness, and materials testing machines; vibration; corrosion; time and frequency; acoustics; electrical standards; power frequency; high voltage; rf and microwave measurement; temperature measurement; optical radiometry; optics; dielectrics; magnetics; thermal and elastic properties of solids; electron transport in metals; low-energy collisions in gases; physics of the fluid state and high pressures; water vapor physics; viscometry; airglow; solar physics; and theoretical astrophysics. (DLC)

Effect of cooling rate on crystallization in an aluminophosphosilicate melt

DEFF Research Database (Denmark)

Liu, S. J.; Zhang, Yanfei; Yue, Yuanzheng

2011-01-01

The effect of cooling rate on spontaneous crystallization behavior of an alumino-phospho-silicate melt is studied by means of differential scanning calorimetry, X-ray diffraction, scanning electron microscopy and viscometry. The cooling rates of 160, 2100 and 12000 K/s are attained by subjecting ......, the opalescence of the glass can be tuned by adjusting the cooling rate. This makes the production of opal glasses or transparent glass ceramics more efficient and energy saving, since the conventional isothermal treatment procedure can be left out....

Peculiarity of counterion - polyion interactions in aqueous solutions of copolymers of acrylamide with cadmium acrylate

Energy Technology Data Exchange (ETDEWEB)

Myagchenkov, V A; Kurenkov, V F; Akhmed' yanova, R A [Kazanskij Khimiko-Tekhnologicheskij Inst. (USSR)

1984-02-01

Binding of Cd/sup 2 +/ ions in aqueous solutions of statistical copolymers of acrylamide with cadmium acrylate with different content of ionogenic groups in copolymers was investigated by polarography, conductometry, viscometry and dialysis. It is shown that the degree of binding of Cd/sup 2 +/ ions increases with increasing of the content of ionogenic groups in the copolymer and with decreasing of ionic strength of the solution. The values of the degree of binding of Cd/sup 2 +/ ions obtained by polarography and dialysis show satisfactory agreement.

The physicochemical properties of the low-temperature ionic liquid silver bromide-1-butyl-3-methylimidazolium bromide

Science.gov (United States)

Grishina, E. P.; Ramenskaya, L. M.; Pimenova, A. M.

2009-11-01

The physicochemical properties of the low-temperature ionic liquid based on 1-butyl-3-methylimidazolium bromide (BMImBr) and silver bromide were studied. Differential scanning calorimetry, Fourier transform IR spectroscopy, densimetry, viscometry, and conductometry measurements were performed to determine the dependences of the parameters under study on the concentration of AgBr. It was shown that the temperature and concentration behavior of the physicochemical properties of BMImBr-AgBr melts characterized the interaction between the system components with the formation of complex particles.

Effect of various solvents on the viscosity-average molecular weight of poly (vinyl acetate)

International Nuclear Information System (INIS)

Rehman, W.U.; But, M.A.; Chughtai, A.; Jamil, T.; Sattar, A.

2006-01-01

Solution polymerization of Vinyl Acetate was carried out in various solvents (benzene, toluene, ethyl acetate, acetonitrile). Dilute solution viscometry was used to determine the viscosity-average molecular weight of the resulting Poly (Vinyl Acetate) (PV Ac) in each case. The viscosity-average molecular weight (M,J of PVAc was found to increase in the order benzene < toluene < ethyl acetate < acetonitrile, It was concluded that under the same reaction conditions (polymerization time, initiator quantity, solvent/monomer ratio, temperature), acetonitrile served as the best solvent for solution. polymerization of Vinyl Acetate monomer. (author)

Issues in the validation of CFD modelling of semi-solid metal forming

International Nuclear Information System (INIS)

Ward, P.J.; Atkinson, H.V.; Kirkwood, D.H.; Liu, T.Y.; Chin, S.B.

2000-01-01

Modelling of die filling during semi-solid metal processing (thixoforming) places particular demands on the CFD package being used. Not only are the velocities of the metal slurry in the die very high, the viscosity is too. Furthermore, the viscosity changes with shear rate (i.e. with changes in cross sectional area of the region the slurry travels through) and with time, as the injected material is thixotropic. The CFD software therefore requires good free surface tracking, accurate implicit solutions of the flow equations (as the CPU times for explicit solutions at high viscosities are impractical) and a model that adequately describes the slurry thixotropy. Finally, reliable, experimentally determined viscosity data are required. This paper describes the experiments on tin-lead and aluminium alloy slurries using compressive tests and rotating cylinder viscometry, followed by modelling using FLOW-3D. This package is known for its ability to track free surfaces accurately. Compressive tests allow rapid changes in shear rate to be imparted to the slurry, without wall slip, while the simple geometry of the viscometer makes it possible to compare analytical and numerical solutions. It is shown that the implicit viscous solver in its original form can reproduce the general trends found in the compressive and viscometry tests. However, sharp changes in shear rate lead to overestimation of pressure gradients in the slurry, making it difficult to separate these effects from those due to thixotropic breakdown. In order to achieve this separation, it is necessary to implement a more accurate implicit solver, which is currently under development. (author)

Electrochemical and visco metric studies on some copolymer/ homopolymer poly electrolytes and transition metal ion interaction

International Nuclear Information System (INIS)

Rajabi, F. H.; Frahani, B. V.

2003-01-01

Some random three-component copolymers have been prepared by condensing of formaldehyde with various aromatic amines. The compositions of the copolymers have been determined by known methods. selective complexation of copolymers have been carried out with PAA, PEI, PVP and some transition metal ions (e.g., Cu 2+ )by adding the components in various sequences. The relative complexation ability of different -NH 2 groups, associated with the various comonomer units, has been interpreted in terms of the these complexes has been studied by conductometry. potentiometry and viscometry techniques. A scheme has presented to explain the mode of interaction of the various components

Novel CO{sub 2}-thickeners for improved mobility control

Energy Technology Data Exchange (ETDEWEB)

Enick, Dr. Robert M.; Beckman, Dr. Eric J.; Hamilton, Dr. Andrew

2000-02-02

The objective of this study was to design, synthesize, and characterize thickening agents for dense carbon dioxide and to evaluate their solubility and viscosity-enhancing potential in CO{sub 2}. Hydrocarbon-fluorocarbon random copolymers, sulfated hydrocarbon-fluorocarbon random copolymers, semifluorinated trialkyltin fluorides and small hydrogen-bonding compounds were evaluated. Random copolymers of styrene and heptadecafluorodecyl acrylate were characterized by high solubility ion dense carbon dioxide and the most substantial increases in solution viscosity. Falling cylinder viscometry results indicated that the 29%styrene--71%fluoroacylate bulk-polymerized copolymer induced 2--250 fold increases in viscosity at copolymer concentrations of 0.2--5.0wt%.

Viscosity of liquid sulfur under high pressure

International Nuclear Information System (INIS)

Terasaki, Hidenori; Kato, T; Funakoshi, K; Suzuki, A; Urakawa, S

2004-01-01

The viscosity of liquid sulfur up to 9.7 GPa and 1067 K was measured using the in situ x-ray radiography falling sphere method. The viscosity coefficients were found to range from 0.11 to 0.69 Pa s, and decreased continuously with increasing pressure under approximately constant homologous temperature conditions. The observed viscosity variation suggests that a gradual structural change occurs in liquid sulfur with pressure up to 10 GPa. The L-L' transition in liquid sulfur proposed by Brazhkin et al (1991 Phys. Lett. A 154 413) from thermobaric measurements has not been confirmed by the present viscometry

Thermodynamics of kappa-Carrageenan-Amphiphilic Drug Interaction as Influenced by Specific Counterions and Temperature: A Microcalorimetric and Viscometric Study.

Science.gov (United States)

Singh; Caram-Lelham

1998-07-15

The adsorption of amphiphilic drug molecules to a polyelectrolyte, kappa-carrageenan, has been shown to be related to hydrophobicity of drug and the conformation of the polyanion which in turn can be regulated by choice of counterion. The binding is of a strongly cooperative nature and the degree of cooperativity has been found to be related to the self-aggregation tendency of the drug molecules. This system has been examined by titration microcalorimetry and capillary viscometry to determine the thermodynamics of the binding phenomenon. The titration calorimetry data confirms the trends and conclusions drawn regarding the factors that control the binding. Viscometry shows that although there is a change in size of the polymeric chains when the drug molecules are adsorbed, the effect is primarily due to charge neutralization and not a conformation change. This allows the microcalorimetry data to be analyzed to recover the enthalpy of binding of the drug molecules to the polymer. Earlier published equilibrium binding data has been analyzed to determine the binding constants and free energy changes in the process (-25 to -90 kJ/mol). A phenomenological model has been derived for the cooperative binding process for this purpose. The binding process is primarily enthalpy driven with the major part of enthalpy change (-10 to -40 kJ/mol) arising from the aggregation of bound drug molecules, i.e., from hydrophobic interactions; the process is also entropically favorable. The size of these aggregates in polymer-bound state is of the order of 2-5 molecules of drug, similar to the pre-micellar aggregates of the drugs in solution. Copyright 1998 Academic Press.

Elongational viscometry and bubble inflation experiments of two HDPE materials with different molecular structures

DEFF Research Database (Denmark)

Rasmussen, Henrik Koblitz; Eggen, Svein; Malmberg, Anneli

2002-01-01

The most common materials used for manufacturing of bottles and containers for household and industrial packaging has been single reactor Chromium-catalyst HDPE materials. These materials etc.......The most common materials used for manufacturing of bottles and containers for household and industrial packaging has been single reactor Chromium-catalyst HDPE materials. These materials etc....

Preparation and characterisation of high-density ionic liquids incorporating halobismuthate anions.

Science.gov (United States)

Cousens, Nico E A; Taylor Kearney, Leah J; Clough, Matthew T; Lovelock, Kevin R J; Palgrave, Robert G; Perkin, Susan

2014-07-28

A range of ionic liquids containing dialkylimidazolium cations and halobismuthate anions ([BiBr(x)Cl(y)I(z)](-) and [Bi2Br(x)Cl(y)I(z)](-)) were synthesised by combining dialkylimidazolium halide ionic liquids with bismuth(III) halide salts. The majority were room temperature liquids, all with very high densities. The neat ionic liquids and their mixtures with 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide were characterised using Densitometry, Viscometry, NMR Spectroscopy, Electrospray Ionisation Mass Spectrometry (ESI), Liquid Secondary Ion Mass Spectrometry (LSIMS), Matrix-assisted Laser Desorption/Ionization Mass Spectrometry (MALDI), X-Ray Photoelectron Spectroscopy (XPS) and Thermogravimetric Analysis (TGA), to establish their speciation and suitability for high-temperature applications.

Selectivity in inter polymer complexation involving phenolic copolymer, poly electrolytes, non-ionic polymers and transition metal ions

International Nuclear Information System (INIS)

Vasheghani Farahani, B.; Hosseinpour Rajabi, F.

2006-01-01

Selectivity in inter polymer complex formation involving a typical four-component phenolic copolymer (ρ-chloro phenol-ρ-aminophenol-ρ-toluidine-ρ-cresol- HCHO copolymer), poly electrolytes such as polyethylene imine and polyacrylic acid, a non-ionic homopolymer polyvinyl pyrrolidone, and some transition metal ions (e.g., Cu (II), Ni (11)) have been studied in dimethylformamide-methanol solvents mixture. The coordinating groups of phenolic copolymer form complexes through hydrogen bonding and ion-dipole interactions. The different stages of interactions have been studied by several experimental techniques, e.g., viscometry, potentiometry and conductometry. Some schemes have been suggested to explain the mode of interaction between these components

Detection methods for irradiated foods: current status. Proceedings

International Nuclear Information System (INIS)

McMurray, C.H.; Gray, R.; Stewart, E.M.; Pearce, J.; Queen's Univ., Belfast, Northern Ireland

1996-01-01

This book contains a scientific record of an international meeting on analytical detection methods for irradiation treatment of food. Apart from encouraging the basic development of detection tests, the meeting also aimed to assess the various test methods critically to determine their suitability for general use by public health laboratories and others concerned with trade in irradiated food. Two sets of criteria have been developed to assess test methods, technical criteria for a qualitative or quantitative test and practical criteria if a method is to be widely applied by food labelling authorities. Agreement has already been achieved for the use of electron spin resonance, thermoluminescence, hydrocarbons, 2-Alkylcyclobutanones, microbiological, viscometry and impedance tests. (UK)

Synthesis and characterization of cellulose derivatives obtained from bacterial cellulose

International Nuclear Information System (INIS)

Oliveira, Rafael L. de; Barud, Hernane; Ribeiro, Sidney J.L.; Messaddeq, Younes

2011-01-01

The chemical modification of cellulose leads to production of derivatives with different properties from those observed for the original cellulose, for example, increased solubility in more traditional solvents. In this work we synthesized four derivatives of cellulose: microcrystalline cellulose, cellulose acetate, methylcellulose and carboxymethylcellulose using bacterial cellulose as a source. These were characterized in terms of chemical and structural changes by examining the degree of substitution (DS), infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy - NMR 13 C. The molecular weight and degree of polymerization were evaluated by viscometry. The characterization of the morphology of materials and thermal properties were performed with the techniques of X-ray diffraction, electron microscopy images, differential scanning calorimetry (DSC) and thermogravimetric analysis. (author)

DNA Modified with Metal Nanoparticles: Preparation and Characterization of Ordered Metal-DNA Nanostructures in a Solution and on a Substrate

Directory of Open Access Journals (Sweden)

Nina Kasyanenko

2016-01-01

Full Text Available DNA interaction with silver and aluminum nanoparticles in a solution has been investigated with the AFM, SEM, dynamic light scattering, viscometry, and spectral methods. The comparison of DNA interaction with nanoparticles synthesized by the reduction of Ag+ ions and with nanoparticles obtained by the electric discharge plasma method was done. DNA metallization in a solution and on n-silicon surface with metal nanoparticles or by the reduction of silver ions after their binding to DNA was executed and studied. It was shown that DNA strands with regular location of silver or aluminum nanoparticles can be prepared. The conditions for the formation of silver nanoparticles and silver nanoclusters on DNA were analyzed.

Molecular interactions in a surfactant-water-polyacrylamide system, according to densimetry, viscometry, conductometry, and spectroscopy data

Science.gov (United States)

Harutyunyan, R. S.

2013-08-01

Molecular interactions in a surfactant-polyacrylamide-water system are investigated. It is established that the interactions affect such physicochemical parameters of the system as viscosity, density, surface tension, conductivity, and critical micelle concentration. It is shown that in a polyacrylamide-water system, raising the polyacrylamide concentration to 0.02% causes conformational changes in its macromolecule.

Characterization of enzymatically induced aggregation of casein micelles in natural concentration by in situ static light scattering and ultra low shear viscosimetry

DEFF Research Database (Denmark)

Lehner, D.; Worning, Peder; G, Fritz

1999-01-01

of multiple scattering whenthe transmission is above 0.85. Due to the very complex and porous structure of the casein aggregates theRayleigh-Debye-Gans scattering theory has been used in the data analysis. Measurements with a newinstrument using ultra low shear showed good agreement with theory. Copyright......The aggregation of casein micelles in undiluted skim milk after the addition of chymosin was studied bystatic light scattering and ultra low shear viscometry. The static light scattering measurements were madewith two different sample thicknesses, 72 and 16 mum. The scattering data were analyzed...... by indirect Fouriertransformation and by the polydispersity inversion technique which led to pair distance distributionfunctions and size distribution function, respectively. The minimum scattering angle was 1 degrees, whichallows for the determination of particle sizes up to a maximum diameter of 12 mum...

End Effects in Rotational Viscometry I. No-Slip Shear-Thinning Samples in the Z40 DIN Sensor.

Czech Academy of Sciences Publication Activity Database

Wein, Ondřej; Večeř, Marek; Havlica, Jaromír

2007-01-01

Roč. 46, 5 (2007) , s. 765-772 ISSN 0035-4511. [Annual Rheology Conference AERC 2006 /3./. Crete, 27.04.2006-29.04.2006] R&D Projects: GA ČR(CZ) GA104/04/0826; GA ČR GP104/06/P287; GA ČR GP104/05/P554 Institutional research plan: CEZ:AV0Z40720504 Keywords : rotational couette flow * shear-thinning fluids * end effects Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 1.110, year: 2007

Microstructure, molecular weight and thermal behavior of natural rubber (NR) from mangabeira (Hancornia speciosa)

International Nuclear Information System (INIS)

Santos, Expedito Flavio dos; Feitosa, Judith P.A.; Ricardo, Nagila M.P.S.

2001-01-01

The natural rubber (NR) from Hancornia speciosa contains characteristics that turns it a good alternative in elastomers supply. The NMR and IR spectra showed that the rubber of mangabeira is composed fundamentally by poly(1,4-cis-isoprene). The rubber molecular weight obtained by GPC and viscometry was 2,0x10 6 and 1,3x10 6 g/mol, respectively, in good agreement with the values determined for seringueira and manicoba NR. The glass transition temperature obtained by DSC (Tg = - 65 deg C) showed the mangabeira rubber is ideal to be utilized in regions of cold climate without compromising its mechanical properties. The rubber has also good thermal stability up to 213 deg C, as indicated by TG curves. This results indicated that the mangabeira NR can be effectively used in vulcanized articles or to be added to asphalt. (author)

Improved resistance of chemically-modified nanocellulose against thermally-induced depolymerization.

Science.gov (United States)

Agustin, Melissa B; Nakatsubo, Fumiaki; Yano, Hiroyuki

2017-05-15

The study demonstrated the improvement in the resistance of nanocellulose against thermally-induced depolymerization by esterification with benzoyl (BNZ) and pivaloyl (PIV). The change in the degree of polymerization (DP) and molecular weight distribution (MWD) after thermal treatment in nitrogen and in air was investigated using viscometry and gel permeation chromatography. BNZ and PIV nanocellulose esters without α-hydrogens gave higher DP and narrower MWD than pure bacterial cellulose; and the acetyl and myristoyl esters, which possess α-hydrogens. Results also showed that when depolymerization is suppressed, thermal discoloration is also reduced. Resistance against depolymerization inhibits the formation of reducing ends which can be active sites for thermal discoloration. Finally, the findings suggest that benzoylation and pivaloylation can be an excellent modification technique to improve the thermal stability of nanocellulose. Copyright © 2017 Elsevier Ltd. All rights reserved.

Synthesis and characterization of hybrid organic-inorganic materials of polyamide-imide (PAI) and copolysilsesquioxanes of 3-aminopropyltriethoxysilane (APES) and phenyltriethoxysilane (PTES)

International Nuclear Information System (INIS)

Demarchi, A.A.; Pezzin, S.H.

2010-01-01

In this work, organic-inorganic hybrids were obtained by adding copolysilsesquioxanes of 3-aminopropyltriethoxysilane (APES) and phenyltriethoxysilane (PTES), prepared by sol-gel, to the polyamide-imide (PAI). The synthesis of PAI oligomer from trimellitic anhydride (TMA) and 4,4-diphenyl-methane diisocyanate (MDI), was monitored by FTIR, noting that two steps of 80 deg C and 120 deg C for 2 h each are sufficient to obtain it. PAI-copolysilsesquioxanes hybrids were characterized by FTIR, viscometry, thermogravimetry, NMR and microscopy. The spectrum of the PAI and PAI-hybrid copolysilsesquioxanes show the formation of amide and imide. Copolysilsesquioxanes with high levels of APES increased the viscosity and generated the PAI oligomer gelatinization, hindering the formation of uniform films. Gelatinization did not occur with copolysilsesquioxanes rich PTES, allowing the formation of homogeneous films improvements in thermal resistance. (author)

Unveiling the Interplay Between Diffusing CO2 and Ethanol Molecules in Champagne Wines by Classical Molecular Dynamics and (13)C NMR Spectroscopy.

Science.gov (United States)

Bonhommeau, David A; Perret, Alexandre; Nuzillard, Jean-Marc; Cilindre, Clara; Cours, Thibaud; Alijah, Alexander; Liger-Belair, Gérard

2014-12-18

The diffusion coefficients of carbon dioxide (CO2) and ethanol (EtOH) in carbonated hydroalcoholic solutions and Champagne wines are evaluated as a function of temperature by classical molecular dynamics (MD) simulations and (13)C NMR spectroscopy measurements. The excellent agreement between theoretical and experimental diffusion coefficients suggest that ethanol is the main molecule, apart from water, responsible for the value of the CO2 diffusion coefficients in typical Champagne wines, a result that could likely be extended to most sparkling wines with alike ethanol concentrations. CO2 and EtOH hydrodynamical radii deduced from viscometry measurements by applying the Stokes-Einstein relationship are found to be mostly constant and in close agreement with MD predictions. The reliability of our approach should be of interest to physical chemists aiming to model transport phenomena in supersaturated aqueous solutions or water/alcohol mixtures.

Synthesis and characterization of hybrid organic-inorganic materials of polyamide-imide (PAI) and copolysilsesquioxanes of 3-aminopropyltriethoxysilane (APES) and phenyltriethoxysilane (PTES); Sintese e caracterizacao de materiais hibridos organico-inorganicos de poliamida-imida e copolisilsesquioxanos de 3-aminopropiltrietoxissilano e feniltrietoxissilano

Energy Technology Data Exchange (ETDEWEB)

Demarchi, A.A., E-mail: aa_demarchi@terra.com.b [WEG Equipamentos Eletricos S.A., Jaragua do Sul, SC (Brazil). Dept. de P e D do Produto; Pezzin, S H [Universidade do Estado de Santa Catarina (UDESC), SC (Brazil). Centro de Ciencias Tecnologicas

2010-07-01

In this work, organic-inorganic hybrids were obtained by adding copolysilsesquioxanes of 3-aminopropyltriethoxysilane (APES) and phenyltriethoxysilane (PTES), prepared by sol-gel, to the polyamide-imide (PAI). The synthesis of PAI oligomer from trimellitic anhydride (TMA) and 4,4-diphenyl-methane diisocyanate (MDI), was monitored by FTIR, noting that two steps of 80 deg C and 120 deg C for 2 h each are sufficient to obtain it. PAI-copolysilsesquioxanes hybrids were characterized by FTIR, viscometry, thermogravimetry, NMR and microscopy. The spectrum of the PAI and PAI-hybrid copolysilsesquioxanes show the formation of amide and imide. Copolysilsesquioxanes with high levels of APES increased the viscosity and generated the PAI oligomer gelatinization, hindering the formation of uniform films. Gelatinization did not occur with copolysilsesquioxanes rich PTES, allowing the formation of homogeneous films improvements in thermal resistance. (author)

Effect of Silica Nanoparticles on the Local Segmental Dynamics in Polyvinylacetate

Science.gov (United States)

Bogoslovov, R. B.; Roland, C. M.; Ellis, A. R.; Randall, A. M.; Robertson, C. G.

2008-07-01

The effect of nanosized silica particles on the properties of polyvinylacetate (PVAc) was investigated for a range of silica concentrations encompassing the filler network percolation threshold. The quantity of polymer adsorbed to the particles ("bound rubber") increased systematically with silica content and was roughly equal to the quantity shielded from shear stresses ("occluded rubber"). A variety of experimental techniques was employed including pressure-volume-temperature measurements, broadband dielectric spectroscopy, thermal analysis (modulated DSC), dynamic-mechanical spectroscopy, viscometry. The glass transition properties of PVAc, i.e. the glass transition temperature and the changes in the thermal expansion coefficient and heat capacity at Tg, as well as the isothermal compressibility and the volume sensitivity of the local segmental dynamics of the polymer chains in the presence of the polymer-filler interface are discussed. The implication of this result and possible directions for new research are considered.

Crystallization, Microstructure, and Viscosity Evolutions in Lithium Aluminosilicate Glass-Ceramics

Directory of Open Access Journals (Sweden)

Qiang Fu

2016-11-01

Full Text Available Lithium aluminosilicate glass-ceramics have found widespread commercial success in areas such as consumer products, telescope mirrors, fireplace windows, etc. However, there is still much to learn regarding the fundamental mechanisms of crystallization, especially related to the evolution of viscosity as a function of the crystallization (ceramming process. In this study, the impact of phase assemblage and microstructure on the viscosity was investigated using high temperature X-ray diffraction (HTXRD, beam bending viscometry (BBV, and transmission electron microscopy (TEM. Results from this study provide a first direct observation of viscosity evolution as a function of ceramming time and temperature. Sharp viscosity increases due to phase separation, nucleation and phase transformation are noticed through BBV measurement. A near-net shape ceramming can be achieved in TiO2-containing compositions by keeping the glass at a high viscosity (> 109 Pa.s throughout the whole thermal treatment.

The effect of gamma radiation on mechanical properties of biodegradable polymers poly(3-hydroxybutyrate and poly(3-hydroxybutyrate-co-3-hydroxyvalerate

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Leticia Maria Oliveira

2013-02-01

Full Text Available Brazilian poly(3-hydroxybutyrate, P(3-HB, and its copolymer, poly (3-hydroxybutyrate-co-3-hydroxyvalerate, P(3-HB-co-3-HV were irradiated with gamma radiation (60Co at room temperature and in the presence of oxygen. The viscosity-average molar mass (Mv was analyzed by viscometry using an Ostwald-type capillary viscometer. Both polymers showed a decrease in molar mass with the increase in dose, reflecting that random main chain scissions occurred. The value G (scissions/100 eV of energy transferred to the system and the parameter α (scissions per original molecule were also determined. Mechanical properties decrease with the increase in dose, revealing that P(3-HB underwent significant changes, especially at doses higher than 50 kGy. Tensile at break and impact resistance properties were the most affected by radiation, while the elastic modulus remained virtually unaltered up to 100 kGy dose.

Size exclusion chromatography and viscometry in paper degradation studies. New Mark-Houwink coefficients for cellulose in cupri-ethylenediamine.

Science.gov (United States)

Łojewski, Tomasz; Zieba, Katarzyna; Lojewska, Joanna

2010-10-15

The paper deals with the application of size exclusion chromatography (SEC) for the studies of paper degradation phenomena. The goal is to solve some of the technical problems connected with the calibration of multi-detector SEC system and to find the correlation between SEC and viscometric results of degree of polymerization of cellulose. The results gathered for the paper samples degraded by acidic air pollutant (NO(2)) are used as an example of SEC-MALLS application. From the correlation between intrinsic viscosities and absolute value of molecular masses obtained with SEC/MALLS (Multi Angle Laser Light Scattering) technique, Mark-Houwink coefficients for cellulose in cupri-ethylenediamine solution were determined. Thus obtained coefficients were used for the determination of viscometric degree of polymerization (molecular mass) of the aged samples. An excellent correlation was found between the chromatographic values of molecular masses obtained with SEC-UV/VIS detection and the viscometric ones utilizing the improved values of Mark-Houwink coefficients. Copyright © 2010 Elsevier B.V. All rights reserved.

Flow curves of Sn and Sn-3.5Ag obtained by rotational viscometry using a stainless steel cone

International Nuclear Information System (INIS)

Yamazaki, Takahisa; Oishi, Shinya; Gamou, Hirosato; Ikeshoji, Toshi-Taka; Suzumura, Akio

2014-01-01

Corrosion of stainless steel in a flow soldering bath by a lead-free solder was investigated using a cone-plate-type rotational viscometer. The rotational torque of the stainless-steel cone in contact with a molten solder was measured at various shear rates. The delicate measured torque was related to the change of the viscosity of the solder owing to dissolution of materials originating from the cone. The estimated viscosity coefficient was ten times greater than the values which have been reported. The result was attributed to the tin content of the solder combined with oxygen from the passive state oxide film on the cone surface. The increase of the viscosity of the silver-containing solder was much greater than in case of pure Sn

Effects from additives on deacetylation of chitin; Efeito de aditivos na desacetilacao de quitina

Energy Technology Data Exchange (ETDEWEB)

Campana Filho, Sergio P.; Signini, Roberta [Sao Paulo Univ., Sao Carlos, SP (Brazil). Inst. de Quimica]. E-mail: scampana@iqsc.sc.usp.br

2001-12-01

Deacetylation reactions of commercial chitin were carried out in aqueous sodium hydroxide solution at 115 deg C for 6 hours. The effect from additives (sodium borohydride or anthraquinone) and of bubbling inert gas (nitrogen or argon) on the characteristics of deacetylated samples were evaluated. Average degrees of acetylation and intrinsic viscosity were determined by {sup 1}H NMR spectroscopy and capillary viscometry, respectively. X-ray diffraction was employed to evaluate changes in crystallinity and infrared spectroscopy was used to monitor structural changes due to deacetylation. The bubbling of inert gas during the deacetylation reaction resulted in more crystalline samples of chitosan. Deacetylation carried out without any additive produced slightly more deacetylated chitosan but they were severely depolymerized. The depolymerization process was much less important when sodium borohydride was added to the reaction medium but the addition of anthraquinone and the bubbling of nitrogen, or argon, did not have any effect, this suggests that oxygen is not required for depolymerization. (author)

Effects from additives on deacetylation of chitin

International Nuclear Information System (INIS)

Campana Filho, Sergio P.; Signini, Roberta

2001-01-01

Deacetylation reactions of commercial chitin were carried out in aqueous sodium hydroxide solution at 115 deg C for 6 hours. The effect from additives (sodium borohydride or anthraquinone) and of bubbling inert gas (nitrogen or argon) on the characteristics of deacetylated samples were evaluated. Average degrees of acetylation and intrinsic viscosity were determined by 1 H NMR spectroscopy and capillary viscometry, respectively. X-ray diffraction was employed to evaluate changes in crystallinity and infrared spectroscopy was used to monitor structural changes due to deacetylation. The bubbling of inert gas during the deacetylation reaction resulted in more crystalline samples of chitosan. Deacetylation carried out without any additive produced slightly more deacetylated chitosan but they were severely depolymerized. The depolymerization process was much less important when sodium borohydride was added to the reaction medium but the addition of anthraquinone and the bubbling of nitrogen, or argon, did not have any effect, this suggests that oxygen is not required for depolymerization. (author)

Influence of oxazolidines and zirconium oxalate crosslinkers on the hydrothermal, enzymatic, and thermo mechanical stability of type 1 collagen fiber

International Nuclear Information System (INIS)

Haroun, Mahdi A.; Khirstova, Palmina K.; Gasmelseed, Gurashi A.; Covington, Antony D.

2009-01-01

Stabilization of type I rat tail tendon (RTT) collagen by crosslink agent oxazolidine and zirconium oxalate was studied to understand the effect on the thermal, enzymatic and mechanical stability of collagen. The results show that both oxazolidine and zirconium oxalate imparts thermal stability to collagen, and oxazolidine exhibits a marked increase in the peak temperature and enthalpy changes when compared to both native and zirconium oxalate tanned RTT. There is a decrease in the peak temperature and the enthalpy changes of oxazolidine tanned RTT fibers after treatment with urea, suggesting the possibility of alterations in the secondary structure of collagen after tanning. Oxazolidine, which forms carbocationic intermediates species in solution, have better crosslinking with collagen as seen from viscometry studies and hence provides better enzymatic stability to collagen than zirconium, which largely forms monomeric species in solution. Zirconium does not seem to change the tensile strength of RTT fibers significantly in wet condition as well as oxazolidine

New polymer syntheses part 46 Synthesis and characterization of New Unsaturated Terpolyesters based on Dibenzylidene cyclohexanone

International Nuclear Information System (INIS)

Aly, K.I.; Ahmed, M.S.

2005-01-01

A new series from unsaturated terployesters were synthesized by interfacial polycondensation of 2,6-bis(4-hydroxybenzylidene) cyclohexanone I, 2,6-bis( 3-hydroxybenzylidene ) cyclohexanone II and 2,6 -bis(4-hydroxy-3- methoxybenzyl-Lidene) cyclohexanone III with isophthaloyl, terephthaloyl, adipoyl and sebacoyl dichloride have been produced. The yield and the value of the inherent viscosity of the ter polyester were found to be affected by the kind of organic phase,.the quantitative ratio of organic to aqueous phase, concentration of hydrogen chloride acceptor, rate of acid chloride addition, contribution of benzyltriethylammonium chloride (BTC) as a catalyst, and the temperature of the polycondensation reaction. The resulting ter polyesters were characterized by IR, elemental analysis, viscometry. DTA, DSC, thermogravimetric analysis, dielectric constant and mechanical properties. The crystallinity of copolyester was examined by X-ray analysis. In addition the electrical properties of the copolyester were investigated and the morphology of two new copolyester have been tested by SEM

Synthesis and Characterization of New Unsaturated Copolyester based on Dibenzylidene cyclohexanone

International Nuclear Information System (INIS)

Aly, K.I.; Ahmed, M.S.

2005-01-01

New unsaturated copolyester were synthesized by the interfacial polycondensation of 2,6-bis (4-hydroxybenzylidene) cyclohexanone I, 2,6- bis( 3-hydroxybenzylidene ) cyclohexanone II, or 2,6 -bis(4-hydroxy-3- methoxybenzylidene) cyclohexanone III with 4,4'-diphenic, isophthaloyl, terephthaloyl, adipoyl and sebacoyl dichloride have been produced. The yield and the value of the inherent viscosity of the copolyester were found to be affected by the kind of organic phase , the quantitative ratio of organic to aqueous phase, concentration of hydrogen chloride acceptor, rate of acid chloride, addition, contribution of benzyltriethylammonium chloride (BTC) as catalyst, and the temperature of the polycondensation reaction. The resulting copolyester were characterized by IR, elemental analysis ,viscometry, DTA,DSC, TGA, thermogravimetric analysis dielectric constant and mechanical properties. The crystallinity of copolyester was examined by Xray analysis. In addition the electrical properties of the copolyester were investigated and morphology of two new copolyester have been tested by SEM

Biocompatible Metal-Oxide Nanoparticles: Nanotechnology Improvement of Conventional Prosthetic Acrylic Resins

Directory of Open Access Journals (Sweden)

Laura S. Acosta-Torres

2011-01-01

Full Text Available Nowadays, most products for dental restoration are produced from acrylic resins based on heat-cured Poly(Methyl MethAcrylate (PMMA. The addition of metal nanoparticles to organic materials is known to increase the surface hydrophobicity and to reduce adherence to biomolecules. This paper describes the use of nanostructured materials, TiO2 and Fe2O3, for simultaneously coloring and/or improving the antimicrobial properties of PMMA resins. Nanoparticles of metal oxides were included during suspension polymerization to produce hybrid metal oxides-alginate-containing PMMA. Metal oxide nanoparticles were characterized by dynamic light scattering, and X-ray diffraction. Physicochemical characterization of synthesized resins was assessed by a combination of spectroscopy, scanning electron microscopy, viscometry, porosity, and mechanical tests. Adherence of Candida albicans cells and cellular compatibility assays were performed to explore biocompatibility and microbial adhesion of standard and novel materials. Our results show that introduction of biocompatible metal nanoparticles is a suitable means for the improvement of conventional acrylic dental resins.

Biocompatible Metal-Oxide Nanoparticles: Nanotechnology Improvement of Conventional Prosthetic Acrylic Resins

International Nuclear Information System (INIS)

Acosta-Torres, L.S.; Lopez-Marin, L.M.; Padron, G.H.; Castano, V.M.; Nunez-Anita, R.E.

2011-01-01

Nowadays, most products for dental restoration are produced from acrylic resins based on heat-cured Poly(Methyl Methacrylate) (PMMA). The addition of metal nanoparticles to organic materials is known to increase the surface hydrophobicity and to reduce adherence to biomolecules. This paper describes the use of nano structured materials, TiO 2 and Fe 2 O 3 , for simultaneously coloring and/or improving the antimicrobial properties of PMMA resins. Nanoparticles of metal oxides were included during suspension polymerization to produce hybrid metal oxides-alginate-containing PMMA. Metal oxide nanoparticles were characterized by dynamic light scattering, and X-ray diffraction. Physicochemical characterization of synthesized resins was assessed by a combination of spectroscopy, scanning electron microscopy, viscometry, porosity, and mechanical tests. Adherence of Candida albicans cells and cellular compatibility assays were performed to explore biocompatibility and microbial adhesion of standard and novel materials. Our results show that introduction of biocompatible metal nanoparticles is a suitable means for the improvement of conventional acrylic dental resins.

Influence of polymers on lysozyme molecules association

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Gromovoy T. Yu

2011-12-01

Full Text Available Aim. Study of lysozyme molecules behaviour at immobilization in gelatin and carboxymethyl cellulose sodium salt solutions by matrix-assisted laser desorption/ionization (MALDI. Methods. Determination of the activity of lysozyme, both free and entrapped in gelatin and carboxymethyl cellulose sodium salt (Na-CMC solutions, was conducted by bacteriolytic method. The enzyme interaction with polymers was confirmed by viscometry and mass-spectrometry methods. Results. The occurrence of lysozyme associates in aqueous solution in monomeric and oligomeric forms was shown. A non-valent interaction of the enzyme with solutions of polymers results in the dissociation of oligomeric associates into subunits, which depends on the support nature and mass ratio of lysozyme to polymer. The quantitative retention of immobilized lysozyme hydrolytic activity was established, which favours obtaining mucoadhesive film forms with bacteriolytic action. Conclusions. The lysozyme immobilization by non-valent interactions in gelatin solution and Na-CMC solutions causes dissociation of the enzyme oligomeric structures; a stronger lysozyme coupling with NaCMC was noted.

Gel-like properties of MCM-41 material and its transformation to MCM-50 in a caustic alkaline surround

International Nuclear Information System (INIS)

Saputra, Hens; Othman, Raihan; Sutjipto, A.G.E.; Muhida, R.; Ani, M.H.

2012-01-01

Highlights: ► MCM-41 material transforms gradually into MCM-50 lamellar gel upon controlled exposure to 6 M KOH. ► The formation of MCM-50 ordered gel structure occurs at KOH weight content of 40–70 wt. %. ► MCM gel phase shows pseudoplastic behavior and possesses homogeneous matrix texture. -- Abstract: MCM-41 material, prepared by sol–gel method, reveals gel-like properties in a caustic alkaline environment, i.e., 6 M potassium hydroxide (KOH) electrolyte. The gellation of MCM-41 starts at a KOH weight ratio of 40 wt.%. The structural change of the material is verified with X-Ray diffractograms and supported by observation using Scanning Electron Microscope (SEM). As the KOH weight ratio increases, the MCM-41 hexagonal arrays structure gradually transforms into MCM-50 lamellar structure before disappearing completely at 80 wt.% KOH. The MCM gel phase is further characterized by rotational viscometry and texture analysis. The gel phase shows shear thinning or pseudoplastic behavior and possesses homogeneous matrix structure.

Behavior of gellan in aqueous-salt solutions and oilfield saline water

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Zhanar Nurakhmetova

2015-09-01

Full Text Available The influence of storage time and temperature on the behavior of low acyl gellan (LAG was studied by viscometry and 1H NMR spectroscopy without salt addition. The viscometric results revealed that the effectiveness of salts to enhance gelation of gellan changes in the following order: BaСl2>CaCl2»MgCl2>KCl>NaCl. The sol-gel and liquid-solid phase transitions of gellan solutions were observed upon addition of oilfield water containing 73 g L-1 of alkaline and alkaline earth metal ions. The effectiveness of salts to induce the separation of liquid and solid phases changes in the sequence: NaCl>KCl>MgCl2»CaCl2»BaСl2. The hydrodynamic behavior of 0.5 wt.% gellan solution injected into the sand pack model with high (20 Darcy and lower (2 Darcy permeability is useful to model the oil reservoirs in the process of enhanced oil recovery.

Acid hydrolysis of sisal cellulose: studies aiming at nano fibers and bio ethanol preparation

International Nuclear Information System (INIS)

Paula, Mauricio P. de; Lacerda, Talita M.; Zambon, Marcia D.; Frollini, Elisabete

2009-01-01

The hydrolysis of cellulose can result in nanofibers and also is an important stage in the bioethanol production process. In order to evaluate the influence of acid (sulfuric) concentration, temperature, and native cellulose (sisal) pretreatment on cellulose hydrolysis, the acid concentration was varied between 5% and 30% (v/v) in the temperature range from 60 to 100 deg C using native and alkali-treated (mercerized) sisal cellulose. The following techniques were used to evaluate the residual (non-hydrolysed) cellulose characteristics: viscometry, average degree of polymerization (DP), X-ray diffraction, crystallinity index, and Scanning Electron Microscopy. The sugar cane liquor was analyzed in terms of sugar composition, using High Performance Liquid Chromatography (HPLC). The results showed that increasing the concentration of sulfuric acid and temperature afforded residual cellulose with lower molecular weight and, up to specific acid concentrations, higher crystallinity indexes, when compared to the original cellulose values, and increased the glucose (the bioethanol precursor ) production of the liquor, which was favored for mercerized cellulose. (author)

Influence of oxazolidines and zirconium oxalate crosslinkers on the hydrothermal, enzymatic, and thermo mechanical stability of type 1 collagen fiber

Energy Technology Data Exchange (ETDEWEB)

Haroun, Mahdi A. [Department of Chemical and Environmental Engineering, Faculty of Engineering, Universiti Putra Malaysia, 43400 UPM, Serdang (Malaysia)], E-mail: Mahdiupm@hotmail.com; Khirstova, Palmina K. [People' s Hall 11113, P.O. Box 6272, Khartoum (Sudan); Gasmelseed, Gurashi A. [Juba University, Leather Dept. P.O. Box 12327 Khartoum (Sudan); Covington, Antony D. [Leather Centre, University College Northampton, Northampton (United Kingdom)

2009-02-20

Stabilization of type I rat tail tendon (RTT) collagen by crosslink agent oxazolidine and zirconium oxalate was studied to understand the effect on the thermal, enzymatic and mechanical stability of collagen. The results show that both oxazolidine and zirconium oxalate imparts thermal stability to collagen, and oxazolidine exhibits a marked increase in the peak temperature and enthalpy changes when compared to both native and zirconium oxalate tanned RTT. There is a decrease in the peak temperature and the enthalpy changes of oxazolidine tanned RTT fibers after treatment with urea, suggesting the possibility of alterations in the secondary structure of collagen after tanning. Oxazolidine, which forms carbocationic intermediates species in solution, have better crosslinking with collagen as seen from viscometry studies and hence provides better enzymatic stability to collagen than zirconium, which largely forms monomeric species in solution. Zirconium does not seem to change the tensile strength of RTT fibers significantly in wet condition as well as oxazolidine.

Continuously Operating Biosensor and Its Integration into a Hermetically Sealed Medical Implant

Directory of Open Access Journals (Sweden)

Mario Birkholz

2016-10-01

Full Text Available An integration concept for an implantable biosensor for the continuous monitoring of blood sugar levels is presented. The system architecture is based on technical modules used in cardiovascular implants in order to minimize legal certification efforts for its perspective usage in medical applications. The sensor chip operates via the principle of affinity viscometry, which is realized by a fully embedded biomedical microelectromechanical systems (BioMEMS prepared in 0.25-µm complementary metal–oxide–semiconductor (CMOS/BiCMOS technology. Communication with a base station is established in the 402–405 MHz band used for medical implant communication services (MICS. The implant shall operate within the interstitial tissue, and the hermetical sealing of the electronic system against interaction with the body fluid is established using titanium housing. Only the sensor chip and the antenna are encapsulated in an epoxy header closely connected to the metallic housing. The study demonstrates that biosensor implants for the sensing of low-molecular-weight metabolites in the interstitial may successfully rely on components already established in cardiovascular implantology.

Influence of the drying method in chitosans purification step

International Nuclear Information System (INIS)

Fonseca, Ana C.M.; Batista, Jorge G.S.; Bettega, Antonio; Lima, Nelson B. de

2015-01-01

Currently, the study of extracellular biopolymers properties has received prominence for being easy extraction and purification. Chitosan has been an attractive proposition for applications in various fields such as engineering, biotechnology, medicine and pharmacology. For such applications, it is necessary purification of chitosan to obtain a product more concentrated and free of undesirable impurities. However, at this stage of the process of obtaining the biopolymer may occur morphological and physicochemical changes. This study evaluated the influence of the drying process after purification of a commercial chitosan sample and the importance of this step and its cost/benefit in applications requiring a high degree of purity. The method of drying influenced in the organoleptic properties and in the main characteristics of material. Analysis of the crystal structure by X-ray diffraction showed that the degree of crystallinity, X (%), in the purified chitosan samples was lower when compared with the unpurified sample. The degree of acetylation, DA (%), was analyzed by spectroscopy infrared with no significant changes on the three drying methods assessed, unlike the viscosimetric molecular weight, M_v, determined by capillary viscometry. (author)

Sustainable Phenolic Fractions as Basis for Furfuryl Alcohol-Based Co-Polymers and Their Use as Wood Adhesives

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Paul Luckeneder

2016-11-01

Full Text Available Furfuryl alcohol is a very interesting green molecule used in the production of biopolymers. In the present paper, the copolymerization in acid environment with natural, easily-available, phenolic derivatives is investigated. The processes of polymerization of the furfuryl alcohol with: (i spent-liquor from the pulping industry and (ii commercial tannin from acacia mimosa were investigated though viscometry and IR-spectroscopy. The curing kinetics of the formulations highlighted the importance of the amount of furfuryl alcohol and catalyst as well as the effect of temperature for both phenolic-furanic polymers. Evidence of covalent copolymerization has been observed through infrared spectrometry (FT-IR combined with principal component analysis (PCA and confirmed with additional solubility tests. These bio-based formulations were applied as adhesives for solid wood and particleboards with interesting results: at 180 °C, the spent-liquor furanic formulations allow wood bonding slightly with lower performance than PVA in dry conditions, while mixed formulations allow the gluing of particleboard with only satisfactory internal bonding tests.

Viscosity of concentrated solutions and of human erythrocyte cytoplasm determined from NMR measurement of molecular correlation times

International Nuclear Information System (INIS)

Endre, Z.H.; Kuchel, P.W.

1986-01-01

Metabolically active human erythrocytes were incubated with [α- 13 C]glycine which led to the specific enrichment of intracellular glutathione. The cells were then studied using 13 C-NMR in which the longitudinal relaxation times (T 1 ) and nuclear Overhauser enhancements of the free glycine and glutathione were measured. Bulk viscosities of the erythrocyte cytoplasm were measured using Ostwald capillary viscometry. Large differences existed between the latter viscosity estimates and those based upon NMR-T 1 measurements. The authors derived an equation from the theory of the viscosity of concentrated solutions which contains two phenomenological interaction parameters, a 'shape' factor and a 'volume' factor; it was fitted to data relating to the concentration dependence of viscosity measured by both methods. Under various conditions of extracellular osmotic pressure, erythrocytes change volume and thus the viscosity of the intracellular milieu is altered. The volume changes resulted in changes in the T 1 of [α- 13 C]glycine. Conversely, the authors showed that alterations in T 1 , when appropriately calibrated, could be used for monitoring changes in volume of metabolically active cells. (Auth.)

Influence of the drying method in chitosans purification step; Influencia do metodo de secagem na etapa de purificacao de quitosanas

Energy Technology Data Exchange (ETDEWEB)

Fonseca, Ana C.M.; Batista, Jorge G.S.; Bettega, Antonio; Lima, Nelson B. de, E-mail: acmfonseca.acf@gmail.com [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

2015-07-01

Currently, the study of extracellular biopolymers properties has received prominence for being easy extraction and purification. Chitosan has been an attractive proposition for applications in various fields such as engineering, biotechnology, medicine and pharmacology. For such applications, it is necessary purification of chitosan to obtain a product more concentrated and free of undesirable impurities. However, at this stage of the process of obtaining the biopolymer may occur morphological and physicochemical changes. This study evaluated the influence of the drying process after purification of a commercial chitosan sample and the importance of this step and its cost/benefit in applications requiring a high degree of purity. The method of drying influenced in the organoleptic properties and in the main characteristics of material. Analysis of the crystal structure by X-ray diffraction showed that the degree of crystallinity, X (%), in the purified chitosan samples was lower when compared with the unpurified sample. The degree of acetylation, DA (%), was analyzed by spectroscopy infrared with no significant changes on the three drying methods assessed, unlike the viscosimetric molecular weight, M{sub v}, determined by capillary viscometry. (author)

Simulation of Injection Molding Process Including Mold Filling and Compound Curing

Directory of Open Access Journals (Sweden)

Mohamad Reza Erfanian

2012-12-01

Full Text Available The present work reports and discusses the results of a 3D simulation of the injection molding process of a rubber compound that includes the mold flling stage and  material curing, using the computer code is developed in “UDF” part of the Fluent 6.3 CAE software. The data obtained from a rheometer (MDR 2000 is used to characterize the rubber material in order to fnd the cure model parameters which exist in curing model. Because of non-newtonian behavior of rubber, in this work the non-newtonian model for viscosity was used and viscosity parameters were computed by mean of viscometry test by RPA. After calculation of the physical and curing properties, vulcanization process was simulated for a complex rubber article with non-uniform thickness by solving the continuity, momentum, energy and curing process equations. Predicted flling and curing time in a complex and 3D rubber part is compared with experimentally measured data which confrmed  the accuracy and applicability of the method.

Structure and characteristics of acid and pepsin-solubilized collagens from the skin of cobia (Rachycentron canadum).

Science.gov (United States)

Zeng, Shaokui; Yin, Juanjuan; Yang, Shuqi; Zhang, Chaohua; Yang, Ping; Wu, Wenlong

2012-12-01

Acid-solubilized collagen (ASC) and pepsin-solubilized collagen (PSC) were extracted from the skin of cobia (Rachycentron canadum). The yields of ASC and PSC were 35.5% and 12.3%, respectively. Based on the protein patterns and carboxymethyl-cellulose chromatography, ASC and PSC were composed of α1α2α3 heterotrimers and were characterised as type I collagen with no disulfide bond. Their amounts of imino acids were 203 and 191 residues per 1000 residues, respectively. LC-MS/MS analysis demonstrated the high sequences similarities of ASC and PSC. Fourier transform infrared spectroscopy spectra showed that the amide I, II and III peaks of PSC were obtained at a lower wave number compared with ASC. The thermal denaturation temperatures of ASC and PSC, as measured by viscometry, were 34.62 and 33.97°C, respectively. The transition temperatures (T(max)) were 38.17 and 36.03°C, respectively, as determined by differential scanning calorimetry (DSC). Both collagens were soluble at acidic pH and below 2% (w/v) NaCl concentration. Copyright © 2012 Elsevier Ltd. All rights reserved.

DNA interaction studies of sesamol (3,4-methylenedioxyphenol) food additive.

Science.gov (United States)

Kashanian, Soheila; Tahmasian Ghobadi, Ameneh; Roshanfekr, Hamideh; Shariati, Zohreh

2013-02-01

The interaction of native calf thymus DNA (CT-DNA) with sesamol (3,4-methylenedioxyphenol) in Tris-HCl buffer at neutral pH 7.4 was monitored by absorption spectrophotometry, viscometry and spectrofluorometry. It is found that sesamol molecules could interact with DNA outside and/or groove binding modes, as are evidenced by: hyperchromism in UV absorption band, very slow decrease in specific viscosity of DNA, and small increase in the fluorescence of methylene blue (MB)-DNA solutions in the presence of increasing amounts of sesamol, which indicates that it is able to partially release the bound MB. Furthermore, the enthalpy and entropy of the reaction between sesamol and CT-DNA showed that the reaction is enthalpy-favored and entropy-disfavored (ΔH = -174.08 kJ mol(-1); ΔS = -532.92 J mol(-1) K(-1)). The binding constant was determined using absorption measurement and found to be 2.7 × 10(4) M(-1); its magnitude suggests that sesamol interacts to DNA with a high affinity.

Transparent phosphosilicate glasses containing crystals formed during cooling of melts

DEFF Research Database (Denmark)

Liu, S. J.; Zhang, Yanfei; He, W.

2011-01-01

The effect of P2O5-SiO2 substitution on spontaneous crystallization of SiO2-Al2O3-P2O5- Na2O-MgO melts during cooling was studied by X-ray diffraction (XRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and rotation viscometry. Results show that addition of P2O5 leads...... to amorphous phase separation (APS), i.e., phosphate- and silicate-rich phases. It is due to the tendency of Mg2+ to form [MgO4] linking with [SiO4]. Molar substitution of P2O5 for SiO2 enhances the network polymerization of silicate-rich phase in the melts, and thereby the spontaneous crystallization of cubic...... Na2MgSiO4 is also enhanced during cooling of the melts. In addition, the sizes of the local crystalline and separated glassy domains are smaller than the wavelength of the visible light, and this leads to the transparency of the obtained glasses containing crystals....

DNA-binding studies of a tetraalkyl-substituted porphyrin and the mutually adaptive distortion principle.

Science.gov (United States)

Ghimire, Srijana; Fanwick, Phillip E; McMillin, David R

2014-10-20

This investigation explores DNA-binding interactions of various forms of an alkyl-substituted cationic porphyrin, H2TC3 (5,10,15,20-tetra[3-(3'-methylimidazolium-1'-yl)]porphyrin). The motivating idea is that incorporating alkyl rather than aryl substituents in the meso positions will enhance the prospects for intercalative as well as external binding to DNA hosts. The ligands may also be applicable for photodynamic and/or anticancer therapy. Methods employed include absorbance, circular dichroism, and emission spectroscopies, as well as viscometry and X-ray crystallography. By comparison with the classical H2T4 system, H2TC3 exhibits a higher molar extinction coefficient but is more prone to self-association. Findings of note include that the copper(II)-containing form Cu(TC3) is adept at internalizing into single-stranded as well as B-form DNA, regardless of the base composition. Surprisingly, however, external binding of H2TC3 occurs within domains that are rich in adenine-thymine base pairs. The difference in the deformability of H2TC3 versus Cu(TC3) probably accounts for the reactivity difference. Finally, Zn(TC3) binds externally, as the metal center remains five-coordinate.

Crosslinkable coatings from phosphorylcholine-based polymers.

Science.gov (United States)

Lewis, A L; Cumming, Z L; Goreish, H H; Kirkwood, L C; Tolhurst, L A; Stratford, P W

2001-01-01

2-Methacryloyloxyethyl phosphorylcholine (MPC) was synthesised and then used in the preparation of crosslinked polymer membranes with lauryl methacrylate, hydroxypropyl methacrylate and trimethoxysilylpropyl methacrylate (crosslinker) comonomers. Some physical aspects of the membrane properties were evaluated in order to establish the basis for the synthesis of a series of post-crosslinkable polymers. These materials were made by copolymerisation of the constituent monomers via a free radical method, and characterised using NMR, FT-IR, viscometry and elemental analysis. The optimum crosslink density and conditions required for curing coatings of these polymers were investigated using atomic force microscopy (AFM) and showed the inclusion of 5 mol% silyl crosslinking agent to be ideal. A nanoindentation technique was employed to determine if the coating developed elasticity upon crosslinking. The biological properties of the coatings were evaluated using a variety of protein adsorption assays and blood contacting experiments, and an enzyme immunoassay was developed to detect E. coli in order to assess the level of bacterial adhesion to these biomaterials. Polymers of this type were shown to be very useful as coating materials for improving the biocompatibility of, or reducing the levels of adherent bacteria to medical devices.

Investigation of viscosity of whole hydrolyze sweetened condensed milk

Directory of Open Access Journals (Sweden)

O. Kalinina

2015-05-01

Full Text Available Introduction. Рaper is aimed at developing of low-lactose (hydrolyzed sweetened condensed milk products technology for lactose intolerant people and for the whole population. Materials and methods: Rheological characteristics were determined on a Reotest device by the 2 nd method of viscometry Results and discussion. Reasonability of ß-galactosidase use for milk lactose hydrolyze during the production of canned products with sugar was proved in the previous works. This technology gives possibility to increase the quality of condensed canned foods, to reduce sugar concentration till 50 %, to increase dietary properties. Due to the reducing of saccharose mass part till 22 and 31 % the products had a liquid consistency that’s why was a necessity to increase the viscosity properties of condensed products. One of method to increase the product viscosity is inoculation of stabilization systems. Reasonability of the usage of stabilization system Bivicioc 1L was proved. The researches of viscosity determination in whole hydrolyzed sweetened condensed milk were shown in the work. Relations of viscosity of whole hydrolyzed condensed milk to the deformation rate were presented. Conclusions Viscosity indices of experimental samples in the fresh produced products and during storage are determined and justified.

Solution properties of a heteropolysaccharide extracted from pumpkin (Cucurbita pepo, lady godiva).

Science.gov (United States)

Song, Yi; Zhao, Jing; Ni, Yuanying; Li, Quanhong

2015-11-05

A water-soluble galactoglucofucomannan was extracted from pumpkin (Cucurbita pepo, lady godiva variety). GC-MS analysis indicated that the polysaccharide was composed of 1,6-linked-glucosyl, 1,2,6-linked-mannosyl, 1,3,6-linked-mannosyl, 1,2,6-linked-galactosyl, 1,2,6-linked-galactosyl, terminal fucosyl and terminal glucose. The solution properties of the polysaccharide were studied systematically by using size-exclusion chromatography combined with multi-angle laser light scattering, viscometry and dynamic light scattering at 25 °C. The weight average molecular masses (Mw), intrinsic viscosity [η], radius of gyration (Rg) and hydrodynamic radius (Rh) were found to be 12.7 × 10(5)g/mol, 780 ml/g, 68 nm and 116 nm, respectively. The fraction dimension and value of ρ (Rg/Rh) of the polysaccharide revealed that it existed in a sphere-like conformation in distilled water. The dependence of zero shear specific viscosity on the coil overlap parameter was analyzed using different models. Furthermore, degradation of samples upon autoclaving has been observed and quantified by intrinsic viscosity determination and SEC-MALLS. Copyright © 2015 Elsevier Ltd. All rights reserved.

The effect of gamma irradiation on chitosan and its application as a plant growth promoter in Chinese kale (Brassica alboglabra)

Science.gov (United States)

Isa, Mohd Hafez Mohd; Yasir, Muhamad Samudi; Hasan, Abu Bakar; Fadilah, Nur Izzah Md; Hassan, Abdul Rahman

2016-01-01

This research project was conducted to study the effects of irradiation on chitosan and its potential application as a plant growth promoter. Chitosan in the form of flakes was irradiated with gamma rays at irradiation dosage of 50 kGy, 100 kGy, 200 kGy and 400 kGy. The effect of irradiation on chitosan in terms of intrinsic viscosity and average molecular weight was measured using Ubbelohde capillary viscometry technique and the results obtained showed irradiation at doses of up to 50 kGy had caused an extremely significant reduction of both parameters and this trend continued at higher irradiation doses, although the decrease were not significant. The effect of various concentrations of chitosan and irradiated chitosan on growth promotion of Chinese kale (Brassica alboglabra) was hydroponically grown and cultivated for 50 days. Statistical analysis showed addition of 10 ppm of irradiated chitosan of 200 kGy and 400 kGy, respectively, resulted in an extremely significant increase in the percentage weight gain of Chinese kale (Brassica alboglabra). Results obtained in this study showed the potential use of irradiated chitosan as a plant growth promoter for plants grown hydroponically.

The effect of gamma irradiation on chitosan and its application as a plant growth promoter in Chinese kale (Brassica alboglabra)

International Nuclear Information System (INIS)

Isa, Mohd Hafez Mohd; Hasan, Abu Bakar; Fadilah, Nur Izzah Md; Hassan, Abdul Rahman; Yasir, Muhamad Samudi

2016-01-01

This research project was conducted to study the effects of irradiation on chitosan and its potential application as a plant growth promoter. Chitosan in the form of flakes was irradiated with gamma rays at irradiation dosage of 50 kGy, 100 kGy, 200 kGy and 400 kGy. The effect of irradiation on chitosan in terms of intrinsic viscosity and average molecular weight was measured using Ubbelohde capillary viscometry technique and the results obtained showed irradiation at doses of up to 50 kGy had caused an extremely significant reduction of both parameters and this trend continued at higher irradiation doses, although the decrease were not significant. The effect of various concentrations of chitosan and irradiated chitosan on growth promotion of Chinese kale (Brassica alboglabra) was hydroponically grown and cultivated for 50 days. Statistical analysis showed addition of 10 ppm of irradiated chitosan of 200 kGy and 400 kGy, respectively, resulted in an extremely significant increase in the percentage weight gain of Chinese kale (Brassica alboglabra). Results obtained in this study showed the potential use of irradiated chitosan as a plant growth promoter for plants grown hydroponically

The effect of gamma irradiation on chitosan and its application as a plant growth promoter in Chinese kale (Brassica alboglabra)

Energy Technology Data Exchange (ETDEWEB)

Isa, Mohd Hafez Mohd, E-mail: m.hafez@usim.edu.my; Hasan, Abu Bakar; Fadilah, Nur Izzah Md; Hassan, Abdul Rahman [Faculty of Science and Technology, Universiti Sains Islam Malaysia, Bandar Baru Nilai, 71800 Nilai, Negeri Sembilan (Malaysia); Yasir, Muhamad Samudi [School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor (Malaysia)

2016-01-22

This research project was conducted to study the effects of irradiation on chitosan and its potential application as a plant growth promoter. Chitosan in the form of flakes was irradiated with gamma rays at irradiation dosage of 50 kGy, 100 kGy, 200 kGy and 400 kGy. The effect of irradiation on chitosan in terms of intrinsic viscosity and average molecular weight was measured using Ubbelohde capillary viscometry technique and the results obtained showed irradiation at doses of up to 50 kGy had caused an extremely significant reduction of both parameters and this trend continued at higher irradiation doses, although the decrease were not significant. The effect of various concentrations of chitosan and irradiated chitosan on growth promotion of Chinese kale (Brassica alboglabra) was hydroponically grown and cultivated for 50 days. Statistical analysis showed addition of 10 ppm of irradiated chitosan of 200 kGy and 400 kGy, respectively, resulted in an extremely significant increase in the percentage weight gain of Chinese kale (Brassica alboglabra). Results obtained in this study showed the potential use of irradiated chitosan as a plant growth promoter for plants grown hydroponically.

Synthesis, spectroscopic characterization, biological screenings, DNA binding study and POM analyses of transition metal carboxylates

Science.gov (United States)

Uddin, Noor; Sirajuddin, Muhammad; Uddin, Nizam; Tariq, Muhammad; Ullah, Hameed; Ali, Saqib; Tirmizi, Syed Ahmed; Khan, Abdur Rehman

2015-04-01

This article contains the synthesis of a novel carboxylic acid derivative, its transition metal complexes and evaluation of biological applications. Six carboxylate complexes of transition metals, Zn(II) and Hg(II), have been successfully synthesized and characterized by FT-IR and NMR (1H, 13C). The ligand, HL, (4-[(2,6-Diethylphenyl)amino]-4-oxobutanoic acid) was also characterized by single crystal X-ray analysis. The complexation occurs via oxygen atoms of the carboxylate moiety. FT-IR date show the bidentate nature of the carboxylate moiety of the ligand as the Δν value in all complexes is less than that of the free ligand. The ligand and its complexes were screened for antifungal and antileishmanial activities. The results showed that the ligand and its complexes are active with few exceptions. UV-visible spectroscopy and viscometry results reveal that the ligand and its complexes interact with the DNA via intercalative mode of interaction. A new and efficient strategy to identify the pharmacophores and anti-pharmacophores sites in carboxylate derivatives for the antibacterial/antifungal activity using Petra, Osiris and Molinspiration (POM) analyses was also carried out.

Methods of viscosity measurements in sealed ampoules

Science.gov (United States)

Mazuruk, Konstantin

1999-07-01

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

Evaluation of Wax Deposition and Its Control During Production of Alaska North Slope Oils

Energy Technology Data Exchange (ETDEWEB)

Tao Zhu; Jack A. Walker; J. Liang

2008-12-31

Due to increasing oil demand, oil companies are moving into arctic environments and deep-water areas for oil production. In these regions of lower temperatures, wax deposits begin to form when the temperature in the wellbore falls below wax appearance temperature (WAT). This condition leads to reduced production rates and larger pressure drops. Wax problems in production wells are very costly due to production down time for removal of wax. Therefore, it is necessary to develop a solution to wax deposition. In order to develop a solution to wax deposition, it is essential to characterize the crude oil and study phase behavior properties. The main objective of this project was to characterize Alaskan North Slope crude oil and study the phase behavior, which was further used to develop a dynamic wax deposition model. This report summarizes the results of the various experimental studies. The subtasks completed during this study include measurement of density, molecular weight, viscosity, pour point, wax appearance temperature, wax content, rate of wax deposition using cold finger, compositional characterization of crude oil and wax obtained from wax content, gas-oil ratio, and phase behavior experiments including constant composition expansion and differential liberation. Also, included in this report is the development of a thermodynamic model to predict wax precipitation. From the experimental study of wax appearance temperature, it was found that wax can start to precipitate at temperatures as high as 40.6 C. The WAT obtained from cross-polar microscopy and viscometry was compared, and it was discovered that WAT from viscometry is overestimated. From the pour point experiment it was found that crude oil can cease to flow at a temperature of 12 C. From the experimental results of wax content, it is evident that the wax content in Alaskan North Slope crude oil can be as high as 28.57%. The highest gas-oil ratio for a live oil sample was observed to be 619.26 SCF

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

Science.gov (United States)

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

Advanced in Macrostatistical Hydrodynamics

International Nuclear Information System (INIS)

Graham, A.L.; Tetlow, N.; Abbott, J.R.; Mondy, L.S.; Brenner, H.

1993-01-01

An overview is presented of research that focuses on slow flows of suspensions in which colloidal and inertial effects are negligibly small (Macrostatistical Hydrodynamics). First, we describe nuclear magnetic resonance imaging experiments to quantitatively measure particle migration occurring in concentrated suspensions undergoing a flow with a nonuniform shear rate. These experiments address the issue of how the flow field affects the microstructure of suspensions. In order to understand the local viscosity in a suspension with such a flow-induced, spatially varying concentration, one must know how the viscosity of a homogeneous suspension depends on such variables as solids concentration and particle orientation. We suggest the technique of falling ball viscometry, using small balls, as a method to determine the effective viscosity of a suspension without affecting the original microstructure significantly. We also describe data from experiments in which the detailed fluctuations of a falling ball's velocity indicate the noncontinuum nature of the suspension and may lead to more insights into the effects of suspension microstructure on macroscopic properties. Finally, we briefly describe other experiments that can be performed in quiescent suspensions (in contrast to the use of conventional shear rotational viscometers) in order to learn more about the microstructure and boundary effects in concentrated suspensions

Particle interactions in concentrated suspensions

International Nuclear Information System (INIS)

Mondy, L.A.; Graham, A.L.; Abbott, J.R.; Brenner, H.

1993-01-01

An overview is presented of research that focuses on slow flows of suspensions in which colloidal and inertial effects are negligibly small. The authors describe nuclear magnetic resonance imaging experiments to quantitatively measure particle migration occurring in concentrated suspensions undergoing a flow with a nonuniform shear rate. These experiments address the issue of how the flow field affects the microstructure of suspensions. In order to understand the local viscosity in a suspension with such a flow-induced, spatially varying concentration, one must know how the viscosity of a homogeneous suspension depends on such variables as solids concentration and particle orientation. The authors suggest the technique of falling ball viscometry, using small balls, as a method to determine the effective viscosity of a suspension without affecting the original microstructure significantly. They also describe data from experiments in which the detailed fluctuations of a falling ball's velocity indicate the noncontinuum nature of the suspension and may lead to more insights into the effects of suspension microstructure on macroscopic properties. Finally, they briefly describe other experiments that can be performed in quiescent suspensions (in contrast to the use of conventional shear rotational viscometers) in order to learn more about boundary effects in concentrated suspensions

Soft-robotic esophageal swallowing as a clinically-inspired bolus rheometry technique

International Nuclear Information System (INIS)

Dirven, Steven; Allen, Jacqueline; Xu, Weiliang; Cheng, Leo K

2017-01-01

To investigate the impact of viscosity and peristaltic transport parameters on manometric pressure signatures, a reproducible swallowing process is required. Due to inter- and intra-subject variability from swallow to swallow, the human body does not represent an optimal mechanism for such an investigation. A smooth and continuous swallowing soft-robot has been developed to produce biomimetic swallowing trajectories, and is proposed to operate as a bench-top bolus rheometric investigation method. The method compares conventional viscometry and pressure signature findings from robotic swallowing experiments. The robotic aspect of experimentation involved 450 biomimetic swallows (10 repetitions of 45 unique experiments). The method examined swallowing transport in three dimensions: bolus formulation, peristaltic wavelength, and peristaltic velocity, each of which are known to contribute to safe and effective swallowing in vivo . It is found that the pressure gradients and magnitudes are commensurate with clinical reports on biological swallowing, on the order of 100 mmHg peak, however, the relationship between viscosity and pressure signatures is less clear. Bolus transport cannot be predicted as a function of bolus viscosity alone. Traditional viscometric data at 50 s −1 , as used in clinical practice, may not be a strong indicator of swallow effort, safety, or efficacy in vivo . (paper)

Micro-Electromechanical Affinity Sensor for the Monitoring of Glucose in Bioprocess Media

Directory of Open Access Journals (Sweden)

Lorenz Theuer

2017-06-01

Full Text Available An affinity-viscometry-based micro-sensor probe for continuous glucose monitoring was investigated with respect to its suitability for bioprocesses. The sensor operates with glucose and dextran competing as binding partner for concanavalin A, while the viscosity of the assay scales with glucose concentration. Changes in viscosity are determined with a micro-electromechanical system (MEMS in the measurement cavity of the sensor probe. The study aimed to elucidate the interactions between the assay and a typical phosphate buffered bacterial cultivation medium. It turned out that contact with the medium resulted in a significant long-lasting drift of the assay’s viscosity at zero glucose concentration. Adding glucose to the medium lowers the drift by a factor of eight. The cglc values measured off-line with the glucose sensor for monitoring of a bacterial cultivation were similar to the measurements with an enzymatic assay with a difference of less than ±0.15 g·L−1. We propose that lectin agglomeration, the electro-viscous effect, and constitutional changes of concanavalin A due to exchanges of the incorporated metal ions may account for the observed viscosity increase. The study has demonstrated the potential of the MEMS sensor to determine sensitive viscosity changes within very small sample volumes, which could be of interest for various biotechnological applications.

Time, temperature, chemical and radiation exposure effects on the mechanical performance of polymeric materials used for the containment of radioactive waste. Abstract 56

International Nuclear Information System (INIS)

Brown, L.; Bui, V.T.; Bonin, H.W.

2004-01-01

'Full text:' The mechanical performance of materials used for the fabrication of materials used for the fabrication of a storage container for radioactive waste is dependent on the environment to which the container will be exposed over its lifetime. There exists a complex relationship between the many variables affecting the properties of the polymer and potentially decreasing the mechanical performance properties of the container. To further complicate the system, the degradation processes are often time dependant. Experimental results for Nylon 6,6, Semi-Aromatic Nylon, and Polycarbonate have been used as a basis for the development of a model, which represents the performance of a polymeric container used for the storage of radioactive waste over time. The experimental work aimed at providing information on the materials performance in a variety of environmental conditions, as well as a function of time. This included exposing the polymeric material samples to a mixed field of radiation in the SLOWPOKE-2 nuclear reactor. A series of dilution viscometry experiments have been used to relate the changes in mechanical performance to changes in the physical characteristics of the polymer molecules. This provided a valuable tool in the extrapolation of the model to other polymeric materials, and allowed for use of the model based on theoretical predictions of a polymer molecules reaction to various environmental conditions. (author)

Time, temperature, chemical and radiation exposure effects on the mechanical performance of polymeric materials used for the containment of radioactive waste. Abstract 56

Energy Technology Data Exchange (ETDEWEB)

Brown, L.; Bui, V.T.; Bonin, H.W. [Royal Military College of Canada, Dept. of Chemistry and Chemical Engineering, Kingston, Ontario (Canada)]. E-mail: Laura-lee.Brown@rmc.ca; bui-v@rmc.ca; bonin-h@rmc.ca

2004-07-01

'Full text:' The mechanical performance of materials used for the fabrication of materials used for the fabrication of a storage container for radioactive waste is dependent on the environment to which the container will be exposed over its lifetime. There exists a complex relationship between the many variables affecting the properties of the polymer and potentially decreasing the mechanical performance properties of the container. To further complicate the system, the degradation processes are often time dependant. Experimental results for Nylon 6,6, Semi-Aromatic Nylon, and Polycarbonate have been used as a basis for the development of a model, which represents the performance of a polymeric container used for the storage of radioactive waste over time. The experimental work aimed at providing information on the materials performance in a variety of environmental conditions, as well as a function of time. This included exposing the polymeric material samples to a mixed field of radiation in the SLOWPOKE-2 nuclear reactor. A series of dilution viscometry experiments have been used to relate the changes in mechanical performance to changes in the physical characteristics of the polymer molecules. This provided a valuable tool in the extrapolation of the model to other polymeric materials, and allowed for use of the model based on theoretical predictions of a polymer molecules reaction to various environmental conditions. (author)

Prolonged Corrosion Stability of a Microchip Sensor Implant during In Vivo Exposure

Directory of Open Access Journals (Sweden)

Paul Glogener

2018-02-01

Full Text Available A microelectronic biosensor was subjected to in vivo exposure by implanting it in the vicinity of m. trapezii (Trapezius muscle from cattle. The implant is intended for the continuous monitoring of glucose levels, and the study aimed at evaluating the biostability of exposed semiconductor surfaces. The sensor chip was a microelectromechanical system (MEMS prepared using 0.25 µm complementary metal–oxide–semiconductor CMOS/BiCMOS technology. Sensing is based on the principle of affinity viscometry with a sensoric assay, which is separated by a semipermeable membrane from the tissue. Outer dimensions of the otherwise hermetically sealed biosensor system were 39 × 49 × 16 mm. The test system was implanted into cattle in a subcutaneous position without running it. After 17 months, the device was explanted and analyzed by comparing it with unexposed chips and systems. Investigations focused on the MEMS chip using SEM, TEM, and elemental analysis by EDX mapping. The sensor chip turned out to be uncorroded and no diminishing of the topmost passivation layer could be determined, which contrasts remarkably with previous results on CMOS biosensors. The negligible corrosive attack is understood to be a side effect of the semipermeable membrane separating the assay from the tissue. It is concluded that the separation has enabled a prolonged biostability of the chip, which will be of relevance for biosensor implants in general.

Molecular Weight and Structural Properties of Biodegradable PLA Synthesized with Different Catalysts by Direct Melt Polycondensation

Directory of Open Access Journals (Sweden)

Hyung Woo Lee

2015-09-01

Full Text Available Production of biodegradable polylactic acid (PLA from biomassbased lactic acid is widely studied for substituting petro-based plastics or polymers. This study investigated PLA production from commercial lactic acid in a batch reactor by applying a direct melt polycondensation method with two kinds of catalyst, γ-aluminium(III oxide (γ-Al2O3 or zinc oxide (ZnO, in reduced pressure. The molecular weight of the synthesized PLA was determined by capillary viscometry and its structural properties were analyzed by functional group analysis using FT-IR. The yields of polymer production with respect to the theoretical conversion were 47% for γ-Al2O3 and 35% for ZnO. However, the PLA from ZnO had a higher molecular weight (150,600 g/mol than that from γ-Al2O3 (81,400 g/mol. The IR spectra of the synthesized PLA from both catalysts using polycondensation show the same behavior of absorption peaks at wave numbers from 4,500 cm-1 to 500 cm-1, whereas the PLA produced by two other polymerization methods – polycondensation and ring opening polymerization –showed a significant difference in % transmittance intensity pattern as well as peak area absorption at a wave number of 3,500 cm-1 as –OH vibration peak and at 1,750 cm-1 as –C=O carbonyl vibrational peak.

Human Growth Hormone Delivery with a Microneedle Transdermal System: Preclinical Formulation, Stability, Delivery and PK of Therapeutically Relevant Doses

Directory of Open Access Journals (Sweden)

Mahmoud Ameri

2014-05-01

Full Text Available This study evaluated the feasibility of coating formulated recombinant human growth hormone (rhGH on a titanium microneedle transdermal delivery system, Zosano Pharma (ZP-hGH, and assessed preclinical patch delivery performance. Formulation rheology and surface activity were assessed by viscometry and contact angle measurement. rhGH liquid formulation was coated onto titanium microneedles by dip-coating and drying. The stability of coated rhGH was determined by size exclusion chromatography-high performance liquid chromatography (SEC-HPLC. Preclinical delivery and pharmacokinetic studies were conducted in female hairless guinea pigs (HGP using rhGH coated microneedle patches at 0.5 and 1 mg doses and compared to Norditropin® a commercially approved rhGH subcutaneous injection. Studies demonstrated successful rhGH formulation development and coating on microneedle arrays. The ZP-hGH patches remained stable at 40 °C for six months with no significant change in % aggregates. Pharmacokinetic studies showed that the rhGH-coated microneedle patches, delivered with high efficiency and the doses delivered indicated linearity with average Tmax of 30 min. The absolute bioavailability of the microneedle rhGH patches was similar to subcutaneous Norditropin® injections. These results suggest that ZP-transdermal microneedle patch delivery of rhGH is feasible and may offer an effective and patient-friendly alternative to currently marketed rhGH injectables.

Human Growth Hormone Delivery with a Microneedle Transdermal System: Preclinical Formulation, Stability, Delivery and PK of Therapeutically Relevant Doses.

Science.gov (United States)

Ameri, Mahmoud; Kadkhodayan, Miryam; Nguyen, Joe; Bravo, Joseph A; Su, Rebeca; Chan, Kenneth; Samiee, Ahmad; Daddona, Peter E

2014-05-15

This study evaluated the feasibility of coating formulated recombinant human growth hormone (rhGH) on a titanium microneedle transdermal delivery system, Zosano Pharma (ZP)-hGH, and assessed preclinical patch delivery performance. Formulation rheology and surface activity were assessed by viscometry and contact angle measurement. rhGH liquid formulation was coated onto titanium microneedles by dip-coating and drying. The stability of coated rhGH was determined by size exclusion chromatography-high performance liquid chromatography (SEC-HPLC). Preclinical delivery and pharmacokinetic studies were conducted in female hairless guinea pigs (HGP) using rhGH coated microneedle patches at 0.5 and 1 mg doses and compared to Norditropin® a commercially approved rhGH subcutaneous injection. Studies demonstrated successful rhGH formulation development and coating on microneedle arrays. The ZP-hGH patches remained stable at 40 °C for six months with no significant change in % aggregates. Pharmacokinetic studies showed that the rhGH-coated microneedle patches, delivered with high efficiency and the doses delivered indicated linearity with average Tmax of 30 min. The absolute bioavailability of the microneedle rhGH patches was similar to subcutaneous Norditropin® injections. These results suggest that ZP-transdermal microneedle patch delivery of rhGH is feasible and may offer an effective and patient-friendly alternative to currently marketed rhGH injectables.

Effects of ioxaglate to blood rheology

International Nuclear Information System (INIS)

Schmid-Schoenbein, H.; Teitel, P.; Tietz, G.; Oezlen, A.

1984-01-01

Almen and Aspelin have shown that the use of non-ionic radio contrast media allows to increase the iodine concentration (which is desirable because of its effect on radio opacity) without a very large increase in osmolarity (which is undesirable because it impaires the fluidity of erythrocytes). This latter effect can also be diminished by reducing the osmolarity of a dimeric contrast medium as it has been achieved by incorporating more iodine atoms into the molecule in the case of Ioxaglate (Hexabrix). In various microrheological test systems, the fluidity of packed red cell suspension, the corrected filtration rate though 5 μm pores and the relative apparent viscosity of blood - contrast media mixtures (1 to 50% concentration) were determined in experiments comparing this compound with Urografin 76 of the same iodine content. In all systems, the former showed lesser rheological effects. In whole blood viscometry, this can be detected only after appropriate corrections for the effects of the two contrast media on hematocrit and plasma viscosity. Owing to a more pronounced water shift from the cells to the plasma, Urografin tends to reduce the viscosity of the plasma-contrast media mixture. The concomitant reduction in MCV and hematocrit level tends to screen the macrorheological effect of the dehydrated cells becomes immediately obvious when the viscometric data are corrected for hematocrit value and plasma viscosity effects. (orig.)

In Situ Hybridization of Pulp Fibers Using Mg-Al Layered Double Hydroxides

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Carl-Erik Lange

2015-04-01

Full Text Available Inorganic Mg2+ and Al3+ containing layered double hydroxide (LDH particles were synthesised in situ from aqueous solution onto chemical pulp fibers of pine (Pinus sylvestris. High super saturated (hss solution with sodium carbonate produced LDH particles with an average diameter of 100–200 nm. Nano-size (70 nm LDH particles were found from fibers external surface and, to a lesser degree, from the S2 cell wall after synthesis via low super saturated (lss route. The synthesis via slow urea hydrolysis (Uhyd yielded micron and clay sized LDH (2–5 μm and enabled efficient fiber densification via mineralization of S2 fiber wall layer as indicated by TEM and compliance analysis. The Uhyd method decreased fiber compliance up to 50%. Reduction in the polymerisation degree of cellulose was observed with capillary viscometry. Thermogravimetric analysis showed that the hybridization with LDH reduced the exothermic heat, indicating, that this material can be incorporated in flame retardant applications. Fiber charge was assessed by Fibers 2015, 3 104 adsorption expermients with methylene blue (MB and metanil yellow (MY. Synthesis via lss route retained most of the fibres original charge and provided the highest capacity (10 μmol/g for anionic MY, indicating cationic character of hybrid fibers. Our results suggested that mineralized fibers can be potentially used in advanced applications such as biocomposites and adsorbent materials.

Effect of selected non-ionic surfactants on the flow behavior of aqueous veegum suspensions.

Science.gov (United States)

Kennedy, Ross A; Kennedy, Michelle L

2007-03-30

The aim of this work was to investigate the influence of some non-ionic surfactants, Tween 80 and Brij 98, on the viscosity and flow behavior of a commercial montmorillonite clay, Veegum Granules. The effect of different concentrations of the surfactants on the shear stress-shear rate rheograms of hydrated concentrated clay suspensions was determined by shear viscometry. The addition of either surfactant increased the plastic viscosity and the yield stress of the suspensions. Furthermore, both surfactants altered the thixotropy of the suspensions to an extent that depended on both the surfactant concentration and the time of equilibration of the surfactant and Veegum. Brij 98 had a greater and more rapid effect. It is proposed that the surfactant polar head-groups anchor at the tetrahedral sheet surface, leaving the alkyl chains extending away from the edges and faces. Consequently, the alkyl chains undergo hydrophobic interactions that facilitate the association between the platelets and increase the physical structure within the suspension. Stereochemical differences between the polar groups may lead to differences in the way the surfactants associate with the tetrahedral sheet and hence their ultimate effect on the rheological behavior. There is a significant interaction between these surfactants and montmorillonite clays, and the rheological changes that occur could have a major impact on any pharmaceutical formulation that uses these ingredients.

Viscosity properties of sodium borophosphate glasses

International Nuclear Information System (INIS)

Gaylord, S.; Tincher, B.; Petit, L.; Richardson, K.

2009-01-01

The viscosity behavior of (1 - x)NaPO 3 -xNa 2 B 4 O 7 glasses (x = 0.05-0.20) have been measured as a function of temperature using beam-bending and parallel-plate viscometry. The viscosity was found to shift to higher temperatures with increasing sodium borate content. The kinetic fragility parameter, m, estimated from the viscosity curve, decreases from 52 to 33 when x increases from 0.05 to 0.20 indicating that the glass network transforms from fragile to strong with the addition of Na 2 B 4 O 7 . The decrease in fragility with increasing x is due to the progressive depolymerization of the phosphate network by the preferred four-coordinated boron atoms present in the low alkali borate glasses. As confirmed by Raman spectroscopy increasing alkali borate leads to enhanced B-O-P linkages realized with the accompanying transition from solely four-coordinated boron (in BO 4 units) to mixed BO 4 /BO 3 structures. The glass viscosity characteristics of the investigated glasses were compared to those of P-SF67 and N-FK5 commercial glasses from SCHOTT. We showed that the dependence of the viscosity of P-SF67 was similar to the investigated glasses due to similar phosphate network organization confirmed by Raman spectroscopy, whereas N-FK5 exhibited a very different viscosity curve and fragility parameter due to its highly coordinated silicate network

Electron beam effects on gelatin polymer

Energy Technology Data Exchange (ETDEWEB)

Inamura, Patricia Y.; Shimazaki, Kleber; Souza, Clecia de M.; Moura, Esperidiana A.B.; Mastro, Nelida L. del, E-mail: patyoko@yahoo.co [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Colombo, Maria A., E-mail: mascolombo@yahoo.com.b [Faculdade de Tecnologia da Zona Leste, Sao Paulo, SP (Brazil)

2009-07-01

The main field of electron-beam radiation processing applications is the modification of polymeric material. Polymer development includes new pathways to produce natural polymers with better mechanical and barrier properties and thermal stability. The aim of this paper was to investigate the behavior of a gelatin/acrylamide polymer treated by electron-beam radiation. Gelatin is a heterogeneous mixture of water-soluble proteins of high average molecular mass derived by hydrolytic action from animal collagen, a fibrous insoluble protein, which is widely found in nature as the major constituent of skin, bones and connective tissue. Hydrolyzed collagen is composed of a unique sequence of amino acids, characterized particularly by the high content of glycine, proline and hydroxyproline. Among biomaterials, gelatin is an interesting material because is a partially crystalline polymer and has a relatively low melting point. Samples of gelatin together with glycerin as plasticizer and acrylamide as copolymer were irradiated with doses of 10 kGy and 40 kGy, using an electron beam accelerator, dose rate 22.41kGy/s, at room temperature in presence of air. After irradiation, some preliminary analyses were done like viscometry, texture analyses and colorimetry. The results of the diverse tests showed changes that can be ascribed to radiation-induced crosslinking. The electron-beam processed acrylamide-gelatin polymer using glycerin as plasticizer must be first extensively characterized before to be used for general applications. (author)

Hard sphere-like glass transition in eye lens α-crystallin solutions.

Science.gov (United States)

Foffi, Giuseppe; Savin, Gabriela; Bucciarelli, Saskia; Dorsaz, Nicolas; Thurston, George M; Stradner, Anna; Schurtenberger, Peter

2014-11-25

We study the equilibrium liquid structure and dynamics of dilute and concentrated bovine eye lens α-crystallin solutions, using small-angle X-ray scattering, static and dynamic light scattering, viscometry, molecular dynamics simulations, and mode-coupling theory. We find that a polydisperse Percus-Yevick hard-sphere liquid-structure model accurately reproduces both static light scattering data and small-angle X-ray scattering liquid structure data from α-crystallin solutions over an extended range of protein concentrations up to 290 mg/mL or 49% vol fraction and up to ca. 330 mg/mL for static light scattering. The measured dynamic light scattering and viscosity properties are also consistent with those of hard-sphere colloids and show power laws characteristic of an approach toward a glass transition at α-crystallin volume fractions near 58%. Dynamic light scattering at a volume fraction beyond the glass transition indicates formation of an arrested state. We further perform event-driven molecular dynamics simulations of polydisperse hard-sphere systems and use mode-coupling theory to compare the measured dynamic power laws with those of hard-sphere models. The static and dynamic data, simulations, and analysis show that aqueous eye lens α-crystallin solutions exhibit a glass transition at high concentrations that is similar to those found in hard-sphere colloidal systems. The α-crystallin glass transition could have implications for the molecular basis of presbyopia and the kinetics of molecular change during cataractogenesis.

Formulation and in vitro/in vivo evaluation of chitosan-based film forming gel containing ketoprofen.

Science.gov (United States)

Oh, Dong-Won; Kang, Ji-Hyun; Lee, Hyo-Jung; Han, Sang-Duk; Kang, Min-Hyung; Kwon, Yie-Hyuk; Jun, Joon-Ho; Kim, Dong-Wook; Rhee, Yun-Seok; Kim, Ju-Young; Park, Eun-Seok; Park, Chung-Woong

2017-11-01

The film forming gel, adhered to skin surfaces upon application and formed a film, has an advantage onto skin to provide protection and continuous drug release to the application site. This study aimed to prepare a chitosan-based film forming gel containing ketoprofen (CbFG) and to evaluate the CbFG and film from CbFG (CbFG-film). CbFG were prepared with chitosan, lactic acid and various skin permeation enhancers. The physicochemical characteristics were evaluated by texture analysis, viscometry, SEM, DSC, XRD and FT-IR. To identify the mechanism of skin permeation, in vitro skin permeation study was conducted with a Franz diffusion cell and excised SD-rat and hairless mouse dorsal skin. In vivo efficacy assessment in mono-iodoacetate (MIA)-induced rheumatoid arthritis animal model was also conducted. CbFG was successfully prepared and, after applying CbFG to the excised rat dorsal skin, the CbFG-film was also formed well. The physicochemical characteristics of CbFG and CbFG-film could be explained by the grafting of oleic acid onto chitosan in the absence of catalysts. In addition, CbFG containing oleic acid had a higher skin permeation rate in comparison with any other candidate enhancers. The in vivo efficacy study also confirmed significant anti-inflammatory and analgesic effects. Consequently, we report the successful preparation of chitosan-based film forming gel containing ketoprofen with excellent mechanical properties, skin permeation and anti-inflammatory and analgesic effects.

The effect of gamma-ray and ethylene oxide sterilization on collagen-based wound-repair materials

International Nuclear Information System (INIS)

Gorham, S.D.; Scott, R.

1993-01-01

The effects of 2.5, 5.0, 7.5 and 10 Mrad gamma-irradiation and ethylene oxide sterilization on collagen-coated vicryl mesh, on collagen film and vicryl mesh were investigated. No cytotoxic effects were observed towards either L929 cells or human fibroblasts with any of the treatments, even at the highest doses of irradiation. Although the rate of biodegradation and tissue reaction towards the test materials appeared to be relatively unaffected by ethylene oxide, the rate of breakdown in the lumbar muscles of laboratory rats was considerably increased by irradiation. Dose-dependent irradiation damage to the vicryl mesh was confirmed in vitro using viscometry and by an increase in the rate of hydrolysis in phosphate-buffered saline (PBS) at 37 o C. Tensiometric studies on irradiated collagen films showed a dose-dependent reduction in both the break load and elongation before breaking. A small reduction in the break load and stretch to breaking was also observed following treatment with ethylene oxide. The findings presented favour ethylene oxide as a method of sterilization of both the composite membrane and its individual components. However, gamma-irradiation produced no toxic effects or adverse tissue reaction under the conditions described, and is more convenient to use. Hence, provided that the efficacy of the membrane would not be compromised by the higher rate of degradation, it could also be considered for sterilization of the material. (author)

A new insight into the interaction of ZnO with calf thymus DNA through surface defects.

Science.gov (United States)

Das, Sumita; Chatterjee, Sabyasachi; Pramanik, Srikrishna; Devi, Parukuttyamma Sujatha; Kumar, Gopinatha Suresh

2018-01-01

Experimental evidences on the binding interaction of ZnO and Calf Thymus (CT) DNA using several biophysical techniques are the centre of interest of the present study. The interaction of ZnO with CT DNA has been investigated in detail by absorption spectral study, fluorescence titration, Raman analysis, zeta potential measurement, viscometric experiment along with thermal melting study and microscopic analysis. Steady-state fluorescence study revealed the quenching (48%) of the surface defect related peak intensity of ZnO on interaction with DNA. The optimized concentration of ZnO and DNA to obtain this level of quenching has been found to be 0.049mM and 1.027μM, respectively. Additional fluorescence study with 8-hydroxy-5-quinoline (HQ) as a fluorescence probe for Zn 2+ ruled out the dissolution effect of ZnO under the experimental conditions. DNA conjugation on the surface of ZnO was also supported by Raman study. The quantitative variation in conductivity as well as electrophoretic mobility indicated significant interaction of ZnO with the DNA molecule. Circular dichroism (CD) and viscometry titrations provided clear evidence in support of the conformational retention of the DNA on interaction with ZnO. The binding interaction was found to be predominantly entropy driven in nature. The bio-physical studies presented in this paper exploring ZnO-CT DNA interaction could add a new horizon to understand the interaction between metal oxide and DNA. Copyright © 2017. Published by Elsevier B.V.

Viscosity characteristics of selected volcanic rock melts

Science.gov (United States)

Hobiger, Manuel; Sonder, Ingo; Büttner, Ralf; Zimanowski, Bernd

2011-02-01

A basic experimental study of the behavior of magma rheology was carried out on remelted volcanic rocks using wide gap viscometry. The complex composition of magmatic melts leads to complicated rheologic behavior which cannot be described with one simple model. Therefore, measurement procedures which are able to quantify non-Newtonian behavior have to be employed. Furthermore, the experimental apparatus must be able to deal with inhomogeneities of magmatic melts. We measured the viscosity of a set of materials representing a broad range of volcanic processes. For the lower viscous melts (low-silica compositions), non-Newtonian behavior is observed, whereas the high-silica melts show Newtonian behavior in the measured temperature and shear rate range (T = 1423 K - 1623 K, γ˙ = 10 - 2 s - 1 - 20 s - 1 ). The non-Newtonian materials show power-law behavior. The measured viscosities η and power-law indexes m lie in the intervals 8 Pa s ≤ η ≤ 210 3 Pa s, 0.71 ≤ m ≤ 1.0 (Grímsvötn basalt), 0.9 Pa s ≤ η ≤ 350 Pa s, 0.61 ≤ m ≤ 0.93 (Hohenstoffeln olivine-melilitite), and 8 Pa s ≤ η ≤ 1.510 4 Pa s, 0.55 ≤ m ≤ 1.0 (Sommata basalt). Measured viscosities of the Newtonian high-silica melts lie in the range 10 4 Pa s ≤ η ≤ 310 5 Pa s.

Electron beam effects on gelatin polymer

International Nuclear Information System (INIS)

Inamura, Patricia Y.; Shimazaki, Kleber; Souza, Clecia de M.; Moura, Esperidiana A.B.; Mastro, Nelida L. del; Colombo, Maria A.

2009-01-01

The main field of electron-beam radiation processing applications is the modification of polymeric material. Polymer development includes new pathways to produce natural polymers with better mechanical and barrier properties and thermal stability. The aim of this paper was to investigate the behavior of a gelatin/acrylamide polymer treated by electron-beam radiation. Gelatin is a heterogeneous mixture of water-soluble proteins of high average molecular mass derived by hydrolytic action from animal collagen, a fibrous insoluble protein, which is widely found in nature as the major constituent of skin, bones and connective tissue. Hydrolyzed collagen is composed of a unique sequence of amino acids, characterized particularly by the high content of glycine, proline and hydroxyproline. Among biomaterials, gelatin is an interesting material because is a partially crystalline polymer and has a relatively low melting point. Samples of gelatin together with glycerin as plasticizer and acrylamide as copolymer were irradiated with doses of 10 kGy and 40 kGy, using an electron beam accelerator, dose rate 22.41kGy/s, at room temperature in presence of air. After irradiation, some preliminary analyses were done like viscometry, texture analyses and colorimetry. The results of the diverse tests showed changes that can be ascribed to radiation-induced crosslinking. The electron-beam processed acrylamide-gelatin polymer using glycerin as plasticizer must be first extensively characterized before to be used for general applications. (author)

Are Non-Newtonian Effects Important in Hemodynamic Simulations of Patients With Autogenous Fistula?

Science.gov (United States)

Javid Mahmoudzadeh Akherat, S. M.; Cassel, Kevin; Boghosian, Michael; Dhar, Promila; Hammes, Mary

2017-01-01

Given the current emphasis on accurate computational fluid dynamics (CFD) modeling of cardiovascular flows, which incorporates realistic blood vessel geometries and cardiac waveforms, it is necessary to revisit the conventional wisdom regarding the influences of non-Newtonian effects. In this study, patient-specific reconstructed 3D geometries, whole blood viscosity data, and venous pulses postdialysis access surgery are used as the basis for the hemodynamic simulations of renal failure patients with native fistula access. Rheological analysis of the viscometry data initially suggested that the correct choice of constitutive relations to capture the non-Newtonian behavior of blood is important because the end-stage renal disease (ESRD) patient cohort under observation experience drastic variations in hematocrit (Hct) levels and whole blood viscosity throughout the hemodialysis treatment. For this purpose, various constitutive relations have been tested and implemented in CFD practice, namely Quemada and Casson. Because of the specific interest in neointimal hyperplasia and the onset of stenosis in this study, particular attention is placed on differences in nonhomeostatic wall shear stress (WSS) as that drives the venous adaptation process that leads to venous geometric evolution over time in ESRD patients. Surprisingly, the CFD results exhibit no major differences in the flow field and general flow characteristics of a non-Newtonian simulation and a corresponding identical Newtonian counterpart. It is found that the vein's geometric features and the dialysis-induced flow rate have far greater influence on the WSS distribution within the numerical domain. PMID:28249082

Are Non-Newtonian Effects Important in Hemodynamic Simulations of Patients With Autogenous Fistula?

Science.gov (United States)

Javid Mahmoudzadeh Akherat, S M; Cassel, Kevin; Boghosian, Michael; Dhar, Promila; Hammes, Mary

2017-04-01

Given the current emphasis on accurate computational fluid dynamics (CFD) modeling of cardiovascular flows, which incorporates realistic blood vessel geometries and cardiac waveforms, it is necessary to revisit the conventional wisdom regarding the influences of non-Newtonian effects. In this study, patient-specific reconstructed 3D geometries, whole blood viscosity data, and venous pulses postdialysis access surgery are used as the basis for the hemodynamic simulations of renal failure patients with native fistula access. Rheological analysis of the viscometry data initially suggested that the correct choice of constitutive relations to capture the non-Newtonian behavior of blood is important because the end-stage renal disease (ESRD) patient cohort under observation experience drastic variations in hematocrit (Hct) levels and whole blood viscosity throughout the hemodialysis treatment. For this purpose, various constitutive relations have been tested and implemented in CFD practice, namely Quemada and Casson. Because of the specific interest in neointimal hyperplasia and the onset of stenosis in this study, particular attention is placed on differences in nonhomeostatic wall shear stress (WSS) as that drives the venous adaptation process that leads to venous geometric evolution over time in ESRD patients. Surprisingly, the CFD results exhibit no major differences in the flow field and general flow characteristics of a non-Newtonian simulation and a corresponding identical Newtonian counterpart. It is found that the vein's geometric features and the dialysis-induced flow rate have far greater influence on the WSS distribution within the numerical domain.

Synthesis and characterization of hydrophobically modified polymeric betaines

Directory of Open Access Journals (Sweden)

Alexey Shakhvorostov

2015-09-01

Full Text Available Polymeric betaines containing long alkyl chains C12H25, C14H29, C16H33 and C18H37 were synthesized by Michael addition reaction of alkylaminocrotonates and methacrylic acid (MAA. They were characterized by FTIR, 13C NMR, DSC, DLS, GPC, cryo-TEM, viscometry and zeta-potential measurements. The polymers were fully soluble in DMF, THF and DMSO, partially dissolved in aromatic hydrocarbons (benzene, toluene, o-xylene and formed colloid solutions in aqueous KOH. In aqueous KOH and DMSO solutions, hydrophobically modified polymeric betaines behaved as polyelectrolytes. The average hydrodynamic size and zeta potential of diluted aqueous solutions of hydrophobic polybetainess containing dodecyl-, tetradecyl-, hexadecyl-, and octadecyl groups were studied as a function of pH. Anomalous low values of the isoelectric point (IEP of amphoteric macromolecules were found to be in the range of pH 2.7-3.4. According to DLS data, the average size of macromolecules tends to decrease with dilution. Zeta-potential of amphoteric macromolecules in aqueous solution is much higher than that in DMSO. The cryo-TEM results revealed that in both aqueous KOH and DMSO media, the micron- and nanosized vesicles existed. The structural organization of vesicles in water and DMSO is discussed. The wax inhibition effect of hydrophobic polybetaines at a decrease of the pour point temperatures of high paraffinic oils was better in comparison with commercial available ethylene-vinylacetate copolymers (EVA.

Spherical LDH-Ag°-montmorillonite heterocoagulated system with a pH-dependent sol-gel structure for controlled accessibility of AgNPs immobilized on the clay lamellae.

Science.gov (United States)

Deák, Ágota; Janovák, László; Tallósy, Szabolcs Péter; Bitó, Tamás; Sebők, Dániel; Buzás, Norbert; Pálinkó, István; Dékány, Imre

2015-02-17

Aqueous suspensions of spherical ZnMgAl-layered double hydroxides [LDH(sph)] and antibacterial silver nanoparticles (AgNPs) deposited on the lamellae of montmorillonite were used for the synthesis of composites, which behave like coherent gels at low pH (≲4.5) and incoherent sols at higher pH (≳4.5). The composition of the composite was chosen as LDH(sph)/Ag°-montm. = 25:75 wt % in order to ensure a sol-gel transition that can also be characterized by viscometry. This pH-sensitive heterocoagulated system consisting of oppositely charged colloid particles was suitable for the release of antimicrobial AgNPs immobilized on the clay lamellae via a pH-controlled gel-sol transition. The heterocoagulation process was also characterized by surface charge titration measurements. Spherical LDH/Ag°-montmorillonite composite samples were identified by X-ray diffraction (XRD) measurements. The morphological properties of the composites were studied, and the presence of the heterocoagulated structure was confirmed by scanning electron microscopy (SEM). The nanoscale structure of the LDH(sph)-Ag°-montmorillonite composite obtained was also verified by small-angle X-ray scattering (SAXS), and the rheological characteristics were studied at various pH values. The viscosity and yield value of the composite decreased by an order of magnitude upon increasing the pH from 3.0 to 5.5. The sol-gel transition of the composite suspension was reversible in the previously mentioned pH range.

Physicochemical Characterization of Biopolymer Chitosan Extracted from Shrimp Shells

Directory of Open Access Journals (Sweden)

Nezamaddin Mengelizadeh

2015-02-01

Full Text Available Chitosan is a deacetylated derivative of chitin, which is a naturally abundant mucopolysaccharide, supporting the matter of crustaceans, insects, and fungi. Because of its unique properties, such as non-toxicity, biodegradability, and biocompatibility, chitosan has a wide range of applications in various fields. The objective of the present work is to extract the polymer chitosan from Persian Gulf shrimp shells. In order to determine the physicochemical characteristics of the extracted chitosan, degree of deacetylation, molecular weight, water and fat binding capacities extraction rate, and apparent viscosity were measured using a variety of techniques including viscometry, weight measurement method and Fourier transform infrared spectroscopy (FTIR. The results of the study of the physicochemical properties, molecular weight (6.7×105 Da, degree of deacetylation (57%, ash content as well as yield (0.5% of the prepared chitosan indicated that shrimp processing wastes (shrimp shells are a good source of chitosan. The water binding capacity (521% and fat binding capacity (327% of the prepared chitosan are in good agreement with the other studies. The elemental analysis showed the C, H and N contents of 35.92%, 7.02%, and 8.66%, respectively. In this study, the antimicrobial activity of chitosan was evaluated against Staphylococcus aureus and Escherichia coli. The results indicated the high potential of chitosan as an antibacterial agent. Moreover, the results of the study indicated that shrimp shells are a rich source of chitin as 25.21% of the shell’s dry weight.

The synthesis and characterization of 7-hydroxy-4-methylcoumarin and the investigation of the fluorescence properties of its 7-hydroxy-4-methylcoumarin-chitosan films

Science.gov (United States)

Wahyuningrum, Deana; Zulqarnaen, Muhammad; Suendo, Veinardi

2014-03-01

Chitosan fluorescent films containing 7-hydroxy-4-methylcoumarin (7H4MC) have been successfully prepared. Used chitosan was obtained from chitin isolated from skin of tiger prawns (Penaeus monodon) through the deproteination, demineralization, and deacetylation process. The yields of chitin and chitosan are 10.66% and 23.83%, respectively. The chitosan has 55.00% degree of deacetylation based on FTIR spectroscopy. Average molecular mass of chitosan which was determined by Ostwald viscometry method is 8.55 × 106 g/mol. The 7H4MC was synthesized from resorcinol and ethyl acetoacetate using amberlyst-15 as catalyst based on Pechmann reaction with chemical yields of 90.01% and the melting point of 189-190°C. The FTIR, 1H-NMR, and 13C-NMR spectroscopies confirmed the structure which corresponds to the structure of 7H4MC. The films of chitosan containing 7H4MC were prepared by solvent evaporation method in 2% (v/v) acetic acid. The 7H4MC content in each film was 0% (blank), 0.2%, 0.4%, 0.6%, and 0.8% (w/w). The UV-Vis spectrum of 7H4MC in methanol showed λmax at 235 and 337 nm. The observed fluorescence is the fluorescence color of cyan. The excitation wavelengths are 200, 235, 275, 337, and 365 nm. The highest intensity of cyan color fluorescence of chitosan containing 7H4MC films was obtained at the concentration of 0.2% of 7-hydroxy-4-methylcoumarin at the excitation wavelength of 275 nm.

Radiation effects on eye components

International Nuclear Information System (INIS)

Durchschlag, H.; Fochler, C.; Abraham, K.; Kulawik, B.

1998-01-01

The radiation damage (X-ray, UV light) of the most important components of the vertebrate eye (crystallins and other proteins, hyaluronic acid, vitreous, aqueous humour, ascorbic acid) has been investigated by various methods of physical chemistry. UV absorption and fluorescence spectroscopy as well as circular dichroism unveiled changes of the chromophores/fluorophores of the constituent biopolymers and low-molecular components, together with alterations of helix content and the occurrence of aggregation. Size-exclusion chromatography, analytical ultracentrifugation, densimetry, viscometry and light scattering experiments monitored changes of the global structure of proteins and polysaccharides involved. Electrophoreses allowed conclusions on fragmentation, unfolding and crosslinking. Analytical methods provided information regarding the integrity of groups of special concern (SH, SS) and revealed the existence of stable noxious species (H 2 O 2 ). By means of various measures and additives, manifold modifications of the impact of both ionizing and nonionizing radiation may be achieved. Caused by differences in the primary reactions, eye polymers are protected efficaciously by typical OH radical scavengers against X-irradiation, whereas compounds which exhibit absorption behavior in the UV range turn out to act as potent protectives ('chemical filters') against UV light. A few substances, such as ascorbate, are able to provide protection against both sorts of radiation and are even able to exhibit a slight chemical repair of already damaged particles. The results obtained are of importance for understanding pathological alterations of the eye (loss of transparency, cataractogenesis) and for developing new strategies for protection and repair of eye components. (author)

Investigating the evolution of the phase behavior of AOT-based w/o microemulsions in dodecane as a function of droplet volume fraction.

Science.gov (United States)

Ganguly, R; Choudhury, N

2012-04-15

AOT-based water in oil (w/o) microemulsions are one of the most extensively studied reverse micellar systems because of their rich phase behavior and their ability to form in the absence of any co-surfactant. The aggregation characteristics and interaction of the microemulsion droplets in these systems are known to be governed by AOT-oil compatibility and water to AOT molar ratio (w). In this manuscript by using Dynamic Light Scattering (DLS) and viscometry techniques, we show that droplet volume fraction too plays an important role in shaping the phase behavior of these microemulsions in dodecane. The phase separation characteristics and the evolution of the viscosity and the hydrodynamic radius of the microemulsion droplets on approaching the cloud points have thus been found to undergo complete transformation as one goes from low to high droplet volume fraction even at a fixed 'w'. Modeling of the DLS data attributes this to the weakening of inter droplet attractive interaction caused by the growing dominance of the excluded volume effect with increase in droplet volume fraction. In the literature, the inter droplet attractive interaction driven phase separation in these microemulsions is explained based on gas-liquid type phase transition, conceptualized in the framework of Baxter adhesive hard sphere theory. The modeling of our viscosity data, however, does not support such proposition as the characteristic stickiness parameter (τ(-1)) of the microemulsion droplets in this system remains much lower than the critical value (τ(c)(-1)≈10.25) required to enforce such phase transition. Copyright © 2012 Elsevier Inc. All rights reserved.

The synthesis and characterization of 7-hydroxy-4-methylcoumarin and the investigation of the fluorescence properties of its 7-hydroxy-4-methylcoumarin-chitosan films

Energy Technology Data Exchange (ETDEWEB)

Wahyuningrum, Deana, E-mail: deana@chem.itb.ac.id [Organic Chemistry Research Division, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jl. Ganesha 10, Bandung 40132 (Indonesia); Zulqarnaen, Muhammad [Chemistry Study Program, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jl. Ganesha 10, Bandung 40132 (Indonesia); Suendo, Veinardi [Inorganic and Physical Chemistry Research Division, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jl. Ganesha 10, Bandung 40132 (Indonesia)

2014-03-24

Chitosan fluorescent films containing 7-hydroxy-4-methylcoumarin (7H4MC) have been successfully prepared. Used chitosan was obtained from chitin isolated from skin of tiger prawns (Penaeus monodon) through the deproteination, demineralization, and deacetylation process. The yields of chitin and chitosan are 10.66% and 23.83%, respectively. The chitosan has 55.00% degree of deacetylation based on FTIR spectroscopy. Average molecular mass of chitosan which was determined by Ostwald viscometry method is 8.55 × 10{sup 6} g/mol. The 7H4MC was synthesized from resorcinol and ethyl acetoacetate using amberlyst-15 as catalyst based on Pechmann reaction with chemical yields of 90.01% and the melting point of 189–190°C. The FTIR, {sup 1}H–NMR, and {sup 13}C–NMR spectroscopies confirmed the structure which corresponds to the structure of 7H4MC. The films of chitosan containing 7H4MC were prepared by solvent evaporation method in 2% (v/v) acetic acid. The 7H4MC content in each film was 0% (blank), 0.2%, 0.4%, 0.6%, and 0.8% (w/w). The UV-Vis spectrum of 7H4MC in methanol showed λ{sub max} at 235 and 337 nm. The observed fluorescence is the fluorescence color of cyan. The excitation wavelengths are 200, 235, 275, 337, and 365 nm. The highest intensity of cyan color fluorescence of chitosan containing 7H4MC films was obtained at the concentration of 0.2% of 7-hydroxy-4-methylcoumarin at the excitation wavelength of 275 nm.

Viscoelastic properties of bovine orbital connective tissue and fat: constitutive models.

Science.gov (United States)

Yoo, Lawrence; Gupta, Vijay; Lee, Choongyeop; Kavehpore, Pirouz; Demer, Joseph L

2011-12-01

Reported mechanical properties of orbital connective tissue and fat have been too sparse to model strain-stress relationships underlying biomechanical interactions in strabismus. We performed rheological tests to develop a multi-mode upper convected Maxwell (UCM) model of these tissues under shear loading. From 20 fresh bovine orbits, 30 samples of connective tissue were taken from rectus pulley regions and 30 samples of fatty tissues from the posterior orbit. Additional samples were defatted to determine connective tissue weight proportion, which was verified histologically. Mechanical testing in shear employed a triborheometer to perform: strain sweeps at 0.5-2.0 Hz; shear stress relaxation with 1% strain; viscometry at 0.01-0.5 s(-1) strain rate; and shear oscillation at 1% strain. Average connective tissue weight proportion was 98% for predominantly connective tissue and 76% for fatty tissue. Connective tissue specimens reached a long-term relaxation modulus of 668 Pa after 1,500 s, while corresponding values for fatty tissue specimens were 290 Pa and 1,100 s. Shear stress magnitude for connective tissue exceeded that of fatty tissue by five-fold. Based on these data, we developed a multi-mode UCM model with variable viscosities and time constants, and a damped hyperelastic response that accurately described measured properties of both connective and fatty tissues. Model parameters differed significantly between the two tissues. Viscoelastic properties of predominantly connective orbital tissues under shear loading differ markedly from properties of orbital fat, but both are accurately reflected using UCM models. These viscoelastic models will facilitate realistic global modeling of EOM behavior in binocular alignment and strabismus.

Radiation Induced Polyvinylpyrrolidone/Polyacrylic Acid Nano-Gel Formation for Biomedical Applications

International Nuclear Information System (INIS)

AbdEl-Rehim, H.; Hegazy, E.A.; Eid, A.; Amr; Ali, A.

2010-01-01

Adopting polyvinylpyrrolidone as template macromolecules and acrylic acid (AA) as monomers, at a concentration ranged from .05 to 1.5%, pH sensitive nano-particle colloids were successfully prepared via template polymerization using gamma radiation in which polymerization of the monomer and self-assembly between the polymer and the template take place simultaneously. The self-assembly was driven by specific interactions between PVP and PAA produced in-situ, leading to PVP/PAAc nano-particles with insoluble inter-polymer complexes. Dynamic light scattering technique was used to indicate size shrinkage and surface charge increase of the PVP/PAAc nano-particles. Many factors affecting the PVP/PAAc nano-particle size such as irradiation dose rate, exposure dose, irradiation temperature and atmosphere, PVP MWt, and feed composition and concentration were investigated. It was found that the reactant feed composition and irradiation temperatures have a great influence on particle size of the prepared nanogel. The structure and morphology of the nano-particles were characterized by FT-IR, UV, viscometry and AFM methods. The structure stability of the nano-particles was studied at different pH solutions. The nano-particles exhibit excellent pH response. When pH changed from acid to base, the particles‘ volume expanded 100 times depending on the irradiation dose at which the nanogel was prepared. The prepared nanogel was loaded with flutamide anticancer drug in the presence of ethanol-water mixture solution and the amount of loaded flutamide was determined. The prepared nano scale polyvinylpyrrolidone/polyacrylic acid bio-polymeric system loaded with flutamide drug is being investigated as anticancer target drug. Also this system will be tested for the treatment of dry-eye-syndrome. (author)

Solid polymer electrolyte from phosphorylated chitosan

Energy Technology Data Exchange (ETDEWEB)

Fauzi, Iqbal, E-mail: arcana@chem.itb.ac.id; Arcana, I Made, E-mail: arcana@chem.itb.ac.id [Inorganic and Physical Chemistry Research Groups, Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jl. Ganesha 10, Bandung 40132 (Indonesia)

2014-03-24

Recently, the need of secondary battery application continues to increase. The secondary battery which using a liquid electrolyte was indicated had some weakness. A solid polymer electrolyte is an alternative electrolytes membrane which developed in order to replace the liquid electrolyte type. In the present study, the effect of phosphorylation on to polymer electrolyte membrane which synthesized from chitosan and lithium perchlorate salts was investigated. The effect of the component’s composition respectively on the properties of polymer electrolyte, was carried out by analyzed of it’s characterization such as functional groups, ion conductivity, and thermal properties. The mechanical properties i.e tensile resistance and the morphology structure of membrane surface were determined. The phosphorylation processing of polymer electrolyte membrane of chitosan and lithium perchlorate was conducted by immersing with phosphoric acid for 2 hours, and then irradiated on a microwave for 60 seconds. The degree of deacetylation of chitosan derived from shrimp shells was obtained around 75.4%. Relative molecular mass of chitosan was obtained by viscometry method is 796,792 g/mol. The ionic conductivity of chitosan membrane was increase from 6.33 × 10{sup −6} S/cm up to 6.01 × 10{sup −4} S/cm after adding by 15 % solution of lithium perchlorate. After phosphorylation, the ionic conductivity of phosphorylated lithium chitosan membrane was observed 1.37 × 10{sup −3} S/cm, while the tensile resistance of 40.2 MPa with a better thermal resistance. On the strength of electrolyte membrane properties, this polymer electrolyte membrane was suggested had one potential used for polymer electrolyte in field of lithium battery applications.

Reactive processing of textile-natural fiber reinforced anionic polyamide-6 composites

International Nuclear Information System (INIS)

Kan, Ze; Chen, Peng; Liu, Zhengying; Feng, Jianmin; Yang, Mingbo

2015-01-01

Nowadays natural fiber, used in reinforced composites, is widely concerned. However, no natural fiber reinforced reactive thermoplastic polymer grades had been prepared so far. Through our studies, it was demonstrated that there was a severe retardation and discoloration occurred in the reactive processing between anionic polyamide-6 (APA-6) and natural fiber, which result in incomplete polymerization when put together. In order to solve the problem, two methods were adopted in this paper, which are fiber pretreatment and usage of a new-style initiator called caprolactam magnesium bromide. The former is to remove sizing agent and impurities on the surface of fiber, and the latter is to weaken the side reactions between APA-6 and natural fiber by the nature of its lower reactivity and weaker alkaline. In cooperation with both methods, the severe retardation and discoloration had been improved significantly, so that the polymerization of APA-6 in natural fiber was occurred smoothly. Following textile-natural fiber reinforced APA-6 composites with an average thickness of 2.5 mm and a fiber volume content of 50% was prepared by vacuum assisted resin transfer molding (VARTM). The soxhlet extraction, dilute solution viscometry and differential scanning calorimeter (DSC) measurements respectively suggested the degree of conversion, viscosity-average molar mass and crystallization of composites was up to 94%, 11.3×104 and 50%. Remarkable improvement of mechanical properties were achieved through dynamic mechanical analysis (DMA), tensile and three-point bending test. Favorable interfacial adhesion and wettability were revealed by scanning electron microscopy (SEM) observation. Therefore, all of the above good performance make this new-style and environmentally friendly composites have broad application prospects

Reactive processing of textile-natural fiber reinforced anionic polyamide-6 composites

Science.gov (United States)

Kan, Ze; Chen, Peng; Liu, Zhengying; Feng, Jianmin; Yang, Mingbo

2015-05-01

Nowadays natural fiber, used in reinforced composites, is widely concerned. However, no natural fiber reinforced reactive thermoplastic polymer grades had been prepared so far. Through our studies, it was demonstrated that there was a severe retardation and discoloration occurred in the reactive processing between anionic polyamide-6 (APA-6) and natural fiber, which result in incomplete polymerization when put together. In order to solve the problem, two methods were adopted in this paper, which are fiber pretreatment and usage of a new-style initiator called caprolactam magnesium bromide. The former is to remove sizing agent and impurities on the surface of fiber, and the latter is to weaken the side reactions between APA-6 and natural fiber by the nature of its lower reactivity and weaker alkaline. In cooperation with both methods, the severe retardation and discoloration had been improved significantly, so that the polymerization of APA-6 in natural fiber was occurred smoothly. Following textile-natural fiber reinforced APA-6 composites with an average thickness of 2.5 mm and a fiber volume content of 50% was prepared by vacuum assisted resin transfer molding (VARTM). The soxhlet extraction, dilute solution viscometry and differential scanning calorimeter (DSC) measurements respectively suggested the degree of conversion, viscosity-average molar mass and crystallization of composites was up to 94%, 11.3×104 and 50%. Remarkable improvement of mechanical properties were achieved through dynamic mechanical analysis (DMA), tensile and three-point bending test. Favorable interfacial adhesion and wettability were revealed by scanning electron microscopy (SEM) observation. Therefore, all of the above good performance make this new-style and environmentally friendly composites have broad application prospects.

Radiation Induced Polyvinylpyrrolidone/Polyacrylic Acid Nano-Gel Formation for Biomedical Applications

Energy Technology Data Exchange (ETDEWEB)

AbdEl-Rehim, H.; Hegazy, E. A.; Eid, A.; Amr,; Ali, A., E-mail: ha_rehim@hotmail.com [National Centre for Radiation Research, Research Centre (NCRRT), Atomic Energy Authority NCRRT, P.O.Box 29, Nasr City, Cairo (Egypt)

2010-07-01

Adopting polyvinylpyrrolidone as template macromolecules and acrylic acid (AA) as monomers, at a concentration ranged from .05 to 1.5%, pH sensitive nano-particle colloids were successfully prepared via template polymerization using gamma radiation in which polymerization of the monomer and self-assembly between the polymer and the template take place simultaneously. The self-assembly was driven by specific interactions between PVP and PAA produced in-situ, leading to PVP/PAAc nano-particles with insoluble inter-polymer complexes. Dynamic light scattering technique was used to indicate size shrinkage and surface charge increase of the PVP/PAAc nano-particles. Many factors affecting the PVP/PAAc nano-particle size such as irradiation dose rate, exposure dose, irradiation temperature and atmosphere, PVP MWt, and feed composition and concentration were investigated. It was found that the reactant feed composition and irradiation temperatures have a great influence on particle size of the prepared nanogel. The structure and morphology of the nano-particles were characterized by FT-IR, UV, viscometry and AFM methods. The structure stability of the nano-particles was studied at different pH solutions. The nano-particles exhibit excellent pH response. When pH changed from acid to base, the particles‘ volume expanded 100 times depending on the irradiation dose at which the nanogel was prepared. The prepared nanogel was loaded with flutamide anticancer drug in the presence of ethanol-water mixture solution and the amount of loaded flutamide was determined. The prepared nano scale polyvinylpyrrolidone/polyacrylic acid bio-polymeric system loaded with flutamide drug is being investigated as anticancer target drug. Also this system will be tested for the treatment of dry-eye-syndrome. (author)

The molar hydrodynamic volume changes of factor VIIa due to GlycoPEGylation.

Science.gov (United States)

Plesner, Bitten; Westh, Peter; Hvidt, Søren; Nielsen, Anders D

2011-06-01

The effects of GlycoPEGylation on the molar hydrodynamic volume of recombinant human rFVIIa were investigated using rFVIIa and two GlycoPEGylated recombinant human FVIIa derivatives, a linear 10kDa PEG and a branched 40kDa PEG, respectively. Molar hydrodynamic volumes were determined by capillary viscometry and mass spectrometry. The intrinsic viscosities of rFVIIa, its two GlycoPEGylated compounds, and of linear 8kDa, 10kDa, 20kDa and branched 40kDa PEG polymers were determined. The measured intrinsic viscosity of rFVIIa is 6.0mL/g, while the intrinsic viscosities of 10kDa PEG-rFVIIa and 40kDa PEG-rFVIIa are 29.5mL/g and 79.0mL/g, respectively. The intrinsic viscosities of the linear PEG polymers are 20, 22.6 and 41.4mL/g for 8, 10, and 20kDa, respectively, and 61.1mL/g for the branched 40kDa PEG. From the results of the intrinsic viscosity and MALDI-TOF measurements it is evident, that the molar hydrodynamic volume of the conjugated protein is not just an addition of the molar hydrodynamic volume of the PEG and the protein. The molar hydrodynamic volume of the GlycoPEGylated protein is larger than the volume of its composites. These results suggest that both the linear and the branched PEG are not wrapped around the surface of rFVIIa but are chains that are significantly stretched out when attached to the protein. Copyright © 2011 Elsevier B.V. All rights reserved.

Chemical composition of Pechora Sea crude oil

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Derkach S. R.

2017-03-01

Full Text Available The physicochemical properties of the Pechora Sea shelf oil and its chemical composition have been studied using the methods of refractometry, titrimetry, viscometry, rheometry and standard methods for the analysis of oil and petroleum products. The fractionation of oil is held at atmospheric pressure, some fractions boiling at the temperature below and above 211 °C have been received. Chemical structural-group composition of oil and its components has been investigated using a Fourier infrared (IR spectroscopy method. The density of oil has been obtained, it is equal to 24.2 API. The chemical composition analysis shows that water content in the investigated oil sample is about 0.03 % (by weight. The oil sample contains hydrocarbons (including alkanes, naphthenes, arenes and asphaltenes with resins; their content is equal to 89 and 10 % (by weight respectively. Alkane content is about 66 %, including alkanes of normal structure – about 37 %. The solidification temperature of oil sample is equal to –43 °C. This low temperature testifies obliquely low content of solid alkanes (paraffin. Bearing in mind the content of asphaltenes with resins we can refer the investigated oil sample to resinous oils. On the other hand spectral coefficient values (aromaticity quotient and aliphaticity quotient show that oil sample belongs to naphthenic oils. According to the data of Fourier IR spectroscopy contents of naphthenes and arenes are 5.9 and 17.8 % respectively. Thus, the obtained data of chemical structural-group composition of crude oil and its fractions indicate that this oil belongs to the heavy resinous naphthenic oils. The rheological parameters obtained at the shear deformation conditions characterize the crude oil as a visco-plastic medium.

Size and shape of soil humic acids estimated by viscosity and molecular weight.

Science.gov (United States)

Kawahigashi, Masayuki; Sumida, Hiroaki; Yamamoto, Kazuhiko

2005-04-15

Ultrafiltration fractions of three soil humic acids were characterized by viscometry and high performance size-exclusion chromatography (HPSEC) in order to estimate shapes and hydrodynamic sizes. Intrinsic viscosities under given solute/solvent/temperature conditions were obtained by extrapolating the concentration dependence of reduced viscosities to zero concentration. Molecular mass (weight average molecular weight (M (w)) and number average molecular weight (M (n))) and hydrodynamic radius (R(H)) were determined by HPSEC using pullulan as calibrant. Values of M (w) and M (n) ranged from 15 to 118 x 10(3) and from 9 to 50 x 10(3) (g mol(-1)), respectively. Polydispersity, as indicated by M (w)/M (n), increased with increasing filter size from 1.5 to 2.4. The hydrodynamic radii (R(H)) ranged between 2.2 and 6.4 nm. For each humic acid, M (w) and [eta] were related. Mark-Houwink coefficients calculated on the basis of the M (w)-[eta] relationships suggested restricted flexible chains for two of the humic acids and a branched structure for the third humic acid. Those structures probably behave as hydrated sphere colloids in a good solvent. Hydrodynamic radii of fractions calculated from [eta] using Einstein's equation, which is applicable to hydrated sphere colloids, ranged from 2.2 to 7.1 nm. These dimensions are fit to the size of nanospaces on and between clay minerals and micropores in soil particle aggregates. On the other hand, the good agreement of R(H) values obtained by applying Einstein's equation with those directly determined by HPSEC suggests that pullulan is a suitable calibrant for estimation of molecular mass and size of humic acids by HPSEC.

In Vitro Evaluation of the Link Between Cell Activation State and Its Rheological Impact on the Microscale Flow of Neutrophil Suspensions

Science.gov (United States)

Akenhead, Michael L.; Horrall, Nolan M.; Rowe, Dylan; Sethu, Palaniappan; Shin, Hainsworth Y.

2015-01-01

Activated neutrophils have been reported to affect peripheral resistance, for example, by plugging capillaries or adhering to the microvasculature. In vivo and ex vivo data indicate that activated neutrophils circulating in the blood also influence peripheral resistance. We used viscometry and microvascular mimics for in vitro corroboration. The rheological impact of differentiated neutrophil-like HL-60 promyelocytes (dHL60s) or human neutrophil suspensions stimulated with 10 nM fMet-Leu-Phe (fMLP) was quantified using a cone-plate rheometer (450 s−1 shear rate). To evaluate their impact on microscale flow resistance, we used 10-μm Isopore® membranes to model capillaries as well as single 200 × 50 μm microchannels and networks of twenty 20 × 50 μm microfluidic channels to mimic noncapillary microvasculature. Stimulation of dHL60 and neutrophil populations significantly altered their flow behavior as evidenced by their impact on suspension viscosity. Notably, hematocrit abrogated the impact of leukocyte activation on blood cell suspension viscosity. In micropore filters, activated cell suspensions enhanced flow resistance. This effect was further enhanced by the presence of erythrocytes. The resistance of our noncapillary microvascular mimics to flow of activated neutrophil suspensions was significantly increased only with hematocrit. Notably, it was elevated to a higher extent within the micronetwork chambers compared to the single-channel chambers. Collectively, our findings provide supportive evidence that activated neutrophils passing through the microcirculation may alter hemodynamic resistance due to their altered rheology in the noncapillary microvasculature. This effect is another way neutrophil activation due to chronic inflammation may, at least in part, contribute to the elevated hemodynamic resistance associated with cardiovascular diseases (e.g., hypertension and hypercholesterolemia). PMID:26065495

Comparison of the rheological properties of ready-to-serve and powdered instant food-thickened beverages at different temperatures for dysphagic patients.

Science.gov (United States)

Adeleye, Bernice; Rachal, Corryn

2007-07-01

Dysphagia, or difficulty swallowing, affects an estimated 15 million Americans. Its management may include use of instant food thickener (IFT) to modify beverage consistency to minimize the risk of aspiration and prevent dehydration. However, inconsistencies with the desired viscosity of these thickened liquids occur both within and across product lines for both ready-to-serve commercially packaged prethickened (CPPT) and IFT-thickened beverages. To examine the rheological property differences between CPPT and similar IFT-thickened beverages, and to assess the stability of these products at two temperature ranges using three viscosity measurement techniques. The rheological properties of five CPPT and IFT-thickened beverages at both nectar- and honey-like consistencies were evaluated at 10 degrees C (50 degrees F) and 20 degrees C (68 degrees F) using the line spread, funnel, and viscometry methods. One-way analysis of variance was used for data analysis. When a significant difference was observed, Tukey's test was used to separate the means. Each viscosity measurement technique showed the CPPT nectar- and honey-like consistency beverages were significantly more viscous (Pbeverages at nectar and honey consistencies were almost always more viscous than the National Dysphagia Diet Task Force-defined standards, whereas the IFT-thickened beverages were more frequently within those standards. A reevaluation of the viscosity of CPPT beverages with reference to the National Dysphagia Diet Task Force set standard ranges needs to be considered. A strong need also exists for development of a standard protocol on product labels that includes the expected rheological properties of CPPT and IFT-thickened beverages. To the clinicians, especially registered dietitians, it is an important clinical consideration to recognize that CPPT products may be thicker than IFT-thickened products and also may be more viscous than the National Dysphagia Diet Task Force-defined standards.

In Vitro Evaluation of the Link Between Cell Activation State and Its Rheological Impact on the Microscale Flow of Neutrophil Suspensions.

Science.gov (United States)

Akenhead, Michael L; Horrall, Nolan M; Rowe, Dylan; Sethu, Palaniappan; Shin, Hainsworth Y

2015-09-01

Activated neutrophils have been reported to affect peripheral resistance, for example, by plugging capillaries or adhering to the microvasculature. In vivo and ex vivo data indicate that activated neutrophils circulating in the blood also influence peripheral resistance. We used viscometry and microvascular mimics for in vitro corroboration. The rheological impact of differentiated neutrophil-like HL-60 promyelocytes (dHL60s) or human neutrophil suspensions stimulated with 10 nM fMet-Leu-Phe (fMLP) was quantified using a cone-plate rheometer (450 s(-1) shear rate). To evaluate their impact on microscale flow resistance, we used 10-μm Isopore® membranes to model capillaries as well as single 200 × 50 μm microchannels and networks of twenty 20 × 50 μm microfluidic channels to mimic noncapillary microvasculature. Stimulation of dHL60 and neutrophil populations significantly altered their flow behavior as evidenced by their impact on suspension viscosity. Notably, hematocrit abrogated the impact of leukocyte activation on blood cell suspension viscosity. In micropore filters, activated cell suspensions enhanced flow resistance. This effect was further enhanced by the presence of erythrocytes. The resistance of our noncapillary microvascular mimics to flow of activated neutrophil suspensions was significantly increased only with hematocrit. Notably, it was elevated to a higher extent within the micronetwork chambers compared to the single-channel chambers. Collectively, our findings provide supportive evidence that activated neutrophils passing through the microcirculation may alter hemodynamic resistance due to their altered rheology in the noncapillary microvasculature. This effect is another way neutrophil activation due to chronic inflammation may, at least in part, contribute to the elevated hemodynamic resistance associated with cardiovascular diseases (e.g., hypertension and hypercholesterolemia).

Synthesis of thermoplastic poly(ester-olefin elastomers

Directory of Open Access Journals (Sweden)

Tanasijević Branka

2004-01-01

Full Text Available A series of thermoplastic poly(ester-olefin elastomers, based on poly(ethylene-stat-butylene, HO-PEB-OH, as the soft segment and poly (butylene terephthalate, PBT, as the hard segment, were synthesized by a catalyzed transesterification reaction in solution. The incorporation of soft hydrogenated poly(butadiene segments into the copolyester backbone was accomplished by the polycondensation of α, ω-dihydroxyl telechelic HO-PEB-OH, (PEB Mn = 3092 g/mol with 1,4-butanediol (BD and dimethyl terephthalate (DMT in the presence of a 50 wt-% high boiling solvent i.e., 1,2,4-trichlorobenzene. The molar ratio of the starting comonomers was selected to result in a constant hard to soft weight ratio of 60:40. The synthesis was optimized in terms of both the concentration of catalyst, tetra-n-butyl-titanate (Ti(OBu4, and stabilizer, N,N'-diphenyl-p-phenylenediamine (DPPD, as well as the reaction time. It was found that the optimal catalyst concentration (Ti(OBu4 for the synthesis of these thermoplastic elastomers was 1.0 mmol/mol ester and the optimal DPPD concentration was 1.0 wt-%. The extent of the reaction was followed by measuring the inherent viscosity of the reaction mixture. The effectiveness of the incorporation of the soft segments into the copolymer chains was proved by Soxhlet extraction with chloroform. The molecular structures, composition and the size of the synthesized poly(ester-butylenes were verified by 1H NMR spectroscopy, viscometry of dilute solutions and the complex dynamic melt viscosity. The thermal properties of poly(ester-olefins were investigated by differential scanning calorimetry (DSC. The degree of crystallinity was also determined by DSC. The thermal and thermo-oxidative stability were investigated by thermogravimetric analysis (TGA. The rheological properties of poly(ester-olefins were investigated by dynamic mechanical spectroscopy in the melt and solid state.

Structure and properties of alumino-boro-silicate glasses and melts

Science.gov (United States)

neuville, D. R.; Florian, P.; Cadars, S.; Massiot, D.

2012-12-01

The relationship between physical properties and structure of glasses and melts in the system MO-T2O3-SiO2 (with M= Na2, Ca and T= Al, B) are technologically and geologically important, in particular to understand the microscopic origin of the configurational thermodynamic properties. The connection of these network former is fundamental to understand the physical properties of magmatic liquids. The configurational properties of melts and glasses provide fundamental information needed to characterize magmatic processes. A principal difficulty, however is to link the "macroscopic" configurational entropy with the structure of melts. This has been done by combining viscometry with Raman and NMR spectroscopy studies. From the viscosity measurements at low and high temperatures, we have obtained the configurational entropy, Sconf (log η = Ae + Be/TSconf, were η is the viscosity, T the temperature and Ae, Be two constants). Silicon, aluminum, and boron are 3 network formers playing different role on the silicate network, whereas Si is the strongest network former in coordination 4, 5 or 6 as a function of T, P; Al can play different function as a network former in 4- or 5-fold coordination and probably as a network modifier in 6 fold coordination. Boron observed in 3 or 4 fold coordination is always a network former but for very "fragile" glasses. For the glass the Al/B substitution produce a small decrease of the molar volume while this substitution produced a strong decrease of viscosity and glass transition temperature while the fragility of the network is less affected by this chemical change. Raman spectra show significant change in the D1 and D2 bands. NMR spectroscopies show also significant change as a function of chemical change and temperature. All this observations will be discussed and interpreted in order to link microscopic versus macroscopic changes.

Interactions of tetracationic porphyrins with DNA and their effects on DNA cleavage

Science.gov (United States)

Lebedeva, Natalya Sh.; Yurina, Elena S.; Gubarev, Yury A.; Syrbu, Sergey A.

2018-06-01

The interaction of tetracationic porphyrins with DNA was studied using UV-Vis absorption, fluorescence spectroscopy and viscometry, and the particle sizes were determined. Аs cationic porphyrins, two isomer porphyrins, 3,3‧,3″,3‴-(5,10,15,20-Porphyrintetrayl)tetrakis(1-methylpyridinium) (TMPyP3) and 4,4‧,4″,4‴-(5,10,15,20-Porphyrintetrayl)tetrakis(1-methylpyridinium) (TMPyP4), were studied. They differ in the position of NCH3+ group in phenyl ring of the porphyrins and hence, in degree of freedom of rotation of the phenyl rings about the central macrocycle. It was found that intercalated complexes are formed at DNA/porphyrin molar ratios (R) of 2.2 and 3.9 for TMPyP3 и TMPyP4, respectively. Decreasing R up to 0.4 and 0.8 for TMPyP3 и TMPyP4, respectively, leads mainly to formation of outside complexes due to π-π stacking between the porphyrin chromophores interacting electrostatically with phosphate framework of DNA. Each type of the obtained complexes was characterized using Scatchard approach. It was ascertained that the affinity of TMPyP4 to DNA is stronger than TMPyP3, meanwhile the wedge effect of the latter is higher. The differences between the porphyrin isomers become more evident at irradiation of their complexes with DNA. It was established that irradiation of the intercalated complexes results in DNA fragmentation. In the case of TMPyP4, DNA fragments of different size are formed. The irradiation of the outside DNA/porphyrin complexes leads to cleavage of DNA (TMPyP3 and TMPyP4) and partial destruction of the complex due to photolysis of the porphyrin (TMPyP3).

FOR STIMUL-RESPONSIVE POLYMERS WITH ENHANCED EFFICIENCY IN RESERVOIR RECOVERY PROCESSES

Energy Technology Data Exchange (ETDEWEB)

Charles McCormick; Roger Hester

2004-03-26

This report contains a series of terpolymers containing acrylic acid, methacrylamide and a twin-tailed hydrophobic monomer that were synthesized using micellar polymerization methods. These polymer systems were characterized using light scattering, viscometry, and fluorescence methods. Viscosity studies indicate that increasing the nonpolar character of the hydrophobic monomer (longer chain length or twin tailed vs. single tailed) results in enhanced viscosity in aqueous solutions. The interactions of these polymers with surfactants were investigated. These surfactants include sodium dodecyl sulfate (SDS), cetyl trimethyl ammonium bromide (CTAB), Triton X-100. Viscosity measurements of DiC{sub 6}AM and DiC{sub 8}AM mixtures indicate little interaction with SDS, gelation with CTAB, and hemimicelle formation followed by polymer hydrophobe solubilization with Triton X-100. The DiC{sub 10}Am terpolymer shows similar interaction behavior with CTAB and Triton X-100. However, the enhanced hydrophobic nature of the DiC{sub 10} polymer allows complex formation with SDS as confirmed by surface tensiometry. Fluorescence measurements performed on a dansyl labeled DiC{sub 10}Am terpolymer in the presence of increasing amounts of each of the surfactant indicate relative interaction strengths to be CTAB>Triton X-100>SDS. A modified model based on Yamakawa-Fujii and Odjik-Skolnick-Fixman theories was found to describe the contribution of electrostatic forces to the excluded volume of a polyelectrolyte in solution. The model was found to be valid for flexible polymer coils in aqueous salt solutions where intermolecular interactions are minimal. The model suggested that a dimensionless group of parameters termed the dimensionless viscosity should be proportional to the dimensionless ratio of solution screening length to polyion charge spacing. Several sets of experimental data from the literature and from our laboratory have been analyzed according to the model and the results

Effects of ionizing radiation on extracellular matrix

Energy Technology Data Exchange (ETDEWEB)

Mohamed, F. [School of Physics, University of Exeter, Exeter EX44QL (United Kingdom)], E-mail: f.mohamed@ex.ac.uk; Bradley, D.A. [Department of Physics, University of Surrey, Guildford GU72XH (United Kingdom); Winlove, C.P. [School of Physics, University of Exeter, Exeter EX44QL (United Kingdom)

2007-09-21

The extracellular matrix is a ubiquitous and important component of tissues. We investigated the effects of ionizing radiation on the physical properties of its principal macromolecular components, pericardial collagen, ligament elastin and hyaluronan, a representative glycosaminoglycan. Samples were exposed to X-rays from an electron linear accelerator in the range of 10-100 Gy to cover the range of irradiation exposure during radiotherapy. A uniaxial mechanical testing protocol was used to characterize the fibrous proteins. For pericardial tissue the major change was an increase in the elastic modulus in the toe region of the curve ({<=}20% strain), from 23{+-}18 kPa for controls to 57{+-}22 kPa at a dose of 10 Gy (p=0.01, {alpha}=0.05). At larger strain ({>=}20% strain), the elastic modulus in the linear region decreased from 1.92{+-}0.70 MPa for control pericardium tissue to 1.31{+-}0.56 MPa (p=0.01, {alpha}=0.05) for 10 Gy X-irradiated sample. Similar observations have been made previously on tendon collagen at larger strains. For elastin, the stress-strain relationship was linear up to 30% strain, but the elastic modulus decreased significantly with irradiation (controls 626{+-}65 kPa, irradiated 474{+-}121 kPa (p=0.02, {alpha}=0.05), at 10 Gy X-irradiation). The results suggest that for collagen the primary effect of irradiation is generation of additional cross-links, while for elastin chain scissions are important. The viscosity of HA (at 1.25% w/v and 0.125% w/v) was measured by both cone and plate and capillary viscometry, the former providing measurement at uniform shear rate and the latter providing a more sensitive indication of changes at low viscosity. Both techniques revealed a dose-dependent reduction in viscosity (from 3400{+-}194 cP for controls to 1500{+-}88 cP at a shear rate of 2 s{sup -1} and dose of 75 Gy), again suggesting depolymerization.

Effects of ionizing radiation on extracellular matrix

International Nuclear Information System (INIS)

Mohamed, F.; Bradley, D.A.; Winlove, C.P.

2007-01-01

The extracellular matrix is a ubiquitous and important component of tissues. We investigated the effects of ionizing radiation on the physical properties of its principal macromolecular components, pericardial collagen, ligament elastin and hyaluronan, a representative glycosaminoglycan. Samples were exposed to X-rays from an electron linear accelerator in the range of 10-100 Gy to cover the range of irradiation exposure during radiotherapy. A uniaxial mechanical testing protocol was used to characterize the fibrous proteins. For pericardial tissue the major change was an increase in the elastic modulus in the toe region of the curve (≤20% strain), from 23±18 kPa for controls to 57±22 kPa at a dose of 10 Gy (p=0.01, α=0.05). At larger strain (≥20% strain), the elastic modulus in the linear region decreased from 1.92±0.70 MPa for control pericardium tissue to 1.31±0.56 MPa (p=0.01, α=0.05) for 10 Gy X-irradiated sample. Similar observations have been made previously on tendon collagen at larger strains. For elastin, the stress-strain relationship was linear up to 30% strain, but the elastic modulus decreased significantly with irradiation (controls 626±65 kPa, irradiated 474±121 kPa (p=0.02, α=0.05), at 10 Gy X-irradiation). The results suggest that for collagen the primary effect of irradiation is generation of additional cross-links, while for elastin chain scissions are important. The viscosity of HA (at 1.25% w/v and 0.125% w/v) was measured by both cone and plate and capillary viscometry, the former providing measurement at uniform shear rate and the latter providing a more sensitive indication of changes at low viscosity. Both techniques revealed a dose-dependent reduction in viscosity (from 3400±194 cP for controls to 1500±88 cP at a shear rate of 2 s -1 and dose of 75 Gy), again suggesting depolymerization

Characterizing string-of-pearls colloidal silica by multidetector hydrodynamic chromatography and comparison to multidetector size-exclusion chromatography, off-line multiangle static light scattering, and transmission electron microscopy.

Science.gov (United States)

Brewer, Amandaa K; Striegel, André M

2011-04-15

The string-of-pearls-type morphology is ubiquitous, manifesting itself variously in proteins, vesicles, bacteria, synthetic polymers, and biopolymers. Characterizing the size and shape of analytes with such morphology, however, presents a challenge, due chiefly to the ease with which the "strings" can be broken during chromatographic analysis or to the paucity of information obtained from the benchmark microscopy and off-line light scattering methods. Here, we address this challenge with multidetector hydrodynamic chromatography (HDC), which has the ability to determine, simultaneously, the size, shape, and compactness and their distributions of string-of-pearls samples. We present the quadruple-detector HDC analysis of colloidal string-of-pearls silica, employing static multiangle and quasielastic light scattering, differential viscometry, and differential refractometry as detection methods. The multidetector approach shows a sample that is broadly polydisperse in both molar mass and size, with strings ranging from two to five particles, but which also contains a high concentration of single, unattached "pearls". Synergistic combination of the various size parameters obtained from the multiplicity of detectors employed shows that the strings with higher degrees of polymerization have a shape similar to the theory-predicted shape of a Gaussian random coil chain of nonoverlapping beads, while the strings with lower degrees of polymerization have a prolate ellipsoidal shape. The HDC technique is contrasted experimentally with multidetector size-exclusion chromatography, where, even under extremely gentle conditions, the strings still degraded during analysis. Such degradation is shown to be absent in HDC, as evidenced by the fact that the molar mass and radius of gyration obtained by HDC with multiangle static light scattering detection (HDC/MALS) compare quite favorably to those determined by off-line MALS analysis under otherwise identical conditions. The

Emplacement dynamics and timescale of a Holocene flow from the Cima Volcanic Field (CA): Insights from rheology and morphology

Science.gov (United States)

Soldati, Arianna; Beem, Jordon; Gomez, Francisco; Huntley, John Warren; Robertson, Timothy; Whittington, Alan

2017-11-01

We present a rheological and morphological study of a Holocene lava flow emitted by a monogenetic cinder cone in the Cima Volcanic Field, eastern California. Our field observations focused on surface morphology, which transitions from smooth core extrusions near the vent to jagged 'a'ā blocks over the majority of the flow, and on channel and levée dimensions. We collected airborne photogrammetry data and used it to generate a digital elevation model. From this, the total flow volume was estimated and surface roughness was quantified in terms of standard deviation of the real surface (5 cm resolution) from the software-generated 1 m-average plane. Sample textural analyses revealed that the near-vent portion of the flow is significantly more crystalline (ϕxtal = 0.95 ± 0.04) than the main flow body (ϕxtal = 0.66 ± 0.11). The rheology of Cima lavas was determined experimentally by concentric cylinder viscometry between 1550 °C and 1160 °C, including the first subliquidus rheology measurements for a continental intraplate trachybasaltic lava. The experimentally determined effective viscosity increases from 54 Pa·s to 1361 Pa·s during cooling from the liquidus ( 1230 °C) to 1160 °C, where crystal fraction is 0.11. The lava viscosity over this range is still lower than most basaltic melts, due to the high alkali content of Cima lavas ( 6 wt% Na2O + K2O). Monte Carlo simulations were used to account for and propagate experimental uncertainties, and to determine which rheological model (Bingham, power law, or Herschel-Bulkley) provides the best-fit of the obtained rheological data. Results suggest that Bingham and Herschel-Bulkley models are statistically indistinguishable from each other, and that both fit the data better than a power law model. By combining field observations and experimental results, we reconstructed the eruption temperature and few days-long emplacement history of the Cima flow.

Emplacement Dynamics and Timescale of a Holocene Flow from the Cima Volcanic Field (CA): Insights from Rheology and Morphology

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Soldati, A.; Beem, J. R.; Gomez, F.; Huntley, J. W.; Robertson, T.; Whittington, A. G.

2017-12-01

We present a rheological and morphological study of a Holocene lava flow emitted by a monogenetic cinder cone in the Cima Volcanic Field, eastern California. By combining field observations and experimental results, we reconstructed the few weeks-long emplacement timeline of the Cima flow. Sample textural analyses revealed that the near-vent portion of the flow is significantly more crystalline (fxtal=0.95±0.04) than the main flow body (fxtal=0.66±0.11), which reveals a multi-stage emplacement history. Airborne photogrammetry data were used to generate a digital elevation model, which allowed us to estimate the flow volume. The rheology of Cima lavas was determined experimentally by concentric cylinder viscometry between 1550 °C and 1160 °C, including the first subliquidus rheology measurements for a continental intraplate trachybasaltic lava. The experimentally determined effective viscosity increases from 54 Pa·s to 1,361 Pa·s during cooling from the liquidus ( 1230 ˚C) to 1160 ˚C, where crystal fraction is 0.11. Flow curves fitted to measurements at different strain rates indicate a Herschel-Bulkley rheological behavior, combining shear-thinning with a yield strength negligible at the higher measured temperatures but increasing up to 357±41 Pa at 1160˚C. The lava viscosity over this range is still lower than most basaltic melts, due to the high alkali content of Cima lavas ( 6 wt% Na2O+K2O). We determined that the morphological pahoehoe to `a'ā transition of this trachybasalt occurs at a temperature of 1160±10 ˚C, similar to that observed for Hawaiian tholeiitic lavas, but at higher apparent viscosity values. Monogenetic volcanism in the Western United States is typically characterized by low effusion rates and eruption on sub-horizontal desert plains. Under these low strain-rate conditions, the pahoehoe to `a'ā transition is likely to occur abruptly upon minimal cooling, i.e. very close to the vent, but lava tubes may transport fluid lava to flow

Solution properties of targacanthin (water-soluble part of gum tragacanth exudate from Astragalus gossypinus).

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Mohammadifar, Mohammad Amin; Musavi, Seyed Mohammad; Kiumarsi, Amir; Williams, Peter A

2006-02-28

Solution properties of tragacanthin (the water-soluble part of gum tragacanth) were studied by gel permeation chromatography (GPC) combined with multi-angle light scattering and viscometry at 25 degrees C. Photon correlation spectroscopy was used to determine the hydrodynamic radius. Ultrasonic degradation was applied to obtain biopolymer fractions of different molecular weights. The dependence of intrinsic viscosity [eta] and radius of gyration (s2)z(1/2) on weight average molecular mass M(w) for this biopolymer were found to be [eta] = 9.077 x 10(-5) M(w)(0.87) (dL g(-1)) and (s2)z(1/2) in the range of M(w) from 1.8 x 10(5) to 1.6 x 10(6). The conformational parameters of tragacanthin were calculated to be 1111 nm for molar mass per unit contour length (M(L)), 26 nm for persistence length (q) and 1.87 ratio of R(g)/R(h). It was found that the Smidsrød parameter B, the empirical stiffness parameter was 0.013, which is lower than that of several polysaccharides indicating the stiff backbone for tragacanthin. The rheological behavior of aqueous solutions of gum tragacanth and its insoluble and soluble fractions (bassorin and tragacanthin, respectively) were studied. For concentrations equal to 1%, at 25 degrees C and in the absence of salt, bassorin solution showed the highest viscosity and shear thinning behaviour. Power law and Williamson models were used to describe the rheological behaviour of bassorin and tragacanthin, respectively. Oscillatory shear experiments showed a gel like structure for the bassorin but for tragacanthin the oscillatory data were as would be expected for semi-dilute to concentrated solution of entangled, random coil polymers. NaCl changed the steady and oscillatory rheological properties of both fractions and in this way the final viscosity of bassorin was even less than tragacanthin. The calculated activation energy for bassorin and tragacanthin indicated a more rapid decrease in viscosity with temperature for tragacanthin. The plot of

Electrospinning of oriented and nonoriented ultrafine fibers of biopolymers

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Vu, David

2005-07-01

Chitosan has long been known as a biocompatible and biodegradable material suitable for tissue engineering applications. Unfortunately, conventional chitosan solutions cannot be used for electrospinning due to their high conductivity, viscosity and surface tension. We have developed a method to produce clear chitosan solutions with conductivities, surface tension and viscosities that facilitate their processing into micron and submicron fibers via electrospinning. Acetic acid, carbon dioxide and organic solvents are key ingredients in preparing the chitosan solutions. Oriented and non oriented chitosan fibers were produced with the ultimate goal of designing a suitable tissue engineering scaffold. Circularly oriented, continuous, and aligned nanofibers were produced via this technique in the form of a thin membrane or fibrous "mat". Chitosan fiber diameters ranged from 5 micrometers down to 100 nanometers. The structure and mechanical properties of oriented and randomly aligned chitosan fiber deposits could potentially be exploited for cartilage tissue engineering. Ultrafine fibers of starch acetate (SA) also were prepared by the electrospinning process. In this study, solvent mixtures based on DMF, DMSO, pyrindine, acetic acid, acetone, THF, DMC, chloroform were used. A two-solvent formulation was used to study the effect of viscosity, surface tension, and conductivity to the fiber diameter. Also, water and ethanol were used to decrease the boiling point of the solvent, and to make bundled fibers. Several techniques such as scanning electron microscopy, conductmetry, viscometry, and tensiometry were used in this study. The results showed that the combined effects of viscosity, surface tension, and conductivity are of great importance in controlling the diameter of the fibers. We were able to produce SA fibers that was less than 40 nm in diameter. The dependence of fiber diameter on flow-rate, electric field and solvents also was investigated. A rotating disk and a

In situ evaluation of supersolidus liquid phase sintering phenomena of stainless steel 316L: Densification and distortion

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Bollina, Ravi

Supersolidus liquid phase sintering (SLPS) is a variant of liquid phase sintering. In SLPS, prealloyed powders are heated between the solidus and liquidus temperature of the alloy. This thesis focuses on processing of stainless steel 316L via SLPS by adding boron. Various amounts of boron were added to study the effect of boron on densification and distortion. The sintering window for water atomized 316L with 0.2% boron ranges from 1430 to 1435°C and 1225 to 1245°C for water atomized 316L with 0.8% boron. The rate of change of liquid content with temperature dVL/dt decreases from 1.5%/°C to 0.1%/°C for in increase in boron content from 0 to 0.8%, giving a wider range and better control during sintering. Further; effect of boron on mechanical properties and corrosion properties was researched. It was possible to achieve tensile strength of 476+/-21 MPa and an yield strength of 250+/-5 MPa with an elongation of 15+/-2 % in water atomized 316L with 0.8% boron. Fracture analysis indicates the presence of a brittle boride phase along the grain boundary causing intergranular fracture resulting in poor ductility. The crux of this thesis discusses the evolution of apparent viscosity and its relation to the microstructure. Beam bending viscometry was successfully used to evaluate the in situ apparent viscosity evolution of water atomized 316L with 0.2 and 0.8% boron additions. The apparent viscosity drops from 174 GPa.s at 1200°C to 4 GPa.s at 1275°C with increasing fractional liquid coverage in the water atomized 316L with 0.8% boron. The apparent viscosity calculated from bending beam and was used as an input into a finite element model (FEM) derived from constitutive equations and gives an excellent, fit between simulation and experiment. The densification behavior of boron doped stainless steel was modelled using Master Sintering Curve (MSC) (based on work of sintering) for the first time. It is proven that MSC can be used to identify change in densification rate

The Anatomy of the Blue Dragon: Changes in Lava Flow Morphology and Physical Properties Observed in an Open Channel Lava Flow as a Planetary Analogue

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Sehlke, A.; Kobs-Nawotniak, S. E.; Hughes, S. S.; Sears, D. W. G.; Downs, M.; Whittington, A. G.; Lim, D. S. S.; Heldmann, J. L.

2017-12-01

Lava terrains on other planets and moons exhibit morphologies similar to those found on Earth, such as smooth pāhoehoe transitioning to rough `a`ā terrains based on the viscosity - strain rate relationship of the lava. Therefore, the morphology of lava flows is governed by eruptive conditions such as effusion rate, underlying slope, and the fundamental thermo-physical properties of the lava, including temperature (T), composition (X), viscosity (η), fraction of crystals (φc) and vesicles (φb), as well as bulk density (ρ). These textural and rheological changes were previously studied for Hawaiian lava, where the lava flow started as channelized pāhoehoe and transitioned into `a`ā, demonstrating a systematic trend in T, X, η, φc, φb, and ρ. NASA's FINESSE focuses on Science and Exploration through analogue research. One of the field sites is Craters of the Moon, Idaho. We present field work done at a 3.0 km long lava flow belonging to the Blue Dragon lavas erupted from a chain of spatter cones, which then coalesced into channelized flows. We acquired UAV imagery along the entire length of the flow, and generated a high resolution DTM of 5 cm/pixel, from which we derived height profiles and surface roughness values. Field work included mapping the change in surface morphology and sample collection every 150 meters. In the laboratory, we measured φc, φb, and ρ for all collected samples. Viscosity measurements were carried out by concentric cylinder viscometry at subliquidus temperatures between 1310ºC to 1160ºC to study the rheology of the lava, enabling us to relate changes in flow behavior to T and φc. Our results are consistent with observations made for Hawaiian lava, including increasing bulk density downflow, and porosity changing from connected to isolated pore space. Crystallinity increases downflow, and the transition from pāhoehoe to `a`ā occurs between 1230ºC to 1150ºC, which is prompted by nucleation and growth of plagioclase

Deformabilidade eritrocitária na anemia ferropriva Erythrocyte deformability in iron deficiency

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Giuseppina M. Patavino

2006-12-01

Full Text Available A deformabilidade é a característica que permite ao eritrócito normal de 7 a 8 micrômetros (µm circular por capilares de até 3 µm de diâmetro. Esse fenômeno depende da geometria celular, da viscosidade interna e de propriedades visco-elásticas da membrana eritrocitária. Dentre as técnicas de estudo da deformabilidade eritrocitária (DE, como aspiração por micropipeta, filtração e reoscopia, destaca-se a ectacitometria. Esta técnica utiliza um viscosímetro de fluxo laminar no qual as modificações de forma dos eritrócitos são monitoradas continuamente por um feixe de raio laser, processadas por microcomputador, gerando o "Índice de Deformabilidade" (ID, que mede a eliptocitogênese dos eritrócitos quando submetidos a uma força denominada "shear stressl". Alterações de DE foram descritas em diversas situações, como em anemias hemolíticas hereditárias ou auto-imunes. Na anemia ferropriva, os trabalhos são controversos. O presente estudo avalia a DE em 21 pacientes portadores de anemia ferropriva, utilizando a ectacitometria. Os resultados obtidos a partir do ID demonstram DE diminuída nesses doentes, quando comparada ao grupo controle (pDeformability allows the 7 to 8 µm red cell to cirDeformability allows the 7- to 8-µm red blood cells to circulate through capillaries of 3 µm. This phenomenon depends on cellular geometry, internal viscosity and viscoelastic properties of the membrane. Among the various techniques of erythrocyte deformability analysis, such as micropipette aspiration, filtration and reoscopy, we chose ektacytometry. This technique uses a laminar flow viscometry, where red blood cell shape changes are continuously monitored by laser, processed by a computer, generating the "Deformability Index", which shows the elliptocytogenesis of the erythrocyte under "shear stressl" force. Erythrocyte deformability has been described in a number of situations like hereditary or autoimmune hemolytic anemia. In

Monitorando a degradação da poliamida 11 (PA-11 via espectroscopia na região do infravermelho médio com transformada de fourier (FTIR Monitoring the degradation of polyamide 11 (PA-11 via fourier transform infrared spectroscopy (FTIR

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Eloilson Domingos

2012-01-01

Full Text Available O potencial da técnica de espectroscopia de infravermelho com transformada de Fourier e acessório de reflexão total atenuada (FTIR-ATR foi avaliado para o monitoramento da degradação da poliamida 11 (PA-11 usada em dutos flexíveis. As amostras foram submetidas a envelhecimento em reatores com pressão controlada e atmosfera inerte. Os corpos de prova foram imersos em água deionizada (pH 7, nas temperaturas de 110, 120 e 140 ºC por um período de até 50 dias. A técnica recomendada para monitoramento da degradação da PA-11 é a viscosimetria, através de medidas da viscosidade inerente corrigida (VIC e a análise termogravimétrica (TGA. O comportamento observado para a VIC e TGA durante o envelhecimento possibilitou a construção de modelos que correlacionam com a técnica de FTIR-ATR. A partir dos resultados de FTIR-ATR, a variação na intensidade da banda atribuída à fase amorfa, 1161 cm-1, possibilitou o monitoramento do envelhecimento quando associamos a técnica a modelos quimiométricos como o de regressão dos mínimos quadrados parciais, PLS. Portanto, a técnica FTIR-ATR pode ser uma nova alternativa no monitoramento da degradação hidrolítica da PA-11, eliminando assim o uso de solventes orgânicos tóxicos e reduzindo, consequentemente, o tempo de análise.The potential of the infrared spectroscopy with the attenuated total reflection technique (FTIR-ATR was evaluated to monitor degradation of polyamide 11, PA-11, applied in flexible pipes. The samples were subjected to aging on reactors with controlled pressure and atmosphere. The samples were immersed in deionized water, pH 7, at temperatures of 110, 120 and 140 ºC over a period of up to 50 days. The typical technique recommended for monitoring PA-11 degradation is viscometry from inherent viscosity corrected (VIC and thermogravimetric (TGA measurements. TGA and VIC results allowed the use of chemometric models that can be related to FTIR-ATR spectra, with

Monitorando a degradação da poliamida 11 (PA-11 via espectroscopia na região do infravermelho médio com transformada de fourier (FTIR Monitoring the degradation of polyamide 11 (PA-11 via fourier transform infrared spectroscopy (FTIR

Directory of Open Access Journals (Sweden)

Eloilson Domingos

2013-01-01

Full Text Available O potencial da técnica de espectroscopia de infravermelho com transformada de Fourier e acessório de reflexão total atenuada (FTIR-ATR foi avaliado para o monitoramento da degradação da poliamida 11 (PA-11 usada em dutos flexíveis. As amostras foram submetidas a envelhecimento em reatores com pressão controlada e atmosfera inerte. Os corpos de prova foram imersos em água deionizada (pH 7, nas temperaturas de 110, 120 e 140 ºC por um período de até 50 dias. A técnica recomendada para monitoramento da degradação da PA-11 é a viscosimetria, através de medidas da viscosidade inerente corrigida (VIC e a análise termogravimétrica (TGA. O comportamento observado para a VIC e TGA durante o envelhecimento possibilitou a construção de modelos que correlacionam com a técnica de FTIR-ATR. A partir dos resultados de FTIR-ATR, a variação na intensidade da banda atribuída à fase amorfa, 1161 cm-1, possibilitou o monitoramento do envelhecimento quando associamos a técnica a modelos quimiométricos como o de regressão dos mínimos quadrados parciais, PLS. Portanto, a técnica FTIR-ATR pode ser uma nova alternativa no monitoramento da degradação hidrolítica da PA-11, eliminando assim o uso de solventes orgânicos tóxicos e reduzindo, consequentemente, o tempo de análise.The potential of the infrared spectroscopy with the attenuated total reflection technique (FTIR-ATR was evaluated to monitor degradation of polyamide 11, PA-11, applied in flexible pipes. The samples were subjected to aging on reactors with controlled pressure and atmosphere. The samples were immersed in deionized water, pH 7, at temperatures of 110, 120 and 140 ºC over a period of up to 50 days. The typical technique recommended for monitoring PA-11 degradation is viscometry from inherent viscosity corrected (VIC and thermogravimetric (TGA measurements. TGA and VIC results allowed the use of chemometric models that can be related to FTIR-ATR spectra, with

Efeito de Aditivos na Desacetilação de Quitina Effects from Additives on Deacetylation of Chitin

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Sérgio P. Campana Fº

2001-01-01

Full Text Available Reações de desacetilação de quitina comercial em suspensão aquosa de hidróxido de sódio foram realizadas em etapa única de 6 horas a 115°C. Os efeitos de aditivos (boro hidreto de sódio ou antraquinona e de borbulhamento de gases inertes (nitrogênio ou argônio sobre as características das amostras desacetiladas foram avaliados. A espectroscopia de ressonância magnética nuclear de hidrogênio e viscosimetria capilar foram empregadas para determinações de graus médios de acetilação e de viscosidades intrínsecas de quitosanas, respectivamente. A difração de raiosX foi empregada para comparar as amostras quanto à cristalinidade e os espectros no infravermelho foram comparados para avaliar modificações estruturais decorrentes da reação de desacetilação. As quitosanas mais cristalinas foram obtidas quando um dos gases inertes foi borbulhado no meio durante a reação de desacetilação. Amostras ligeiramente mais desacetiladas foram obtidas na ausência de qualquer aditivo, mas severa despolimerização ocorreu nesses casos. A adição de boro hidreto de sódio ao meio reacional reduziu significativamente a despolimerização, mas a presença de antraquinona e o borbulhamento de nitrogênio, ou de argônio, não surtiu qualquer efeito, sugerindo que a presença de oxigênio não é um pré-requisito para a ocorrência de despolimerização.Deacetylation reactions of commercial chitin were carried out in aqueous sodium hydroxide solution at 115°C for 6 hours. The effect from additives (sodium borohydride or anthraquinone and of bubbling inert gas (nitrogen or argon on the characteristics of deacetylated samples were evaluated. Average degrees of acetylation and intrinsic viscosity were determined by ¹H NMR spectroscopy and capillary viscometry, respectively. X-ray diffraction was employed to evaluate changes in crystallinity and infrared spectroscopy was used to monitor structural changes due to deacetylation. The

Effect of molecular weight on radiation chemical degradation yield of chain scission of γ-irradiated chitosan in solid state and in aqueous solution

International Nuclear Information System (INIS)

Tahtat, Djamel; Mahlous, Mohamed; Benamer, Samah; Nacer Khodja, Assia; Larbi Youcef, Souad

2012-01-01

Chitosan A 1 , A 2 and A 3 with molecular weight of 471, 207 and 100 kDa respectively, produced from squid pen chitin was degraded by gamma rays in the solid state and in aqueous solution with various doses in air at ambient temperature. Effect of molecular weight on radiation chemical degradation yield of chain scission and degradation rate constants of γ-irradiated chitosan in solid state and in aqueous solution was investigated. The radiation chemical degradation yield G (s) and degradation rate values were calculated. The molecular weight changes were monitored by capillary viscometry method and the chemical structure changes were followed by UV analysis. The results showed that, the degradation of chitosan was faster in solution, than in solid state. The values of G (s) in solid state and in aqueous solution were respectively 1.1×10 −8 mol/J and 0.074×10 −7 mol/J for A 1 , 4.42×10 −8 mol/J and 0.28×10 −7 mol/J for A 2 and 6.08×10 −8 mol/J and 0.38×10 −7 mol/J for A 3 . Degradation rate constants values ranged from 0.41×10 −5 to 2.1×10 −5 kGy −1 in solid state, whereas in solution they ranged from 13×10 −5 to 68×10 −5 kGy −1 . The chitosan A 3 was more sensitive to radiolysis than A 1 and A 2 . The chain scission yield, G (s) and degradation rate constants seems to be greatly influenced by the initial molecular weight of the chitosan. Structural changes in irradiated chitosan are revealed by the apparition of absorption peaks at 261 and 295 nm, which could be attributed to the formation of carbonyl groups. In both conditions the peak intensity was higher in chitosan A 3 than in A 1 and A 2 , the oxidative products decreased with increasing molecular weight of chitosan. - Highlights: ► We investigated the effects of MW on G (s) value of γ-irradiated chitosan in solid and aqueous state. ► Chitosan with low molecular weight was more sensitive to radiolysis than high molecular weight. ► G (s) value and degradation rate

Adsorption of recombinant human granulocyte colony stimulating factor (rhG-CSF) to polyvinyl chloride, polypropylene, and glass: effect of solvent additives.

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Johnston, T P

1996-01-01

The adsorption of recombinant-derived proteins to glass and polymeric materials used in their packaging and delivery remains a problem. Loss of these very expensive proteins to surface adsorption not only results in reduced yields during purification and scale-up, but also to decreased therapeutic efficacy. The purpose of the present investigation was to inhibit/minimize adsorption of a model protein, namely, recombinant human granulocyte colony stimulating factor (rhG-CSF) to glass, polyvinyl chloride (PVC), and polypropylene by inclusion of select solvent additives. Solvent additives used to inhibit/minimize surface adsorption included glycerin, U.S.P. (0.5%, 1%, 5%, and 25% v/v), Pluronic F-127 (0.005%, 0.05%, and 0.5% w/w), Pluronic F-68 (0.005%, 0.05%, and 0.5% w/w), Tween 80 (0.005% and 0.05% w/w) and Tween 20 (0.005%, 0.05%, and 0.5% w/w). Over the rhG-CSF concentration range of 0.0 ng/ml to 300 ng/ml, the amount of rhG-CSF bound per cm2 of PVC increased with an increase in the rhG-CSF concentration tested. At rhG-CSF equilibrium concentrations of 262 +/- 3.7 ng/ml and 136 +/- 1.9 ng/ml, the rhG-CSF bound/cm2 of PVC at 22 degrees C and 45 degrees C reached a maximum of 37.6 +/- 9.8 ng/cm2 and 165.2 +/- 11.7 ng/cm2, respectively. The adsorption isotherms determined at each temperature were described by the classic Freundlich equation. Moreover, the rate of adsorption of rhG-CSF to PVC was extremely rapid. The mean values of the percent of rhG-CSF bound to PVC after only 10 minutes of equilibration at 22 degrees C and 45 degrees C were 92.8 +/- 9.2 percent and 97.3 +/- 17.9 percent, respectively. The mean values of the percent of rhG-CSF bound to PVC at 22 degrees C and 45 degrees C after 24 hours were 52.4 +/- 10.9% and 70.0 +/- 9.7%, respectively, indicating that some desorption of rhG-CSF does occur during 24 hr. However, surface adsorption of rhG-CSF to PVC was shown to be irreversible over a 1 hr time period. Using viscometry, an estimate of the thickness

THE RHEOLOGY OF THE BLOOD. V.

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Bingham, E C

1945-07-20

A study has been made of those proteins which might offer exceptions to the law that the fluidity of a protein solution is a linear function of the volume concentration; viz., egg albumin, serum albumin, pseudoglobulin, euglobulin, gelatin, and sodium caseinogenate. Solutions of egg albumin below 20 per cent by weight obey the above law but somewhat below 30 per cent the fluidities begin to be too high, presumably due to the contribution to the fluidity made by the deformation of the particles as they come into contact, as the fluidity approaches zero. The fluidity of serum albumin solutions shows a similar behavior, being exceptional above 15 per cent in weight. Pseudoglobulin and euglobulin give fluidity-concentration curves (Fig. 4) which are linear up to about 2.5 per cent each in a total range of 20 and 14 per cent respectively. From this singular point both compounds show a second range which is linear. Pseudoglobulin is the only substance whose solutions seem to show a third linear range. We have also used the data of Chick and Martin for sodium caseinogenate and found evidence for two linear régimes. It is desirable at this time to call attention to the measurements of the flow of glycogen solutions by Botazzi and d'Errico (14) which in Fluidity and See PDF for Structure plasticity, page 207, are expressed in rhes. The data show two linear fluidity curves of different slopes. In this case it was definitely known that the data for each curve were measured with different viscometers which suggested the possibility of an error in viscometry entering in to confuse the issue. We have no suspicions as to the reliability of the data studied in this paper; we only wish to caution the readers that our hypotheses based on these data must be regarded with due reserve until confirmed. We have found a formula (11) based on the supposed linear relation between logarithmic fluidities and concentration which is convenient to use within the range, but close examination

Effect of the Net Charge Distribution on the Aqueous Solution Properties of Polyampholytes Effet de la répartition de la charge nette sur les propriétés des solutions aqueuses de polyampholytes

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Candau F.

2006-12-01

Full Text Available The zwitterion nature of ampholytic polymers provides features that are useful in environmental and industrial applications, e. g. ion-exchange membrane, as flocculants in sewage treatment and in oil recovery processes. In the latter case, the increase in viscosity which is observed in the presence of brine (anti -polyelectrolyte behavior make them ideal candidates for high salinity media. The aqueous solution properties of a series of ampholytic terpolymers based on sodium-2-acrylamido-2- rilethylpropanesulfonate (NaAMPS, Methacryloyloxyethyltrimethylammonium chloride (MADQUAT and acrylamide (AM, prepared in inverse micro emulsions have been investigated by viscometry and light scattering experiments. The distribution of the net charge among the chains was varied by adjusting the initial monomer composition and the degree of conversion. The effect of this distribution on the solubility of the samples and on the chain conformation was studied. It was found that samples with a narrow distribution of net charges were soluble in water even if the average net charge is small. Addition of salt produces a transition from an extended conformation to a more compact one in qualitative agreement with theoretical predictions. A practically alternated NaAMPS- MADQUAT copolymer prepared in homogeneous solution and with a small average net charge shows a behaviour quite similar to that of the terpolymers. La nature zwitterioniquedes polymères ampholytes présente des caractéristiques qui sont utiles dans les applications environnementales et industrielles, comme les membranes d'échange ionique, les floculants dans le traitement des eaux usées et dans les procédés de récupération de pétrole. Dans ce dernier cas, l'augmentation de viscosité qui est observée en présence de saumure (comportement antipolyélectrolyte en fait des candidats idéaux pour des milieux de salinité élevée. Les propriétés de la solution aqueuse d'une série de terpolym

Influência da técnica de pressão expiratória positiva oscilante utilizando pressões expiratórias pré-determinadas na viscosidade e na transportabilidade do escarro em pacientes com bronquiectasia Influence that oscillating positive expiratory pressure using predetermined expiratory pressures has on the viscosity and transportability of sputum in patients with bronchiectasis

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Ercy Mara Cipulo Ramos

2009-12-01

(P15 and 25 cmH2O (P25. The protocol consisted of a voluntary cough; another voluntary cough 20 min later, designated time zero (T0; a 10-min rest period; and two 10-min series (S1 and S2, using OPEP at P15 and P25 in both, with a 10-min interval between the two. The viscosity and transportability of sputum were evaluated by viscometry, relative transport velocity on frog palate, transport in a simulated cough machine and contact angle. Sputum samples were collected at T0, after S1 and after S2. Specific statistical tests were performed depending on the type of data distribution. RESULTS: In comparison with the values obtained at T0, sputum viscosity decreased significantly after S1 at P15 and after S2 at P25. There were no significant differences among all of the samples in terms of transportability. CONCLUSIONS: The fact that sputum viscosity decreased whether OPEP was performed at P15 or at P25 suggests that there is no need to generate high expiratory pressure to achieve the desired result.

Fabrication de structures tridimensionnelles de nanocomposites polymeres charges de nanotubes de carbone a simple paroi

Science.gov (United States)

Laberge Lebel, Louis

-covalent functionalization of the nanotubes by zinc protoporphyrin IX molecule and high shear mixing using a three-roll mill. The incorporation of the C-SWNTs into the resin led to an increase of the viscosity and the apparition of a shear thinning behaviour, characterized by capillary viscometry. The nanocomposite UV-curing behavior is characterized under differential scanning calorimetry coupled with a UV source. A further adjustment of the shear thinning behavior using fumed silica enabled the UV-DW fabrication of microbeams. Mechanical characterization reveals significant increase in both strength (by ˜64%) and modulus (by more than 15 times). These mechanical enhancements are attributed to both the covalent and the non-covalent functionalizations of the C-SWNTs. Nanocomposite spring networks composed of three micro-coils fabricated using the UV-DW technique are mechanically tested under compression and show a rigidity of ˜11.5 mN/mm. A micro-coil is also deposited between two uneven electrodes and a 10-6 S/cm electrical conductivity is measured. Nanocomposite scaffold structures are also deposited using the UV-DW technique. This thesis also reports the fabrication of 3D micro structured beams reinforced with the C-SWNT/polymer nanocomposite by using an approach based on the infiltration of 3D microfluidic networks. The 3D microfluidic network is first fabricated by the direct-write assembly method, which consists of the robotized deposition of fugitive ink filaments on an epoxy substrate, forming a 3D micro structured scaffold. After encapsulating the 3D micro-scaffold structure with an epoxy resin, the fugitive ink is liquefied and removed, resulting in a 3D network of interconnected microchannels. This microfluidic network is then infiltrated by the C-SWNT/polyurethane nanocomposite and subsequently cured. The final samples consist of rectangular beams having a complex 3D-skeleton structure of C-SWNT/polyrner nanocomposite fibers, adapted to offer better performance under flexural

Bulk and interfacial molecular structure near liquid-liquid critical points

Energy Technology Data Exchange (ETDEWEB)

Manzanares-Papayanopoulos, Emilio

2000-09-01

behaviour, and aqueous surfactant solutions.The classical techniques have included capillary viscometry yielding the shear viscosities. The modern techniques have fallen into two groups. The first, aimed at investigating adsorption and wetting layers at vapour-liquid and liquid-solid interfaces, comprise determinations of neutron reflection. In the second, fluorescence depolarization decay and muon spin relaxation rates have been directed towards a better understanding of the rotational behaviour in liquids of a large probe molecule BTBP, with the ultimate goal of exploring the nano rheology of near-critical systems. These modern measurements were made in Large Scale Central Laboratories at different centers in Europe, for example, the Rutherford Appleton Laboratory (RAL) and Daresbury Laboratory (DL) in England, the Institut Laue-Langevin (ILL) in France, and the Hahn-Meitner Institut (HMI) in Germany. The results of this kind of studies can be applied to interfacial problems across a wide range of industries such as the petroleum, paints, surfactants and refrigerants among others. [Spanish] Un comportamiento critico ocurre cuando dos fases coexistentes fusionan su identidad sin un cambio abrupto de las propiedades fisicas. El detalle de este comportamiento es considerado actualmente universal, siendo dominado por divergencia de la longitud de la correlacion {xi}. Siguiendo esta universalidad, el comportamiento detallado puede estudiarse experimentalmente usando cualquier sistema conveniente. Por esa razon, el estudio de fluidos y en particular de mezclas de fluidos ofrece una util plataforma puesto que el comportamiento critico en tales sistemas a menudo puede ser estudiado a temperaturas y presiones convenientes. A pesar de que la criticidad es una consecuencia de la divergencia de {xi}, y de esta manera, en cierto sentido, es un fenomeno a gran escala, a pesar de todo tiene influencia sobre los eventos a nivel molecular. A este aspecto de criticidad se le ha dedicado