Encapsulation of nanoclusters in dried gel materials via an inverse micelle/sol gel synthesis

DOEpatents

Martino, Anthony; Yamanaka, Stacey A.; Kawola, Jeffrey S.; Showalter, Steven K.; Loy, Douglas A.

1998-01-01

A dried gel material sterically entrapping nanoclusters of a catalytically active material and a process to make the material via an inverse micelle/sol-gel synthesis. A surfactant is mixed with an apolar solvent to form an inverse micelle solution. A salt of a catalytically active material, such as gold chloride, is added along with a silica gel precursor to the solution to form a mixture. To the mixture are then added a reducing agent for the purpose of reducing the gold in the gold chloride to atomic gold to form the nanoclusters and a condensing agent to form the gel which sterically entraps the nanoclusters. The nanoclusters are normally in the average size range of from 5-10 nm in diameter with a monodisperse size distribution.

Low temperature fuel behavior studies

NASA Technical Reports Server (NTRS)

Stockemer, F. J.

1980-01-01

Aircraft fuels at low temperatures near the freezing point. The principal objective was an improved understanding of the flowability and pumpability of the fuels in a facility that simulated the heat transfer and temperature profiles encountered during flight in the long range commercial wing tanks.

Kinetic resolution of racemic mixtures in gel media

NASA Astrophysics Data System (ADS)

Petrova, Rositza Iordanova

The goal of this research was to investigate the effect of chiral gels on the chiral crystal nucleation and growth and assess the gels' potential as media for kinetic separation of racemic mixtures. The morphologies of asparagine monohydrate and sodium bromate crystals grown in different gel media were examined in order to discern the effect of gel structure and density on the relative growth rates of those materials. Different crystal habits were observed when the gel chemical composition, density and solute concentration were varied. These studies showed that the physical properties of the gel, such as gel density and pore size, as well as its chemical composition affect the crystal habit. The method of kinetic resolution in gel media was first applied to sodium chlorate, which is achiral in solution but crystallizes in a chiral space group. Crystallization in agarose gels yielded an enantiomorphic bias, the direction and magnitude of which could be affected by changing the temperature or by the addition of an achiral cosolvent. Aqueous gels at 6°C produced crystalline mixtures enriched with the d-enantiomorph, while crystallization under MeOH diffusion favored l-crystals. Optimized conditions yielded e.e. of 53% of l-enantiomorph. The method was next applied to the organic molecular crystals of asparagine monohydrate and threonine. Asparagine monohydrate growth in aqueous agarose and iota-carrageenan gels produced crystal mixtures enriched with D-enantiomer. The degree of resolution was higher when the total amount of asparagine crystallized was low. The success of the resolution depends strongly on the concentrations of solute and the geling substance. Growth from agarose gels yielded e.e. of 44% under optimized conditions. The same method was applied to the resolution of Thr, albeit with modest success. In an effort to improve the resolution of asparagine monohydrate, agarose was synthetically modified by esterifying its side chains with homochiral asparagyl groups and used as a kinetic resolution media. The crystallization from L-Asn-agarose favored crystallization of L-enantiomer (28% e.e.), while D-Asn-agarose favored D-enantiomer (40% e.e.). The degree of resolution was sensitive to the concentrations of the gel and the total amount of crystallized asparagine, but the media was no better than that in pure agarose.

Encapsulation of nanoclusters in dried gel materials via an inverse micelle/sol gel synthesis

DOEpatents

Martino, A.; Yamanaka, S.A.; Kawola, J.S.; Showalter, S.K.; Loy, D.A.

1998-09-29

A dried gel material sterically entrapping nanoclusters of a catalytically active material and a process to make the material via an inverse micelle/sol-gel synthesis are disclosed. A surfactant is mixed with an apolar solvent to form an inverse micelle solution. A salt of a catalytically active material, such as gold chloride, is added along with a silica gel precursor to the solution to form a mixture. To the mixture are then added a reducing agent for the purpose of reducing the gold in the gold chloride to atomic gold to form the nanoclusters and a condensing agent to form the gel which sterically entraps the nanoclusters. The nanoclusters are normally in the average size range of from 5--10 nm in diameter with a monodisperse size distribution. 1 fig.

Ceramic composite coating

DOEpatents

Wicks, George G.

1997-01-01

A thin, room-temperature-curing, ceramic composite for coating and patching etal substrates comprises a sol gel silica glass matrix filled with finely ground particles or fibers, preferably alumina. The sol gel glass is made by adding ethanol to water to form a first mixture, then separately adding ethanol to tetraethyl orthosilicate to form a second mixture, then slowly adding the first to the second mixture to make a third mixture, and making a slurry by adding the finely ground particles or fibers to the third mixture. The composite can be applied by spraying, brushing or trowelling. If applied to patch fine cracks, densification of the ceramic composite may be obtained to enhance sealing by applying heat during curing.

Ceramic composite coating

DOEpatents

Wicks, G.G.

1997-01-21

A thin, room-temperature-curing, ceramic composite for coating and patching metal substrates comprises a sol gel silica glass matrix filled with finely ground particles or fibers, preferably alumina. The sol gel glass is made by adding ethanol to water to form a first mixture, then separately adding ethanol to tetraethyl orthosilicate to form a second mixture, then slowly adding the first to the second mixture to make a third mixture, and making a slurry by adding the finely ground particles or fibers to the third mixture. The composite can be applied by spraying, brushing or trowelling. If applied to patch fine cracks, densification of the ceramic composite may be obtained to enhance sealing by applying heat during curing.

33 CFR 155.1020 - Definitions.

Code of Federal Regulations, 2014 CFR

2014-07-01

... the outer boundary of the nearshore area. Oil field waste means non-pumpable drilling fluids with... OIL OR HAZARDOUS MATERIAL POLLUTION PREVENTION REGULATIONS FOR VESSELS Tank Vessel Response Plans for Oil § 155.1020 Definitions. Except as otherwise defined in this section, the definitions in § 155.110...

(Ultra) High Pressure Homogenization for Continuous High Pressure Sterilization of Pumpable Foods – A Review

PubMed Central

Georget, Erika; Miller, Brittany; Callanan, Michael; Heinz, Volker; Mathys, Alexander

2014-01-01

Bacterial spores have a strong resistance to both chemical and physical hurdles and create a risk for the food industry, which has been tackled by applying high thermal intensity treatments to sterilize food. These strong thermal treatments lead to a reduction of the organoleptic and nutritional properties of food and alternatives are actively searched for. Innovative hurdles offer an alternative to inactivate bacterial spores. In particular, recent technological developments have enabled a new generation of high pressure homogenizer working at pressures up to 400 MPa and thus, opening new opportunities for high pressure sterilization of foods. In this short review, we summarize the work conducted on (ultra) high pressure homogenization (U)HPH to inactivate endospores in model and food systems. Specific attention is given to process parameters (pressure, inlet, and valve temperatures). This review gathers the current state of the art and underlines the potential of UHPH sterilization of pumpable foods while highlighting the needs for future work. PMID:25988118

Pectin extraction from lemon by-product with acidified date juice: rheological properties and microstructure of pure and mixed pectin gels.

PubMed

Masmoudi, M; Besbes, S; Ben Thabet, I; Blecker, C; Attia, H

2010-04-01

The microstructure and the rheological properties of lemon-pectin mixtures were studied and compared to those of pure lemon (high methoxyl: HM) and date (low methoxyl: LM) pectins. Rheological properties were carried out in the presence of 30%, 45% and 60% sucrose, and increasing calcium concentrations (0-0.1%). The presence of date with lemon pectin led to a gel formation at 45% sucrose and in the presence of calcium, which was not the case for lemon pectin alone under the same conditions. It is suggested that lemon and date pectins interacted, leading to gel formations at different gelling temperatures, which were strongly dependent on degree of methylation. These results were confirmed by scanning electron microscopy, which revealed inhomogeneous gels where dense aggregated network and loose, open network areas were present. Addition of calcium to pectin mixture gels led to stronger and faster gel formation.

Methods for synthesizing microporous crystals and microporous crystal membranes

DOEpatents

Dutta, Prabir; Severance, Michael; Sun, Chenhu

2017-02-07

A method of making a microporous crystal material, comprising: a. forming a mixture comprising NaOH, water, and one or more of an aluminum source, a silicon source, and a phosphate source, whereupon the mixture forms a gel; b. heating the gel for a first time period, whereupon a first volume of water is removed from the gel and micoroporous crystal nuclei form, the nuclei having a framework; and c.(if a membrane is to be formed) applying the gel to a solid support seeded with microporous crystals having a framework that is the same as the framework of the nuclei; d. heating the gel for a second time period. during which a second volume of water is added to the gel; wherein the rate of addition of the second volume of water is between about 0.5 and about 2.0 fold the rate of removal of the first volume of water.

Dynamics of the sol—gel transition in organic—inorganic nanocomposites

NASA Astrophysics Data System (ADS)

Judeinstein, P.; Oliveira, P. W.; Krug, H.; Schmidt, H.

1994-03-01

Two different techniques have been used to follow the gelation of photochromic organic—inorganic nanocomposites. The variations of molecular and macromolecular motions in these complex systems have been analyzed. Photo-correlation spectroscopy probes the formation of the gel network. Forced Rayleigh scattering experiences the microstructure of the mixtures via the measurement of the translational diffusion coefficient of entrapped photoreactive targets. In the different mixtures, a drop of the network mobility could be observed around the sol to gel conversion, while the entrapped molecules do not experience the macroscopic transition.

Mechanically robust, electrically conductive ultralow-density carbon nanotube-based aerogels

DOEpatents

Worsley, Marcus A; Baumann, Theodore F; Satcher, Jr., Joe H

2014-04-01

A method of making a mechanically robust, electrically conductive ultralow-density carbon nanotube-based aerogel, including the steps of dispersing nanotubes in an aqueous media or other media to form a suspension, adding reactants and catalyst to the suspension to create a reaction mixture, curing the reaction mixture to form a wet gel, drying the wet gel to produce a dry gel, and pyrolyzing the dry gel to produce the mechanically robust, electrically conductive ultralow-density carbon nanotube-based aerogel. The aerogel is mechanically robust, electrically conductive, and ultralow-density, and is made of a porous carbon material having 5 to 95% by weight carbon nanotubes and 5 to 95% carbon binder.

Mechanically robust, electrically conductive ultralow-density carbon nanotube-based aerogels

DOEpatents

Worsley, Marcus A.; Baumann, Theodore F.; Satcher, Jr, Joe H.

2016-07-05

A method of making a mechanically robust, electrically conductive ultralow-density carbon nanotube-based aerogel, including the steps of dispersing nanotubes in an aqueous media or other media to form a suspension, adding reactants and catalyst to the suspension to create a reaction mixture, curing the reaction mixture to form a wet gel, drying the wet gel to produce a dry gel, and pyrolyzing the dry gel to produce the mechanically robust, electrically conductive ultralow-density carbon nanotube-based aerogel. The aerogel is mechanically robust, electrically conductive, and ultralow-density, and is made of a porous carbon material having 5 to 95% by weight carbon nanotubes and 5 to 95% carbon binder.

L-cysteine-derived ambidextrous gelators of aromatic solvents and ethanol/water mixtures.

PubMed

Pal, Amrita; Dey, Joykrishna

2013-02-19

A series of L-cysteine-derived double hydrocarbon chain amphiphilic gelators L-(3-alkyl-carbamoylsulfanyl)-2-(3-alkylurido)propionic acid with different hydrocarbon chain lengths (C6-C16) was designed and synthesized. These gelators efficiently gelate only aromatic solvents. The gelation ability increased with the increase of chain length up to C14, but then it dropped with further increase of chain length. The C12 and C14 derivatives also gelled ethanol/water mixtures. The gels were characterized by a number of methods, including FT-IR, NMR, and XRD spectroscopy, electron microscopy, and rheology. The amphiphiles were observed to form either flat lamellar or ribbonlike aggregates in aromatic solvents as well as in ethanol/water mixtures. The gelation in all the solvents employed was observed to be thermoreversible. The gel-to-sol transition temperature as well as mechanical strength of the organogels were observed to increase with the hydrocarbon chain length. Both types of gels of C8-C16 amphiphiles have gel-to-sol transition temperatures above the physiological temperature (310 K). FT-IR and variable temperature (1)H NMR measurements suggested that van der Waals interactions have major contribution in the gelation process. The gel-to-sol transition temperature and mechanical strength of the organogels in ethanol/water mixtures was observed to be higher than those of benzene organogel.

Enhanced gel formation in binary mixtures of nanocolloids with short-range attraction

NASA Astrophysics Data System (ADS)

Harden, James L.; Guo, Hongyu; Bertrand, Martine; Shendruk, Tyler N.; Ramakrishnan, Subramanian; Leheny, Robert L.

2018-01-01

Colloidal suspensions transform between fluid and disordered solid states as parameters such as the colloid volume fraction and the strength and nature of the colloidal interactions are varied. Seemingly subtle changes in the characteristics of the colloids can markedly alter the mechanical rigidity and flow behavior of these soft composite materials. This sensitivity creates both a scientific challenge and an opportunity for designing suspensions for specific applications. In this paper, we report a novel mechanism of gel formation in mixtures of weakly attractive nanocolloids with modest size ratio. Employing a combination of x-ray photon correlation spectroscopy, rheometry, and molecular dynamics simulations, we find that gels are stable at remarkably weaker attraction in mixtures with size ratio near two than in the corresponding monodisperse suspensions. In contrast with depletion-driven gelation at larger size ratio, gel formation in the mixtures is triggered by microphase demixing of the species into dense regions of immobile smaller colloids surrounded by clusters of mobile larger colloids that is not predicted by mean-field thermodynamic considerations. These results point to a new route for tailoring nanostructured colloidal solids through judicious combination of interparticle interaction and size distribution.

Investigation of novel sol-gel hydrophobic surfaces for desorption electrospray ionization-mass spectrometry analysis.

PubMed

Penna, Andrea; Elviri, Lisa; Careri, Maria; Mangia, Alessandro; Predieri, Giovanni

2011-05-01

Sol-gel-based materials were synthesized, characterized and finally tested as solid supports for desorption electrospray ionization-mass spectrometry (DESI-MS) analysis of a mixture of compounds of different polarity. Films with thickness in the 2-4 μm range were obtained by a dip-coating process using tetraethoxysilane (TEOS) and octyltriethoxysilane (OTES) as sol-gel precursors. Three types of surface with different hydrophobic character were obtained by varying the TEOS/OTES ratio in the sol-gel mixture. Each coating was characterized by atomic force microscopy investigations, gaining insight into homogeneity, smoothness and thickness of the obtained films. To study hydrophobicity of each surface, surface free energy measurements were performed. Different DESI-MS responses were observed when different solvent mixture deposition procedures and solvent spray compositions were investigated. Results were finally compared to those obtained by using commercial polytetrafluoroethylene-coated slides. It was found that surface free energy plays an important role in the desorption/ionization process as a function of the polarity of analytes.

Gelling Properties of Fish/Pork Mince Mixtures.

PubMed

Liu, Ru; Zhao, Siming; Regenstein, Joe M; Liu, Qing; Yang, Hong; Xiong, Shanbai

2016-02-01

The gel properties of silver carp/pork mince mixtures were investigated as well as the protein structural changes and interactions during gelling using rheology, SEM, and FT-Raman spectroscopy. The breaking force values for gels containing 0% to 40% pork was significantly lower (P < 0.05) compared with gels containing 50% to 100% pork. Gels containing 70% to 100% pork had significantly higher (P < 0.05) breaking force values compared with gels containing 50% to 60% pork. Deformation values were more mixed. Dynamic rheological data suggested that mixing fish and pork at 3:7 could strengthen the gel network. The addition of 40% pork or above, significantly decreased (P < 0.05) the water retention of the gels compared with the 100% fish gels. The dimensional ordering of gels was also reduced by addition of pork. The reduced ordering was one of the reasons for the low water retention for fish/pork mixed gels. Raman spectral analysis confirmed that mixing fish and pork in 7:3 and 3:7 ratios could promote hydrophobic interactions such as bringing tyrosine residues into the intermolecular interface. The interactions in the 3:7 fish/pork mixed gels were favorable for forming a stronger gel. However, the interactions in the 7:3 fish/pork mixed gels were adverse. The water retention of gels was related to both molecular interactions and secondary structures of protein as well as the microstructure of the gels. © 2016 Institute of Food Technologists®

Superabsorbing gel for actinide, lanthanide, and fission product decontamination

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

Kaminski, Michael D.; Mertz, Carol J.

The present invention provides an aqueous gel composition for removing actinide ions, lanthanide ions, fission product ions, or a combination thereof from a porous surface contaminated therewith. The composition comprises a polymer mixture comprising a gel forming cross-linked polymer and a linear polymer. The linear polymer is present at a concentration that is less than the concentration of the cross-linked polymer. The polymer mixture is at least about 95% hydrated with an aqueous solution comprising about 0.1 to about 3 percent by weight (wt %) of a multi-dentate organic acid chelating agent, and about 0.02 to about 0.6 molar (M)more » carbonate salt, to form a gel. When applied to a porous surface contaminated with actinide ions, lanthanide ions, and/or other fission product ions, the aqueous gel absorbs contaminating ions from the surface.« less

Energy-Efficient Bioalcohol Recovery by Gel Stripping

NASA Astrophysics Data System (ADS)

Godbole, Rutvik; Ma, Lan; Hedden, Ronald

2014-03-01

Design of energy-efficient processes for recovering butanol and ethanol from dilute fermentations is a key challenge facing the biofuels industry due to the high energy consumption of traditional multi-stage distillation processes. Gel stripping is an alternative purification process by which a dilute alcohol is stripped from the fermentation product by passing it through a packed bed containing particles of a selectively absorbent polymeric gel material. The gel must be selective for the alcohol, while swelling to a reasonable degree in dilute alcohol-water mixtures. To accelerate materials optimization, a combinatorial approach is taken to screen a matrix of copolymer gels having orthogonal gradients in crosslinker concentration and hydrophilicity. Using a combination of swelling in pure solvents, the selectivity and distribution coefficients of alcohols in the gels can be predicted based upon multi-component extensions of Flory-Rehner theory. Predictions can be validated by measuring swelling in water/alcohol mixtures and conducting h HPLC analysis of the external liquid. 95% + removal of butanol from dilute aqueous solutions has been demonstrated, and a mathematical model of the unsteady-state gel stripping process has been developed. NSF CMMI Award 1335082.

A study of normoxic polymer gel using monomer 2-hydroxyethyl methacrylate (HEMA)

NASA Astrophysics Data System (ADS)

Ishak, Siti Atiqah; Mustafa, Iskandar Shahrim; Rahman, Azhar Abdul; Moktar, Mohd; Min, Ung Ngie

2015-04-01

The aim of this study is to determine the sensitivity of HEMA-polymer gel mixture consist of monomer 2-hydroxyethyl methacrylate (HEMA) with different types of composition. Several composition of HEMA-polymer gel were fabricated and the gels were irradiated with radiation dose between 10 cGy to 100cGy by using x-ray machine and 100 cGy to 1400 cGy by using 6 MV photon beam energy of linear accelerator. The degree of polymerization was evaluated by using magnetic resonance imaging (MRI) with dependence of R2-dose response. Polymer gel consists of cross-linker, anti-oxidant Tetrakis(Hydroxymethyl)phosphonium chloride solution (THPC) and oxygen scavenger hydroquinone shows a stable sensitivity with highest dose dependency. Besides, the results shows the stage polymerization consist of induction, propagation, termination, and chain transfer were dependence with type of chemical mixture and radiation dose. Thus, normoxic HEMA-polymer gel with the different gel formulations can have a better dose resolution and an appropriate recipe must be selected to increase of the sensitivity required and the stability of the dosimeter.

A study of normoxic polymer gel using monomer 2-hydroxyethyl methacrylate (HEMA)

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

Ishak, Siti Atiqah; Mustafa, Iskandar Shahrim; Rahman, Azhar Abdul

2015-04-24

The aim of this study is to determine the sensitivity of HEMA-polymer gel mixture consist of monomer 2-hydroxyethyl methacrylate (HEMA) with different types of composition. Several composition of HEMA-polymer gel were fabricated and the gels were irradiated with radiation dose between 10 cGy to 100cGy by using x-ray machine and 100 cGy to 1400 cGy by using 6 MV photon beam energy of linear accelerator. The degree of polymerization was evaluated by using magnetic resonance imaging (MRI) with dependence of R2-dose response. Polymer gel consists of cross-linker, anti-oxidant Tetrakis(Hydroxymethyl)phosphonium chloride solution (THPC) and oxygen scavenger hydroquinone shows a stable sensitivitymore » with highest dose dependency. Besides, the results shows the stage polymerization consist of induction, propagation, termination, and chain transfer were dependence with type of chemical mixture and radiation dose. Thus, normoxic HEMA-polymer gel with the different gel formulations can have a better dose resolution and an appropriate recipe must be selected to increase of the sensitivity required and the stability of the dosimeter.« less

Morphology of molecular soy protein fractions in binary composite gels.

PubMed

Kasapis, Stefan; Tay, Sok Li

2009-08-04

We investigate the structural properties of gels of binary mixtures of the three major soy protein fractions: 11S, 7S, and 2S. Gels are formed at 25 degrees C in the presence of glucono-delta-lactone and studied using a combination of dynamic rheology and scanning electron microscopy. The theological data was then modeled using a blending-law approach that yields insights into the solvent distribution between the gelled protein fractions and first-order reaction kinetics that follow the gelation process of the single fractions and their mixtures. Gelled mixtures of 11S and 7S yielded enhanced network strength with increasing solid content; in these gels, 50% more solvent partitioned into the 11S phase as compared to that in the 7S phase. In contrast, the addition of small-molecular-weight counterpart 2S to either 11S or 7S results in a catastrophic drop in the values of the overall strength of the mixture. The unexpected phase behavior has been rationalized on the basis of the high water-holding capacity of 2S; 450% more solvent partitions preferentially into the 2S phase as compared to that in the 11S phase. As the concentration of 2S is increased relative to that of 11S or 7S, it becomes the dominant phase and entraps the polymeric segments of 11S (or 7S), thus preventing them from becoming the structural knots of the gel. In addition to the solvent distribution in the gel, the rates of gelation differ markedly between 11S and 2S (with the 11S rate of gelation being up to 2 orders of magnitude greater); a fixed 11S concentration, the rate of gelation decreases with increasing amounts of 2S, further confirming that the latter essentially becomes the dominant phase in the composite gel.

Phase behavior of gemini surfactant hexylene-1,6-bis(dodecyldimethylammonium bromide) and polyelectrolyte NaPAA.

PubMed

Pi, Yingying; Shang, Yazhuo; Peng, Changjun; Liu, Honglai; Hu, Ying; Jiang, Jianwen

2006-07-01

The phase behavior of aqueous mixtures of gemini surfactant hexylene-1,6-bis(dodecyldimethylammonium bromide) (12-6-12) and oppositely charged polyelectrolyte sodium polyacrylate (NaPAA) has been studied experimentally. Compared to the mixtures of the traditional surfactant dodecyltrimethylammonium bromide (DTAB) and NaPAA, the gel phase region in the 12-6-12/NaPAA solution is larger. Element analysis reveals that NaPAA in the gel phase tends to replace the counterions of surfactant micelle and to release its own counterions. Spherical aggregates are observed in either top or bottom gel phase as detected by transmission electron microscopy. The addition of sodium bromide (NaBr) leads to a decrease in the gel phase region and the occurrence of a new cream phase.

High-density 3D graphene-based monolith and related materials, methods, and devices

DOEpatents

Worsley, Marcus A.; Baumann, Theodore F.; Biener, Juergen; Charnvanichborikarn, Supakit; Kucheyev, Sergei; Montalvo, Elizabeth; Shin, Swanee; Tylski, Elijah

2017-03-21

A composition comprising at least one high-density graphene-based monolith, said monolith comprising a three-dimensional structure of graphene sheets crosslinked by covalent carbon bonds and having a density of at least 0.1 g/cm.sup.3. Also provided is a method comprising: preparing a reaction mixture comprising a suspension and at least one catalyst, said suspension selected from a graphene oxide (GO) suspension and a carbon nanotube suspension; curing the reaction mixture to produce a wet gel; drying the wet gel to produce a dry gel, said drying step is substantially free of supercritical drying and freeze drying; and pyrolyzing the dry gel to produce a high-density graphene-based monolith. Exceptional combinations of properties are achieved including high conductive and mechanical properties.

Gel-forming reagents and uses thereof for preparing microarrays

DOEpatents

Golova, Julia; Chernov, Boris; Perov, Alexander

2010-11-09

New gel-forming reagents including monomers and cross-linkers, which can be applied to gel-drop microarray manufacturing by using co-polymerization approaches are disclosed. Compositions for the preparation of co-polymerization mixtures with new gel-forming monomers and cross-linker reagents are described herein. New co-polymerization compositions and cross-linkers with variable length linker groups between unsaturated C.dbd.C bonds that participate in the formation of gel networks are disclosed.

Sol-gel antireflective coating on plastics

DOEpatents

Ashley, C.S.; Reed, S.T.

1988-01-26

An antireflection film made from reliquified sol-gel hydrolyzation, condensation polymeric reaction product of a silicon, alkoxides and/or metal alkoxides, or mixtures thereof. The film is particularly useful for coating plastics.

Sol-gel antireflective coating on plastics

DOEpatents

Ashley, Carol S.; Reed, Scott T.

1990-01-01

An antireflection film made from a reliquified sol-gel hydrolyzation, condensation polymeric reaction product of a silicon, alkoxides and/or metal alkoxides, or mixtures thereof. The film is particularly useful for coating plastics.

Method for molding ceramic powders using a water-based gel casting

DOEpatents

Janney, Mark A.; Omatete, Ogbemi O.

1991-07-02

A method for molding ceramic powders comprises forming a slurry mixture including ceramic powder, a dispersant, and a monomer solution. The monomer solution includes at least one monofunctional monomer and at least one difunctional monomer, a free-radical initiator, and a aqueous solvent. The slurry mixture is transferred to a mold, and the mold containing the slurry mixture is heated to polymerize and crosslink the monomer and form a firm polymer-solvent gel matrix. The solid product any be removed from the mold and heated to first remove the solvent and subsequently remove the polymer, whereafter the product may be sintered.

Method for molding ceramic powders using a water-based gel casting process

DOEpatents

Jenny, Mark A.; Omalete, Ogbemi O.

1992-09-08

A method for molding ceramic powders comprises forming a slurry mixture including ceramic powder, a dispersant, and a monomer solution. The monomer solution includes at least one monofunctional monomer and at least one difunctional monomer, a free-radical initiator, and a aqueous solvent. The slurry mixture is transferred to a mold, and the mold containing the slurry mixture is heated to polymerize and crosslink the monomer and form a firm polymer-solvent gel matrix. The solid product may be removed from the mold and heated to first remove the solvent and subsequently remove the polymer, whereafter the product may be sintered.

Apparatus for converting biomass to a pumpable slurry

DOEpatents

Ergun, Sabri; Schaleger, Larry L.; Wrathall, James A.; Yaghoubzadeh, Nasser

1986-01-01

An apparatus used in the pretreatment of wood chips in a process for converting biomass to a liquid hydrocarbonaceous fuel. The apparatus functions to break down the wood chips to a size distribution that can be readily handled in a slurry form. Low maintenance operation is obtained by hydrolyzing the chips in a pressure vessel having no moving parts.

How do monomeric components of a polymer gel dosimeter respond to ionising radiation: A steady-state radiolysis towards preparation of a 3D polymer gel dosimeter

NASA Astrophysics Data System (ADS)

Kozicki, Marek

2011-12-01

Ionising radiation-induced reactions of aqueous single monomer solutions and mixtures of poly(ethylene glycol) diacrylate (PEGDA) and N, N'-methylenebisacrylamide (Bis) in a steady-state condition are presented below and above gelation doses in order to highlight reactions in irradiated 3D polymer gel dosimeters, which are assigned for radiotherapy dosimetry. Both monomers are shown to undergo radical polymerisation and cross-linking, which result in the measured increase in molecular weight and radius of gyration of the formed polydisperse polymer coils. The formation of nanogels was also observed for Bis solutions at a low concentration. In the case of PEGDA-Bis mixtures, co-polymerisation is suggested as well. At a sufficiently high radiation dose, the formation of a polymer network was observed for both monomers and their mixture. For this reason a sol-gel analysis for PEGDA and Bis was performed gravimetrically and a proposition of an alternative to this method employing a nuclear magnetic resonance technique is made. The two monomers were used for preparation of 3D polymer gel dosimeters having the acronyms PABIG and PABIG nx. The latter is presented for the first time in this work and is a type of the formerly established PABIG polymer gel dosimeter. The elementary characteristics of the new composition are presented, underlining the ease of its preparation, low dose threshold, and slightly increased sensitivity but lower quasi-linear range of dose response in comparison to PABIG.

Starch gel electrophoresis of conifer seeds: a laboratory manual

Treesearch

M. Thompson Conkle; Paul D. Hodgskiss; Lucy B. Nunnally; Serena C. Hunter

1982-01-01

This manual describes fast, low-cost biochemical procedures for separating enzymes representing numerous genes of forest trees. During electrophoresis the mixture of enzymes from a megagametophyte or embryo of a germinated seed separates in a gel. Specific stains applied to gel slices locate each enzyme. These procedures expand on those developed for crops research....

Method for preparing hydrous iron oxide gels and spherules

DOEpatents

Collins, Jack L.; Lauf, Robert J.; Anderson, Kimberly K.

2003-07-29

The present invention is directed to methods for preparing hydrous iron oxide spherules, hydrous iron oxide gels such as gel slabs, films, capillary and electrophoresis gels, iron monohydrogen phosphate spherules, hydrous iron oxide spherules having suspendable particles homogeneously embedded within to form composite sorbents and catalysts, iron monohydrogen phosphate spherules having suspendable particles of at least one different sorbent homogeneously embedded within to form a composite sorbent, iron oxide spherules having suspendable particles homogeneously embedded within to form a composite of hydrous iron oxide fiber materials, iron oxide fiber materials, hydrous iron oxide fiber materials having suspendable particles homogeneously embedded within to form a composite, iron oxide fiber materials having suspendable particles homogeneously embedded within to form a composite, dielectric spherules of barium, strontium, and lead ferrites and mixtures thereof, and composite catalytic spherules of barium or strontium ferrite embedded with oxides of Mg, Zn, Pb, Ce and mixtures thereof. These variations of hydrous iron oxide spherules and gel forms prepared by the gel-sphere, internal gelation process offer more useful forms of inorganic ion exchangers, catalysts, getters, dielectrics, and ceramics.

Aerosol gels

NASA Technical Reports Server (NTRS)

Sorensen, Christopher M. (Inventor); Chakrabarti, Amitabha (Inventor); Dhaubhadel, Rajan (Inventor); Gerving, Corey (Inventor)

2010-01-01

An improved process for the production of ultralow density, high specific surface area gel products is provided which comprises providing, in an enclosed chamber, a mixture made up of small particles of material suspended in gas; the particles are then caused to aggregate in the chamber to form ramified fractal aggregate gels. The particles should have a radius (a) of up to about 50 nm and the aerosol should have a volume fraction (f.sub.v) of at least 10.sup.-4. In preferred practice, the mixture is created by a spark-induced explosion of a precursor material (e.g., a hydrocarbon) and oxygen within the chamber. New compositions of matter are disclosed having densities below 3.0 mg/cc.

Controlled Sol-Gel Transitions of a Thermoresponsive Polymer in a Photoswitchable Azobenzene Ionic Liquid as a Molecular Trigger.

PubMed

Wang, Caihong; Hashimoto, Kei; Tamate, Ryota; Kokubo, Hisashi; Watanabe, Masayoshi

2018-01-02

Producing ionic liquids (ILs) that function as molecular trigger for macroscopic change is a challenging issue. Photoisomerization of an azobenzene IL at the molecular level evokes a macroscopic response (light-controlled mechanical sol-gel transitions) for ABA triblock copolymer solutions. The A endblocks, poly(2-phenylethyl methacrylate), show a lower critical solution temperature in the IL mixture containing azobenzene, while the B midblock, poly(methyl methacrylate), is compatible with the mixture. In a concentrated polymer solution, different gelation temperatures were observed in it under dark and UV conditions. Light-controlled sol-gel transitions were achieved by a photoresponsive solubility change of the A endblocks upon photoisomerization of the azobenzene IL. Therefore, an azobenzene IL as a molecular switch can tune the self-assembly of a thermoresponsive polymer, leading to macroscopic light-controlled sol-gel transitions. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fuel system technology overview

NASA Technical Reports Server (NTRS)

Friedman, R.

1980-01-01

Fuel system research and technology studies are being conducted to investigate the correlations and interactions of aircraft fuel system design and environment with applicable characteristics of the fuel. Topics include: (1) analysis of in-flight fuel temperatures; (2) fuel systems for high freezing point fuels; (3) experimental study of low temperature pumpability; (4) full scale fuel tank simulation; and (5) rapid freezing point measurement.

Naproxen-imprinted xerogels in the micro- and nanospherical formsby emulsion technique.

PubMed

Ornelas, Mariana; Azenha, Manuel; Pereira, Carlos; Silva, A Fernando

2015-11-27

Naproxen-imprinted xerogels in the microspherical and nanospherical forms were prepared by W/O emulsion and microemulsion, respectively. The work evolved from a sol–gel mixture previously reported for bulk synthesis. It was relatively simple to convert the original sol–gel mixture to one amenable to emulsion technique. The microspheres thus produced presented mean diameter of 3.7 μm, surface area ranging 220–340 m2/g, selectivity factor 4.3 (against ibuprofen) and imprinting factor 61. A superior capacity (9.4 μmol/g) was found, when comparing with imprints obtained from similar pre-gelification mixtures. However, slow mass transfer kinetics was deduced from column efficiency results. Concerning the nanospherical format, which constituted the first example of the production of molecularly imprinted xerogels in that format by microemulsion technique, adapting the sol–gel mixture was troublesome. In the end, nanoparticles with diameter in the order of 10 nm were finally obtained, exhibiting good indications of an efficient molecular imprinting process. Future refinements are necessary to solve serious aggregation issues, before moving to more accurate characterization of the binding characteristics or to real applications of the nanospheres.

Fabricating porous materials using interpenetrating inorganic-organic composite gels

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

Seo, Dong-Kyun; Volosin, Alex

Porous materials are fabricated using interpenetrating inorganic-organic composite gels. A mixture or precursor solution including an inorganic gel precursor, an organic polymer gel precursor, and a solvent is treated to form an inorganic wet gel including the organic polymer gel precursor and the solvent. The inorganic wet gel is then treated to form a composite wet gel including an organic polymer network in the body of the inorganic wet gel, producing an interpenetrating inorganic-organic composite gel. The composite wet gel is dried to form a composite material including the organic polymer network and an inorganic network component. The composite materialmore » can be treated further to form a porous composite material, a porous polymer or polymer composite, a porous metal oxide, and other porous materials.« less

Antibacterial effect of triantibiotic mixture, chlorhexidine gel, and two natural materials Propolis and Aloe vera against Enterococcus faecalis: An ex vivo study.

PubMed

Bazvand, Leila; Aminozarbian, Mohammad Ghasem; Farhad, Alireza; Noormohammadi, Hamid; Hasheminia, Seyed Mohsen; Mobasherizadeh, Sina

2014-07-01

The aim of this ex vivo study was to compare the antimicrobial effect of triantibiotic paste, 0.2% chlorhexidine gel, Propolis and Aloe vera on Enterococcus faecalis in deep dentin. Ninety fresh extracted single-rooted teeth were used in a dentin block model. Seventy-five teeth were infected with E. faecalis and divided into four experimental groups (n = 15). Experimental groups were treated with triantibiotic mixture with distilled water, 0.2% chlorhexidine gel, 70% ethanol + Propolis and Aloe vera. Fifteen teeth treated with distilled water as the positive control and 15 samples, free of bacterial contamination, were considered as the negative control. Gates-Glidden drill #4 was used for removal of surface dentin and Gates-Glidden drill #5 was used to collect samples of deep dentin. The samples were prepared and colony-forming units were counted. Data were analyzed by one-way ANOVA and post hoc Tukey tests. Statistical significance was defined at P < 0.05. Triantibiotic mixture group exhibited the least bacterial growth. However, the rate of bacterial growth showed no significant differences between chlorhexidine and Propolis groups (P > 0.05). Aloe vera had antibacterial effects on E. faecalis, but in comparison with other medicaments, it was less effective (P < 0.05). This experimental study showed that triantibiotic mixture, 0.2% chlorhexidine gel, Propolis and Aleo vera were relatively effective against E. faecalis. All the intracanal medicements had similar effects on E. faecalis in deep dentin except for Aloe vera.

Structure influence on mechanical and acoustic properties of freeze-dried gels obtained with the use of hydrocolloids.

PubMed

Ciurzyńska, Agnieszka; Marzec, Agata; Mieszkowska, Arleta; Lenart, Andrzej

2017-04-01

The influence of the structure formed by the type of hydrocolloids (low-methoxyl pectin, the mixture of xanthan gum, and locust bean gum, and mixture of xanthan gum, and guar gum) and the aeration time (3, 5, 7, and 9 min) on textural properties of freeze-dried gels were investigated. The hardest texture generating the strongest acoustic emission was obtained by freeze-dried pectin gel, characterised by the lowest porosity and the largest pore diameter. Aeration time significantly affected mechanical and acoustic properties of the pectin gel lyophilisate. No effect of gel aeration time on tested characteristics of samples with mixture of hydrocolloids was observed. Strong positive correlations between acoustic energy as well as the maximum force and work and negative ones between porosity and pore diameter indicate that greater resilience and stronger acoustic emission of freeze-dried gels was caused by the reduction of porosity and the increase in the pore size of the material. The research is expected to show the phenomenon of structure formation when preparing and freeze-drying gels and explain the influence of the process parameters (time of aeration, the type of hydrocolloids) on the formation of the internal structure and physical properties of a dried product, especially mechanical and acoustic properties. This achievement will contribute to the development of the science of food and human nutrition, especially within the context of the popular research on aerated diet products. The expected result will be the ability to develop a new technology for producing food with a delicate texture, using the phenomenon of sublimation. As a result, designing changes in the structure of freeze-dried fruit gels with a delicate structure will be possible due to the choice of ingredients and aeration parameters in order to develop innovative food characterised by favorable nutritional, health and functional properties, which will be attractive for the consumers. © 2016 Wiley Periodicals, Inc.

A STUDY OF THE MECHANISM OF RADIATION-INDUCED GELATION IN MONOMER-POLYMER MIXTURES. Quarterly Summary Report, August 1, 1961-October 31, 1961

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

Odian, G.; Bernstein, B.S.; Kelly, J.J.

1961-11-01

Gel contents can be obtained with polyethylene swollen with inhibitor- free allyl acrylate or inhibitor-free allyl methacrylate at a dose of only 0.05 Mrads Using Co/sup 60/ as the radiation source, allyl methacrylate gives higher gel content than allyl acrylate under similar conditions. icant and continues after Co/sup 60/ irradiation has been completed. Monomer desorption after a dose of 1.2 Mrads is less than after 0.05 Mrads, and does not continue after irradiation is stopped. Gel contents can be obtained without prior equilibrium swelling of polymer--monomer mixtures by irradiating the polymer in the presence of the monomer in a nitrogenmore » atmosphere. By irradiating under these conditions with prior equilibrium swelling, gel fractions appear to be higher than those normally obtained. Gel contents of irradiated equilibrium-swollen polyethylene/ allyl acrylate and polyethylene/allyl methacrylate increase with increasing radiation dose from 0.05 to 1.2 Mrads. Gel contents of 1.2 Mrad irradiated polyethyleneallyl methacrylate systems containing various initial amounts of monomer, increase with increasing monomer content. Polypropylene can be radiation crosslinked to give over 40% gel by prior equilibrium swelling with allyl acrylate or allyl methacrylate. (auth)« less

Synthetic biological membrane with self organizing properties

DOEpatents

Firestone, Millicent A.; Tiede, David M.

2003-01-01

A mixture is provided which manifests a gel phase at a temperature higher than that in which the mixture manifests a liquid phase. The mixture is a combination of a lipid, a polymer-grafted phospholipid and a surfactant. It is biomimetic in nature and changes phases when subjected to one or a plurality of environmental stimuli.

Hydrocarbonaceous material processing methods and apparatus

DOEpatents

Brecher, Lee E [Laramie, WY

2011-07-12

Methods and apparatus are disclosed for possibly producing pipeline-ready heavy oil from substantially non-pumpable oil feeds. The methods and apparatus may be designed to produce such pipeline-ready heavy oils in the production field. Such methods and apparatus may involve thermal soaking of liquid hydrocarbonaceous inputs in thermal environments (2) to generate, though chemical reaction, an increased distillate amount as compared with conventional boiling technologies.

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

PubMed

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

2014-08-01

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

Polymer gel electrolytes for application in aluminum deposition and rechargeable aluminum ion batteries

DOE PAGES

Sun, Xiao -Guang; Fang, Youxing; Jiang, Xueguang; ...

2015-10-22

Polymer gel electrolyte using AlCl3 complexed acrylamide as functional monomer and ionic liquids based on acidic mixture of 1-ethyl-3-methylimidazolium chloride (EMImCl) and AlCl 3 as plasticizer has been successfully prepared for the first time by free radical polymerization. Aluminum deposition is successfully obtained with a polymer gel membrane contianing 80 wt% ionic liquid. As a result, the polymer gel membranes are also good candidates for rechargeable aluminum ion batteries.

Fast and efficient proteolysis by reusable pepsin-encapsulated magnetic sol-gel material for mass spectrometry-based proteomics applications.

PubMed

Kayili, H Mehmet; Salih, Bekir

2016-08-01

Hydrophobic silicon-based material having magnetic properties was fairly synthesized by a classical sol-gel approach. Pepsin enzyme was encapsulated in the sol-gel material and the enzyme activity was evaluated in consequence of the digestion of some common proteins such as α- and β-casein, cytochrome c, myoglobin, and bovine serum albumin (BSA) both in a single protein batch and in the protein mixture. The optimum digestion time of the studied proteins using pepsin-encapsulated magnetic sol-gel material was found to be 20min. To produce the magnetic sol-gel material for convenient and easy proteomics applications, Fe3O4 was doped inside sol-gel material during the gelation step. It was observed that the activity of encapsulated pepsin was not affected by the amount of Fe3O4. Poly(ethylene glycol) was also inserted in sol-gel bulk to obtain suitable roughness and increase the hydrophilicity of the material surface to let protein molecules reach to the sol-gel material easily. The digestion of the protein mixture and non-fat bovine milk was performed with the pepsin-encapsulated magnetic sol-gel material and the digested solutions were analyzed using SDS-PAGE, MALDI-TOF-MS and LC-MS/MS for the protein identification. Reusability of the pepsin-encapsulated sol-gel material was examined and it was determined that they could be used at least 20 times. Finally, IgG digestions with a fast incubation time period were carried out using pepsin-encapsulated sol-gel material for generation of (Fab)2 product to evaluate the kinetic performance of the material. Copyright © 2016 Elsevier B.V. All rights reserved.

Pressure-temperature phase behavior of mixtures of natural sphingomyelin and ceramide extracts.

PubMed

Barriga, Hanna M G; Parsons, Edward S; McCarthy, Nicola L C; Ces, Oscar; Seddon, John M; Law, Robert V; Brooks, Nicholas J

2015-03-31

Ceramides are a group of sphingolipids that act as highly important signaling molecules in a variety of cellular processes including differentiation and apoptosis. The predominant in vivo synthetic pathway for ceramide formation is via sphingomyelinase catalyzed hydrolysis of sphingomyelin. The biochemistry of this essential pathway has been studied in detail; however, there is currently a lack of information on the structural behavior of sphingomyelin- and ceramide-rich model membrane systems, which is essential for developing a bottom-up understanding of ceramide signaling and platform formation. We have studied the lyotropic phase behavior of sphingomyelin-ceramide mixtures in excess water as a function of temperature (30-70 °C) and pressure (1-200 MPa) by small- and wide-angle X-ray scattering. At low ceramide concentrations the mixtures form the ripple gel phase (P(β)') below the gel transition temperature for sphingomyelin, and this observation has been confirmed by atomic force microscopy. Formation of the ripple gel phase can also be induced at higher temperatures via the application of hydrostatic pressure. At high ceramide concentration an inverse hexagonal phase (HII) is formed coexisting with a cubic phase.

Gel sealants for the mitigation of spontaneous heatings in coal mines. Report of investigations/1995

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

Miron, Y.

1995-12-31

The U.S. Bureau of Mines evaluated three sealant systems for this purpose, bentonite-water mixtures, silicate gel, and guar gum gels. The guar gum-based gel was the only sealant that possessed the desired properties of elasticity, ease of preparation, adaptability to the mine, and a long life. In addition, since the gel consists mostly of water, it could quench or cool nearby heatings. Optimal formulations were determined in laboratory tests, and then tested in the U.S. Bureau of Mines` Safety Research Coal Mine. Two formulations resulted in stable gels that lasted for at least 12 months in the mine. Semi-continuous preparationmore » of gel using an eductor was evaluated and appears feasible.« less

Disaggregation of adenylate cyclase during polyacrylamide-gel electrophoresis in mixtures of ionic and non-ionic detergents.

PubMed

Newby, A C; Chrambach, A

1979-02-01

1. Adenylate cyclase [ATP pyrophosphate-lyase (cyclizing), EC 4.6.1.1] solubilized from the rat liver plasma membrane with 1% Lubrol PX and partially purified by gel filtration in buffer containing 0.01% Lubrol PX was physically characterized by polyacrylamide-gel electrophoresis. 2. The molecular radius determined for the partially purified enzyme was 4.9nm, compared with the value of 3.9nm obtained for the enzyme before gel filtration. 3. This difference, representing an approximate doubling of the molecular volume of the enzyme, implied that aggregation with itself or other proteins had occurred during partial purification. 4. Aggregation was not reversed by electrophoresis in the presence of high Lubrol concentrations. 5. Substitution of deoxycholate or N-dodecylsarcosinate for Lubrol PX either for solubilization or during electrophoresis led to poorer resolution of membrane proteins at concentrations giving greater than 70% loss of enzyme activity. 6. Partially purified adenylate cyclase was electrophoresed in the presence of mixed micelles of Lubrol PX and deoxycholate or Lubrol PX and N-dodecylsarcosinate. Different mixtures were examined simultaneously in a suitable apparatus. 7. Electrophoresis in the presence of 0.1% Lubrol plus 0.03% deoxycholate decreased the molecular radius of the cyclase to 4.0nm, with greater than 90% recovery of enzymic activity. The net charge of the enzyme was also increased, indicating ionic detergent binding. 8. With 0.1% Lubrol plus 0.03% N-dodecylsarcosinate the molecular radius was 4.3nm, recovery approx. 50% and net charge similar to that seen in Lubrol plus deoxycholate. 9. The resolution of cyclase from bulk protein, on an analytical scale, was improved in the presence of detergent mixtures, as compared with resolution in Lubrol alone. 10. The results demonstrate the usefulness of polyacrylamide-gel electrophoresis to detect and overcome aggregation problems with membrane proteins and suggest that detergent mixtures in specific ratios may be useful in the purification of adenylate cyclase and other intrinsic membrane proteins.

High Pulse Energy Flashlamp Pumpable Laser Dyes

DTIC Science & Technology

1990-04-09

on a large scale, and the difficult alkylation to 35 accomplished with 1-iodopropane with sodium hydroxide in acetone. Coupling the Grignard reagent ...dialkylated with 4-(chloromethyl)stilbene (47), which recently became available from Aldrich, to give 48b. The attempt to couple the Grignard reagent from 4...search turned up a useful procedure for coupling aryl Grignard reagents with benzyl halides, the process in Scheme E was largely completed. The Grignard

Rheology and microstructure of binary mixed gel of rice bran protein-whey: effect of heating rate and whey addition.

PubMed

Rafe, Ali; Vahedi, Elnaz; Hasan-Sarei, Azadeh Ghorbani

2016-08-01

Rice bran protein (RBP) is a valuable plant protein which has unique nutritional and hypoallergenic properties. Whey proteins have wide applications in the food industry, such as in dairy, meat and bakery products. Whey protein concentrate (WPC), RBP and their mixtures at different ratios (1:1, 1:2, 1:5 and 1:10 w/w) were heated from 20 to 90 °C at different heating rates (0.5, 1, 5 and 10 °C min(-1) ). The storage modulus (G') and gelling point (Tgel ) of WPC were higher than those of RBP, indicating the good ability of WPC to develop stiffer networks. By increasing the proportion of WPC in mixed systems, G' was increased and Tgel was reduced. Nevertheless, the elasticity of all binary mixtures was lower than that of WPC alone. Tgel and the final G' of RBP-WPC blends were increased by raising the heating rate. The RBP-WPC mixtures developed more elastic gels than RBP alone at different heating rates. RBP had a fibrillar and lentil-like structure whose fibril assembly had smaller structures than those of WPC. The gelling structure of the mixed gel of WPC-RBP was improved by adding WPC. Indeed, by adding WPC, gels tended to show syneresis and had lower water-holding capacity. Furthermore, the gel structure was produced by adding WPC to the non-gelling RBP, which is compatible with whey and can be applied as a functional food for infants and/or adults. © 2015 Society of Chemical Industry. © 2015 Society of Chemical Industry.

Influence of polyols on the formation of nanocrystalline nickel ferrite inside silica matrices

NASA Astrophysics Data System (ADS)

Stoia, Marcela; Barvinschi, Paul; Barbu-Tudoran, Lucian; Bunoiu, Mădălin

2017-01-01

We have synthesized nickel ferrite/silica nanocomposites, using a modified sol-gel method that combines the sol-gel processing with the thermal decomposition of metal-organic precursors, leading to a homogenous dispersion of ferrite nanoparticles within the silica matrix and a narrow size distribution. We used as starting materials tetraethyl orthosilicate (TEOS) as source of silica, Fe(III) and Ni(II) nitrates as sources of metal cations, and polyols as reducing agent (polyvinyl alcohol, 1,4-butanediol and their mixture). TG/DTA coupled technique evidenced the redox interaction between the polyol and the mixture of metal nitrates during the heating of the gel, with formation of nickel ferrite precursors in the pores of the silica-gels. FT-IR spectroscopy confirmed the formation of metal carboxylates inside the silica-gels and the interaction of the polyols with the Si-OH groups of the polysiloxane network. X-ray diffractometry evidenced that in case of nanocomposites obtained by using a single polyol, nickel ferrite forms as single crystalline phase inside the amorphous silica matrix, while in case of using a mixture of polyols the nickel oxide appears as a secondary phase. TEM microscopy and elemental mapping evidenced the fine nature of the obtained nickel ferrite nanoparticles that are homogenously dispersed within the silica matrix. The obtained nanocomposites exhibit magnetic behavior very close to superparamagnetism slightly depending on the presence and nature of the organic compounds used in synthesis; the magnetization reached at 5 kOe magnetic field was 7 emu/g for all composites.

The Effect of Poly (Glycerol Sebacate) Incorporation within Hybrid Chitin-Lignin Sol-Gel Nanofibrous Scaffolds.

PubMed

Abudula, Tuerdimaimaiti; Gzara, Lassaad; Simonetti, Giovanna; Alshahrie, Ahmed; Salah, Numan; Morganti, Pierfrancesco; Chianese, Angelo; Fallahi, Afsoon; Tamayol, Ali; Bencherif, Sidi A; Memic, Adnan

2018-03-19

Chitin and lignin primarily accumulate as bio-waste resulting from byproducts of crustacean crusts and plant biomass. Recently, their use has been proposed for diverse and unique bioengineering applications, amongst others. However, their weak mechanical properties need to be improved in order to facilitate their industrial utilization. In this paper, we fabricated hybrid fibers composed of a chitin-lignin (CL)-based sol-gel mixture and elastomeric poly (glycerol sebacate) (PGS) using a standard electrospinning approach. Obtained results showed that PGS could be coherently blended with the sol-gel mixture to form a nanofibrous scaffold exhibiting remarkable mechanical performance and improved antibacterial and antifungal activity. The developed hybrid fibers showed promising potential in advanced biomedical applications such as wound care products. Ultimately, recycling these sustainable biopolymers and other bio-wastes alike could propel a "greener" economy.

Comparison of water gel desserts from fish skin and pork gelatins using instrumental measurements.

PubMed

Zhou, Peng; Regenstein, Joe M

2007-05-01

The objective of this study was to compare water gel desserts from various gelatins using instrumental measurements. The puncture test and texture profile analysis (TPA) with compression were determined at 25% and 75% deformation; the melting properties were determined rheologically by monitoring the change of storage modulus (G') with increasing temperature. The measurements with 25% deformation were always nondestructive, while measurements with 75% deformation were mostly destructive. Desserts made from Alaska pollock gelatin (AG) or gelatin mixtures containing AG were more resistant to the destruction caused by the large deformation than tilapia gelatin and pork gelatins. In addition, the gel dessert made from AG melted at a lower temperature than those from tilapia skin gelatin and pork gelatins, while desserts made from gelatin mixtures reflected the melting properties of the separate gelatins.

Rheological and micro-Raman time-series characterization of enzyme sol–gel solution toward morphological control of electrospun fibers

PubMed Central

Oriero, Dennis A; Weakley, Andrew T; Aston, D Eric

2012-01-01

Rheological and micro-Raman time-series characterizations were used to investigate the chemical evolutionary changes of silica sol–gel mixtures for electrospinning fibers to immobilize an enzyme (tyrosinase). Results of dynamic rheological measurements agreed with the expected structural transitions associated with reacting sol–gel systems. The electrospinning sols exhibited shear-thinning behavior typical of a power law model. Ultrafine (200–300 nm diameter) fibers were produced at early and late times within the reaction window of approximately one hour from initial mixing of sol solutions with and without enzyme; diameter distributions of these fibers showed much smaller deviations than expected. The enzyme markedly increased magnitudes of both elastic and viscous moduli but had no significant impact on final fiber diameters, suggesting that the shear-thinning behavior of both sol–gel mixtures is dominant in the fiber elongation process. The time course and scale for the electrospinning batch fabrication show strong correlations between the magnitudes in rheological property changes over time and the chemical functional group evolution obtained from micro-Raman time-series analysis of the reacting sol–gel systems. PMID:27877486

Electrically controlled polymeric gel actuators

DOEpatents

Adolf, Douglas B.; Shahinpoor, Mohsen; Segalman, Daniel J.; Witkowski, Walter R.

1993-01-01

Electrically controlled polymeric gel actuators or synthetic muscles capable of undergoing substantial expansion and contraction when subjected to changing pH environments, temperature, or solvent. The actuators employ compliant containers for the gels and their solvents. The gels employed may be cylindrical electromechanical gel fibers such as polyacrylamide fibers or a mixture of poly vinyl alcohol-polyacrylic acid arranged in a parallel aggregate and contained in an electrolytic solvent bath such as salt water. The invention includes smart, electrically activated devices exploiting this phenomenon. These devices are capable of being manipulated via active computer control as large displacement actuators for use in adaptive structure such as robots.

Electrically controlled polymeric gel actuators

DOEpatents

Adolf, D.B.; Shahinpoor, M.; Segalman, D.J.; Witkowski, W.R.

1993-10-05

Electrically controlled polymeric gel actuators or synthetic muscles are described capable of undergoing substantial expansion and contraction when subjected to changing pH environments, temperature, or solvent. The actuators employ compliant containers for the gels and their solvents. The gels employed may be cylindrical electromechanical gel fibers such as polyacrylamide fibers or a mixture of poly vinyl alcohol-polyacrylic acid arranged in a parallel aggregate and contained in an electrolytic solvent bath such as salt water. The invention includes smart, electrically activated devices exploiting this phenomenon. These devices are capable of being manipulated via active computer control as large displacement actuators for use in adaptive structure such as robots. 11 figures.

Structurally stable gel bead containing entrapped enzyme and method for manufacture thereof

DOEpatents

Woodward, J.

1998-12-08

This research provides a structurally stable gel bead containing an entrapped enzyme and a method for its manufacture. The enzyme is covalently cross-linked to gelatin in the presence of glutaraldehyde prior to the formation of the gel bead, to prevent leakage of the enzyme. Propylene glycol alginate is then added to the mixture. Once the gel beads are formed, they are then soaked in glutaraldehyde, which imparts structural stability to the gel beads. This method can be used with many types of enzymes, such as proteases, carbohydrases, proteases, ligases, isomerases, oxidoreductases, and specialty enzymes. These and other enzymes can be immobilized in the gel beads and utilized in a number of enzymatic processes. Exogenously added ions are not required to maintain the structural stability of these gel beads. 7 figs.

Structurally stable gel bead containing entrapped enzyme and method for manufacture thereof

DOEpatents

Woodward, Jonathan

1998-01-01

A structurally stable gel bead containing an entrapped enzyme and a method for its manufacture. The enzyme is covalently cross-linked to gelatin in the presence of glutaraldehyde prior to the formation of the gel bead, to prevent leakage of the enzyme. Propylene glycol alginate is then added to the mixture. Once the gel beads are formed, they are then soaked in glutaraldehyde, which imparts structural stability to the gel beads. This method can be used with many types of enzymes, such as proteases, carbohydrases, proteases, ligases, isomerases, oxidoreductases, and specialty enzymes. These and other enzymes can be immobilized in the gel beads and utilized in a number of enzymatic processes. Exogenously added ions are not required to maintain the structural stability of these gel beads.

Thiolated polymers: evidence for the formation of disulphide bonds with mucus glycoproteins.

PubMed

Leitner, Verena M; Walker, Greg F; Bernkop-Schnürch, Andreas

2003-09-01

Disulphide bonds between thiolated polymers (thiomers) and cysteine-rich subdomains of mucus glycoproteins are supposed to be responsible for the enhanced mucoadhesive properties of thiomers. This study set out to provide evidence for these covalent interactions using poly(acrylic acid)-cysteine conjugates of 2 and 450 kDa (PAA2-Cys, PAA450-Cys) displaying 402.5-776.0 micromol thiol groups per gram polymer. The effect of the disulphide bond breaker cysteine on thiomer-mucin disulphide bonds was monitored by (1) mucoadhesion studies and (2) rheological studies. Furthermore, (3) diffusion studies and (4) gel filtration studies were performed with thiomer-mucus mixtures. The addition of cysteine significantly (P<0.01) reduced the adhesion of thiomer tablets to porcine mucosa and G'/G" values of thiomer-mucin mixtures, whereas unthiolated controls were not influenced. These results indicate the cleavage of disulphide bonds between thiomer and mucus glycoproteins. Diffusion studies demonstrated that a 12.8-fold higher concentration of the thiomer (PAA2-Cys) remains in the mucin gel than the corresponding unmodified polymer. Gel filtration studies showed that PAA2-Cys was able to form disulphide bonds with mucin glycoproteins resulting in an altered elution profile of the mucin/PAA2-Cys mixture in comparison to mucin alone or mucin/PAA2 mixture. According to these results, the study provides evidence for the formation of covalent bonds between thiomer and mucus glycoproteins.

In situ analysis of phase transformation in sol-gel cogelified nanopowder mixture of Al 2O 3 and TiO 2 using synchrotron X-ray radiation diffraction experiments

NASA Astrophysics Data System (ADS)

Jianu, A.; Stanciu, L.; Groza, J. R.; Lathe, Ch.; Burkel, E.

2003-01-01

Aluminium titanate (Al 2TiO 5) has been selected for study due to its high melting point and thermal shock resistance. In situ analysis of phase transformation and of transformation kinetics of sol-gel powder mixture of alumina and titania cogelified samples was performed using high-temperature synchrotron radiation X-ray diffraction experiments. The high reactivity and molecular mixing of sol-gel cogelified precursor powders contributed to the evolution of the reaction. The stability of the TiO 2-tetragonal structure (anatase) increases due to Al 2O 3 presence. The temperature of the aluminium titanate endothermic reaction decreases when heating rate increases. The results obtained by in situ analysis have been used to establish the sintering parameters in order to obtain fully transformed, dense aluminium titanate bulk ceramics.

The Effect of Poly (Glycerol Sebacate) Incorporation within Hybrid Chitin–Lignin Sol–Gel Nanofibrous Scaffolds

PubMed Central

Abudula, Tuerdimaimaiti; Gzara, Lassaad; Simonetti, Giovanna; Alshahrie, Ahmed; Salah, Numan; Morganti, Pierfrancesco; Chianese, Angelo; Fallahi, Afsoon; Tamayol, Ali; Memic, Adnan

2018-01-01

Chitin and lignin primarily accumulate as bio-waste resulting from byproducts of crustacean crusts and plant biomass. Recently, their use has been proposed for diverse and unique bioengineering applications, amongst others. However, their weak mechanical properties need to be improved in order to facilitate their industrial utilization. In this paper, we fabricated hybrid fibers composed of a chitin–lignin (CL)-based sol–gel mixture and elastomeric poly (glycerol sebacate) (PGS) using a standard electrospinning approach. Obtained results showed that PGS could be coherently blended with the sol–gel mixture to form a nanofibrous scaffold exhibiting remarkable mechanical performance and improved antibacterial and antifungal activity. The developed hybrid fibers showed promising potential in advanced biomedical applications such as wound care products. Ultimately, recycling these sustainable biopolymers and other bio-wastes alike could propel a “greener” economy. PMID:29562729

Surface chemistry and moisture sorption properties of wood coated with multifunctional alkoxysilanes by sol-gel process

Treesearch

Mandla A. Tshabalala; Peter Kingshott; Mark R. VanLandingham; David Plackett

2003-01-01

Sol-gel surface deposition of a hydrophobic polysiloxane coating on wood was accomplished by using a mixture of a low molecular weight multifunctional alkoxysilane, methyltrimethoxysilane (MTMOS), and a high molecular weight multifunctional alkoxysilane, hexadecyltrimethoxysilane (HDTMOS). Investigation of the surface chemistry and morphology of the wood specimens by...

Increased efficacy of Eimeria oocysts delivery by gel beads or spray vaccination

USDA-ARS?s Scientific Manuscript database

Control of avian coccidiosis is increasingly being achieved by the administration of low doses of Eimeria oocysts to newly hatched chicks. The purpose of this study was to test the efficacy of gel-beads containing a mixture of E. acervulina, E. maxima, and E. tenella oocysts as a vaccine to protect ...

Organic carbon aerogels from the sol-gel polymerization of phenolic-furfural mixtures

DOEpatents

Pekala, R.W.

1998-04-28

The sol-gel polymerization of a phenolic-furfural mixture in dilute solution leads to a highly cross-linked network that can be supercritically dried to form a high surface area foam. These porous materials have cell/pore sizes {<=}1000 {angstrom}, and although they are dark brown in color, they can be classified as a new type of aerogel. The phenolic-furfural aerogel can be pyrolyzed in an inert atmosphere at 1050 C to produce carbon aerogels. This new aerogel may be used for thermal insulation, chromatographic packing, water filtration, ion-exchange, and carbon electrodes for energy storage devices, such as batteries and double-layer capacitors. 8 figs.

Organic carbon aerogels from the sol-gel polymerization of phenolic-furfural mixtures

DOEpatents

Pekala, Richard W.

1998-04-28

The sol-gel polymerization of a phenolic-furfural mixture in dilute solution leads to a highly cross-linked network that can be supercritically dried to form a high surface area foam. These porous materials have cell/pore sizes .ltoreq.1000 .ANG., and although they are dark brown in color, they can be classified as a new type of aerogel. The phenolic-furfural aerogel can be pyrolyzed in an inert atmosphere at 1050.degree. C. to produce carbon aerogels. This new aerogel may be used for thermal insulation, chromatographic packing, water filtration, ion-exchange, and carbon electrodes for energy storage devices, such as batteries and double-layer capacitors.

Organic aerogels from the sol-gel polymerization of phenolic-furfural mixtures

DOEpatents

Pekala, Richard W.

1995-01-01

The sol-gel polymerization of a phenolic-furfural mixture in dilute solution leads to a highly cross-linked network that can be supercritically dried to form a high surface area foam. These porous materials have cell/pore sizes.ltoreq.1000.ANG., and although they are dark brown in color, they can be classified as a new type of aerogel. The phenolic-furfural aerogel can be pyrolyzed in an inert atmosphere at 1050.degree. C. to produce carbon aerogels. This new aerogel may be used for thermal insulation, chromatographic packing, water filtration, ion-exchange, and carbon electrodes for energy storage devices, such as batteries and double-layer capacitors.

Organic aerogels from the sol-gel polymerization of phenolic-furfural mixtures

DOEpatents

Pekala, R.W.

1995-12-19

The sol-gel polymerization of a phenolic-furfural mixture in dilute solution leads to a highly cross-linked network that can be supercritically dried to form a high surface area foam. These porous materials have cell/pore sizes{<=}1000{angstrom}, and although they are dark brown in color, they can be classified as a new type of aerogel. The phenolic-furfural aerogel can be pyrolyzed in an inert atmosphere at 1050 C to produce carbon aerogels. This new aerogel may be used for thermal insulation, chromatographic packing, water filtration, ion-exchange, and carbon electrodes for energy storage devices, such as batteries and double-layer capacitors. 8 figs.

Organic aerogels from the sol-gel polymerization of phenolic-furfural mixtures

DOEpatents

Pekala, Richard W.

1996-01-01

The sol-gel polymerization of a phenolic-furfural mixture in dilute solution leads to a highly cross-linked network that can be supercritically dried to form a high surface area foam. These porous materials have cell/pore sizes .ltoreq.1000.ANG., and although they are dark brown in color, they can be classified as a new type of aerogel. The phenolic-furfural aerogel can be pyrolyzed in an inert atmosphere at 1050.degree. C. to produce carbon aerogels. This new aerogel may be used for thermal insulation, chromatographic packing, water filtration, ion-exchange, and carbon electrodes for energy storage devices, such as batteries and double-layer capacitors.

Phase change material for temperature control and material storage

NASA Technical Reports Server (NTRS)

Wessling, Jr., Francis C. (Inventor); Blackwood, James M. (Inventor)

2011-01-01

A phase change material comprising a mixture of water and deuterium oxide is described, wherein the mole fraction of deuterium oxide is selected so that the mixture has a selected phase change temperature within a range between 0.degree. C. and 4.degree. C. The mixture is placed in a container and used for passive storage and transport of biomaterials and other temperature sensitive materials. Gels, nucleating agents, freezing point depression materials and colorants may be added to enhance the characteristics of the mixture.

Dynamic and static fluctuations in polymer gels studied by neutron spin-echo

NASA Astrophysics Data System (ADS)

Kanaya, T.; Takahashi, N.; Nishida, K.; Seto, H.; Nagao, M.; Takeba, Y.

2006-11-01

We report neutron spin-echo measurements on three types of poly(vinyl alcohol) (PVA) gels. The first is PVA gel in a mixture of dimethyl sulfoxide (DMSO) and water with volume ratio 60/40, the second is PVA gel in an aqueous borax solution and the third is chemically cross-linked PVA gel. The observed normalized intermediate scattering functions I( Q, t)/ I( Q,0) were very different among them. The I( Q, t)/ I( Q,0) of the first and third gels showed a non-decaying component in addition to a decaying component, but the second one did not have the non-decaying one. This clearly indicates that the fluctuations in the first and third PVA gels consist of static and dynamic fluctuations whereas the second PVA gel does include only the dynamic fluctuations. The dynamic and static fluctuations of the PVA gels were analyzed in terms of a restricted motion in the gel network and the Zimm motion, respectively.

Photochemical synthesis of simple organic free radicals on simulated planetary surfaces - An ESR study

NASA Technical Reports Server (NTRS)

Tseng, S.-S.; Chang, S.

1975-01-01

Electron spin resonance (ESR) spectroscopy provided evidence for formation of hydroxyl radicals during ultraviolet photolysis (254 nm) at -170 C of H2O adsorbed on silica gel or of silica gel alone. The carboxyl radical was observed when CO or CO2 or a mixture of CO and CO2 adsorbed on silica gel at -170 C was irradiated. The ESR signals of these radicals slowly disappeared when the irradiated samples were warmed to room temperature. However, reirradiation of CO or CO2, or the mixture CO and CO2 on silica gel at room temperature then produced a new species, the carbon dioxide anion radical, which slowly decayed and was identical with that produced by direct photolysis of formic acid adsorbed on silica gel. The primary photochemical process may involve formation of hydrogen and hydroxyl radicals. Subsequent reactions of these radicals with adsorbed CO or CO2 or both yield carboxyl radicals, CO2H, the precursors of formic acid. These results confirm the formation of formic acid under simulated Martian conditions and provide a mechanistic basis for gauging the potential importance of gas-solid photochemistry for chemical evolution on other extraterrestrial bodies, on the primitive earth, and on dust grains in the interstellar medium.

Evaluation of Ho:KPb2Cl5 as a Diode-Pumpable Mid-IR Laser Material

DTIC Science & Technology

2016-09-01

is the decay of the upper laser level without emitting light , due to the simultaneous emission of enough lattice vibrational quanta (phonons) to...have an energy level spacing that can result in emission at the desired laser wavelength, and that state must emit light efficiently. It is also...extremely desirable that it absorb light in the wavelength region where laser diodes operate most efficiently, approximately 800–1000 nm. This enables

Effect of Sol Concentration, Aging and Drying Process on Cerium Stabilization Zirconium Gel Produced by External Gelation

NASA Astrophysics Data System (ADS)

Sukarsono, R.; Rachmawati, M.; Susilowati, S. R.; Husnurrofiq, D.; Nurwidyaningrum, K.; Dewi, A. K.

2018-02-01

Cerium Stabilized Zirconium gel has been prepared using external gelation process. As the raw materials was used ZrO(NO3)2 and Ce(NO3)4 nitrate salt which was dissolved with water into Zr-Ce nitrate mixture. The concentration of the nitrate salt mixture in the sol solution was varied by varying the concentration of zirconium and cerium nitrate in the sol solution and the addition of PVA and THFA to produce a sol with a viscosity of 40-60 cP. The viscosity range of 40-60cP is the viscosity of the sol solution that was easy to produce a good gel in the gelation apparatus. Sol solution was casted in a gelation column equipped with following tools: a 1 mm diameter drip nozzle which was vibrated to adjust the best frequency and amplitude of vibration, a flow meter to measure the flow rate of sol, flowing of NH3 gas to presolidification process. Gelation column was contained NH4OH solution as gelation medium and gel container to collect gel product. Gel obtained from the gelation process than processed with ageing, washing, drying and calcinations to get round gel and not broken at calcinations up to 500°C. The parameters observed in this research are variation of Zr nitrate concentration, Ce nitrate concentration, ratio of Zr and Ce in the sol and ageing and drying process method which was appropriate to get a good gel. From the gelation processes that has been done, it can be seen that with the presolidification process can be obtained a round gel and without presolidification process, produce not round gel. In the process of ageing to get not broken gel, ageing was done on the rotary flask so that during the ageing, gels rotate in gelation media. Gels, then be washed by dilute ammonium nitrate, demireralized water and iso prophyl alcohol. The washed gel was then dried by vacuum drying to form pores on the gel which become the path for the gases resulting from decomposition of the gel to exit the gel. Vacuum drying can prevent cracking because the pores allow the gel to release the decomposition of the material during heating. Larger the concentration of nitric metal in sol solution, yields a gel with a larger diameter of gels. This research allows us to plan the diameter of the sintered particles to be made.

Backfilling behavior of a mixed aggregate based on construction waste and ultrafine tailings

PubMed Central

Zhang, Qinli; Xiao, Chongchun; Chen, Xin

2017-01-01

To study the possibility of utilizing mixed construction waste and ultrafine tailings (CW&UT) as a backfilling aggregate that can be placed underground in a mine, physicochemical evaluation, proportioning strength tests, and pumpability experiments were conducted. It was revealed that mixed CW&UT can be used as a backfilling aggregate due to the complementarities of their physicochemical properties. In addition, as the results of the proportioning strength tests show, the compressive strength of a cemented CW&UT backfilling specimen cured for 28 days, with a mass fraction of 72–74%, a cement-sand ratio of 1:12, and a CW proportion of 30%, is higher than 1.0 MPa, which meets the safety requirements and economic consideration of backfilling technology in many underground metal mines, and can also be enhanced with an increase in the cement-sand ratio. The results of the pumpability experiments show that cemented backfilling slurry based on CW&UT can be transported to the stope underground with a common filling pump, with a 16.6 MPa maximum pressure, with the condition that the time of emergency shut-down is less than approximately 20 min. All in all, the research to utilize mixed CW&UT as a backfilling aggregate can not only provide a way to dispose of CW&UT but also will bring large economic benefits and can provide constructive guidance for environmental protection. PMID:28662072

Backfilling behavior of a mixed aggregate based on construction waste and ultrafine tailings.

PubMed

Chen, Qiusong; Zhang, Qinli; Xiao, Chongchun; Chen, Xin

2017-01-01

To study the possibility of utilizing mixed construction waste and ultrafine tailings (CW&UT) as a backfilling aggregate that can be placed underground in a mine, physicochemical evaluation, proportioning strength tests, and pumpability experiments were conducted. It was revealed that mixed CW&UT can be used as a backfilling aggregate due to the complementarities of their physicochemical properties. In addition, as the results of the proportioning strength tests show, the compressive strength of a cemented CW&UT backfilling specimen cured for 28 days, with a mass fraction of 72-74%, a cement-sand ratio of 1:12, and a CW proportion of 30%, is higher than 1.0 MPa, which meets the safety requirements and economic consideration of backfilling technology in many underground metal mines, and can also be enhanced with an increase in the cement-sand ratio. The results of the pumpability experiments show that cemented backfilling slurry based on CW&UT can be transported to the stope underground with a common filling pump, with a 16.6 MPa maximum pressure, with the condition that the time of emergency shut-down is less than approximately 20 min. All in all, the research to utilize mixed CW&UT as a backfilling aggregate can not only provide a way to dispose of CW&UT but also will bring large economic benefits and can provide constructive guidance for environmental protection.

Disaggregation of adenylate cyclase during polyacrylamide-gel electrophoresis in mixtures of ionic and non-ionic detergents

PubMed Central

Newby, Andrew C.; Chrambach, Andreas

1979-01-01

1. Adenylate cyclase [ATP pyrophosphate-lyase (cyclizing), EC 4.6.1.1] solubilized from the rat liver plasma membrane with 1% Lubrol PX and partially purified by gel filtration in buffer containing 0.01% Lubrol PX was physically characterized by polyacrylamide-gel electrophoresis. 2. The molecular radius determined for the partially purified enzyme was 4.9nm, compared with the value of 3.9nm obtained for the enzyme before gel filtration. 3. This difference, representing an approximate doubling of the molecular volume of the enzyme, implied that aggregation with itself or other proteins had occurred during partial purification. 4. Aggregation was not reversed by electrophoresis in the presence of high Lubrol concentrations. 5. Substitution of deoxycholate or N-dodecylsarcosinate for Lubrol PX either for solubilization or during electrophoresis led to poorer resolution of membrane proteins at concentrations giving greater than 70% loss of enzyme activity. 6. Partially purified adenylate cyclase was electrophoresed in the presence of mixed micelles of Lubrol PX and deoxycholate or Lubrol PX and N-dodecylsarcosinate. Different mixtures were examined simultaneously in a suitable apparatus. 7. Electrophoresis in the presence of 0.1% Lubrol plus 0.03% deoxycholate decreased the molecular radius of the cyclase to 4.0nm, with greater than 90% recovery of enzymic activity. The net charge of the enzyme was also increased, indicating ionic detergent binding. 8. With 0.1% Lubrol plus 0.03% N-dodecylsarcosinate the molecular radius was 4.3nm, recovery approx. 50% and net charge similar to that seen in Lubrol plus deoxycholate. 9. The resolution of cyclase from bulk protein, on an analytical scale, was improved in the presence of detergent mixtures, as compared with resolution in Lubrol alone. 10. The results demonstrate the usefulness of polyacrylamide-gel electrophoresis to detect and overcome aggregation problems with membrane proteins and suggest that detergent mixtures in specific ratios may be useful in the purification of adenylate cyclase and other intrinsic membrane proteins. ImagesFig. 3. PMID:435255

A combined fluorescence spectroscopy, confocal and 2-photon microscopy approach to re-evaluate the properties of sphingolipid domains.

PubMed

Pinto, Sandra N; Fernandes, Fábio; Fedorov, Alexander; Futerman, Anthony H; Silva, Liana C; Prieto, Manuel

2013-09-01

The aim of this study is to provide further insight about the interplay between important signaling lipids and to characterize the properties of the lipid domains formed by those lipids in membranes containing distinct composition. To this end, we have used a combination of fluorescence spectroscopy, confocal and two-photon microscopy and a stepwise approach to re-evaluate the biophysical properties of sphingolipid domains, particularly lipid rafts and ceramide (Cer)-platforms. By using this strategy we were able to show that, in binary mixtures, sphingolipids (Cer and sphingomyelin, SM) form more tightly packed gel domains than those formed by phospholipids with similar acyl chain length. In more complex lipid mixtures, the interaction between the different lipids is intricate and is strongly dictated by the Cer-to-Chol ratio. The results show that in quaternary phospholipid/SM/Chol/Cer mixtures, Cer forms gel domains that become less packed as Chol is increased. Moreover, the extent of gel phase formation is strongly reduced in these mixtures, even though Cer molar fraction is increased. These results suggest that in biological membranes, lipid domains such as rafts and ceramide platforms, might display distinctive biophysical properties depending on the local lipid composition at the site of the membrane where they are formed, further highlighting the potential role of membrane biophysical properties as an underlying mechanism for mediating specific biological processes. Copyright © 2013 Elsevier B.V. All rights reserved.

Graphite Waste Tank Cleanup and Decontamination under the Marcoule UP1 D and D Program - 13166

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

Thomasset, Philippe; Chabeuf, Jean-Michel; Thiebaut, Valerie

2013-07-01

The UP1 plant in Marcoule reprocessed nearly 20,000 tons of used natural uranium gas cooled reactor fuel coming from the first generation of civil nuclear reactors in France. During more than 40 years, the decladding operations produced thousands of tons of processed waste, mainly magnesium and graphite fragments. In the absence of a French repository for the graphite waste, the graphite sludge content of the storage pits had to be retrieved and transferred into a newer and safer pit. After an extensive R and D program, the equipment and process necessary for retrieval operations were designed, built and tested. Themore » innovative process is mainly based on the use of two pumps (one to capture and the other one to transfer the sludge) working one after the other and a robotic arm mounted on a telescopic mast. A dedicated process was also set up for the removal of the biggest fragments. The retrieval of the most irradiating fragments was a challenge. Today, the first pit is totally empty and its stainless steel walls have been decontaminated using gels. In the second pit, the sludge retrieval and transfer operations have been almost completed. Most of the non-pumpable graphite fragments has been removed and transferred to a new storage pit. After more than 6 years of operations in sludge retrieval, a lot of experience was acquired from which important 'lessons learned' could be shared. (authors)« less

Organic aerogels from the sol-gel polymerization of phenolic-furfural mixtures

DOEpatents

Pekala, R.W.

1996-09-17

The sol-gel polymerization of a phenolic-furfural mixture in dilute solution leads to a highly cross-linked network that can be supercritically dried to form a high surface area foam. These porous materials have cell/pore sizes {<=}1,000{angstrom}, and although they are dark brown in color, they can be classified as a new type of aerogel. The phenolic-furfural aerogel can be pyrolyzed in an inert atmosphere at 1,050 C to produce carbon aerogels. This new aerogel may be used for thermal insulation, chromatographic packing, water filtration, ion-exchange, and carbon electrodes for energy storage devices, such as batteries and double-layer capacitors. 8 figs.

Dual release and molecular mechanism of bilayered aceclofenac tablet using polymer mixture.

PubMed

Van Nguyen, Hien; Nguyen, Van Hong; Lee, Beom-Jin

2016-12-30

The objectives of the present study were to develop a controlled-release bilayered tablet of aceclofenac (AFN) 200mg with dual release and to gain a mechanistic understanding of the enhanced sustained release capability achieved by utilizing a binary mixture of the sustained release materials. Different formulations of the sustained-release layer were formulated by employing hydroxypropyl methylcellulose (HPMC) and hydroxypropyl cellulose (HPC) as the major retarding polymers. The in vitro dissolution studies of AFN bilayered tablets were carried out in intestinal fluid (pH 6.8 buffer). The mechanism of the synergistic rate-retarding effect of the polymer mixture containing HPC and carbomer was elucidated by the rate of swelling and erosion in intestinal fluid and the molecular interactions in the polymer network. The optimized bilayered tablets had similar in vitro dissolution profiles to the marketed tablet Clanza ® CR based on the similarity factor (f2) in combination with their satisfactory micromeritic, physicochemical properties, and stability profiles. Drug release from HPMC-based matrix was controlled by non-Fickian transport, while drug release from HPC-based matrix was solely governed by drug diffusion. The swelling and erosion data exhibited a dramatic increase of water uptake and a reduction of weight loss in the polymer mixture-loaded tablet. Fourier transform infrared (FTIR) spectra revealed strong hydrogen bonding between HPC and carbomer in the polymer mixture. Regarding spatial distribution of polymers in the polymer mixture-loaded tablet, carbomer was found to be the main component of the gel layer during the first 2h of the hydration process, which was responsible for retarding drug release at initial stage. This process was then followed by a gradual transition of HPC from the glassy core to the gel layer for further increasing gel strength. Copyright © 2016 Elsevier B.V. All rights reserved.

Contaminant Flux Reduction Barriers for Managing Difficult to Treat Source Zones in Unconsolidated Media

DTIC Science & Technology

2017-06-20

39  Table 7.4:  Description of Case Study Site... Research Flux Reduction Materials: Several novel silica gel/vegetable oil- formulations were developed and tested in lab-scale batch and column studies by...Demonstration Results The project demonstration had these results:  Two grout mixtures were selected based on gel tests and a treatability study by

Evaluation of the electroosmotic medium pump system for preparative disk gel electrophoresis.

PubMed

Hayakawa, M; Hosogi, Y; Takiguchi, H; Saito, S; Shiroza, T; Shibata, Y; Hiratsuka, K; Kiyama-Kishikawa, M; Abiko, Y

2001-01-15

This paper describes an improved electroosmotic elution system for preparative sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) based on the epochal idea of H. V. Tan et al. (Nucleic Acids Res. 1988, 16, 1921-1930). In this elution system, a semipermeable membrane, mounted under the gel terminal end, works as the elution pump as well as the partition of the elution chamber. We refer to this system as the "electroosmotic medium pump system." Operation of the constructed apparatus (3.6 cm i.d. disk gel column) and resolution of the protein bands were examined by separation of the model protein mixture (bovine serum albumin (BSA), ovalbumin, bovine carbonic anhydrase, soybean trypsin inhibitor) and purification of the membrane protein, dipeptidyl peptidase IV (DPP IV). The Spectra/Por 7 dialysis membrane provided a better flow profile for the elution buffer. The four model proteins of the protein mixture were able to be completely separated from each other and recovered without dilution. The maximum protein concentration of eluate achieved was 93 mg/ml, when applying a single component, BSA fraction V, as a sample. Furthermore, the multifunctional ectoenzyme, DPP IV, was purified in a single step. Copyright 2001 Academic Press.

Aerogel and xerogel composites for use as carbon anodes

DOEpatents

Cooper, John F.; Tillotson, Thomas M.; Hrubesh, Lawrence W.

2010-10-12

A method for forming a reinforced rigid anode monolith and fuel and product of such method. The method includes providing a solution of organic aerogel or xerogel precursors including at least one of a phenolic resin, phenol (hydroxybenzene), resorcinol(1,3-dihydroxybenzene), or catechol(1,2-dihydroxybenzene); at least one aldehyde compound selected from the group consisting of formaldehyde, acetaldehyde, and furfuraldehyde; and an alkali carbonate or phosphoric acid catalyst; adding internal reinforcement materials comprising carbon to said precursor solution to form a precursor mixture; gelling said precursor mixture to form a composite gel; drying said composite gel; and pyrolyzing said composite gel to form a wettable aerogel/carbon composite or a wettable xerogel/carbon composite, wherein said composites comprise chars and said internal reinforcement materials, and wherein said composite is suitable for use as an anode with the chars being fuel capable of being combusted in a molten salt electrochemical fuel cell in the range from 500 C to 800 C to produce electrical energy. Additional methods and systems/compositions are also provided.

A cost-effective device for the rapid transfer of gel-separated proteins onto membranes.

PubMed

Tam, Hann W; Huang, Yu-Chen; Tam, Ming F

2009-03-01

We describe here the fabrication of a cost-effective semi-dry blotting apparatus for the transfer of proteins onto membranes. Graphite sheets were used as electrodes. Protein mixtures were separated on NuPAGE 4% to 12% polyacrylamide gradient gels. With a Tris-bicine buffer, we demonstrated that close to 80% of the proteins with apparent molecular mass of 80kDa or less were removed from the gels after 8min of blotting. The process is much faster than the techniques reported previously in the literature.

A sensitive gel-based global O-glycomics approach reveals high levels of mannosyl glycans in the high mass region of the mouse brain proteome.

PubMed

Breloy, Isabelle; Pacharra, Sandra; Aust, Christina; Hanisch, Franz-Georg

2012-08-01

We developed a gel-based global O-glycomics method applicable for highly complex protein mixtures entrapped in discontinuous gradient gel layers. The protocol is based on in-gel proteolysis with pronase followed by (glyco)peptide elution and off-gel reductive β-elimination. The protocol offers robust performance with sensitivity in the low picomolar range, is compatible with gel-based proteomics, and shows superior performance in global applications in comparison with workflows eliminating glycans in-gel or from electroblotted glycoproteins. By applying this method, we analyzed the O-glycome of human myoblasts and of the mouse brain O-glycoproteome. After semipreparative separation of mouse brain proteins by one-dimensional SDS gel electrophoresis, the O-glycans from proteins in different mass ranges were characterized with a focus on O-mannose-based glycans. The relative proportion of the latter, which generally represent a rare modification, increases to comparatively high levels in the mouse brain proteome in dependence of increasing protein masses.

Mapping Glycosaminoglycan–Hydroxyapatite Colloidal Gels as Potential Tissue Defect Fillers

PubMed Central

2015-01-01

Malleable biomaterials such as Herschel–Bulkley (H–B) fluids possess shear responsive rheological properties and are capable of self-assembly and viscoelastic recovery following mechanical disruption (e.g., surgical placement via injection or spreading). This study demonstrated that the addition of moderate molecular weight glycosaminoglycans (GAGs) such as chondroitin sulfate (CS) (Mw = 15–30 kDa) and hyaluronic acid (HA) (Mw = 20–41 kDa) can be used to modify several rheological properties including consistency index (K), flow-behavior index (n), and yield stress (τy) of submicrometer hydroxyapatite (HAP) (Davg ≤ 200 nm) colloidal gels. GAG–HAP colloidal mixtures exhibited substantial polymer–particle synergism, likely due to “bridging” flocculation, which led to a synergistic increase in consistency index (KGAG-HAP ≥ KGAG + KHAP) without compromising shear-thinning behavior (n < 1) of the gel. In addition, GAG–HAP colloids containing high concentrations of HAP (60–80% w/v) exhibited substantial yield stress (τy ≥ 100 Pa) and viscoelastic recovery properties (G′recovery ≥ 64%). While rheological differences were observed between CS–HAP and HA–HAP colloidal gels, both CS and HA represent feasible options for future studies involving bone defect filling. Overall, this study identified mixture regions where rheological properties in CS–HAP and HA–HAP colloidal gels aligned with desired properties to facilitate surgical placement in non-load-bearing tissue-filling applications such as calvarial defects. PMID:24606047

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

Sakurada, I.; Okada, T.; Hutakeyama, S.

Experiments on radioinduced graft copolymerization of binary mixtures such as butadiene -- styrene, butadiene-acrylonitrile, styrene-- acrylonitrile and some other systems onto cellulose and PVA (polyvinyl alcohol) fibers were carried out with the use of methanol as a solvent. A very marked maximum of graft was observed in every case at a certain composition of the comonomer mixture. It seemed that such a marked maximum was closely connected with popcorn polymerization for the case of butadiene-- styrene, but popcorn polymerization was not a necessary condition for the appearance of the maximum. Only a combined effect of swelling of the gel, formationmore » of radicals in the gel, homocopolymerization, and some other unknown factors is considered likely to lead to a very high degree of grafting. (auth)« less

Quantitative measurement of indomethacin crystallinity in indomethacin-silica gel binary system using differential scanning calorimetry and X-ray powder diffractometry.

PubMed

Pan, Xiaohong; Julian, Thomas; Augsburger, Larry

2006-02-10

Differential scanning calorimetry (DSC) and X-ray powder diffractometry (XRPD) methods were developed for the quantitative analysis of the crystallinity of indomethacin (IMC) in IMC and silica gel (SG) binary system. The DSC calibration curve exhibited better linearity than that of XRPD. No phase transformation occurred in the IMC-SG mixtures during DSC measurement. The major sources of error in DSC measurements were inhomogeneous mixing and sampling. Analyzing the amount of IMC in the mixtures using high-performance liquid chromatography (HPLC) could reduce the sampling error. DSC demonstrated greater sensitivity and had less variation in measurement than XRPD in quantifying crystalline IMC in the IMC-SG binary system.

Preliminary investigation of PAGAT polymer gel radionuclide dosimetry of Tc-99m

NASA Astrophysics Data System (ADS)

Braun, Kelly; Bailey, Dale; Hill, Brendan; Baldock, Clive

2009-05-01

PAGAT polymer gel was investigated as a suitable dosimeter materials for measuring absorbed dose from the unsealed source radionuclide Tc-99m. Differing amounts of Tc-99m over the range of 25-5000 MBq were introduced into a normoxic polymer gel mixture (PAGAT) in sealed nitrogen-filled P6 glass vials. After irradiation the gels were evaluated using MRI more than 48 hours after preparation to allow for radioactive decay. The dose delivered to the vial was also calculated empirically. R2 versus total activity curves were obtained over a number of experiments and these were used to evaluate the relationship between the amount of gel polymerization and the dose deposited by the radionuclide. A linear response up to 1000 MBq (corresponding to 20Gy) was displayed and was still behaving monotonically at 5000 MBq. Polymer gels offer the potential to measure radiation dose three-dimensionally using MRI.

Characterization of the bioactive and mechanical behavior of dental ceramic/sol-gel derived bioactive glass mixtures.

PubMed

Abbasi, Zahra; Bahrololoum, Mohammad E; Bagheri, Rafat; Shariat, Mohammad H

2016-02-01

Dental ceramics can be modified by bioactive glasses in order to develop apatite layer on their surface. One of the benefits of such modification is to prolong the lifetime of the fixed dental prosthesis by preventing the formation of secondary caries. Dental ceramic/sol-gel derived bioactive glass mixture is one of the options for this modification. In the current study, mixtures of dental ceramic/bioactive glass with different compositions were successfully produced. To evaluate their bioactive behavior, prepared samples were immersed in a simulated body fluid at various time intervals. The prepared and soaked specimens were characterized using Fourier transform infrared spectroscopy, X-ray diffractometry and scanning electron microscopy. Since bioactive glasses have deleterious effects on the mechanical properties of dental ceramics, 3-point bending tests were used to evaluate the flexural strength, flexural strain, tangent modulus of elasticity and Weibull modulus of the specimens in order to find the optimal relationship between mechanical and bioactive properties. Copyright © 2015 Elsevier Ltd. All rights reserved.

The influence of white and blue silica gels as adsorbents in adsorptive-distillation of ethanol-water mixture

NASA Astrophysics Data System (ADS)

Megawati, Jannah, Reni Ainun; Rahayuningtiyas, Indi

2017-01-01

This research studied the difference of white and blue silica gels when used as an adsorbent for ethanol purification that is processed via Adsorptive-Distillation (AD) at 1 atm pressure. The effect of process duration to purification process is also recorded and studied to evaluate the performance of designed AD equipment. The experiment was conducted using boiling flask covered with a heating mantle and the temperature was maintained at 78°C. The vapour flowed into the adsorbent column and was condensed using water as a cooling medium. The initial ethanol concentration was 90.8% v/v and volume was 300 mL. Experiment shows that designed AD equipment could be used to purify ethanol. The average vapour velocity was about 39.29 and 45.91 m/s for white and blue silica gels, respectively, which is considered very high. Therefore the saturated adsorption could not be obtained. Highest ethanol concentration achieved using white silica gel is about 96.671% v/v after 50 minutes. Thus AD with white silica gel showed good performance and passed azeotropic point. But AD with blue silica gel showed a different result, the adsorption of blue silica gel failed to break the azeotropic point. The outlet average water concentration for white and blue silica gels is 3.54 and 3.42 mole/L. Based on the weight ratio of adsorbed water per adsorbent, at 55th minutes of time; this ratio of blue silica gel is about 0.053 gwater/gads. The time required by the blue silica to achieve 0.5 wwater-adsorbed/wwater-initial is 45 minutes, and the average outlet water concentration is 3.42 mole/L. Meanwhile, the time required by a white silica to complete 0.5 wwater-adsorbed/wwater-initial is 35 minutes, and the average outlet water level is 3.54 mole/L. Based on the results, the blue silica as an adsorbent for AD of ethanol-water mixture is better than white silica gel.

Phase behaviour in complementary DNA-coated gold nanoparticles and fd-viruses mixtures: a numerical study.

PubMed

Chiappini, Massimiliano; Eiser, Erika; Sciortino, Francesco

2017-01-01

A new gel-forming colloidal system based on a binary mixture of fd-viruses and gold nanoparticles functionalized with complementary DNA single strands has been recently introduced. Upon quenching below the DNA melt temperature, such a system results in a highly porous gel state, that may be developed in a new functional material of tunable porosity. In order to shed light on the gelation mechanism, we introduce a model closely mimicking the experimental one and we explore via Monte Carlo simulations its equilibrium phase diagram. Specifically, we model the system as a binary mixture of hard rods and hard spheres mutually interacting via a short-range square-well attractive potential. In the experimental conditions, we find evidence of a phase separation occurring either via nucleation-and-growth or via spinodal decomposition. The spinodal decomposition leads to the formation of small clusters of bonded rods and spheres whose further diffusion and aggregation leads to the formation of a percolating network in the system. Our results are consistent with the hypothesis that the mixture of DNA-coated fd-viruses and gold nanoparticles undergoes a non-equilibrium gelation via an arrested spinodal decomposition mechanism.

Neutron spin-echo studies on dynamic and static fluctuations in two types of poly(vinyl alcohol) gels

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

Kanaya, T.; Takahashi, N.; Nishida, K.

2005-01-01

We report neutron spin-echo measurements on two types of poly(vinyl alcohol) (PVA) gels. The first is PVA gel in a mixture of dimethyl sulfoxide (DMSO) and water with volume ratio 60/40, and the second is PVA gel in an aqueous borax solution. The observed normalized intermediate scattering functions I(Q,t)/I(Q,0) are very different between them. The former I(Q,t)/I(Q,0) shows a nondecaying component in addition to a fast decay, but the latter does not have the nondecaying one. This clearly indicates that the fluctuations in the former PVA gel consist of static and dynamic fluctuations whereas the latter PVA gel does includemore » only the dynamic fluctuations. The dynamic fluctuations of the former and latter gels have been analyzed in terms of a restricted motion in the network and Zimm motion, respectively, and the origins of these motions will be discussed.« less

Are individual NOEC levels safe for mixtures? A study on mixture toxicity of brominated flame-retardants in the copepod Nitocra spinipes.

PubMed

Breitholtz, Magnus; Nyholm, Jenny Rattfelt; Karlsson, Jenny; Andersson, Patrik L

2008-07-01

In aquatic ecosystems organisms are exposed to mixtures of pollutants. Still, risk assessment focuses almost exclusively on effect characterization of individual substances. The main objective of the current study was therefore to study mixture toxicity of a common group of industrial substances, i.e., brominated flame-retardants (BFRs), in the harpacticoid copepod Nitocra spinipes. Initially, 10 BFRs with high hydrophobicity but otherwise varying chemical characteristics were selected based on multivariate chemical characterization and tested individually for effects on mortality and development using a partial life cycle test (six days) where silica gel is used as a carrier of the hydrophobic substances. Based on these findings, six of the 10 BFRs were mixed in a series of NOEC proportions (which were set to 0.008, 0.04, 0.2, 1, and five times the NOEC concentrations for each individual BFR), loaded on silica gel and tested in a full life cycle test (26 days). Significantly increased mortality was observed in N. spinipes after six and 26 days exposure at a NOEC proportion that equals the NOEC LDR value (x1) for each BFR in the mixture (p=0.0015 and p=0.0105, respectively). At the NOECx5 proportion all animals were dead. None of the other NOEC proportions caused significant negative responses related to development and reproduction. This shows that low concentrations of individual substances can cause toxicity if exposed in mixtures, which highlights the need to consider mixture toxicity to a greater extent in regulatory work.

Carrageenan :the difference between PNG and KCL gel precipitation method as Lactobacillus acidophilus encapsulation material

NASA Astrophysics Data System (ADS)

Setijawati, D.; Nursyam, H.; Salis, H.

2018-04-01

The study on the effects of using of materials and methods in the preparation of the microcapsules Lactobacillus acidophilus towards the viability has been done. The research method used is experimental laboratory design. Variable research was kind of material (A) as the first factor with sub factor (A1 = Eucheuma cottonii) (A2 = Eucheuma spinosum) (A3 = mixture of Eucheuma cottonii and Eucheuma spinosum 1:1 ratio), while the second factor is a method of extraction to produce caragenan (B) with sub factor (B1 = Philipine Natural Grade modification) (B2 = KCl gel Press Precipitation). Analysis of different influences uses Analysis Of Varians followed by Fisher’s test. Analysis of data uses Mini tab 16. The results shows that the kind of extraction factors and methods gave significantly different effects on the viability of Lactobacillus acidophilus. The highest mean of Viablity obtained in the treatment of materials with a mixture of Eucheuma cottonii and Eucheuma spinosum and used KCl Gel Press method is equal to 7.14 log (CFU / mL). It is ssuggested using of kappa-iota carrageenanmixture asencapsulation material with KCl Gel Press method on Lactobacillus acidophilus microencapsulation process because it treatment gavethe highest average of Lactobacillus acidophilus viability.

Proton conducting gel polyelectrolytes based on 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPSA) copolymers with polyfunctional monomers. Part I. Anhydrous systems

NASA Astrophysics Data System (ADS)

Zygadło-Monikowska, Ewa; Florjańczyk, Zbigniew; Wielgus-Barry, Edyta; Paśniewski, Jarosław

The synthesis of crosslinked gel polyelectrolytes in polar aprotic solvents such as dimethylformamide (DMF) and a DMF and propylene carbonate (PC) mixture has been carried out in the copolymerization of 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPSA) and polyfunctional monomers. N, N‧-Methylene-bis-acrylamide, trioxyethylene dimethacrylate (M n ∼ 330) and trimethylolpropane ethoxylate (14/3 EO/OH) triacrylate were used as crosslinking monomers. The reactions were initiated thermally or by UV irradiation in the presence of Irgacure 184 or methyl benzoin ether. The crosslinking monomer was used in an amount of 0.5-13 wt.%. The effect of the type and concentration of the polyfunctional comonomer and type of solvent on the optical (color, transparency) and mechanical properties as well as the ability to conduct electrical charges have been studied. The application of a DMF and PC mixture enables to obtain transparent systems of good mechanical properties and high ambient temperature ionic conductivity of the order of 10 -3 to 10 -4 S cm -1, slightly lowered as compared with that of gels comprising DMF alone. The conducting properties of crosslinked gels have been compared with that of the AMPSA homopolymer solutions in analogous solvents.

Transdermal agomelatine microemulsion gel: pyramidal screening, statistical optimization and in vivo bioavailability.

PubMed

Said, Mayada; Elsayed, Ibrahim; Aboelwafa, Ahmed A; Elshafeey, Ahmed H

2017-11-01

Agomelatine is a new antidepressant having very low oral drug bioavailability less than 5% due to being liable to extensive hepatic 1st pass effect. This study aimed to deliver agomelatine by transdermal route through formulation and optimization of microemulsion gel. Pyramidal screening was performed to select the most suitable ingredients combinations and then, the design expert software was utilized to optimize the microemulsion formulations. The independent variables of the employed mixture design were the percentages of capryol 90 as an oily phase (X 1 ), Cremophor RH40 and Transcutol HP in a ratio of (1:2) as surfactant/cosurfactant mixture 'S mix ' (X 2 ) and water (X 3 ). The dependent variables were globule size, optical clarity, cumulative amount permeated after 1 and 24 h, respectively (Q1 and Q 24 ) and enhancement ratio (ER). The optimized formula was composed of 5% oil, 45% S mix and 50% water. The optimized microemulsion formula was converted into carbopol-based gel to improve its retention on the skin. It enhanced the drug permeation through rat skin with an enhancement ratio of 37.30 when compared to the drug hydrogel. The optimum ME gel formula was found to have significantly higher C max , AUC 0-24 h and AUC 0-∞ than that of the reference agomelatine hydrogel and oral solution. This could reveal the prosperity of the optimized microemulsion gel formula to augment the transdermal bioavailability of agomelatine.

Detection of mechanically recovered chicken meat using capillary gel electrophoresis.

PubMed

Day, L; Brown, H

2001-05-01

This study investigated the use of capillary gel electrophoresis (CGE) as a method for differentiating between raw mechanically recovered chicken meat (MRM) and hand deboned chicken breast meat (HDM). Twenty samples of MRM were obtained and twenty samples of HDM were prepared in the laboratory. They were extracted and analysed using Prosort™ SDS-protein analysis reagent. There were obvious differences in the relative peak areas within the profiles obtained which distinguished raw MRM from raw HDM; specifically, that of haemoglobin was higher in MRM. Using the peak area of haemoglobin and its ratio to other peaks, the technique was tested using composite MRM-HDM mixtures. The results suggest that it is possible to differentiate mixtures containing 7.5% MRM from that of 0% MRM using the CGE method.

Lamellar Biogels: Fluid-Membrane-Based Hydrogels Containing Polymer Lipids

NASA Astrophysics Data System (ADS)

Warriner, Heidi E.; Idziak, Stefan H. J.; Slack, Nelle L.; Davidson, Patrick; Safinya, Cyrus R.

1996-02-01

A class of lamellar biological hydrogels comprised of fluid membranes of lipids and surfactants with small amounts of low molecular weight poly(ethylene glycol)-derived polymer lipids (PEG-lipids) were studied by x-ray diffraction, polarized light microscopy, and rheometry. In contrast to isotropic hydrogels of polymer networks, these membrane-based birefringent liquid crystalline biogels, labeled Lα,g, form the gel phase when water is added to the liquid-like lamellar L_α phase, which reenters a liquid-like mixed phase upon further dilution. Furthermore, gels with larger water content require less PEG-lipid to remain stable. Although concentrated (~50 weight percent) mixtures of free PEG (molecular weight, 5000) and water do not gel, gelation does occur in mixtures containing as little as 0.5 weight percent PEG-lipid. A defining signature of the Lα,g regime as it sets in from the fluid lamellar L_α phase is the proliferation of layer-dislocation-type defects, which are stabilized by the segregation of PEG-lipids to the defect regions of high membrane curvature that connect the membranes.

Evaluation of transcutol as a clonazepam transdermal permeation enhancer from hydrophilic gel formulations.

PubMed

Mura, P; Faucci, M T; Bramanti, G; Corti, P

2000-02-01

The influence of diethyleneglycol monoethyl ether (transcutol), alone or in combination with propylene glycol, on clonazepam permeation through an artificial membrane and excised rabbit ear skin from Carbopol hydrogels was investigated. Drug kinetic permeation parameters were determined for both series of experiments and compared. Rheological characteristics, drug solubility and membrane/vehicle partition coefficient for each gel formulation were also determined, and their role in the formulation performance was investigated. Both series of experiments showed an increase of drug permeation as a function of transcutol content in the formulation. The combination of transcutol and propylene glycol resulted in a synergistic enhancement of clonazepam flux. A different trend was found in experiments with gels containing mixtures of the two enhancers, where an increase (in the case of artificial membrane) or a decrease (in the case of rabbit ear skin) of drug permeation was found by increasing the transcutol/propylene glycol ratio in the mixture. Such a result is explained on the basis of the particular mechanism of action demonstrated for transcutol which associates the increase of drug solubility to the potent effect of a depot in the skin.

Determination of the sequences of protein-derived peptides and peptide mixtures by mass spectrometry

PubMed Central

Morris, Howard R.; Williams, Dudley H.; Ambler, Richard P.

1971-01-01

Micro-quantities of protein-derived peptides have been converted into N-acetylated permethyl derivatives, and their sequences determined by low-resolution mass spectrometry without prior knowledge of their amino acid compositions or lengths. A new strategy is suggested for the mass spectrometric sequencing of oligopeptides or proteins, involving gel filtration of protein hydrolysates and subsequent sequence analysis of peptide mixtures. Finally, results are given that demonstrate for the first time the use of mass spectrometry for the analysis of a protein-derived peptide mixture, again without prior knowledge of the protein or components within the mixture. PMID:5158904

Differential Activity-Driven Instabilities in Biphasic Active Matter

NASA Astrophysics Data System (ADS)

Weber, Christoph A.; Rycroft, Chris H.; Mahadevan, L.

2018-06-01

Active stresses can cause instabilities in contractile gels and living tissues. Here we provide a generic hydrodynamic theory that treats these systems as a mixture of two phases of varying activity and different mechanical properties. We find that differential activity between the phases causes a uniform mixture to undergo a demixing instability. We follow the nonlinear evolution of the instability and characterize a phase diagram of the resulting patterns. Our study complements other instability mechanisms in mixtures driven by differential adhesion, differential diffusion, differential growth, and differential motion.

Formation and functional properties of protein-polysaccharide electrostatic hydrogels in comparison to protein or polysaccharide hydrogels.

PubMed

Le, Xuan T; Rioux, Laurie-Eve; Turgeon, Sylvie L

2017-01-01

Protein and polysaccharide mixed systems have been actively studied for at least 50years as they can be assembled into functional particles or gels. This article reviews the properties of electrostatic gels, a recently discovered particular case of associative protein-polysaccharide mixtures formed through associative electrostatic interaction under appropriate solution conditions (coupled gel). This review highlights the factors influencing gel formation such as protein-polysaccharide ratio, biopolymer structural characteristics, final pH, ionic strength and total solid concentration. For the first time, the functional properties of protein-polysaccharide coupled gels are presented and discussed in relationship to individual protein and polysaccharide hydrogels. One of their outstanding characteristics is their gel water retention. Up to 600g of water per g of biopolymer may be retained in the electrostatic gel network compared to a protein gel (3-9g of water per g of protein). Potential applications of the gels are proposed to enable the food and non-food industries to develop new functional products with desirable attributes or new interesting materials to incorporate bioactive molecules. Copyright © 2016 Elsevier B.V. All rights reserved.

Chemical Processing of Nanostructured Coatings

DTIC Science & Technology

2000-01-01

increasing particle loading in sol-gel process (8-10). This approach involved dispersing large ceramic powders in sol-gel solution, and the mixture...the high loading of ceramic powders. One way to prepare thicker coatings is to add powders into the sol. This helps to reduce the capillary stresses...thickness that range between 2 and 4 microns. In order to investigate the nature and origin of the textured region of the coatings, GIXS was used to

Polysilicic acid gel method derived V2O5/SiO2 composite materials: Synthesis and characterization

NASA Astrophysics Data System (ADS)

Wang, Dawei; Zhou, Linzong; Feng, Xiaofei; Zhao, Ning; Yang, Bin

2017-01-01

The V2O5/SiO2 composite was prepared by a sol-gel method followed a sintering procedure. The low-cost Na2SiO3•9H2O was used as silicon source, while NH4VO3 was used as vanadium source. By adding NH4VO3 to Na2SiO3 solution and adjusting the mixture's pH with saturated (NH4)2SO4 solution the polysilicic acid gel was formed to give a homogeneous gel composite with VO3-well-distributed in it. The gel composite was dried at 100 °C to give the xerogel, then the xerogel was calcined in air to obtain the V2O5/SiO2 composite. The V2O5/SiO2 composites were characterized by SEM analysis, FT-IR spectroscopy and powder X-ray diffractions.

Pozzolanic activity and durability of nano silica, micro silica and silica gel contained concrete

NASA Astrophysics Data System (ADS)

Al Ghabban, Ahmed; Al Zubaidi, Aseel B.; Fakhri, Zahraa

2018-05-01

This paper aims to investigate the influence of replacement of cement with nano silica, micro silica and silica gel admixtures on pozzolanic activity, the replacement ratio was10% for all admixture, silica gel used in two forms (beads and crushed powder). Also, the water absorption test was investigated for obtaining the durability properties of concrete, in specimens for this test admixtures were added in four different dosages 1%, 2%, 3% and 4% by weight of the cementitious material into the concrete mixture. Experimental investigations of modified concrete were conducted after 28 days of water curing. Results showed that mixes of nano silica and crushed silica gel showed a higher pozzolanic activity index. For the water absorption test, all mixes incorporating nano silica, micro silica and silica gel showed lower absorption than control mixes best result were noticed with crushed silica gel and nano silica mixes. DTA analysis confirms the results for both poisonous activity and water absorption.

An Undergraduate Thin-Layer Chromatography Experiment: Olfactory Delights

NASA Astrophysics Data System (ADS)

Lynch, Mary Anne; Gloffke, Wendy; Rauner, Richard A.

1995-12-01

Mixtures of flavors and fragrances were separated on silica gel sheets, employing toluene/ethyl acetate (90:10) as the solvent. Constituents were located using alkaline potassium permanganate and 2,4-dinitrophenylhydrazine.

Mucoadhesive in situ gel formulation for vaginal delivery of clotrimazole: formulation, preparation, and in vitro/in vivo evaluation.

PubMed

Rençber, Seda; Karavana, Sinem Yaprak; Şenyiğit, Zeynep Ay; Eraç, Bayri; Limoncu, Mine Hoşgör; Baloğlu, Esra

2017-06-01

The purpose of this study was to develop a suitable mucoadhesive in situ gel formulation of clotrimazole (CLO) for the treatment of vaginal candidiasis. For this aim, the mixture of poloxamer (PLX) 407 and 188 were used to prepare in situ gels. Hydroxypropyl methylcellulose (HPMC) K100M or E50 was added to in situ gels in 0.5% ratio to improve the mucoadhesive and mechanical properties of formulations and to prolong the residence time in vaginal cavity. After the preparation of mucoadhesive in situ gels; gelation temperature/time, viscosity, mechanical, mucoadhesive, syringeability, spreadibility and rheological properties, in vitro release behavior, and anticandidal activities were determined. Moreover vaginal retention of mucoadhesive in situ gels was investigated with in vivo distribution studies in rats. Based on the obtained results, it was found that gels prepared with 20% PLX 407, 10% PLX 188 and 0.5% HPMC K100M/E50 might be suitable for vaginal administration of CLO. In addition, the results of in vivo distribution studies showed that gel formulations remained on the vaginal mucosa even 24 h after application. In conclusion, the mucoadhesive in situ gels of CLO would be alternative candidate for treatment of vaginal candidiasis since it has suitable gel properties with good vaginal retention.

Copolymers For Capillary Gel Electrophoresis

DOEpatents

Liu, Changsheng; Li, Qingbo

2005-08-09

This invention relates to an electrophoresis separation medium having a gel matrix of at least one random, linear copolymer comprising a primary comonomer and at least one secondary comonomer, wherein the comonomers are randomly distributed along the copolymer chain. The primary comonomer is an acrylamide or an acrylamide derivative that provides the primary physical, chemical, and sieving properties of the gel matrix. The at least one secondary comonomer imparts an inherent physical, chemical, or sieving property to the copolymer chain. The primary and secondary comonomers are present in a ratio sufficient to induce desired properties that optimize electrophoresis performance. The invention also relates to a method of separating a mixture of biological molecules using this gel matrix, a method of preparing the novel electrophoresis separation medium, and a capillary tube filled with the electrophoresis separation medium.

Ethanol effects on binary and ternary supported lipid bilayers with gel/fluid domains and lipid rafts.

PubMed

Marquês, Joaquim T; Viana, Ana S; De Almeida, Rodrigo F M

2011-01-01

Ethanol-lipid bilayer interactions have been a recurrent theme in membrane biophysics, due to their contribution to the understanding of membrane structure and dynamics. The main purpose of this study was to assess the interplay between membrane lateral heterogeneity and ethanol effects. This was achieved by in situ atomic force microscopy, following the changes induced by sequential ethanol additions on supported lipid bilayers formed in the absence of alcohol. Binary phospholipid mixtures with a single gel phase, dipalmitoylphosphatidylcholine (DPPC)/cholesterol, gel/fluid phase coexistence DPPC/dioleoylphosphatidylcholine (DOPC), and ternary lipid mixtures containing cholesterol, mimicking lipid rafts (DOPC/DPPC/cholesterol and DOPC/sphingomyelin/cholesterol), i.e., with liquid ordered/liquid disordered (ld/lo) phase separation, were investigated. For all compositions studied, and in two different solid supports, mica and silicon, domain formation or rearrangement accompanied by lipid bilayer thinning and expansion was observed. In the case of gel/fluid coexistence, low ethanol concentrations lead to a marked thinning of the fluid but not of the gel domains. In the case of ld/lo all the bilayer thins simultaneously by a similar extent. In both cases, only the more disordered phase expanded significantly, indicating that ethanol increases the proportion of disordered domains. Water/bilayer interfacial tension variation and freezing point depression, inducing acyl chain disordering (including opening and looping), tilting, and interdigitation, are probably the main cause for the observed changes. The results presented herein demonstrate that ethanol influences the bilayer properties according to membrane lateral organization. Copyright © 2010 Elsevier B.V. All rights reserved.

High Pressure Windowed Chamber Burned Rate Determination of Liquid Propellant XM46

DTIC Science & Technology

1994-06-01

being produced. Kelzan. sold by the Kelco Company, is a gum or polysaccharide obtaincd from a fermentation process of the bacteria which occurs naturally...mixture (gel) started forming small bubbles and changing color from clear to slightly yellow. When opening the plastic bag an odor similar to vinegar was...These results were not satisfactory and another Kelco product, Rhamsam gum KIAIl2, was iavestigated. This gel is also a fermentation polysaccharide which

Method for molding ceramic powders

DOEpatents

Janney, Mark A.

1990-01-01

A method for molding ceramic powders comprises forming a slurry mixture including ceramic powder, a dispersant for the metal-containing powder, and a monomer solution. The monomer solution includes at least one multifunctional monomer, a free-radical initiator, and an organic solvent. The slurry mixture is transferred to a mold, and the mold containing the slurry mixture is heated to polymerize and crosslink the monomer and form a firm polymer-solvent gel matrix. The solid product may be removed from the mold and heated to first remove the solvent and subsequently remove the polymer, whereafter the product may be sintered.

Method for molding ceramic powders

DOEpatents

Janney, M.A.

1990-01-16

A method for molding ceramic powders comprises forming a slurry mixture including ceramic powder, a dispersant for the metal-containing powder, and a monomer solution. The monomer solution includes at least one multifunctional monomer, a free-radical initiator, and an organic solvent. The slurry mixture is transferred to a mold, and the mold containing the slurry mixture is heated to polymerize and crosslink the monomer and form a firm polymer-solvent gel matrix. The solid product may be removed from the mold and heated to first remove the solvent and subsequently remove the polymer, where after the product may be sintered.

Inkjet Gene Printing: A Novel Approach to Achieve Gene Modified Cells for Tissue Engineering

DTIC Science & Technology

2008-12-01

and pIRES-VEGF-GFP (BD Biosciences, Bedford, MA) encoding the cDNAs of jellyfish Aequorea victoria green fluorescent protein, driven by the...prepared from rat-tail Type I collagen gels using a previously reported protocol(Xu et al. 2005). Briefly, rat- tail Type I collagen (BD Biosciences...aliquots of the mixture were dispersed onto coverslips and cured in an incubator for 3–5 h. Once the gel set, the collagen bio-paper was ready for

Lectin-Array Blotting.

PubMed

Pazos, Raquel; Echevarria, Juan; Hernandez, Alvaro; Reichardt, Niels-Christian

2017-09-01

Aberrant protein glycosylation is a hallmark of cancer, infectious diseases, and autoimmune or neurodegenerative disorders. Unlocking the potential of glycans as disease markers will require rapid and unbiased glycoproteomics methods for glycan biomarker discovery. The present method is a facile and rapid protocol for qualitative analysis of protein glycosylation in complex biological mixtures. While traditional lectin arrays only provide an average signal for the glycans in the mixture, which is usually dominated by the most abundant proteins, our method provides individual lectin binding profiles for all proteins separated in the gel electrophoresis step. Proteins do not have to be excised from the gel for subsequent analysis via the lectin array but are transferred by contact diffusion from the gel to a glass slide presenting multiple copies of printed lectin arrays. Fluorescently marked glycoproteins are trapped by the printed lectins via specific carbohydrate-lectin interactions and after a washing step their binding profile with up to 20 lectin probes is analyzed with a fluorescent scanner. The method produces the equivalent of 20 lectin blots in a single experiment, giving detailed insight into the binding epitopes present in the fractionated proteins. © 2017 by John Wiley & Sons, Inc. Copyright © 2017 John Wiley & Sons, Inc.

A multiphase approach to model ultrafiltration of deformable colloids

NASA Astrophysics Data System (ADS)

Haribabu, Malavika; Dunstan, Dave; Davidson, Malcolm; Harvie, Dalton

2017-11-01

Ultrafiltration (UF) is widely used in the dairy industry to fractionate and concentrate proteins, during the manufacture of milk protein concentrate and cheese. The protein build-up, comprising casein micelles (CM) and whey proteins, at the membrane surface during UF increases the resistance of the membrane system, thereby decreasing the performance of the process unit. CM have a complex structure that hydrodynamically behaves as a hard-sphere when dilute, but deforms beyond the random packing limit, forming a shear-thinning gel. This study employs a mixture model, based on the mixture phase continuity, Navier-Stokes equations, and solids continuity equation, to predict the solid concentration and velocity distribution during UF of CM. Micelle deformation is modelled as a function of volume fraction and dependent on its elastic modulus and particle size. The effect of deformation on gel permeability is implemented via Happel's permeability for hard spheres. Under crossflow conditions, the gel thickness is observed to increase along the membrane length, followed by a decrease towards the end of the membrane, resulting in an increase in flux at the latter section of the membrane. This study demonstrates that the membrane end-effects are important in determining UF performance.

Isolation and separation of physicochemically distinct fimbrial types expressed on a single culture of Escherichia coli O7:K1:H6.

PubMed Central

Karch, H; Leying, H; Büscher, K H; Kroll, H P; Opferkuch, W

1985-01-01

The fimbrial (pili) profile of a single strain of Escherichia coli O7:K1:H6 (WF96) was evaluated. Fimbriae were isolated by sucrose density gradient ultracentrifugation, purified from flagellae by the use of 0.4% sodium dodecyl sulfate (SDS), and separated into distinct fimbrial types. Analysis of the purified WF96 fimbriae by SDS-polyacrylamide gel electrophoresis revealed two polypeptide bands with molecular weights of 16,000 and 21,000. Treatment of the fimbrial mixture with saturated guanidine hydrochloride resulted in the appearance of a third band with a molecular weight of 19,500. The relative susceptibilities of the WF96 fimbrial types to disrupting chemicals (octyl-glucoside, urea, SDS, and guanidine hydrochloride) were assessed by exposure of the fimbrial mixture to each agent, separation of the depolymerized fimbriae from intact fimbriae by gel filtration on Sepharose CL-4B, and identification of the disaggregated fimbrial types by SDS-polyacrylamide gel electrophoresis of column fractions. The physicochemical heterogeneity of the three fimbrial types coexpressed on WF96 was exploited to develop a method for separation of individual fimbriae. Images PMID:2857155

Nanocrystalline (U0.5Ce0.5)O2±x solid solutions through citrate gel-combustion

NASA Astrophysics Data System (ADS)

Maji, D.; Ananthasivan, K.; Venkata Krishnan, R.; Balakrishnan, S.; Amirthapandian, S.; Joseph, Kitheri; Dasgupta, Arup

2018-04-01

Nanocrystalline powders of (U0.5Ce0.5)O2±x solid solutions were synthesized in bulk (100-200 g) through the citrate gel combustion. The fuel (citric acid) to oxidant (nitrate) mole ratio (R) was varied from 0.1 to 1.0. Two independent lots of the products obtained through the gel-combustion were calcined at 973 K in air and in a mixture of argon containing 8% H2 respectively. All these powders were characterized for their bulk density, X-ray crystallite size, specific surface area, size distribution of the particles, porosity as well as residual carbon. The morphology and microstructures of these powders were studied by using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) respectively. Nanocrystalline single phase fluorite solid solutions having a typical crystallite size of about (7-15 nm) were obtained. These powders were highly porous comprising cuboidal flaky agglomerates. The combustion mixture with an 'R' value of 0.25 was found to undergo volume combustion and was found to yield a product that was distinctly different. The systematic investigation on synthesis and characterization of nanocrystalline UCeO2 is reported for the first time.

Transungual Gel of Terbinafine Hydrochloride for the Management of Onychomycosis: Formulation, Optimization, and Evaluation.

PubMed

Thatai, Purva; Sapra, Bharti

2017-08-01

The present study was aimed to optimize, develop, and evaluate microemulsion and microemulsion-based gel as a vehicle for transungual drug delivery of terbinafine hydrochloride for the treatment of onychomycosis. D-optimal mixture experimental design was adopted to optimize the composition of microemulsion having amount of oil (X 1 ), Smix (mixture of surfactant and cosurfactant; X 2 ), and water (X 3 ) as the independent variables. The formulations were assessed for permeation (micrograms per square centimeter per hour; Y 1 ), particle size (nanometer; Y 2 ), and solubility of the drug in the formulation (milligrams per milliliter; Y 3 ). The microemulsion containing 3.05% oil, 24.98% Smix, and 71.96% water was selected as the optimized formulation. The microemulsion-based gel showed better penetration (∼5 folds) as well as more retention (∼9 fold) in the animal hoof as compared to the commercial cream. The techniques used to screen penetration enhancers (hydration enhancement factor, ATR-FTIR, SEM, and DSC) revealed the synergistic effect of combination of urea and n-acetyl cysteine in disruption of the structure of hoof and hence, leading to enhanced penetration of drug.

Molecular insights into early stage aggregation of di-Fmoc-L-lysine in binary mixture of organic solvent and water

NASA Astrophysics Data System (ADS)

Huda, Md Masrul; Rai, Neeraj

Molecular gels are relatively new class of soft materials, which are formed by the supramolecular aggregation of low molecular weight gelators (LMWGs) in organic solvents and/or water. Hierarchical self-assembly of small gelator molecules lead to three-dimensional complex fibrillar networks, which restricts the flow of solvents and results in viscous solid like materials or gels. These gels have drawn significant attentions for their potential applications for drug delivery, tissue engineering, materials for sensors etc. As of now, self-assembly of gelator molecules into one-dimensional fibers is not well understood, although that is very important to design new gelators for desired applications. Here, we present molecular dynamics study that provides molecular level insight into early stage aggregation of selected gelator, di-Fmoc-L-lysine in binary mixture of organic solvent and water. We will present the role of different functional groups of gelator molecule such as aromatic ring, amide, and carboxylic group on aggregation. We will also present the effect of concentrations of gelator and solvent on self-assembly of gelators. This study has captured helical fiber growth and branching of fiber, which is in good agreement with experimental observations.

Impact of future fuel properties on aircraft engines and fuel systems

NASA Technical Reports Server (NTRS)

Rudey, R. A.; Grobman, J. S.

1978-01-01

The effect of modifications in hydrocarbon jet fuels specifications on engine performance, component durability and maintenance, and aircraft fuel system performance is discussed. Specific topics covered include: specific fuel consumption; ignition at relight limits; exhaust emissions; combustor liner temperatures; carbon deposition; gum formation in fuel nozzles, erosion and corrosion of turbine blades and vanes; deposits in fuel system heat exchangers; and pumpability and flowability of the fuel. Data that evaluate the ability of current technology aircraft to accept fuel specification changes are presented, and selected technological advances that can reduce the severity of the problems are described and discussed.

Solid-phase assays for small molecule screening using sol-gel entrapped proteins.

PubMed

Lebert, Julie M; Forsberg, Erica M; Brennan, John D

2008-04-01

With compound libraries exceeding one million compounds, the ability to quickly and effectively screen these compounds against relevant pharmaceutical targets has become crucial. Solid-phase assays present several advantages over solution-based methods. For example, a higher degree of miniaturization can be achieved, functional- and affinity-based studies are possible, and a variety of detection methods can be used. Unfortunately, most protein immobilization methods are either too harsh or require recombinant proteins and thus are not amenable to delicate proteins such as kinases and membrane-bound receptors. Sol-gel encapsulation of proteins in an inorganic silica matrix has emerged as a novel solid-phase assay platform. In this minireview, we discuss the development of sol-gel derived protein microarrays and sol-gel based monolithic bioaffinity columns for the high-throughput screening of small molecule libraries and mixtures.

Metal ion promoted hydrogels for bovine serum albumin adsorption: Cu(II) and Co(II) chelated poly[(N-vinylimidazole)-maleic acid].

PubMed

Pekel, Nursel; Salih, Bekir; Güven, Olgun

2005-05-10

Poly[(N-vinylimidazole)-maleic acid] (poly(VIm-MA)), copolymeric hydrogels were prepared by gamma-irradiating ternary mixtures of N-vinylimidazole-maleic acid-water in a (60)Co-gamma source. Cu(II) and Co(II) ions were chelated within the gels at pH=5.0. The maximum adsorption capacity of the gels were 3.71 mmol/g dry gel for Cu(II) and 1.25 mmol/g dry gel for Co(II) at pH=5.0. The swelling ratios of the gels were 1200% for poly(VIm-MA), 60 and 45% for Cu(II) and Co(II)-chelated poly(VIm-MA) gels at pH=5.0 in acetate buffer solution. These affinity gels with different swelling ratios for plain poly(VIm-MA), Cu(II)-, and Co(II)-chelated poly(VIm-MA), in acetate and phosphate buffers were used in the bovine serum albumin (BSA) adsorption/desorption studies in batch reactor. The maximum BSA adsorption capacities of the gels were 0.38 g/g dry gel for plain, 0.88 g/g dry gel for Cu(II)-chelated poly(VIm-MA) and 1.05 g/g dry gel for Co(II)-chelated poly(VIm-MA) gels. Adsorption capacity of BSA by the gels was reduced dramatically by increasing the ionic strength adjusted with NaCl. More than 95% of BSA were desorbed in 10 h in desorption medium containing 0.1M of EDTA for metal ion-chelated gels at pH=4.7.

Water dispersible microbicidal cellulose acetate phthalate film

PubMed Central

Neurath, A Robert; Strick, Nathan; Li, Yun-Yao

2003-01-01

Background Cellulose acetate phthalate (CAP) has been used for several decades in the pharmaceutical industry for enteric film coating of oral tablets and capsules. Micronized CAP, available commercially as "Aquateric" and containing additional ingredients required for micronization, used for tablet coating from water dispersions, was shown to adsorb and inactivate the human immunodeficiency virus (HIV-1), herpesviruses (HSV) and other sexually transmitted disease (STD) pathogens. Earlier studies indicate that a gel formulation of micronized CAP has a potential as a topical microbicide for prevention of STDs including the acquired immunodeficiency syndrome (AIDS). The objective of endeavors described here was to develop a water dispersible CAP film amenable to inexpensive industrial mass production. Methods CAP and hydroxypropyl cellulose (HPC) were dissolved in different organic solvent mixtures, poured into dishes, and the solvents evaporated. Graded quantities of a resulting selected film were mixed for 5 min at 37°C with HIV-1, HSV and other STD pathogens, respectively. Residual infectivity of the treated viruses and bacteria was determined. Results The prerequisites for producing CAP films which are soft, flexible and dispersible in water, resulting in smooth gels, are combining CAP with HPC (other cellulose derivatives are unsuitable), and casting from organic solvent mixtures containing ≈50 to ≈65% ethanol (EtOH). The films are ≈100 µ thick and have a textured surface with alternating protrusions and depressions revealed by scanning electron microscopy. The films, before complete conversion into a gel, rapidly inactivated HIV-1 and HSV and reduced the infectivity of non-viral STD pathogens >1,000-fold. Conclusions Soft pliable CAP-HPC composite films can be generated by casting from organic solvent mixtures containing EtOH. The films rapidly reduce the infectivity of several STD pathogens, including HIV-1. They are converted into gels and thus do not have to be removed following application and use. In addition to their potential as topical microbicides, the films have promise for mucosal delivery of pharmaceuticals other than CAP. PMID:14617380

Influence of cryoprotectant levels on storage stability of surimi from Nemipterus japonicus and quality of surimi-based products.

PubMed

U, Parvathy; George, Sajan

2014-05-01

A study was undertaken with the aim of reducing the concentration of cryoprotectants in surimi without adversely affecting frozen storage stability. Minced meat from a tropical fish, Nemipterus japonicus, was strained, water leached and mixed with different levels of sucrose-sorbitol (1:1) mixture (henceforth called sugar mixture), quick frozen at -35 °C and frozen stored at -20 °C. The surimi samples were subjected to storage stability studies for a period of 5 months. Water leaching resulted in slight absorption of water by meat and reduction in protein, fat and mineral contents. Surimi was found to have moderately white colour. Sensory evaluation studies were conducted on three products, viz., sausage, patty and cake, prepared using surimi containing different concentrations of sugar mixture. Sugar mixture content varying from 0% (control) to 4% in surimi resulted in products that were more acceptable to the taste panelists compared those with 6% and 8% sugar mixture. During frozen storage of surimi pH and total plate count remained nearly steady for all sugar mixture concentrations and throughout the storage period. Moisture content appeared to remain constant during storage, but decreased with increase in sugar concentration. The salt soluble nitrogen content of surimi and gel strength of sausage prepared from it decreased with storage period in all surimi samples, and increased with sugar mixture concentration. Expressible water content of surimi sausage showed an increasing trend with storage period of surimi and a decreasing trend with sugar mixture concentration. Sensory evaluation parameters-elasticity, sweetness and preference-remained more or less steady during storage. However elasticity and sweetness increased and preference decreased with sugar mixture concentration beyond 4%. Elasticity and gel strength of surimi sausage seemed to be much lower for control compared to even the lowest concentration of sugar (2%) used. A concentration of 2 to 4% sucrose-sorbitol mixture is well-accepted by the consumers in products-surimi sausage, patty and cake and at this range of concentration surimi could be well-preserved at -20 °C for at least 5 months.

Process for preparing fine grain silicon carbide powder

DOEpatents

Wei, G.C.

Method of producing fine-grain silicon carbide powder comprises combining methyltrimethoxysilane with a solution of phenolic resin, acetone and water or sugar and water, gelling the resulting mixture, and then drying and heating the obtained gel.

Controlled release of sulfasalazine release from "smart" pectin gel microspheres under physiological simulated fluids.

PubMed

Costas, Luciana; Pera, Licia M; López, Azucena Gómez; Mechetti, Magdalena; Castro, Guillermo R

2012-07-01

Sulfasalazine (SLZ) is a synthetic nonsteroidal anti-inflammatory drug used mainly for the treatment of an inflammatory bowel and other diseases. Two pectins with different methylation degrees were blended to synthesized gel microspheres by ionotropic gelation for SLZ encapsulation. The encapsulation efficiency was found to be around of 99% in all formulations tested. However, different SLZ release profiles related to the methylation degrees of pectin were observed. Mixture of low methylated (LM) and high methylated (HM) pectins in the presence of calcium(II) displayed the best microsphere morphologies among the formulations tested determined by optical and electronic microscopies. The percentage of drug release using a mixture of LM and HM pectins after 255 min in simulated gastric fluid (pH = 1.2), simulated intestinal fluid (pH = 6.8), and phosphate buffer (pH = 7.4) were 15.0%, 47.0%, and 52.2%, respectively.

Pre-Steady-State Kinetic Analysis of Single-Nucleotide Incorporation by DNA Polymerases

PubMed Central

Su, Yan; Guengerich, F. Peter

2016-01-01

Pre-steady-state kinetic analysis is a powerful and widely used method to obtain multiple kinetic parameters. This protocol provides a step-by-step procedure for pre-steady-state kinetic analysis of single-nucleotide incorporation by a DNA polymerase. It describes the experimental details of DNA substrate annealing, reaction mixture preparation, handling of the RQF-3 rapid quench-flow instrument, denaturing polyacrylamide DNA gel preparation, electrophoresis, quantitation, and data analysis. The core and unique part of this protocol is the rationale for preparation of the reaction mixture (the ratio of the polymerase to the DNA substrate) and methods for conducting pre-steady-state assays on an RQF-3 rapid quench-flow instrument, as well as data interpretation after analysis. In addition, the methods for the DNA substrate annealing and DNA polyacrylamide gel preparation, electrophoresis, quantitation and analysis are suitable for use in other studies. PMID:27248785

Phase equilibria and formation of vesicles of dioleoylphosphatidylcholine in glycerol/water mixtures.

PubMed

Johansson, L B; Kalman, B; Wikander, G; Fransson, A; Fontell, K; Bergenståhl, B; Lindblom, G

1993-07-04

The lipid 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) forms a lamellar liquid crystalline phase (L alpha) in arbitrary mixtures of glycerol and water. The phase has been characterized by means of X-ray diffraction, 31P-NMR spectroscopy and differential scanning calorimetry (DSC). In the L alpha state, and for DOPC concentrations greater than 50% (w/w), the thickness of the lipid bilayer decreases, while the area of the polar head group increases with increasing glycerol concentration. The phase transition from gel to L alpha state occurs in the range of 240 to 260 K. Contrary to a previous (McDaniel, R.V., McIntosh, T.J. and Simon, S.A. (1983) Biochim. Biophys. Acta 731, 97) study of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) we find that in the gel state, the thickness of the DOPC lipid bilayer is greater than that in the L alpha state. This suggests that in the gel state, the lipid acyl chains of DOPC are in extended configuration. The lamellar phase reaches its maximum swelling at about 50% (w/w) of DOPC. At lower DOPC concentrations a two-phase system is formed where the lamellar phase exists in equilibrium with excess of solvent. Unilamellar vesicles can be prepared from a diluted suspension of the lamellar phase either by using the sonicator or extruder technique. We show this by means of 31P-NMR, EPR and fluorescence spectroscopy. The mean radius of the vesicles, prepared by a sonicator, has been determined at different glycerol/water mixtures. It is found to decrease continuously from 100 A at 100% water to a minimum of 75 A at about 50% water in the solvent mixture. By further decreasing the water content in the solution, the radius rapidly increases, and a mean radius of 450 A is estimated at a water content of 10%. The rotational relaxation times of a fluorescent probe and two EPR spin probes, solubilized in DOPC vesicles, have been measured at different glycerol/water mixtures. It is found that the rotational rates are always much slower in the systems containing glycerol.

A Sol-gel Integrated Dual-readout Microarray Platform for Quantification and Identification of Prostate-specific Antigen.

PubMed

Lee, SangWook; Lee, Jong Hyun; Kwon, Hyuck Gi; Laurell, Thomas; Jeong, Ok Chan; Kim, Soyoun

2018-01-01

Here, we report a sol-gel integrated affinity microarray for on-chip matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) that enables capture and identification of prostate?specific antigen (PSA) in samples. An anti-PSA antibody (H117) was mixed with a sol?gel, and the mixture was spotted onto a porous silicon (pSi) surface without additional surface modifications. The antibody easily penetrates the sol-gel macropore fluidic network structure, making possible high affinities. To assess the capture affinity of the platform, we performed a direct assay using fluorescein isothiocyanate-labeled PSA. Pure PSA was subjected to on-chip MALDI-TOF-MS analysis, yielding three clear mass peptide peaks (m/z = 1272, 1407, and 1872). The sol-gel microarray platform enables dual readout of PSA both fluorometric and MALDI-TOF MS analysis in biological samples. Here we report a useful method for a means for discovery of biomarkers in complex body fluids.

Separation of pharmacologically active nitrogen-containing compounds on silica gels modified with 6,10-ionene, dextran sulfate, and gold nanoparticles

NASA Astrophysics Data System (ADS)

Ioutsi, A. N.; Shapovalova, E. N.; Ioutsi, V. A.; Mazhuga, A. G.; Shpigun, O. A.

2017-12-01

New stationary phases for HPLC are obtained via layer-by-layer deposition of polyelectrolytes and studied: (1) silica gel modified layer-by-layer with 6,10-ionene and dextran sulfate (Sorbent 1); (2) silica gel twice subjected to the above modification (Sorbent 2); and (3) silica gel modified with 6,10-ionene, gold nanoparticles, and dextran sulfate (Sorbent 3). The effect the content of the organic solvent in the mobile phase and the concentration and pH of the buffer solution have on the chromatographic behavior of several pharmacologically active nitrogen-containing compounds is studied. The sorbents are stable during the process and allow the effective separation of beta-blockers, calcium channel blockers, alpha-agonists, and antihistamines. A mixture of caffeine, nadolol, tetrahydrozoline, pindolol, orphenadrine, doxylamine, carbinoxamine, and chlorphenamine is separated in 6.5 min on the silica gel modified with 6,10-ionene, gold nanoparticles, and dextran sulfate.

TM4SF5 promotes metastatic behavior of cells in 3D extracellular matrix gels by reducing dependency on environmental cues

PubMed Central

Nam, Seo Hee; Cheong, Jin-Gyu; Jeong, Doyoung; Lee, Seo-Jin; Pan, Cheol-Ho; Jung, Jae Woo; Kim, Hye-Jin; Ryu, Jihye; Kim, Ji Eon; Kim, Somi; Cho, Chang Yun; Kang, Min-Kyung; Lee, Kyung-Min; Lee, Jung Weon

2017-01-01

Transmembrane 4 L six family member 5 (TM4SF5) is highly expressed in hepatocellular carcinoma tissues and enhances migration in two-dimensional environments. Here, we investigated how TM4SF5 is involved in diverse pro-metastatic phenotypes in in vivo-like three-dimensional (3D) extracellular matrix gels. TM4SF5-positive cells aggressively formed invasive foci in 3D Matrigel, depending on TM4SF5-mediated signaling activity, cytoskeletal organization, and matrix metallopeptidase (MMP) 2-mediated extracellular remodeling, whereas TM4SF5-null cells did not. The TM4SF5-null cells did, however, form invasive foci in 3D Matrigel following inhibition of Rho-associated protein kinase or addition of collagen I, suggesting that collagen I compensated for TM4SF5 expression. Similarly, TM4SF5-positive cells expressing vascular endothelial-cadherin formed network-like vasculogenic mimicry in 3D Matrigel and collagen I mixture gels, whereas TM4SF5-negative cells in the mixture gels displayed the network structures only upon further treatment with epidermal growth factor. The foci formation also required MMP2-mediated remodeling of the extracellular matrix. Co-cultures exhibited TM4SF5-positive or cancer-associated fibroblasts at the outward edges of TM4SF5-null cell clusters. Compared with TM4SF5-null cells, TM4SF5-positive cells in 3D collagen gels showed a more invasive outgrowth with dramatic invadopodia. These observations suggest that TM4SF5 plays roles in the promotion of diverse metastatic properties with fewer environmental requirements than TM4SF5-negative cells. PMID:29137358

A new route for preparation of sodium-silicate-based hydrophobic silica aerogels via ambient-pressure drying

PubMed Central

Bangi, Uzma K H; Venkateswara Rao, A; Parvathy Rao, A

2008-01-01

An in-depth investigation into the synthesis of hydrophobic silica aerogels prepared by the surface derivatization of wet gels followed by subsequent drying at ambient pressure is reported. The following sol–gel parameters were examined for their effect on the physical properties of the derived aerogels: number of gel washings with water, percentage of hexane or methanol in silylating mixture, molar ratio of tartaric acid: Na2SiO3, gel aging period, weight% of silica, trimethylchlorosilane (TMCS) percentage, and silylation period. These parameters were varied from 1 to 4, 0 to 100%, 0.27 to 1.2, 0 to 4 h, 1.5 to 8 wt.%, 20 to 40% and 6 to 24 h, respectively. The properties of hydrophobic silica aerogels synthesized by this new route were investigated in terms of bulk density, percentage volume shrinkage, percentage porosity, thermal conductivity and contact angle with water, and by Fourier transform infrared spectroscopy (FTIR). The as-prepared hydrophobic silica aerogels exhibited high temperature stability (up to approximately 435 °C) as measured by thermogravimetric/differential thermal analysis (TGA-DTA). The optimal sol-gel parameters were found to be a molar ratio of Na2SiO3:H2O : tartaric acid : TMCS of 1 : 146.67 : 0.86 : 9.46, an aging period of 3 h, four washings with water in 24 h and the use of a 50% hexane- or methanol-based silylating mixture. Aerogels prepared with these optimal parameters were found to exhibit 50% optical transparency in the visible range, 84 kg m−3 density, 0.090 W mK−1 thermal conductivity, 95% porosity and a contact angle of 146° with water. PMID:27878003

Electrophoretic separator for purifying biologicals

NASA Technical Reports Server (NTRS)

1976-01-01

This technique separates a single narrow zone of sample mixture in an electrolyte medium into many zones containing a single component of the mixture and electrolyte between them. Since the densities of the separated zones generally differ from that of the intervening medium, such systems are gravitationally unstable and stabilization is required. The various techniques for stabilization include using the capillary space provided by thin films, the interstices of solid material such as filter paper and a variety of gel-forming substances.

Selective removal of 2,4-dichlorophenoxyacetic acid from water by molecularly-imprinted amino-functionalized silica gel sorbent.

PubMed

Han, Deman; Jia, Wenping; Liang, Huading

2010-01-01

A molecularly-imprinted amino-functionalized sorbent for selective removal of 2,4-dichlorophenoxyacetic acid (2,4-D) was prepared by a surface imprinting technique in combination with a sol-gel process. The 2,4-D-imprinted amino-functionalized silica sorbent was characterized by FT-IR, nitrogen adsorption and static adsorption experiments. The selectivity of the sorbent was investigated by a batch competitive binding experiment using an aqueous 2,4-D and 2,4-dichlorophenol (2,4-DCP) mixture or using an aqueous 2,4-D and 2,4-dichlorophenylacetic acid (DPAC) mixture. The largest selectivity coefficient for 2,4-D in the presence of 2,4-DCP was found to be over 18, the largest relative selectivity coefficient between 2,4-D and 2,4-DCP over 9. The static uptake capacity and selectivity coefficient of the 2,4-D-imprinted functionalized sorbent are higher than those of the non-imprinted sorbent. The imprinted functionalized silica gel sorbent offered a fast kinetics for the extraction/stripping of 2,4-D, 73% of binding capacity (200 mg/L 2,4-D onto 20 mg of imprinted sorbent) was obtained within 5 min and the adsorbed 2,4-D can be easily stripped by the mixture solution of ethanol and 6 mol/L HCl (V:V = 1:1). In a test of five extraction/stripping cycles, the adsorption capacity of the sorbent was all above 93% of that of the fresh sorbent. Experimental result showed the potential of molecularly-imprinted amino-functionalized sorbent for selective removal of 2,4-D.

Structural characteristics of gels prepared from sonohydrolysis and conventional hydrolysis of TEOS: an emphasis on the mass fractal as determined from the pore size distribution

NASA Astrophysics Data System (ADS)

Vollet, D. R.; Torres, R. R.; Donatti, D. A.; Ibañez Ruiz, A.

2005-11-01

Silica gels were preparated from fixed proportion mixtures of tetraethoxysilane, water and hydrocloric acid, using either ultrasound stimulation (US) or conventional method (CO) in the hydrolysis step of the process. Wet gels were obtained with the same silica volume concentration and density. According to small-angle X-ray scattering, the structure of the wet gels can be described as mass fractal structures with mass fractal dimension D = 2.20 in a length scale = 7.9 nm, in the case of wet gels US, and D = 2.26 in a length scale = 6.9 nm, in the case of wet gels CO. The mass fractal characteristics of the wet gels US and CO account for the different structures evolved in the drying of the gels US and CO in the obtaining of xerogels and aerogels. The pore structure of the dried gels was studied by nitrogen adsorption as a function of the temperature. Aerogels (US and CO) present high porosity with pore size distribution (PSD) curves in the mesopore region while xerogels (US and CO) present minor porosity with PSD curves mainly in the micropore region. The dried gels US (aerogels and xerogels) generally present pore volume and specific surface area greater than the dried gels CO. The mass fractal structure of the aerogels has been studied from an approach based on the PSD curves exclusively.

Different Effects of Long- and Short-Chain Ceramides on the Gel-Fluid and Lamellar-Hexagonal Transitions of Phospholipids: A Calorimetric, NMR, and X-Ray Diffraction Study

PubMed Central

Sot, Jesús; Aranda, Francisco J.; Collado, M.-Isabel; Goñi, Félix M.; Alonso, Alicia

2005-01-01

The effects on dielaidoylphosphatidylethanolamine (DEPE) bilayers of ceramides containing different N-acyl chains have been studied by differential scanning calorimetry small angle x-ray diffraction and 31P-NMR spectroscopy. N-palmitoyl (Cer16), N-hexanoyl (Cer6), and N-acetyl (Cer2) sphingosines have been used. Both the gel-fluid and the lamellar-inverted hexagonal transitions of DEPE have been examined in the presence of the various ceramides in the 0-25 mol % concentration range. Pure hydrated ceramides exhibit cooperative endothermic order-disorder transitions at 93°C (Cer16), 60°C (Cer6), and 54°C (Cer2). In DEPE bilayers, Cer16 does not mix with the phospholipid in the gel phase, giving rise to high-melting ceramide-rich domains. Cer16 favors the lamellar-hexagonal transition of DEPE, decreasing the transition temperature. Cer2, on the other hand, is soluble in the gel phase of DEPE, decreasing the gel-fluid and increasing the lamellar-hexagonal transition temperatures, thus effectively stabilizing the lamellar fluid phase. In addition, Cer2 was peculiar in that no equilibrium could be reached for the Cer2-DEPE mixture above 60°C, the lamellar-hexagonal transition shifting with time to temperatures beyond the instrumental range. The properties of Cer6 are intermediate between those of the other two, this ceramide decreasing both the gel-fluid and lamellar-hexagonal transition temperatures. Temperature-composition diagrams have been constructed for the mixtures of DEPE with each of the three ceramides. The different behavior of the long- and short-chain ceramides can be rationalized in terms of their different molecular geometries, Cer16 favoring negative curvature in the monolayers, thus inverted phases, and the opposite being true of the micelle-forming Cer2. These differences may be at the origin of the different physiological effects that are sometimes observed for the long- and short-chain ceramides. PMID:15695626

Western Blot of Stained Proteins from Dried Polyacrylamide Gels

NASA Technical Reports Server (NTRS)

Gruber, Claudia; Stan-Lotter, Helga

1996-01-01

Western blotting of proteins is customarily performed following their separation on polyacrylamide gels, either prior to staining (1) or, as recently reported, following staining (2). We describe here Western blotting with stained gels, which had been dried and some of which had been stored for years. This procedure permits immunological analysis of proteins, to which antisera may have become available only later, or where the application of newly developed sensitive detection methods is desired. Once rehydration of the gels is achieved, proteins can be-transferred to blotting membranes by any appropriate protocol. Proteins stained with Coomassie Blue have to be detected with a non-chromogenic method, such as the film-based enhanced chemiluminescence (ECL)2) procedure (3). Silver stained proteins, which transfer in the colorless form, may be visualized by any detection method, although, because of the usually very low amounts of proteins, detection by ECL is preferable. Blotting of stained proteins from rehydrated gels is as rapid and as quantitative as from freshly prepared gels, in contrast to blotting from wet stained gels, which requires extensive washing and results in low transfer efficiency (2). Together with a photographic record of the gel pattern, unambiguous identification of immunoreactive proteins from complex mixtures is possible. Some further applications of this work are discussed.

Glycosaminoglycan blotting on nitrocellulose membranes treated with cetylpyridinium chloride after agarose-gel electrophoretic separation.

PubMed

Maccari, Francesca; Volpi, Nicola

2002-09-01

We describe a method for blotting and immobilizing several nonsulfated and sulfated complex polysaccharides on membranes made hydrophilic and positively charged by a cationic detergent after their separation by conventional agarose gel electrophoresis. Nitrocellulose membranes were derivatized with the cationic detergent cetylpyridinium chloride (CPC) and mixtures of glycosaminoglycans (GAGs) were capillary-blotted after their separation in agarose gel electrophoresis in barium acetate/1,2-diaminopropane. Single purified species of variously sulfated polysaccharides were transferred onto the derivatized membranes after electrophoresis with an efficiency of 100% and stained with alcian blue (irreversible staining) and toluidine blue (reversible staining) permitting about 0.1 nug threshold of detection. Nonsulfated polyanions, hyaluronic acid, a fructose-containing polysaccharide with a chondroitin backbone purified from Escherichia coli U1-41, and its defructosylated product, were also electrophoretically separated and transferred onto membranes. The limit of detection for desulfated GAGs was about 0.1-0.5 nug after irreversible or reversible staining. GAG extracts from bovine, lung and aorta, and human aorta and urine were separated by agarose gel electrophoresis and blotted on CPC-treated nitrocellulose membranes. The polysaccharide composition of these extracts was determined. The membrane stained with toluidine blue (reversible staining) was destained and the same lanes used for immunological detection or other applications. Reversible staining was also applied to recover single species of polysaccharides after electrophoretic separation of mixtures of GAGs and their transfer onto membranes. Single bands were released from the membrane with an efficiency of 70-100% for further biochemical characterization.

Resemblance of actin-binding protein/actin gels to covalently crosslinked networks

NASA Astrophysics Data System (ADS)

Janmey, Paul A.; Hvidt, Søren; Lamb, Jennifer; Stossel, Thomas P.

1990-05-01

THE maintainance of the shape of cells is often due to their surface elasticity, which arises mainly from an actin-rich cytoplasmic cortex1,2. On locomotion, phagocytosis or fission, however, these cells become partially fluid-like. The finding of proteins that can bind to actin and control the assembly of, or crosslink, actin filaments, and of intracellular messages that regulate the activities of some of these actin-binding proteins, indicates that such 'gel sol' transformations result from the rearrangement of cortical actin-rich networks3. Alternatively, on the basis of a study of the mechanical properties of mixtures of actin filaments and an Acanthamoeba actin-binding protein, α-actinin, it has been proposed that these transformations can be accounted for by rapid exchange of crosslinks between actin filaments4: the cortical network would be solid when the deformation rate is greater than the rate of crosslink exchange, but would deform or 'creep' when deformation is slow enough to permit crosslinker molecules to rearrange. Here we report, however, that mixtures of actin filaments and actin-binding protein (ABP), an actin crosslinking protein of many higher eukaryotes, form gels Theologically equivalent to covalently crosslinked networks. These gels do not creep in response to applied stress on a time scale compatible with most cell-surface movements. These findings support a more complex and controlled mechanism underlying the dynamic mechanical properties of cortical cytoplasm, and can explain why cells do not collapse under the constant shear forces that often exist in tissues.

Influences of urea–glycerol mixtures as mixed mesopore-controlling agents on tailoring physicochemical properties and photocatalytic H{sub 2} production activity of sol–gel-derived mesoporous-assembled TiO{sub 2} nanocrystals

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

Sreethawong, Thammanoon, E-mail: sreethawongt@imre.a-star.edu.sg; Ngamsinlapasathian, Supachai, E-mail: wonone@hotmail.com; Yoshikawa, Susumu

2013-01-15

Graphical abstract: Display Omitted Highlights: ► Mesoporous-assembled TiO{sub 2} nanocrystals were synthesized by modified sol–gel process. ► Urea–glycerol mixtures were applied as mixed mesopore-controlling agents. ► Urea and glycerol contents affected physicochemical properties of synthesized TiO{sub 2}. ► Photocatalytic H{sub 2} production activity also depended on urea and glycerol contents. ► 75 mol% urea and 25 mol% glycerol yielded the most photocatalytically active TiO{sub 2}. -- Abstract: In this work, the mesoporous-assembled TiO{sub 2} nanocrystal photocatalysts were successfully synthesized by a sol–gel process with the aid of urea–glycerol mixtures used as mixed mesopore-controlling agents. The photocatalytic activity of the synthesizedmore » mesoporous-assembled TiO{sub 2} nanocrystal photocatalysts was investigated for hydrogen production from the water splitting reaction using methanol as a hole scavenger under UV light irradiation. The synthesized TiO{sub 2} nanocrystal photocatalysts were systematically characterized by TG–DTA, N{sub 2} adsorption–desorption, SEM, high resolution TEM, and XRD analyses. The characterization results showed that the well-controlled contents of urea and glycerol in a urea–glycerol mixture at 75 mol% urea and 25 mol% glycerol resulted in not only the most highly porous network (i.e. the highest specific surface area and total pore volume, and the smallest mean mesopore diameter), but also the smallest crystallite size of the synthesized TiO{sub 2} nanocrystal photocatalyst. The photocatalytic reaction results, hence, revealed a much superior photocatalytic hydrogen production activity of the mesoporous-assembled TiO{sub 2} nanocrystal synthesized with 75 mol% urea and 25 mol% glycerol to the other synthesized TiO{sub 2} nanocrystals, also being much higher than those of the commercially available P-25 TiO{sub 2} and ST-01 TiO{sub 2} powders.« less

Clinical and radiographic evaluation of zinc oxide with aloe vera as an obturating material in pulpectomy: an in vivo study.

PubMed

Khairwa, Abhishek; Bhat, Manohar; Sharma, Rajesh; Satish, V; Maganur, Prabhadevi; Goyal, Anil Kumar

2014-01-01

Pulp therapy for pulpally involved primary teeth continues to be a challenge to clinicians. One of the major areas of continued research is in the area of finding obturating materials to suit the specific properties of these teeth. Zinc oxide eugenol is used frequently in pulpectomy for the obturation of the primary teeth. To evaluate clinically and radiographically a mixture of zinc oxide eugenol and aloe vera as an obturating material. A total of 50 children, aged between 4 and 9 years, who were screened for unilateral or bilateral carious deciduous molars were studied. Out of these, 15 children were randomly selected for endodontic treatment. Obturation was done with a mixture of zinc oxide powder and aloe vera gel. Clinical and radiographic evaluation was done after 7 days, 1 month, 3 months, 6 months, and 9 months. The data were statistically analyzed. Endodontic treatment using a mixture of zinc oxide powder and aloe vera gel in primary teeth has shown good clinical and radiographic success. A detailed observational study with longer follow-up will highlight the benefits of aloe vera in primary teeth as an obturating medium.

Choosing the best molecular precursor to prepare Li4Ti5O12 by the sol-gel method using (1)H NMR: evidence of [Ti3(OEt)13](-) in solution.

PubMed

García-Herbosa, Gabriel; Aparicio, Mario; Mosa, Jadra; Cuevas, José V; Torroba, Tomás

2016-09-21

(1)H NMR spectroscopy at 400 MHz in toluene-d8 of evaporated mixtures of lithium ethoxide and titanium(iv) isopropoxide in ethanol, used to prepare the spinel Li4Ti5O12 by the sol-gel method, may help clarify why the atomic ratio 5Li : 5Ti and not 4Li : 5Ti is the right choice to obtain the pure phase when performing hydrolysis at room temperature. The mixtures xLiOEt/yTi(OPr(i))4 in ethanol undergo alcohol exchange at room temperature, and the evaporated residues contain double lithium-titanium ethoxide [LiTi3(OEt)13] rather than simple mixtures of single metal alkoxides; this is of great relevance to truly understanding the chemistry and structural changes in the sol-gel process. Detailed inspection of the (1)H and (13)C VT NMR spectra of mixtures with different Li/Ti atomic ratios unequivocally shows the formation of [LiTi3(OEt)13] in a solution at low temperature. The methylene signals of free lithium ethoxide and Li[Ti3(OEt)13] coalesce at 20 °C when the atomic ratio is 5 : 5; however, the same coalescence is only observed above 60 °C when the atomic ratio is 4 : 5. We suggest that the highest chemical equivalence observed by (1)H NMR spectroscopy achieved through chemical exchange of ethoxide groups involves the highest microscopic structural homogeneity of the sol precursor and will lead to the best gel after hydrolysis. Variable temperature (1)H NMR spectra at 400 MHz of variable molar ratios of LiOEt/Ti(OPr(i))4 are discussed to understand the structural features of the sol precursor. While the precursor with the atomic ratio 5Li : 5Ti shows no signal of free LiOEt at 20 °C, both 4Li : 5Ti and 7Li : 5Ti show free LiOEt at 20 °C in their (1)H NMR spectra, indicating that the molar ratio 5Li : 5Ti gives the maximum rate of chemical exchange. DFT calculations have been performed to support the structure of the anion [Ti3(OEt)13](-) at room temperature.

Development and application of new composite grouting material for sealing groundwater inflow and reinforcing wall rock in deep mine.

PubMed

Jinpeng, Zhang; Limin, Liu; Futao, Zhang; Junzhi, Cao

2018-04-04

With cement, bentonite, water glass, J85 accelerator, retarder and water as raw materials, a new composite grouting material used to seal groundwater inflow and reinforce wall rock in deep fractured rock mass was developed in this paper. Based on the reaction mechanism of raw material, the pumpable time, stone rate, initial setting time, plastic strength and unconfined compressive strength of multi-group proportion grouts were tested by orthogonal experiment. Then, the optimum proportion of composite grouting material was selected and applied to the grouting engineering for sealing groundwater inflow and reinforcing wall rock in mine shaft lining. The results show the mixing proportion of the maximum pumpable time, maximum stone rate and minimum initial setting time of grout are A K4 B K1 C K4 D K2 , A K3 B K1 C K1 D K4 and A K3 B K3 C K4 D K1 , respectively. The mixing proportion of the maximum plastic strength and unconfined compressive strength of grouts concretion bodies are A K1 B K1 C K1 D K3 and A K1 B K1 C K1 D K1 , respectively. Balanced the above 5 indicators overall and determined the optimum proportion of grouts: bentonite-cement ratio of 1.0, water-solid ratio of 3.5, accelerator content of 2.9% and retarder content of 1.45%. This new composite grouting material had good effect on the grouting engineering for sealing groundwater inflow and reinforcing wall rock in deep fractured rock mass.

Combustion characterization of carbonized RDF, Joint Venture Task No. 7. Topical Report

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

None, None

1995-04-30

The overall objective of this research program was to demonstrate EnerTech's and the Energy & Environmental Research Center's (EERC) process of slurry carbonization for producing homogeneous, pumpable titels from refuse-derived fuel (RDF) with continuous pilot plant facilities, and to characterize flue gas and ash emissions from combustion of the carbonizd RDF slurry fuel. Please note that "Wet Thermal Oxidation" is EnerTech's trademark mme for combustion of the carbonized RDF slurry fuel. Carbonized RDF slurry fuels were produced with the EERC'S 7.5-tpd (wet basis) pilot plant facility. A hose diaphragm pump pressurized a 7- lo-wt% feed RDF slurry, with a viscositymore » of 500 cP, to approximately 2500 psig. The pressurized RDF slurry was heated by indirect heat exchangers to between 5850 -626°F, and its temperature and pressure was maintained in a downflow reactor. The carbonized slurry was flashed, concentrated in a filter press, and ground in an attritor. During operation of the pilot plant, samples of the feed RDF slurry, carbonization gas, condensate, carbonized solids, and filtrate were taken and analyzed. Pilot-scale slurry carbonization experiments with RDF produced a homogeneous pumpable slurry fuel with a higher heating value (HHV) of 3,000-6,600 Btu/lb (as-received basis), at a viscosity of 500 CP at 100 Hz decreasing, and ambient temperature. Greater-heating-value slurry fuels were produced at higher slurry carbonization temperatures. During slurry carbonization, polyvinyl chloride (PVC) plastics in the feed RDF also decompose to form hydrochloric acid and salts. Pilot-scale slurty carbonization experiments extracted 82-94% of the feed RDF chlorine content as chloride salts. Higher carbonization temperatures and higher alkali additions to the feed slurry produced a higher chlorine extraction.« less

Comparison of topical anesthetics (EMLA/Oraqix vs. benzocaine) on pain experienced during palatal needle injection.

PubMed

Al-Melh, Manal Abu; Andersson, Lars

2007-05-01

The aim of this study was to compare the topical anesthetic effect of 20% benzocaine gel with 2.5% lidocaine/2.5% prilocaine (L/P) cream and gel on the pain experienced during palatal anesthetic infiltration. Two groups were studied, each containing 20 subjects. Two types of L/P mixtures were tested, an anesthetic cream (EMLA) and a thermosetting gel (Oraqix), and benzocaine was used as control. The topical agents were applied on the palatal mucosa at the canine region. A needle prick was given on each side every 2 minutes during a period of 10 minutes. The subjects recorded their findings using verbal and VAS scales. Pain scores were significantly less (P < .05) with EMLA and Oraqix than with benzocaine. Topical application of EMLA and Oraqix before palatal anesthetic infiltration is associated with less pain than with benzocaine gel.

Mechanism of Action of Ribavirin: An Antiviral Drug of Military Importance,

DTIC Science & Technology

1980-06-01

was suspended in 120 mM Tris, 60 mM sodium ace- tate, 3 mM EDTA (pH 7.4) plus 10% glycerol and 0.1% bromophenol blue. Following electrophoresis, gels ... polyacryl - amide gels . J. Mol. Biol. 26:373-387. 2. Browne, M. J. 1979. Mechanism and specificity of action of ri- bavirin. Antimicrob. Agents...of 10 mM EDTA, 1% sodi- um dodecylsulfate (SDS) and 0.4 N sodium acetate (pH 5.2) then ex- tracted twice with a mixture of 50% phenol, 49% chloroform

Purification and some properties of the protein component of tissue thromboplastin from human brain.

PubMed Central

Bjorklid, E; Storm, E

1977-01-01

The protein component of tissue thromboplastib (Factor III) from human brain was purified by extraction of a microsomal fraction with sodium deoxycholate, gel filtration of the extract on Sephadex G-100 and preparative polyacrylamide-gel electrophoresis in the presence of sodium dodecyl sulphate. The product, apoprotein III, was homogeneous by anayltical polyacrylamide-gel electrophoresis, and it induced monospecific antibodies in rabbits and goat as shown by immunodiffusion and immunoelectrophoresis. Amino acid- and carbohydrate-analysis data for apoprotein III are presented. The carbohydrate moiety of the protein consists of fucose, mannose, galactose, N-acetylglucosamine and N-acetylneuraminate, amounting to a total content of 6.3g/100g. The apoprotein alone had no procoagulant activity. When Factor III was reconstituted by combining the pure apoprotein with a purified lipid fraction from the deoxycholate extract of crude Factor III, a high and optimal procoagulant activity was obtained at a phospholipid/protein ratio of 1.1g/g. Phosphatidylethanolamine alone had a weak but significant ability to restore activity, whereas phosphatidylcholine and phosphatidylserine separately had almost none. Two-component mixtures were on average more effective, and three-component mixtures far more effective, than the single phospholipids. The inclusion of a small amount of phosphatidylserine was very important for high activity. Images Fig. 2. PLATE 1 PMID:889578

Citrate gel-combustion synthesis and sintering of nanocrystalline ThO2 powders

NASA Astrophysics Data System (ADS)

Sanjay Kumar, D.; Ananthasivan, K.; Amirthapandian, S.; Dasgupta, Arup; Jogeswara Rao, G.

2017-12-01

A systematic study of the influence of citric acid to nitrate mole (R) ratio (R = 0 to 0.50) on the citrate gel-combustion synthesis of nanocrystalline (nc) ThO2 in bulk quantities (30 g) by using citrate gel-combustion was carried out. The nc-ThO2 powders were characterized for their bulk density, size distribution of particles, specific surface area, carbon residue and X-ray crystallite size. All these powders were compacted at pressures varying from 60 to 353 MPa and sintered by using the "two-step sintering" method. Powders prepared from a mixture with an "R" value of 0.125 compacted at 243 MPa yielded a maximum sintered density of 98.8 ± 0.3% T.D. For nc-ThO2, this is the highest sintered density reported so far. The microstructural investigations on nc-ThO2 powders were carried out by using both scanning electron microscopy (SEM) and transmission electron microscopy (TEM). SEM images of the sintered thoria monoliths revealed faceted grains with well defined grain boundaries. Shrinkage anisotropy factor (α) revealed that the compacts prepared from the powders obtained from starting mixtures with R values of 0.125-0.50 had undergone uniform sintering (near isotropic shrinkage).

A gel probe equilibrium sampler for measuring arsenic porewater profiles and sorption gradients in sediments: I. Laboratory development

USGS Publications Warehouse

Campbell, K.M.; Root, R.; O'Day, P. A.; Hering, J.G.

2008-01-01

A gel probe equilibrium sampler has been developed to study arsenic (As) geochemistry and sorption behavior in sediment porewater. The gels consist of a hydrated polyacrylamide polymer, which has a 92% water content. Two types of gels were used in this study. Undoped (clear) gels were used to measure concentrations of As and other elements in sediment porewater. The polyacrylamide gel was also doped with hydrous ferric oxide (HFO), an amorphous iron (Fe) oxyhydroxide. When deployed in the field, HFO-doped gels introduce a fresh sorbent into the subsurface thus allowing assessment of in situ sorption. In this study, clear and HFO-doped gels were tested under laboratory conditions to constrain the gel behavior prior to field deployment. Both types of gels were allowed to equilibrate with solutions of varying composition and re-equilibrated in acid for analysis. Clear gels accurately measured solution concentrations (??1%), and As was completely recovered from HFO-doped gels (??4%). Arsenic speciation was determined in clear gels through chromatographic separation of the re-equilibrated solution. For comparison to speciation in solution, mixtures of As(III) and As(V) adsorbed on HFO embedded in gel were measured in situ using X-ray absorption spectroscopy (XAS). Sorption densities for As(III) and As(V) on HFO embedded in gel were obtained from sorption isotherms at pH 7.1. When As and phosphate were simultaneously equilibrated (in up to 50-fold excess of As) with HFO-doped gels, phosphate inhibited As sorption by up to 85% and had a stronger inhibitory effect on As(V) than As(III). Natural organic matter (>200 ppm) decreased As adsorption by up to 50%, and had similar effects on As(V) and As(III). The laboratory results provide a basis for interpreting results obtained by deploying the gel probe in the field and elucidating the mechanisms controlling As partitioning between solid and dissolved phases in the environment. ?? 2008 American Chemical Society.

New scale-down methodology from commercial to lab scale to optimize plant-derived soft gel capsule formulations on a commercial scale.

PubMed

Oishi, Sana; Kimura, Shin-Ichiro; Noguchi, Shuji; Kondo, Mio; Kondo, Yosuke; Shimokawa, Yoshiyuki; Iwao, Yasunori; Itai, Shigeru

2018-01-15

A new scale-down methodology from commercial rotary die scale to laboratory scale was developed to optimize a plant-derived soft gel capsule formulation and eventually manufacture superior soft gel capsules on a commercial scale, in order to reduce the time and cost for formulation development. Animal-derived and plant-derived soft gel film sheets were prepared using an applicator on a laboratory scale and their physicochemical properties, such as tensile strength, Young's modulus, and adhesive strength, were evaluated. The tensile strength of the animal-derived and plant-derived soft gel film sheets was 11.7 MPa and 4.41 MPa, respectively. The Young's modulus of the animal-derived and plant-derived soft gel film sheets was 169 MPa and 17.8 MPa, respectively, and both sheets showed a similar adhesion strength of approximately 4.5-10 MPa. Using a D-optimal mixture design, plant-derived soft gel film sheets were prepared and optimized by varying their composition, including variations in the mass of κ-carrageenan, ι-carrageenan, oxidized starch and heat-treated starch. The physicochemical properties of the sheets were evaluated to determine the optimal formulation. Finally, plant-derived soft gel capsules were manufactured using the rotary die method and the prepared soft gel capsules showed equivalent or superior physical properties compared with pre-existing soft gel capsules. Therefore, we successfully developed a new scale-down methodology to optimize the formulation of plant-derived soft gel capsules on a commercial scale. Copyright © 2017 Elsevier B.V. All rights reserved.

Temperature and flow measurements on near-freezing aviation fuels in a wing-tank model

NASA Technical Reports Server (NTRS)

Friedman, R.; Stockemer, F. J.

1980-01-01

Freezing behavior, pumpability, and temperature profiles for aviation turbine fuels were measured in a 190-liter tank chilled to simulate internal temperature gradients encountered in commercial airplane wing tanks. When the bulk of the fuel was above the specification freezing point, pumpout of the fuel removed all fuel except a layer adhering to the bottom chilled surfaces, and the unpumpable fraction depended on the fuel temperature near these surfaces. When the bulk of the fuel was at or below the freezing point, pumpout ceased when solids blocked the pump inlet, and the unpumpable fraction depended on the overall average temperature.

Experimental Study of Low Temperature Behavior of Aviation Turbine Fuels in a Wing Tank Model

NASA Technical Reports Server (NTRS)

Stockemer, Francis J.

1979-01-01

An experimental investigation was performed to study aircraft fuels at low temperatures near the freezing point. The objective was an improved understanding of the flowability and pumpability of the fuels under conditions encoutered during cold weather flight of a long range commercial aircraft. The test tank simulated a section of an outer wing tank and was chilled on the upper and lower surfaces. Fuels included commercial Jet A and Diesel D-2; JP-5 from oil shale; and Jet A, intermediate freeze point, and D-2 fuels derived from selected paraffinic and naphthenic crudes. A pour point depressant was tested.

Direct analysis of in-gel proteins by carbon nanotubes-modified paper spray ambient mass spectrometry.

PubMed

Han, Feifei; Yang, Yuhan; Ouyang, Jin; Na, Na

2015-02-07

The in situ and direct extraction, desorption and ionization of in-gel intact proteins after electrophoresis has been achieved by carbon nanotubes (CNTs)-modified paper spray mass spectrometry at ambient conditions. Characteristics of CNTs (including larger surface area, smaller pore diameter and enhanced conductivity) were endowed to the porous filter paper substrate by uniformly dispersing the CNTs on the filter paper. Upon applying electric potential to the CNTs-modified paper, the in-gel proteins were extracted from the gel and subsequently migrated to the tip of the filter paper by electrophoresis-like behavior for paper spray ionization, which was monitored by extracted ion chronograms. The characterizations of modified filter papers and CNTs nanoparticles further confirmed the role of CNTs in in-gel protein extraction, protein migration as well as spray ionization at the paper tip. Under optimized conditions, a mixture of cytochrome c, lysozyme and myoglobin was successfully separated by native electrophoresis and subsequently analysed by the present method, showing a limit of detection of 10 ng per gel band. The present strategy offers a new pathway for the direct detection of in-gel intact proteins at ambient conditions without any pre-treatment (e.g. digestion, chemical extraction and desalting), which exhibits potential applications in top-down proteomics.

Titanium Dioxide Photocatalytic Polymerization of Acrylamide for Gel Electrophoresis (TIPPAGE) of Proteins and Structural Identification by Mass Spectrometry

NASA Astrophysics Data System (ADS)

Zhang, Wenyang; Yuan, Zhiwei; Huang, Lulu; Kang, Jie; Jiang, Ruowei; Zhong, Hongying

2016-02-01

Polyacrylamide gel electrophoresis (PAGE) coupled with mass spectrometry has been well established for separating, identifying and quantifying protein mixtures from cell lines, tissues or other biological samples. The copolymerization process of acrylamide and bis-acrylamide is the key to mastering this powerful technique. In general, this is a vinyl addition reaction initiated by free radical-generating reagents such as ammonium persulfate (APS) and tetramethylethylenediamine (TEMED) under basic pH and degassing experimental condition. We report herein a photocatalytic polymerization approach that is based on photo-generated hydroxyl radicals with nanoparticles of titanium dioxide. It was shown that the polymerization process is greatly accelerated in acidic condition when ultraviolet light shots on the gel solution containing TiO2 nanoparticles without degassing. This feature makes it very useful in preparing Triton X-100 acid urea (TAU) gel that has been developed for separating basic proteins such as histones and variants in acidic experimental condition. Additionally, the presence of titanium dioxide in the gel not only improves mechanistic property of gels but also changes the migration pattern of different proteins that have different affinities to titanium dioxide.

Analysis of charge transport in gels containing polyoxometallates using methods of different sensitivity to migration.

PubMed

Caban, Karolina; Lewera, Adam; Zukowska, Grazyna Z; Kulesza, Pawel J; Stojek, Zbigniew; Jeffrey, Kenneth R

2006-08-04

Two methods have been used for examination of transport of charge in gels soaked with DMF and containing dissolved polyoxometallates. The first method is based on the analysis of both Cottrellian and steady-state currents and therefore is capable of giving the concentration of the electroactive redox centres and their transport (diffusion-type) coefficient. The second method provides the real diffusion coefficients, i.e. transport coefficients free of migrational influence, for both the substrate and the product of the electrode reaction. Several gels based on poly(methyl methacrylate), with charged (addition of 1-acrylamido-2-methyl-2-propanesulphonic acid to the polymerization mixture) and uncharged chains, have been used in the investigation. The ratio obtained for the diffusion coefficient (second method) and transport coefficient (first method) was smaller for the gels containing charged polymer chains than for the gels with uncharged chains. In part these changes could be explained by the contribution of migration to the transport of polyoxomatallates in the gels. However, the impact of the changes in the polymer-channel capacity at the electrode surface while the electrode process proceeds was also considered. These structural changes should affect differently the methods based on different time domains.

Wax-incorporated emulsion gel beads of calcium pectinate for intragastric floating drug delivery.

PubMed

Sriamornsak, Pornsak; Asavapichayont, Panida; Nunthanid, Jurairat; Luangtana-Anan, Manee; Limmatvapirat, Sontaya; Piriyaprasarth, Suchada

2008-01-01

The purpose of this study was to prepare wax-incorporated pectin-based emulsion gel beads using a modified emulsion-gelation method. The waxes in pectin-olive oil mixtures containing a model drug, metronidazole, were hot-melted, homogenized and then extruded into calcium chloride solution. The beads formed were separated, washed with distilled water and dried for 12 h. The influence of various types and amounts of wax on floating and drug release behavior of emulsion gel beads of calcium pectinate was investigated. The drug-loaded gel beads were found to float on simulated gastric fluid if the sufficient amount of oil was used. Incorporation of wax into the emulsion gel beads affected the drug release. Water-soluble wax (i.e. polyethylene glycol) increased the drug release while other water-insoluble waxes (i.e. glyceryl monostearate, stearyl alcohol, carnauba wax, spermaceti wax and white wax) significantly retarded the drug release. Different waxes had a slight effect on the drug release. However, the increased amount of incorporated wax in the formulations significantly sustained the drug release while the beads remained floating. The results suggest that wax-incorporated emulsion gel beads could be used as a carrier for intragastric floating drug delivery.

Titanium Dioxide Photocatalytic Polymerization of Acrylamide for Gel Electrophoresis (TIPPAGE) of Proteins and Structural Identification by Mass Spectrometry.

PubMed

Zhang, Wenyang; Yuan, Zhiwei; Huang, Lulu; Kang, Jie; Jiang, Ruowei; Zhong, Hongying

2016-02-11

Polyacrylamide gel electrophoresis (PAGE) coupled with mass spectrometry has been well established for separating, identifying and quantifying protein mixtures from cell lines, tissues or other biological samples. The copolymerization process of acrylamide and bis-acrylamide is the key to mastering this powerful technique. In general, this is a vinyl addition reaction initiated by free radical-generating reagents such as ammonium persulfate (APS) and tetramethylethylenediamine (TEMED) under basic pH and degassing experimental condition. We report herein a photocatalytic polymerization approach that is based on photo-generated hydroxyl radicals with nanoparticles of titanium dioxide. It was shown that the polymerization process is greatly accelerated in acidic condition when ultraviolet light shots on the gel solution containing TiO2 nanoparticles without degassing. This feature makes it very useful in preparing Triton X-100 acid urea (TAU) gel that has been developed for separating basic proteins such as histones and variants in acidic experimental condition. Additionally, the presence of titanium dioxide in the gel not only improves mechanistic property of gels but also changes the migration pattern of different proteins that have different affinities to titanium dioxide.

Titanium Dioxide Photocatalytic Polymerization of Acrylamide for Gel Electrophoresis (TIPPAGE) of Proteins and Structural Identification by Mass Spectrometry

PubMed Central

Zhang, Wenyang; Yuan, Zhiwei; Huang, Lulu; Kang, Jie; Jiang, Ruowei; Zhong, Hongying

2016-01-01

Polyacrylamide gel electrophoresis (PAGE) coupled with mass spectrometry has been well established for separating, identifying and quantifying protein mixtures from cell lines, tissues or other biological samples. The copolymerization process of acrylamide and bis-acrylamide is the key to mastering this powerful technique. In general, this is a vinyl addition reaction initiated by free radical-generating reagents such as ammonium persulfate (APS) and tetramethylethylenediamine (TEMED) under basic pH and degassing experimental condition. We report herein a photocatalytic polymerization approach that is based on photo-generated hydroxyl radicals with nanoparticles of titanium dioxide. It was shown that the polymerization process is greatly accelerated in acidic condition when ultraviolet light shots on the gel solution containing TiO2 nanoparticles without degassing. This feature makes it very useful in preparing Triton X-100 acid urea (TAU) gel that has been developed for separating basic proteins such as histones and variants in acidic experimental condition. Additionally, the presence of titanium dioxide in the gel not only improves mechanistic property of gels but also changes the migration pattern of different proteins that have different affinities to titanium dioxide. PMID:26865351

The influence of polymer molecular weight in lamellar gels based on PEG-lipids.

PubMed Central

Warriner, H E; Keller, S L; Idziak, S H; Slack, N L; Davidson, P; Zasadzinski, J A; Safinya, C R

1998-01-01

We report x-ray scattering, rheological, and freeze-fracture and polarizing microscopy studies of a liquid crystalline hydrogel called Lalpha,g. The hydrogel, found in DMPC, pentanol, water, and PEG-DMPE mixtures, differs from traditional hydrogels, which require high MW polymer, are disordered, and gel only at polymer concentrations exceeding an "overlap" concentration. In contrast, the Lalpha,g uses very low-molecular-weight polymer-lipids (1212, 2689, and 5817 g/mole), shows lamellar order, and requires a lower PEG-DMPE concentration to gel as water concentration increases. Significantly, the Lalpha,g contains fluid membranes, unlike Lbeta' gels, which gel via chain ordering. A recent model of gelation in Lalpha phases predicts that polymer-lipids both promote and stabilize defects; these defects, resisting shear in all directions, then produce elasticity. We compare our observations to this model, with particular attention to the dependence of gelation on the PEG MW used. We also use x-ray lineshape analysis of scattering from samples spanning the fluid-gel transition to obtain the elasticity coefficients kappa and B; this analysis demonstrates that although B in particular depends strongly on PEG-DMPE concentration, gelation is uncorrelated to changes in membrane elasticity. PMID:9649387

Apparatus for the production of gel beads containing a biocatalyst

DOEpatents

Scott, C.D.; Scott, T.C.; Davison, B.H.

1998-03-19

An apparatus is described for the large-scale and continuous production of gel beads containing a biocatalyst. The apparatus is a columnar system based on the chemical cross-linking of hydrocolloidal gels that contain and immobilize a biocatalyst, the biocatalyst being a microorganism or an enzyme. Hydrocolloidal gels, such as alginate, carrageenan, and a mixture of bone gelatin and modified alginate, provide immobilization matrices that can be used to entrap and retain the biocatalyst while allowing effective contact with substrates and release of products. Such immobilized biocatalysts are generally formulated into small spheres or beads that have high concentrations of the biocatalyst within the gel matrix. The columnar system includes a gel dispersion nozzle submerged in a heated non-interacting liquid, typically an organic liquid, that is immiscible with water to allow efficient formation of spherical gel droplets, the non-interacting liquid having a specific gravity that is less than water so that the gel droplets will fall through the liquid by the force of gravity. The heated non-interacting liquid is in direct contact with a chilled upflowing non-interacting liquid that will provide sufficient residence time for the gel droplets as they fall through the liquid so that they will be cooled below the gelling temperature and form solid spheres. The upflowing non-interacting liquid is in direct contact with an upflowing temperature-controlled aqueous solution containing the necessary chemicals for cross-linking or fixing of the gel beads to add the necessary stability. The flow rates of the two liquid streams can be varied to control the proper residence time in each liquid section to accommodate the production of gel beads of differing settling velocities. A valve is provided for continuous removal of the stabilized gel beads from the bottom of the column. 1 fig.

Apparatus and method for the production of gel beads containing a biocatalyst

DOEpatents

Scott, Charles D.; Scott, Timothy C.; Davison, Brian H.

1998-01-01

An apparatus and method for the large-scale and continuous production of gel beads containing a biocatalyst. The apparatus is a columnar system based on the chemical cross-linking of hydrocolloidal gels that contain and immobilize a biocatalyst, the biocatalyst being a microorganism or an enzyme. Hydrocolloidal gels, such as alginate, carrageenan, and a mixture of bone gelatin and modified alginate, provide immobilization matrices that can be used to entrap and retain the biocatalyst while allowing effective contact with substrates and release of products. Such immobilized biocatalysts are generally formulated into small spheres or beads that have high concentrations of the biocatalyst within the gel matrix. The columnar system includes a gel dispersion nozzle submerged in a heated non-interacting liquid, typically an organic liquid, that is immiscible with water to allow efficient formation of spherical gel droplets, the non-interacting liquid having a specific gravity that is less than water so that the gel droplets will fall through the liquid by the force of gravity. The heated non-interacting liquid is in direct contact with a chilled upflowing non-interacting liquid that will provide sufficient residence time for the gel droplets as they fall through the liquid so that they will be cooled below the gelling temperature and form solid spheres. The upflowing non-interacting liquid is in direct contact with an upflowing temperature-controlled aqueous solution containing the necessary chemicals for cross-linking or fixing of the gel beads to add the necessary stability. The flow rates of the two liquid streams can be varied to control the proper residence time in each liquid section to accommodate the production of gel beads of differing settling velocities. A valve is provided for continuous removal of the stabilized gel beads from the bottom of the column.

Apparatus for the production of gel beads containing a biocatalyst

DOEpatents

Scott, Charles D.; Scott, Timothy C.; Davison, Brian H.

1998-01-01

An apparatus for the large-scale and continuous production of gel beads containing a biocatalyst. The apparatus is a columnar system based on the chemical cross-linking of hydrocolloidal gels that contain and immobilize a biocatalyst, the biocatalyst being a microorganism or an enzyme. Hydrocolloidal gels, such as alginate, carrageenan, and a mixture of bone gelatin and modified alginate, provide immobilization matrices that can be used to entrap and retain the biocatalyst while allowing effective contact with substrates and release of products. Such immobilized biocatalysts are generally formulated into small spheres or beads that have high concentrations of the biocatalyst within the gel matrix. The columnar system includes a gel dispersion nozzle submerged in a heated non-interacting liquid, typically an organic liquid, that is immiscible with water to allow efficient formation of spherical gel droplets, the non-interacting liquid having a specific gravity that is less than water so that the gel droplets will fall through the liquid by the force of gravity. The heated non-interacting liquid is in direct contact with a chilled upflowing non-interacting liquid that will provide sufficient residence time for the gel droplets as they fall through the liquid so that they will be cooled below the gelling temperature and form solid spheres. The upflowing non-interacting liquid is in direct contact with an upflowing temperature-controlled aqueous solution containing the necessary chemicals for cross-linking or fixing of the gel beads to add the necessary stability. The flow rates of the two liquid streams can be varied to control the proper residence time in each liquid section to accommodate the production of gel beads of differing settling velocities. A valve is provided for continuous removal of the stabilized gel beads from the bottom of the column.

A facile approach to fabricate porous nanocomposite gels based on partially hydrolyzed polyacrylamide and cellulose nanocrystals for adsorbing methylene blue at low concentrations.

PubMed

Zhou, Chengjun; Lee, Sunyoung; Dooley, Kerry; Wu, Qinglin

2013-12-15

Porous nanocomposite gels were fabricated by a facile method consisting of the electrospinning and subsequent heat treatment based on partially hydrolyzed polyacrylamide (HPAM) of ultra-high molecular weight, with cellulose nanocrystals (CNCs) as crosslinker. The effects of three electrospinning parameters (i.e., solution concentration, composition of solvent mixture, and CNC loading level) on morphology and diameter of electrospun fibers were systematically investigated. The swelling properties of porous gels and their application in the removal of methylene blue dye (as a compound representative of contaminants) were evaluated. Electrospun fiber morphologies without beads, branches, and ribbons were achieved by optimizing the electrospinning solutions. The thermal crosslinking between HPAM and CNCs was realized through esterification, rendering the product nanocomposite membranes insoluble in water. Electrospun fibers of approximately 220 nm in diameter comprised the 3D porous nanocomposite gels, with porosity greater than 50%. The porous nanocomposite gels displayed a rapid swelling rate and an efficient adsorption capacity in removing methylene blue at low concentrations from aqueous solutions. Copyright © 2013 Elsevier B.V. All rights reserved.

Surface-deacetylated chitin nanofibers reinforced with a sulfobutyl ether β-cyclodextrin gel loaded with prednisolone as potential therapy for inflammatory bowel disease.

PubMed

Tabuchi, Ryo; Anraku, Makoto; Iohara, Daisuke; Ishiguro, Takako; Ifuku, Shinsuke; Nagae, Tomone; Uekama, Kaneto; Okazaki, Shoko; Takeshita, Keizo; Otagiri, Masaki; Hirayama, Fumitoshi

2017-10-15

Surface-deacetylated chitin nanofibers (SDACNFs) reinforced with a sulfobutyl ether β-cyclodextrin (SBE-β-CD) (NFs-CDs) gel were developed to obtain a controlled release carrier of prednisolone (PD) for the treatment of colitis. PD was released slowly from the gel at both pH 1.2 and 6.8. The in vitro slow release of PD from the NFs-CDs gel was reflected in the in vivo absorption of the drug after oral administration to rats. These results suggest that a simple gel composed of a mixture of SDACNFs and SBE-β-CD has the potential for use in the controlled release of PD. We also evaluated the therapeutic effects of the NFs-CDs gel containing PD on dextran sulfate sodium (DSS)-induced colitis model mice. The administration of the NFs-CDs gel at intervals of 3days from the beginning of the DSS treatment resulted in a significant improvement, not only in colitis symptoms but also histopathological changes in colon tissue. In addition, the therapeutic effects of the NFs-CDs gel on colitis can be attributed to decreased levels of neutrophil infiltration and the development of oxidative stress. These efficacy profiles of the NFs-CDs gel containing PD suggest that it has the potential for use in the treatment of, not only colitis, but also a variety of other disorders associated with inflammation and oxidative injuries. Copyright © 2017 Elsevier Ltd. All rights reserved.

A multiphase mixture model for substrate concentration distribution characteristics and photo-hydrogen production performance of the entrapped-cell photobioreactor.

PubMed

Guo, Cheng-Long; Cao, Hong-Xia; Pei, Hong-Shan; Guo, Fei-Qiang; Liu, Da-Meng

2015-04-01

A multiphase mixture model was developed for revealing the interaction mechanism between biochemical reactions and transfer processes in the entrapped-cell photobioreactor packed with gel granules containing Rhodopseudomonas palustris CQK 01. The effects of difference operation parameters, including operation temperature, influent medium pH value and porosity of packed bed, on substrate concentration distribution characteristics and photo-hydrogen production performance were investigated. The results showed that the model predictions were in good agreement with the experimental data reported. Moreover, the operation temperature of 30 °C and the influent medium pH value of 7 were the most suitable conditions for photo-hydrogen production by biodegrading substrate. In addition, the lower porosity of packed bed was beneficial to enhance photo-hydrogen production performance owing to the improvement on the amount of substrate transferred into gel granules caused by the increased specific area for substrate transfer in the elemental volume. Copyright © 2015 Elsevier Ltd. All rights reserved.

Preparation of powders suitable for conversion to useful .beta.-aluminas

DOEpatents

Morgan, Peter E. D.

1982-01-01

A process for forming a precursor powder which, when suitably pressed and sintered forms highly pure, densified .beta.- or .beta."-alumina, comprising the steps of: (1) forming a suspension (or slurry) of Bayer-derived Al(OH).sub.3 in a water-miscible solvent; (2) adding an aqueous solution of a Mg compound, a Li compound, a Na compound or mixtures thereof to the Bayer-derived Al(OH).sub.3 suspension while agitating the mixture formed thereby, to produce a gel; (3) drying the gel at a temperature above the normal boiling point of water to produce a powder material; (4) lightly ball milling and sieving said powder material; and (5) heating the ball-milled and sieved powder material at a temperature of between 350.degree. to 900.degree. C. to form the .beta.- or .beta."-alumina precursor powder. The precursor powder, thus formed, may be subsequently isopressed at a high pressure and sintered at an elevated temperature to produce .beta.- or .beta."-alumina. BACKGROUND OF THE INVENTION

Biofoam II

DOEpatents

Morrison, R.L.

1994-11-01

Biofoam is a rigid, microcellular organic foam made from organic materials derived from natural products and biological organisms. Starting materials include agar, agarose, gelatin, algin, alginates, gellan gum, and microcrystalline cellulose. The organic material is dissolved in a polar solvent, typically water, and the mixture is gelled. The water in the gel pores is replaced at least once with another solvent to reduce the pore size of the final biofoam. The solvent in the gel pores may be replaced several times. After the final replacement of solvent, the gel is frozen and freeze-dried to form a biofoam. Translucent biofoams are formed by selecting a final solvent that forms very small crystals. A variety of crystalline, fibrous, amorphous, or metallic additives may be incorporated into the foam structure to produce lightweight composite materials with enhanced strength and insulating properties. 1 fig.

Biofoam II

DOEpatents

Morrison, Robert L.

1994-01-01

Biofoam is a rigid, microcellular organic foam made from organic materials derived from natural products and biological organisms. Starting materials include agar, agarose, gelatin, algin, alginates, gellan gum, and microcrystalline cellulose. The organic material is dissolved in a polar solvent, typically water, and the mixture is gelled. The water in the gel pores is replaced at least once with another solvent to reduce the pore size of the final biofoam. The solvent in the gel pores may be replaced several times. After the final replacement of solvent, the gel is frozen and freeze-dried to form a biofoam. Translucent biofoams are formed by selecting a final solvent that forms very small crystals. A variety of crystalline, fibrous, amorphous, or metallic additives may be incorporated into the foam structure to produce lightweight composite materials with enhanced strength and insulating properties.

Development and application of a sol-gel immunosorbent-based method for the determination of isoproturon in surface water.

PubMed

Zhang, Xiuli; Martens, Dieter; Krämer, Petra M; Kettrup, Antonius A; Liang, Xinmiao

2006-01-13

An immunosorbent was fabricated by encapsulation of monoclonal anti-isoproturon antibodies in sol-gel matrix. The immunosorbent-based loading, rinsing and eluting processes were optimized. Based on these optimizations, the sol-gel immunosorbent (SG-IS) selectively extracted isoproturon from an artificial mixture of 68 pesticides. In addition to this high selectivity, the SG-IS proved to be reusable. The SG-IS was combined with liquid chromatography-tandem mass spectrometry (LC-MS-MS) to determine isoproturon in surface water, and the linear range was up to 2.2 microg/l with correlation coefficient higher than 0.99 and relative standard deviation (RSD) lower than 5% (n=8). The limit of quantitation (LOQ) for 25-ml surface water sample was 5 ng/l.

Sol-gel open tubular ODS columns with reversed electroosmotic flow for capillary electrochromatography.

PubMed

Hayes, J D; Malik, A

2001-03-01

Sol-gel chemistry was successfully used for the fabrication of open tubular columns with surface-bonded octadecylsilane (ODS) stationary-phase coating for capillary electrochromatography (OT-CEC). Following column preparations, a series of experiments were performed to investigate the performance of the sol-gel coated ODS columns in OT-CEC. The incorporation of N-octadecyldimethyl[3-(trimethoxysilyl)propyl]ammonium chloride as one of the sol-gel precursors played an important role in the electrochromatographic performance of the prepared columns. This chemical reagent possesses a chromatographically favorable, bonded ODS moiety, in conjunction with three methoxy groups allowing for sol-gel reactivity. In addition, a positively charged nitrogen atom is present in the molecular structure of this reagent and provides a positively charged capillary surface responsible for the reversed electroosmotic flow (EOF) in the columns during CEC operation. Comparative studies involving the EOF within such sol-gel ODS coated and uncoated capillaries were performed using acetonitrile and methanol as the organic modifiers in the mobile phase. The use of a deactivating reagent, phenyldimethylsilane, in the sol-gel solution was evaluated. Efficiency values of over 400,000 theoretical plates per meter were achieved in CEC on a 64 cm x 25 microm i.d. sol-gel ODS open tubular column. Test mixtures of polycyclic aromatic hydrocarbons, benzene derivatives, and aromatic aldehydes and ketones were used to evaluate the CEC performances of both nondeactivated and deactivated open tubular sol-gel columns. The effects of mobile-phase organic modifier contents and pH on EOF in such columns were evaluated. The prepared sol-gel ODS columns are characterized by switchable electroosmotic flow. A pH value of approximately 8.5 was found correspond to the isoelectric point for the prepared sol-gel ODS coatings.

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

Saunders, C.B.; Carmichael, A.A.; Kremers, W.

The mechanical and physical properties of electron-beam (EB) curable carbon-fiber-reinforced composites were investigated, using a resin matrix made from a mixture of 50 percent of an epoxy diacrylate oligomer, 30 percent of a polybutadiene diacrylate oligomer, and 20 percent of dipentaerythritol monohydroxypentaacrylate monomer, and applying varying EB doses for curing the mixture. It was found that the gel content in the cured prepreg polymer depended upon the total EB dose below 50 kGy, the dose rate, and, at a low dose of 16 kGy/hr, on the atmosphere and pressure during irradiation. 14 refs.

Extraction, Purification, and Spectroscopic Characterization of a Mixture of Capsaicinoids

ERIC Educational Resources Information Center

Wagner, Carl E.; Cahill, Thomas M.; Marshall, Pamela A.

2011-01-01

This laboratory experiment provides a safe and effective way to instruct undergraduate organic chemistry students about natural-product extraction, purification, and NMR spectroscopic characterization. On the first day, students extract dried habanero peppers with toluene, perform a pipet silica gel column to separate carotenoids from…

Survival of Steinernema feltiae in different formulation substrates: improved longevity in a mixture of gel and vermiculite

USDA-ARS?s Scientific Manuscript database

Entomopathogenic nematodes (genera Steinernema and Heterorhabditis) have a symbiotic association with bacteria, which make them highly virulent to insects. These nematodes have been commercially produced as biopesticides, but nematode products still face significant barriers related to the preservat...

Solid materials for removing metals and fabrication method

DOEpatents

Coronado, Paul R.; Reynolds, John G.; Coleman, Sabre J.

2004-10-19

Solid materials have been developed to remove contaminating metals and organic compounds from aqueous media. The contaminants are removed by passing the aqueous phase through the solid materials which can be in molded, granular, or powder form. The solid materials adsorb the metals and the organics leaving a purified aqueous stream. The materials are sol-gel and or sol-gel and granulated activated carbon (GAC) mixtures. The species-specific adsorption occurs through specific chemical modifications of the solids tailored towards the contaminant(s). The contaminated solid materials can then be disposed of or the contaminant can be removed and the solids recycled.

Condition of Development of Channeled Flow in Analogue Partially Molten Medium

NASA Astrophysics Data System (ADS)

Takashima, S.; Kumagai, I.; Kurita, K.

2003-12-01

Melt migration in partially molten medium is conceptually classified into two contrasting models; homogeneous permeable flow and localized channeled flow. The transition from homogeneous flow to localized one is promoted with advance of melting and deformation of the medium, but the physics behind this transition is not yet clarified well. Here we show two kinds of experimental results which are mutually related. One is a development of the channeled flow in a so-called Rayleigh-Taylor Instability experiments. Dense viscous fluid is poured at the top of the matrix fluid; homogeneous mixture of soft transparent gel and viscous fluid having equal density. Liquid fraction is varied for this matrix fluid to see how the fraction controls the development. At the intermediate gel fraction (between70% to about 40%) the dense fluid at first migrates through the grain boundary as permeable flow. But local heterogeneity in the gel fraction induces relative movement of solid phase, which in turns enhances the localization of the flow and deformation. We measured the motion of fluid phase and solid phase separately by PIV/PTV methods. Estimated relative motion and divergence of velocity field of the solid phase show that the state in the relative movement of the solid phase could cause heterogeneous distribution of the solid fraction. The deformation-induced compaction plays an important role. The second experimental result is rheology of the dense suspension of soft gel and viscous fluid. Deformation experiment with concentric cylinders shows that the mixture system has yield strength at the intermediate gel fraction. In the stress state above the yield strength the region where deformation rate is large has low viscosity and its internal structure evolves to the state in heterogeneous distribution of viscosity. We would like to show that this nature is critical in the development of flow from homogeneous one to localized one.

Multi-stimuli-responsive organometallic gels based on ferrocene-linked poly(aryl ether) dendrons: reversible redox switching and Pb2+-ion sensing.

PubMed

Lakshmi, Neelakandan Vidhya; Mandal, Dipendu; Ghosh, Sundargopal; Prasad, Edamana

2014-07-14

We describe the design, synthesis, and "stimuli-responsive" study of ferrocene-linked Fréchet-type [poly(aryl ether)]-dendron-based organometallic gels, in which the ferrocene moiety is attached to the dendron framework through an acyl hydrazone linkage. The low-molecular-weight gelators (LMWGs) form robust gels in both polar and non-polar solvent/solvent mixtures. The organometallic gels undergo stimuli-responsive behavior through 1) thermal, 2) chemical, and 3) electrochemical methods. Among them, conditions 1 and 3 lead to seamlessly reversible with repeated cycles of identical efficiency. Results indicate that the flexible nature of the poly(aryl ether) dendron framework plays a key role in retaining the reversible electrochemical behavior of ferrocene moiety in the LMWGs. Further, the organometallic gelators have exhibited unique selectivity towards Pb(2+) ions (detection limit ≈10(-8)  M). The metal ion-sensing results in a gel-sol phase transition associated with a color change visible to the naked eye. Most importantly, decomplexing the metal ion from the system leads to the regeneration of the initial gel morphology, indicating the restoring ability of the organometallic gel. The metal-ligand binding nature has been analyzed by using (1)H NMR spectroscopy, mass spectrometry, and DFT calculations. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Low-fat pork liver pâtés enriched with n-3 PUFA/konjac gel: dynamic rheological properties and technological behaviour during chill storage.

PubMed

Delgado-Pando, G; Cofrades, S; Ruiz-Capillas, C; Triki, M; Jiménez-Colmenero, F

2012-09-01

Low-fat pork liver pâtés enriched with n-3 PUFA/konjac gel were formulated by replacing (total or partially) pork backfat by a combination of healthier oils (olive, linseed and fish oils) and konjac gel. Dynamic rheological properties and technological behaviour of pâtés during chill storage (2 °C, 85 days) were analysed. Cooking yields were affected (P<0.05) by formulation, with percentages ranging between 88 and 98%. According to the frequency sweep test, pâtés presented a gel/emulsion-like pattern with a loosely-structured network and the consistency of a viscoelastic gel. Thermal processing caused the formation of a protein gel network with a considerable element of emulsion-like characteristics. Pâtés became lighter and less red (P<0.05) during chill storage. Purge losses of around 1% were observed at the end of the storage period, irrespective of formulation. Textural parameters of pâtés were affected by formulation and storage time. The results suggest that the replacement of pork back fat by oil-in-water emulsion and the incorporation of konjac gel could provide a mixture of ingredients that effectively mimics the normal animal fat content in pâtés. Copyright © 2012 Elsevier Ltd. All rights reserved.

Effect of nanocomposite synthesis on the combustion performance of a ternary thermite.

PubMed

Prentice, Daniel; Pantoya, Michelle L; Clapsaddle, Brady J

2005-11-03

Nanocomposite thermites are attractive materials for their diverse applications from metallurgy to ordnance technologies. While there are a plethora of combinations of fuel and oxidizers, this work shows that the composite's overall performance is intimately tied to how the fuel and oxidizer are prepared and combined. Comparison of the combustion velocities of two separate ternary mixtures of Al-Fe(2)O(3)-SiO(2), one prepared in situ using sol-gel processing and the other prepared by physically mixing discrete nanoscale particles, demonstrated different burning behaviors as a result of preparation technique. The stoichiometry of the two sets of thermite was varied to examine the influence of SiO(2) on combustion velocity as a means to control the reaction behavior. For pure Fe(2)O(3) + Al reactions, results show that the sol-gel synthesized materials (40 m/s) exhibit increased velocities over the physically mixed materials (9 m/s) by approximately 4 times. This trend is not observed, however, upon addition of SiO(2) to the thermite mixture; ternary thermites with 40 wt % SiO(2) showed decreased burn velocities of 0.02 m/s for sol-gel prepared thermites compared to 0.2 m/s for their physically mixed counterparts. The observed trends are believed to be caused by the unique mixing between the Fe(2)O(3) and SiO(2) phases resulting from the two synthesis techniques.

A simple and high-resolution stereolithography-based 3D bioprinting system using visible light crosslinkable bioinks.

PubMed

Wang, Zongjie; Abdulla, Raafa; Parker, Benjamin; Samanipour, Roya; Ghosh, Sanjoy; Kim, Keekyoung

2015-12-22

Bioprinting is a rapidly developing technique for biofabrication. Because of its high resolution and the ability to print living cells, bioprinting has been widely used in artificial tissue and organ generation as well as microscale living cell deposition. In this paper, we present a low-cost stereolithography-based bioprinting system that uses visible light crosslinkable bioinks. This low-cost stereolithography system was built around a commercial projector with a simple water filter to prevent harmful infrared radiation from the projector. The visible light crosslinking was achieved by using a mixture of polyethylene glycol diacrylate (PEGDA) and gelatin methacrylate (GelMA) hydrogel with eosin Y based photoinitiator. Three different concentrations of hydrogel mixtures (10% PEG, 5% PEG + 5% GelMA, and 2.5% PEG + 7.5% GelMA, all w/v) were studied with the presented systems. The mechanical properties and microstructure of the developed bioink were measured and discussed in detail. Several cell-free hydrogel patterns were generated to demonstrate the resolution of the solution. Experimental results with NIH 3T3 fibroblast cells show that this system can produce a highly vertical 3D structure with 50 μm resolution and 85% cell viability for at least five days. The developed system provides a low-cost visible light stereolithography solution and has the potential to be widely used in tissue engineering and bioengineering for microscale cell patterning.

Radial Chromatography for the Separation of Nitroaniline Isomers

ERIC Educational Resources Information Center

Miller, Robert B.; Case, William S.

2011-01-01

Separation techniques are usually presented in the undergraduate organic laboratory to teach students how to purify and isolate compounds. Often the concept of liquid chromatography is introduced by having students create "silica gel columns" to separate components of a reaction mixture. Although useful, column chromatography can be a laborious…

21 CFR 866.4500 - Immunoelectrophoresis equipment.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Immunoelectrophoresis equipment. 866.4500 Section 866.4500 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES.... Immunoelectrophoresis is a procedure in which a complex protein mixture is placed in an agar gel and the various...

21 CFR 866.4500 - Immunoelectrophoresis equipment.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Immunoelectrophoresis equipment. 866.4500 Section 866.4500 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES.... Immunoelectrophoresis is a procedure in which a complex protein mixture is placed in an agar gel and the various...

Difference in volatile profile between pericarp tissue and locular gel in tomato fruit

USDA-ARS?s Scientific Manuscript database

Aroma, a complex mixture of volatile compounds, plays an important role in the perception and acceptability of tomato products by consumers. Numerous studies have reported volatile profiles in tomatoes based on measurement of the whole fruit or pericarp tissue, however, little is understood regardin...

Macroporous polyacrylamide monolithic gels with immobilized metal affinity ligands: the effect of porous structure and ligand coupling chemistry on protein binding.

PubMed

Plieva, Fatima; Bober, Beata; Dainiak, Maria; Galaev, Igor Yu; Mattiasson, Bo

2006-01-01

Macroporous polyacrylamide gels (MPAAG) with iminodiacetic acid (IDA) functionality were prepared by (i) chemical modification of polyacrylamide gel, (ii) co-polymerization of acrylamide with allyl glycidyl ether (AGE) and N,N'metylene-bis(acrylamide) (MBAAm) followed by coupling IDA ligand or (iii) by copolymerization of acrylamide and MBAAm with functional monomer carrying IDA-functionality (1-(N,N-bis(carboxymethyl)amino-3-allylglycerol). Screening for optimized conditions for the production of the MPAAG with required porous properties was performed in a 96-well chromatographic format that allowed parallel production and analysis of the MPAAG prepared from reaction mixtures with different compositions. Scanning electron microscopy of the fabricated MPAAG revealed two different types of the porous structures: monomodal macroporous structure with large interconnected pores separated by dense non-porous pore walls in case of plain gels or gels produced via copolymerization with AGE. The other type of the MPAAG (gel produced via co-polymerization with functional monomer carrying IDA-functionality) had bimodal pore structure with large interconnected pores separated by the pore walls pierced through with micropores. The effect of different modifications of MPAAG monoliths and of porous structure of the MPAAG (monomodal and bimodal porous structure) on protein binding has been evaluated. Copyright 2006 John Wiley & Sons, Ltd.

Hydrothermal synthesis of ammonium illite

USGS Publications Warehouse

Šucha, Vladimír; Elsass, F.; Eberl, D.D.; Kuchta, L'.; Madejova, J.; Gates, W.P.; Komadel, P.

1998-01-01

Synthetic gel and glass of illitic composition, natural kaolinite, and mixed-layer illite-smectite were used as starting materials for hydrothermal synthesis of ammonium illite. Ammonium illite was prepared from synthetic gel by hydrothermal treatment at 300??C. The onset of crystallization began within 3 h, and well-crystallized ammonium illite appeared at 24 h. Increasing reaction time (up to four weeks) led to many illite layers per crystal. In the presence of equivalent proportions of potassium and ammonium, the gel was transformed to illite with equimolar contents of K and NH4. In contrast, synthesis using glass under the same conditions resulted in a mixture of mixed-layer ammonium illite-smectite with large expandability and discrete illite. Hydrothermal treatments of the fine fractions of natural kaolinite and illite-smectite produced ammonium illite from kaolinite but the illite-smectite remained unchanged.

The design of an irradiator for the continuous processing of liquid latex

NASA Astrophysics Data System (ADS)

Reuter, O.; Langley, R.; Zn, Wan Manshol Bin W.

1998-06-01

This paper presents anew design concept for a gamma irradiation plant for the continuous processing of pumpable liquids. Typical applications of such a plant include ∗ the irradiation vulcanisation of natural latex rubber ∗ disinfection of municipal sewage sludge for agricultural use ∗ sterilisation of liquids in the pharmaceutical and cosmetics industries ∗ industrial processing of bulk liquids The authors describe the design and operation of the latex irradiator now operating on a small production scale in Malaysia and proposed developments. The design allows irradiation processing to be carried out under an inert or other gaseous environment. State-of-the-art computer control system ensures the fully automatic processing operation needed by industrial computers.

The influence of fine aggregates on the 3D printing performance

NASA Astrophysics Data System (ADS)

Lin, J. C.; Wu, X.; Yang, W.; Zhao, R. X.; Qiao, L. G.

2018-01-01

Influences of nature Particle, size, grain shape and fineness modulus of fine aggregates on the 3D printing performance of cement-based mortar were investigated. Results showed that the working performance of the mortar is not only dependent on the fineness of the aggregate, but also the gradation and grain size of the aggregate. And the mechanical properties of the mortar are increasing with the increase of Mx in the same test condition. The research shows that it is effective to choose different properties of materials for different design requirements, and the fluidity of mortar must be decreased under assuring construction quality and the pumpability of 3D printing materials.

Novel route for rapid sol-gel synthesis of hydroxyapatite, avoiding ageing and using fast drying with a 50-fold to 200-fold reduction in process time.

PubMed

Ben-Arfa, Basam A E; Salvado, Isabel M Miranda; Ferreira, José M F; Pullar, Robert C

2017-01-01

We have developed an innovative, rapid sol-gel method of producing hydroxyapatite nanopowders that avoids the conventional lengthy ageing and drying processes (over a week), being 200 times quicker in comparison to conventional aqueous sol-gel preparation, and 50 times quicker than ethanol based sol-gel synthesis. Two different sets of experimental conditions, in terms of pH value (5.5 and 7.5), synthesis temperature (45 and 90°C), drying temperature (60 and 80°C) and calcination temperature (400 and 700°C) were explored. The products were characterised by X-ray diffraction (XRD) Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and specific surface area (SSA) measurements. Pure hydroxyapatite (Ca 10 (PO 4 ) 6 (OH) 2 , HAp) was obtained for the powders synthesised at pH7.5 and calcined at 400°C, while biphasic mixtures of HAp/β-tricalcium phosphate (β-Ca 3 (PO 4 ) 2 , TCP) were produced at pH5.5 and (pH7.5 at elevated temperature). The novel rapid drying was up to 200 times faster than conventional drying, only needing 1h with no prior ageing step, and favoured the formation of smaller/finer nanopowders, while producing pure HAp or phase mixtures virtually identical to those obtained from the slow conventional drying method, despite the absence of a slow ageing process. The products of this novel rapid process were actually shown to have smaller crystallite sizes and larger SSA, which should result in increased bioactivity. Copyright © 2016 Elsevier B.V. All rights reserved.

Antibacterial activity evaluation of bioactive glass and biphasic calcium phosphate nanopowders mixtures

NASA Astrophysics Data System (ADS)

Nazemi, Zahra; Mehdikhani-Nahrkhalaji, Mehdi; Haghbin-Nazarpak, Masoumeh; Staji, Hamid; Kalani, Mohammad Mehdi

2016-12-01

The aim of this work was to evaluate the antibacterial activity of bioactive glass (BG) and biphasic calcium phosphate (BCP) nanopowders mixtures for the first time. 37S BG and BCP (50% HA-50% β-TCP) nanopowders were prepared via sol-gel technique. Characterization techniques such as X-ray diffraction, scanning electron microscopy, transition electron microscopy, and X-ray fluorescent. The antibacterial activity was studied using Escherichia coli and Salmonella typhi as gram-negative, and Staphylococcus aureus as gram-positive bacteria. The antibacterial effect of BG, BCP nanopowders, and their mixtures was evaluated at different concentrations. The 37S BG nanopowders showed minimum bactericidal concentration at 25 mg/ml. At broth concentrations below 300 mg/ml, BCP showed no antibacterial activity. BCP and BG nanopowders mixture (M2) with 60/40 ratio of BCP/BG showed noticeable antibacterial effect. It was concluded that BCP and 37S BG nanopowders mixture could be used as a good candidate for dental and orthopedic applications.

Synthesis and Properties of Nanoparticle Forms Saponite Clay, Cancrinite Zeolite and Phase Mixtures Thereof.

PubMed

Shao, Hua; Pinnavaia, Thomas J

2010-09-01

The low-temperature synthesis (90°C) of nanoparticle forms of a pure phase smectic clay (saponite) and zeolite (cancrinite) is reported, along with phase mixtures thereof. A synthesis gel corresponding to the Si:Al:Mg unit cell composition of saponite (3.6:0.40:3.0) and a NaOH/Si ratio of 1.39 affords the pure phase clay with disordered nanolayer stacking. Progressive increases in the NaOH/Si ratio up to a value of 8.33 results in the co-crystallization of first garronite and then cancrinite zeolites with nanolath morphology. The resulting phase mixtures exhibit a compound particulate structure of intertwined saponite nanolayers and cancrinite nanolaths that cannot be formed through physical mixing of the pure phase end members. Under magnesium-free conditions, pure phase cancrinite nanocrystals are formed. The Si/Al ratio of the reaction mixture affects the particle morphology as well as the chemical composition of the cancrinite zeolite. Ordinarily, cancrinite crystallizes with a Si/Al ratio of 1.0, but a silicon-rich form of the zeolite (Si/Al=1.25) is crystallized at low temperature from a silica rich synthesis gel, as evidenced by (29)Si NMR spectroscopy and XEDS-TEM. Owing to the exceptionally high external surface areas of the pure phase clay (875 m(2)/g) and zeolite end members (8.9 - 40 m(2)/g), as well as their unique mixed phase composites (124 - 329 m(2)/g), these synthetic derivatives are promising model nanoparticles for studies of the bioavailability of poly-aromatic hydrocarbons immobilized in silicate bearing sediments and soils.

Mixture genotoxicity of 2,4-dichlorophenoxyacetic acid, acrylamide, and maleic hydrazide on human Caco-2 cells assessed with comet assay.

PubMed

Syberg, Kristian; Binderup, Mona-Lise; Cedergreen, Nina; Rank, Jette

2015-01-01

Assessment of genotoxic properties of chemicals is mainly conducted only for single chemicals, without taking mixture genotoxic effects into consideration. The current study assessed mixture effects of the three known genotoxic chemicals, 2,4-dichlorophenoxyacetic acid (2,4-D), acrylamide (AA), and maleic hydrazide (MH), in an experiment with a fixed ratio design setup. The genotoxic effects were assessed with the single-cell gel electrophoresis assay (comet assay) for both single chemicals and the ternary mixture. The concentration ranges used were 0-1.4, 0-20, and 0-37.7 mM for 2,4-D, AA, and MH, respectively. Mixture toxicity was tested with a fixed ratio design at a 10:23:77% ratio for 2.4-D:AA:MH. Results indicated that the three chemicals yielded a synergistic mixture effect. It is not clear which mechanisms are responsible for this interaction. A few possible interactions are discussed, but further investigations including in vivo studies are needed to clarify how important these more-than-additive effects are for risk assessment.

Hyaluronic Acid Gel Injection to Prevent Thermal Injury of Adjacent Gastrointestinal Tract during Percutaneous Liver Radiofrequency Ablation

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

Hasegawa, Takaaki, E-mail: hasegawat@clin.medic.mie-u.ac.jp; Takaki, Haruyuki; Miyagi, Hideki

2013-08-01

This study evaluated the safety, feasibility, and clinical utility of hyaluronic acid gel injection to separate the gastrointestinal tract from the tumor during liver radiofrequency ablation (RFA). Eleven patients with liver tumors measuring 0.9-3.5 cm (mean {+-} standard deviation, 2.1 {+-} 0.8 cm) that were adjacent to the gastrointestinal tracts received RFA after the mixture of hyaluronic acid gel and contrast material (volume, 26.4 {+-} 14.5 mL; range, 10-60 mL) was injected between the tumor and the gastrointestinal tract under computed tomographic-fluoroscopic guidance. Each tumor was separated from the gastrointestinal tract by 1.0-1.5 cm (distance, 1.2 {+-} 0.2 cm) aftermore » injection of hyaluronic acid gel, and subsequent RFA was performed without any complications in all patients. Although tumor enhancement disappeared in all patients, local tumor progression was found in a patient (9.1 %, 1 of 11) during the follow-up of 5.5 {+-} 3.2 months (range, 0.4-9.9 months). In conclusion, hyaluronic acid gel injection is a safe and useful technique to avoid thermal injury of the adjacent gastrointestinal tract during liver RFA.« less

Method for the quantitation of gastric emptying time of gel test meals.

PubMed

Russell, J; Bass, P

1984-09-01

Isotopic markers were developed to allow measurement of the gastric emptying times of homogeneous and nonhomogeneous gel meals. Meals containing the dietary fibers psyllium and guar gum presented as homogeneous, viscous gels while meals containing the synthetic polymer polycarbophil presented as discrete gel particle-water mixtures. Fiber meals were labeled differently than polycarbophil meals. Fiber meals were labeled with 51Cr-CM-Sephadex. The marker was uniformly suspended in meals containing at least 1% guar or 2% psyllium. In contrast, polycarbophil particles were labeled by hydrating the dried granules with saline in which Na2(51)CrO4 had been dissolved. Use of the markers to measure gastric emptying was demonstrated in dogs fitted with duodenal cannulas. Half of the fiber meals emptied from the stomach in about 40 min without significant dilution by secretions. In contrast, only 8% of the polycarbophil particles emptied by 90 min. Particle-specific labeling of polycarbophil was important because the meal effluent was diluted extensively by secretions. We conclude that 51Cr-CM-Sephadex and soluble Cr-51 may be used as meal markers for estimation of the gastric emptying times of certain homogeneous and nonhomogeneous gel-type meals, respectively.

Cross-linked Composite Gel Polymer Electrolyte using Mesoporous Methacrylate-Functionalized SiO2 Nanoparticles for Lithium-Ion Polymer Batteries

PubMed Central

Shin, Won-Kyung; Cho, Jinhyun; Kannan, Aravindaraj G.; Lee, Yoon-Sung; Kim, Dong-Won

2016-01-01

Liquid electrolytes composed of lithium salt in a mixture of organic solvents have been widely used for lithium-ion batteries. However, the high flammability of the organic solvents can lead to thermal runaway and explosions if the system is accidentally subjected to a short circuit or experiences local overheating. In this work, a cross-linked composite gel polymer electrolyte was prepared and applied to lithium-ion polymer cells as a safer and more reliable electrolyte. Mesoporous SiO2 nanoparticles containing reactive methacrylate groups as cross-linking sites were synthesized and dispersed into the fibrous polyacrylonitrile membrane. They directly reacted with gel electrolyte precursors containing tri(ethylene glycol) diacrylate, resulting in the formation of a cross-linked composite gel polymer electrolyte with high ionic conductivity and favorable interfacial characteristics. The mesoporous SiO2 particles also served as HF scavengers to reduce the HF content in the electrolyte at high temperature. As a result, the cycling performance of the lithium-ion polymer cells with cross-linked composite gel polymer electrolytes employing methacrylate-functionalized mesoporous SiO2 nanoparticles was remarkably improved at elevated temperatures. PMID:27189842

Apparatus and method for the production of gel beads containing a biocatalyst

DOEpatents

Scott, C.D.; Scott, T.C.; Davison, B.H.

1998-01-27

An apparatus and method are disclosed for the large-scale and continuous production of gel beads containing a biocatalyst. The apparatus is a columnar system based on the chemical cross-linking of hydrocolloidal gels that contain and immobilize a biocatalyst, the biocatalyst being a microorganism or an enzyme. Hydrocolloidal gels, such as alginate, carrageenan, and a mixture of bone gelatin and modified alginate, provide immobilization matrices that can be used to entrap and retain the biocatalyst while allowing effective contact with substrates and release of products. Such immobilized biocatalysts are generally formulated into small spheres or beads that have high concentrations of the biocatalyst within the gel matrix. The columnar system includes a gel dispersion nozzle submerged in a heated non-interacting liquid, typically an organic liquid, that is immiscible with water to allow efficient formation of spherical gel droplets, the non-interacting liquid having a specific gravity that is less than water so that the gel droplets will fall through the liquid by the force of gravity. The heated non-interacting liquid is in direct contact with a chilled upflowing non-interacting liquid that will provide sufficient residence time for the gel droplets as they fall through the liquid so that they will be cooled below the gelling temperature and form solid spheres. The upflowing non-interacting liquid is in direct contact with an upflowing temperature-controlled aqueous solution containing the necessary chemicals for cross-linking or fixing of the gel beads to add the necessary stability. The flow rates of the two liquid streams can be varied to control the proper residence time in each liquid section to accommodate the production of gel beads of differing settling velocities. A valve is provided for continuous removal of the stabilized gel beads from the bottom of the column. 1 fig.

Percolation, phase separation, and gelation in fluids and mixtures of spheres and rods

NASA Astrophysics Data System (ADS)

Jadrich, Ryan; Schweizer, Kenneth S.

2011-12-01

The relationship between kinetic arrest, connectivity percolation, structure and phase separation in protein, nanoparticle, and colloidal suspensions is a rich and complex problem. Using a combination of integral equation theory, connectivity percolation methods, naïve mode coupling theory, and the activated dynamics nonlinear Langevin equation approach, we study this problem for isotropic one-component fluids of spheres and variable aspect ratio rigid rods, and also percolation in rod-sphere mixtures. The key control parameters are interparticle attraction strength and its (short) spatial range, total packing fraction, and mixture composition. For spherical particles, formation of a homogeneous one-phase kinetically stable and percolated physical gel is predicted to be possible, but depends on non-universal factors. On the other hand, the dynamic crossover to activated dynamics and physical bond formation, which signals discrete cluster formation below the percolation threshold, almost always occurs in the one phase region. Rods more easily gel in the homogeneous isotropic regime, but whether a percolation or kinetic arrest boundary is reached first upon increasing interparticle attraction depends sensitively on packing fraction, rod aspect ratio and attraction range. Overall, the connectivity percolation threshold is much more sensitive to attraction range than either the kinetic arrest or phase separation boundaries. Our results appear to be qualitatively consistent with recent experiments on polymer-colloid depletion systems and brush mediated attractive nanoparticle suspensions.

Purification of the major endoglucanase from Aspergillus fumigatus Fresenius.

PubMed

Parry, J B; Stewart, J C; Heptinstall, J

1983-08-01

Aspergillus fumigatus (Fresenius), IMI 246651, A.T.C.C. 46324, produces two beta-glucosidase enzymes, cotton-solubilizing activity, xylanase and endoglucanase enzymes which can be separated by gel-filtration chromatography. The major endoglucanase does not bind to concanavalin A-Sepharose and does not stain with periodic acid/Schiff reagent. It is homogeneous on polyacrylamide isoelectric focusing (pI = 7.1) and has a mol.wt. of 12500 by sodium dodecyl sulphate/polyacrylamide-gel electrophoresis. The endoglucanase produces glucose and a mixture of oligosaccharides from cellulose; the purified enzyme has a small dextranase activity. It is stable at 50 degrees C and pH 6.

Method of making thermally removable polymeric encapsulants

DOEpatents

Small, James H.; Loy, Douglas A.; Wheeler, David R.; McElhanon, James R.; Saunders, Randall S.

2001-01-01

A method of making a thermally-removable encapsulant by heating a mixture of at least one bis(maleimide) compound and at least one monomeric tris(furan) or tetrakis(furan) compound at temperatures from above room temperature to less than approximately 90.degree. C. to form a gel and cooling the gel to form the thermally-removable encapsulant. The encapsulant can be easily removed within approximately an hour by heating to temperatures greater than approximately 90.degree. C., preferably in a polar solvent. The encapsulant can be used in protecting electronic components that may require subsequent removal of the encapsulant for component repair, modification or quality control.

Inorganic-organic nanocomposites for optical coatings

NASA Astrophysics Data System (ADS)

Schmidt, Helmut K.; Krug, Herbert; Sepeur-Zeitz, Bernhard; Geiter, Elisabeth

1997-10-01

The fabrication of nanoparticles by the sol-gel process and their use in polymeric or sol-gel-derived inorganic-organic composite matrices opens up interesting possibilities for designing new optical materials. Two different routes have been chosen for preparing optical nanocomposites: The first is the so-called 'in situ route,' where the nanoparticles are synthesized in a liquid mixture from Zr-alkoxides in a polymerizable system and diffractive gratings were produced by embossing uncured film. The second is the 'separate' preparation route, where a sterically stabilized dry nanoboehmite powder was completely redispersed in an epoxy group-containing matrix and hard coatings with optical quality on polycarbonate were prepared.

Cellular thermosetting fluoropolymers and process for making them

NASA Technical Reports Server (NTRS)

Lee, Sheng Y.

1988-01-01

Thermosetting fluoropolymer foams are made by mixing fluid from thermosetting fluoropolymer components having a substantial fluoride content, placing the mixture in a pressure tight chamber, filling the chamber with a gas, at a relatively low pressure, that is unreactive with the fluoropolymer components, allowing the mixture to gel, removing the gelled fluoropolymer from the chamber and therafter heating the fluoropolymer at a relatively low temperature to simultaneously cure and foam the fluoropolymer. The resulting fluoropolymer product is closed celled with the cells storing the gas employed for foaming. The fluoropolymer resins employed may be any thermosetting fluoropolymer including fluoroepoxies, fluoropolyurethanes and fluoroacrylates.

Cellular thermosetting fluorodiepoxide polymers

NASA Technical Reports Server (NTRS)

Lee, Sheng Y. (Inventor)

1989-01-01

Thermosetting fluoropolymer foams are made by mixing fluid form thermosetting fluoropolymer components having a substantial fluorine content, placing the mixture in a pressure tight chamber, filling the chamber with a gas, at relatively low pressure, that is unreactive with the fluoropolymer components, allowing the mixture to gel, removing the gelled fluoropolymer from the chamber and thereafter heating the fluoropolymer at a relatively low temperature to simultaneously sure and foam the fluoropolymer. The resulting fluoropolymer product is closed celled with the cells storing the gas employed for foaming. The fluoropolymer resins employed may be any thermosetting fluoropolymer including fluoroepoxies, fluoropolyurethanes and fluoroacrylates.

Standards for electron probe microanalysis of silicates prepared by convenient method

NASA Technical Reports Server (NTRS)

Walter, L. S.

1966-01-01

Standard compositions suitable for electron probe microanalysis of various silicates are prepared by coprecipitation of specified salts with colloidal silica to form a gel which is decomposed into a powdered oxide mixture and compressed into thin pellets. These pellets of predetermined standard are compared with a silicate sample to determine its composition.

Colorful Column Chromatography: A Classroom Demonstration of a Three-Component Separation

ERIC Educational Resources Information Center

Heumann, Lars V.

2008-01-01

A classroom demonstration detailing the procedure for the separation of a ternary mixture consisting of intensely colored compounds using silica gel column chromatography is described. The audience can follow the compounds during their passage through the column as individual, colored bands while learning about different tools and techniques used…

Syntheses and structural analyses of cocondensed resins from urea and methylolphenols

Treesearch

Bunchiro Tomita; Chung-Yun Hse

1993-01-01

The reactions of urea with polymethylolphenol mixtures in acidic states were investigated by changing the reaction condition such as the molar ratio and acidity. The cocondensates were analyzed with carbon 13 nuclear magnetic resonance (13C-NMR) spectroscopy and gel permeation chromatography(GPC). The quantity of each chemical structure in the...

21 CFR 173.165 - Candida lipolytica.

Code of Federal Regulations, 2010 CFR

2010-04-01

... description for Candida lipolytica variety lipolytica listed in “The Yeasts—A Toxonomic Study,” 2d Ed. (1970... equivalent). Activate as follows: Slurry 900 grams of silica gel reagent with 2 liters of purified water in a 3-liter beaker. Cool the mixture and pour into a 80 × 900 chromatographic column with coarse fritted...

21 CFR 173.165 - Candida lipolytica.

Code of Federal Regulations, 2011 CFR

2011-04-01

... description for Candida lipolytica variety lipolytica listed in “The Yeasts—A Toxonomic Study,” 2d Ed. (1970... equivalent). Activate as follows: Slurry 900 grams of silica gel reagent with 2 liters of purified water in a 3-liter beaker. Cool the mixture and pour into a 80 × 900 chromatographic column with coarse fritted...

Choline chloride-thiourea, a deep eutectic solvent for the production of chitin nanofibers.

PubMed

Mukesh, Chandrakant; Mondal, Dibyendu; Sharma, Mukesh; Prasad, Kamalesh

2014-03-15

Deep eutectic solvents (DESs) consisting of the mixtures of choline halide (chloride/bromide)-urea and choline chloride-thiourea were used as solvents to prepare α-chitin nanofibers (CNFs). CNFs of diameter 20-30 nm could be obtained using the DESs comprising of the mixture of choline chloride and thiourea (CCT 1:2); however, NFs could not be obtained using the DESs having urea (CCU 1:2) as hydrogen bond donor. The physicochemical properties of thus obtained NFs were compared with those obtained using a couple of imidazolium based ionic liquids namely, 1-butyl-3-methylimidazolium hydrogen sulphate [(Bmim)HSO4] and 1-methylimidazolium hydrogen sulphate [(Hmim)HSO4] as well as choline based bio-ILs namely, choline hydrogen sulphate [(Chol)HSO4] and choline acrylate. The CNFs obtained using the DES as a solvent were used to prepare calcium alginate bio-nanocomposite gel beads having enhanced elasticity in comparison to Ca-alginate beads. The bio-nanocomposite gel beads thus obtained were used to study slow release of 5-fluorouracil, an anticancer drug. Copyright © 2014 Elsevier Ltd. All rights reserved.

Studies of the acetylcholinesterase from houseflies (Musca domestica L.) resistant and susceptible to organophosphorus insecticides.

PubMed Central

Devonshire, A L

1975-01-01

Acetylcholinesterase from the heads of insecticide-resistant and -susceptible houseflies (Musca domestica L.) was studied in vitro. The enzymes could not be distinguished electrophoretically, and their behaviour on polyacrylamide-disc-gel electrophoresis was influenced by the presence of Triton X-100 in both the homogenate and the gels. In the absence of detergent, the acetylcholinesterase was heterogeneous, but behaved as a single enzyme when it was present. By analogy with studies of acetylcholinesterase from other sources, these observations were attributed to aggregation of the enzyme when not bound by membranes. The enzyme from resistant flies was more slowly inhibited than the susceptible enzyme, bimolecular rate constants (ki) differing by approx. 4-20-fold for a range of organophosphorus compounds. The kinetics of inhibition of acetylcholinesterase were consistent with the results of electrophoresis, i.e. they corresponded to those of a single enzyme in the presence of Triton X-100, but a mixture of enzymes in its absence. The susceptibility of the more sensitive components in these mixtures was determined. Images PLATE 1 PMID:1180906

High Surface Area, Thermally Stable, Hydrophobic, Microporous, Rigid Gels Generated at Ambient from MeSi(OEt)3 /(EtO)3 SiCH2 CH2 Si(OEt)3 Mixtures by F- -Catalyzed Hydrolysis.

PubMed

Furgal, Joseph C; Yamane, Honami; Odykirk, Timothy R; Yi, Eongyu; Chujo, Yoshiki; Laine, Richard M

2018-01-02

High surface area materials are of considerable interest for gas storage/capture, molecular sieving, catalyst supports, as well as for slow-release drug-delivery systems. We report here a very simple and fast route to very high surface area, mechanically robust, hydrophobic polymer gels prepared by fluoride-catalyzed hydrolysis of mixtures of MeSi(OEt) 3 and bis-triethoxysilylethane (BTSE) at room temperature. These materials offer specific surface areas up to 1300 m 2  g -1 , peak pore sizes of 0.8 nm and thermal stabilities above 200 °C. The gelation times and surface areas can be controlled by adjusting the solvent volume (dichloromethane), percent fluoride (as nBu 4 NF or TBAF) and the BTSE contents. Polymers with other corners and linkers were also explored. These materials will further expand the materials databank for use in vacuum insulation panels and as thermally stable release and capture media. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Vesicle Origami and the Influence of Cholesterol on Lipid Packing.

PubMed

Tanasescu, Radu; Lanz, Martin A; Mueller, Dennis; Tassler, Stephanie; Ishikawa, Takashi; Reiter, Renate; Brezesinski, Gerald; Zumbuehl, Andreas

2016-05-17

The artificial phospholipid Pad-PC-Pad was analyzed in 2D (monolayers at the air/water interface) and 3D (aqueous lipid dispersions) systems. In the gel phase, the two leaflets of a Pad-PC-Pad bilayer interdigitate completely, and the hydrophobic bilayer region has a thickness comparable to the length of a single phospholipid acyl chain. This leads to a stiff membrane with no spontaneous curvature. Forced into a vesicular structure, Pad-PC-Pad has faceted geometry, and in its extreme form, tetrahedral vesicles were found as predicted a decade ago. Above the main transition temperature, a noninterdigitated Lα phase with fluid chains has been observed. The addition of cholesterol leads to a slight decrease of the main transition temperature and a gradual decrease in the transition enthalpy until the transition vanishes at 40 mol % cholesterol in the mixture. Additionally, cholesterol pulls the chains apart, and a noninterdigitated gel phase is observed. In monolayers, cholesterol has an ordering effect on liquid-expanded phases and disorders condensed phases. The wavenumbers of the methylene stretching vibration indicate the formation of a liquid-ordered phase in mixtures with 40 mol % cholesterol.

Organogel-emulsions with mixtures of β-sitosterol and γ-oryzanol: influence of water activity and type of oil phase on gelling capability.

PubMed

Sawalha, Hassan; den Adel, Ruud; Venema, Paul; Bot, Arjen; Flöter, Eckhard; van der Linden, Erik

2012-04-04

In this study, water-in-oil emulsions were prepared from water containing different salt concentrations dispersed in an oil phase containing a mixture of β-sitosterol and γ-oryzanol. In pure oil, the β-sitosterol and γ-oryzanol molecules self-assemble into tubular microstructures to produce a firm organogel. However, in the emulsion, the water molecules bind to the β-sitosterol molecules, forming monohydrate crystals that hinder the formation of the tubules and resulting in a weaker emulsion-gel. Addition of salt to the water phase decreases the water activity, thereby suppressing the formation of sitosterol monohydrate crystals even after prolonged storage times (∼1 year). When the emulsions were prepared with less polar oils, the tubular microstructure was promoted, which significantly increased the firmness of the emulsion-gel. The main conclusion of this study is that the formation of oryzanol and sitosterol tubular microstructure in the emulsion can be promoted by reducing the water activity and/or by using oils of low polarity.

Purification and Characterization of the Crown Gall-specific Enzyme, Octopine Synthase 1

PubMed Central

Hack, Ethan; Kemp, John D.

1980-01-01

A single enzyme catalyzes the synthesis of all four N2-(1-carboxyethyl)-amino acid derivatives found in a crown gall tumor tissue induced by Agrobacterium tumefaciens (E. F. Sm. and Town.) Conn strain B6 on sunflower (Helianthus annuus L.). This enzyme, octopine synthase, has been purified by ammonium sulfate fractionation and chromatography on diethylaminoethylcellulose, blue agarose, and hydroxylapatite. The purified enzyme has all the N2-(1-carboxyethyl)-amino acid synthesizing activities found in crude preparations, and the relative activities with six amino acids remain nearly constant during purification. Although the maximum velocities (V) and Michaelis constants (Km) differ, the ratio V/Km is the same for all amino acid substrates. Thus an equimolar mixture of amino acids will give rise to an equimolar mixture of products. The kinetic properties of the enzyme are consistent with a partially ordered mechanism with arginine (NADPH, then arginine or pyruvate). Octopine synthase is a monomeric enzyme with a molecular weight of 39,000 by gel filtration and 38,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Images PMID:16661312

Contribution of piezometric measurement on knowledge and management of low water levels

NASA Astrophysics Data System (ADS)

Bessiere, Hélène; Stollsteiner, Philippe; Allier, Delphine; Nicolas, Jérôme; Gourcy, Laurence

2014-05-01

This article is based on a BRGM study on piezometric indicators, threshold values of discharges and groundwater levels for the assessment of potentially pumpable volumes of chalky watersheds. A method for estimating low water levels from groundwater levels is presented from three examples of chalk aquifer; the first one is located in Picardy and the two other in the Champagne Ardennes region. Piezometers with "annual" cycles, used in these examples, are supposed to be representative of the aquifer hydrodynamics. The analysis leads to relatively precise and satisfactory relationships between groundwater levels and observed discharges for this chalky context. These relationships may be useful for monitoring, validation, extension or reconstruction of the low water flow. On the one hand, they allow defining the piezometric levels corresponding to the different alert thresholds of river discharges. On the other hand, they clarify the distribution of low water flow from runoff or the draining of the aquifer. Finally, these correlations give an assessment of the minimum flow for the coming weeks using of the rate of draining of the aquifer. Nevertheless the use of these correlations does not allow to optimize the value of pumpable volumes because it seems to be difficult to integrate the amount of the effective rainfall that may occur during the draining period. In addition, these relationships cannot be exploited for multi-annual cycle systems. In these cases, the solution seems to lie on the realization of a rainfall-runoff-piezometric level model. Therefore, two possibilities are possible. The first one is to achieve each year, on a given date, a forecast for the days or months to come with various frequential distributions rainfalls. However, the forecast must be reiterated each year depending on climatic conditions. The principle of the second method is to simulate forecasts for different rainfall intensities and following different initial conditions. The results are presented in chart form. In addition, this last method is currently tested for the problem of floods by groundwater level rise.

Enhanced rectal bioavailability of ibuprofen in rats by poloxamer 188 and menthol.

PubMed

Yong, Chul Soon; Yang, Chae Ha; Rhee, Jong-Dal; Lee, Beom-Jin; Kim, Dong-Chool; Kim, Dae-Duk; Kim, Chong-Kook; Choi, Jun-Shik; Choi, Han-Gon

2004-01-09

To improve the bioavailability of poorly water-soluble ibuprofen in the rectum with poloxamer and menthol, the effects of menthol and poloxamer 188 on the aqueous solubility of ibuprofen were investigated. The dissolution and pharmacokinetic study of ibuprofen delivered by the poloxamer gels composed of poloxamer 188 and menthol were then performed. In the absence of poloxamer, the solubility of ibuprofen increased until the ratio of menthol to ibuprofen increased from 0:10 to 4:6 followed by an abrupt decrease in solubility above the ratio of 4:6, indicating that four parts menthol formed eutectic mixture with six parts ibuprofen. In the presence of poloxamer, the solutions with the same ratio of menthol to ibuprofen showed abrupt increase in the solubility of ibuprofen. The poloxamer gel with menthol/ibuprofen ratio of 1:9 and higher than 15% poloxamer 188 showed the maximum solubility of ibuprofen, 1.2mg/ml. Menthol improved the dissolution rates of ibuprofen from poloxamer gels. Release mechanism showed that the release rate of ibuprofen from the poloxamer gels without menthol was independent of the time but the drug might be released from the poloxamer gels with menthol by Fickian diffusion. Furthermore, the poloxamer gel with menthol (poloxamer/menthol/ibuprofen (15%/0.25%/2.5%)) gave significantly higher initial plasma concentrations, C(max) and AUC of ibuprofen than did solid suppository, indicating that the drug from poloxamer gel could be more absorbed than that from solid one in rats. Thus, the poloxamer gel with poloxamer 188 and menthol was a more effective rectal dosage form for ibuprofen.

Enhanced bone regeneration composite scaffolds of PLLA/β-TCP matrix grafted with gelatin and HAp.

PubMed

Wang, Jie-Lin; Chen, Qian; Du, Bei-Bei; Cao, Lu; Lin, Hong; Fan, Zhong-Yong; Dong, Jian

2018-06-01

The composite polylactide PLLA/β-TCP scaffolds were fabricated by solution casting and were coated with gelatin/hydroxyapatite (Gel/HAp) to improve the biological properties of the composite scaffolds. The Gel/HAp mixture was prepared using an in situ reaction, and a grafting-coating method was used to increase the efficiency of coating the PLLA/β-TCP matrix with Gel/HAp. First, free amino groups were introduced by 1,6-hexanediamine to aminolyze the PLLA/β-TCP matrix surface. Second, glutaraldehyde was coupled to Gel/HAp as a crosslinking agent. The structure and properties of Gel/HAp-modified PLLA/β-TCP films were characterized by Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and water contact angle measurements (WCA). The experimental results show that 23 wt% HAp was uniformly dispersed in the gelatin coating by in situ synthesis. The Gel/HAp composite coating was successfully immobilized on the aminolyzed PLLA/β-TCP surface via a chemical grafting method, which promoted a lower degradation rate and was more hydrophilic than a physical grafting method. The Gel/HAp composite coating adhered tightly and homogeneously to the hydrophobic PLLA/β-TCP surface. Moreover, mouse embryo osteoblast precursor (MC3T3-E1) cells grown on the scaffolds were behaviorally and morphologically characterized. The results indicated that the Gel/HAp composite coating was favorable for the attachment and proliferation of preosteoblasts and that Gel/HAp-NH-PLLA/β-TCP would be a candidate scaffold for bone repair. Copyright © 2018 Elsevier B.V. All rights reserved.

Assessment of a gel-type chelating preparation containing 1-hydroxyethylidene-1, 1-bisphosphonate.

PubMed

Girard, S; Paqué, F; Badertscher, M; Sener, B; Zehnder, M

2005-11-01

To test an aqueous gel containing 1-hydroxyethylidene-1, 1-bisphosphonate (HEBP) regarding its interactions with sodium hypochlorite, its calcium binding capacity, and its potential in preventing the formation of a smear layer when used in conjunction with rotary root canal preparation. The experimental aqueous gel consisted of (w/v) 2% alginate, 3% aerosil, 10% Tween 80 and 18% HEBP. Interactions of gel components with hypochlorite were assessed using iodometric titration and monochromatic ultraviolet spectrometry. Two commercial paste-type chelators containing ethylenediaminetetraacetic acid (EDTA) and peroxide (RC-Prep and Glyde) served as controls. Calcium-binding capacities were measured in mixtures with a Ca2+ standard solution buffered at pH 10 using a calcium-selective measuring chain. Finally, root canals of 16 extracted single-rooted premolars per group were instrumented using ProFile instruments dipped in the experimental gel, RC-Prep, or nothing. Additionally, canals were rinsed with 10 mL of a 1% NaOCl solution during/after preparation. Smear scores in instrumented teeth were monitored using scanning electron microscopy. None of the experimental gel components showed short-term interactions with hypochlorite, whilst EDTA, peroxide, RC-Prep and Glyde immediately reduced the hypochlorite in solution. The experimental gel chelated 30 mg Ca2+ g-1, compared with 16 mg Ca2+ g-1 and 11 mg Ca2+ g-1 chelated by RC-Prep and Glyde respectively. Smear scores obtained with the experimental gel were significantly (P<0.05) lower than with RC-Prep in coronal and middle root thirds, whilst no differences were observed in apical root thirds. Under the conditions of this study, an HEBP gel appeared advantageous over currently available products.

Effect of ethanol on the gelation of aqueous solutions of Pluronic F127.

PubMed

Chaibundit, Chiraphon; Ricardo, Nágila M P S; Ricardo, Nádja M P S; Muryn, Christopher A; Madec, Marie-Beatrice; Yeates, Stephen G; Booth, Colin

2010-11-01

In dilute aqueous solution unimers of copolymer F127 (E(98)P(67)E(98)) associate to form micelles, and in more concentrated solution micelles pack to form high-modulus gels. Cosolvents are known to affect these processes, and ethanol/water mixtures have been of particular interest. Dynamic light scattering from dilute solutions was used to confirm micellization, but major attention was directed towards the gels. Visual observation of mobility (tube inversion) was used to detect gel formation, oscillatory rheometry to confirm gel formation and provide values of the elastic moduli over a wide temperature range, and small-angle X-ray scattering to determine gel structure. The solvents were limited to 10, 20 and 30 wt.% ethanol/water. Critical concentrations for gel formation were similar for 10 and 20 wt.% ethanol/water but were significantly increased for 30 wt.% ethanol/water, e.g. at T=45 degrees C from c approximately 15 wt.% to c approximately 28 wt.%. The elastic moduli reached maximum values at T approximately 50 degrees C: e.g. G' approximately 25 kPa for 25 wt.% F127 in 10 and 20 wt.% ethanol/water and a similar value for 30 wt.% F127 in 30 wt.% ethanol/water. Hard gels of 30 and 35 wt.% F127 in ethanol/water at 25 and 40 degrees C had the body-centered cubic (bcc) structure. Copyright 2010 Elsevier Inc. All rights reserved.

Effect of egg albumen protein addition on physicochemical properties and nanostructure of gelatin from fish skin.

PubMed

Cai, Luyun; Feng, Jianhui; Peng, Xichun; Regenstein, Joe M; Li, Xiuxia; Li, Jianrong; Zhao, Wei

2016-12-01

The physicochemical properties and nanostructure of mixtures of egg albumen protein (EAP) and gelatin from under-utilised grass carp ( Ctenopharyngodon idella ) skins were studied. The gelatin with 1% EAP had an acceptable gel strength. The addition of 5% EAP significantly increased the melting and gelling temperatures of gelatin gels. Additionally, the colour turned white and the crystallinity was higher in gelatin gels with gradient concentrations of EAP (1, 3, and 5%). Gelatin with 5% EAP had the highest G' values while gelatin with 1% EAP had the lowest G' values. Atomic force microscopy showed the heterogeneous nanostructure of fish gelatin, and a simple coacervate with a homogeneous distribution was only observed with the addition of 1% EAP, indicating interaction between gelatin and EAP. These results showed that EAP effect fish gelatin's physicochemical and nanostructure properties and has potential applications in foods and pharmaceuticals.

Light-weight ceramic insulation

NASA Technical Reports Server (NTRS)

Hsu, Ming-Ta S. (Inventor); Chen, Timothy S. (Inventor)

2002-01-01

Ultra-high temperature, light-weight, ceramic insulation such as ceramic tile is obtained by pyrolyzing a siloxane gel derived from the reaction of at least one organo dialkoxy silane and at least one tetralkoxy silane in an acid or base liquid medium. The reaction mixture of the tetra- and dialkoxy silanes may contain also an effective amount of a mono- or trialkoxy silane to obtain the siloxane gel. The siloxane gel is dried at ambient pressures to form a siloxane ceramic precursor without significant shrinkage. The siloxane ceramic precursor is subsequently pyrolyzed, in an inert atmosphere, to form the black ceramic insulation comprising atoms of silicon, carbon and oxygen. The ceramic insulation, can be characterized as a porous, uniform ceramic tile resistant to oxidation at temperatures ranging as high as 1700.degree. C. and is particularly useful as lightweight tiles for spacecraft and other high-temperature insulation applications.

Tetraethyl orthosilicate-based glass composition and method

DOEpatents

Wicks, George G.; Livingston, Ronald R.; Baylor, Lewis C.; Whitaker, Michael J.; O'Rourke, Patrick E.

1997-01-01

A tetraethyl orthosilicate-based, sol-gel glass composition with additives selected for various applications. The composition is made by mixing ethanol, water, and tetraethyl orthosilicate, adjusting the pH into the acid range, and aging the mixture at room temperature. The additives, such as an optical indicator, filler, or catalyst, are then added to the mixture to form the composition which can be applied to a substrate before curing. If the additive is an indicator, the light-absorbing characteristics of which vary upon contact with a particular analyte, the indicator can be applied to a lens, optical fiber, reagant strip, or flow cell for use in chemical analysis. Alternatively, an additive such as alumina particles is blended into the mixture to form a filler composition for patching cracks in metal, glass, or ceramic piping.

Acoustic Levitator Power Device: Study of Ethylene-Glycol Water Mixtures

NASA Astrophysics Data System (ADS)

Caccamo, M. T.; Cannuli, A.; Calabrò, E.; Magazù, S.

2017-05-01

Acoustic levitator power device is formed by two vertically and opposed high output acoustic transducers working at 22 kHz frequency and produces sound pressure levels of 160 dB. The acoustic waves are monitored from an oscilloscope using a signal amplifier. The ability to perform contactless measurements, avoidance of undesired contamination from the container, are some of advantages of this apparatus. Acoustic levitation can be also used for sample preparation of high concentrated mixtures starting from solutions. In the present paper, an acoustic levitator power device is employed to collect data on levitated water mixtures of Ethylene Glycol (EG) which are then analysed by Infra-Red spectroscopy. The study allows to follow the drying process versus time and to obtain a gel-like compound characterized by an extended chemical crosslinking.

Tyrosinase-containing chitosan gels: A combined catalyst and sorbent for selective phenol removal

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

Sun, W.Q.; Payne, G.F.

There are a series of examples in which phenols appear as contaminants in process streams and their selective removal is required for waste minimization. For the selective removal of a phenol from a mixture, the authors are exploiting the substrate specificity of the enzyme tyrosinase to convert phenols into reactive o-quinones which are then adsorbed onto the amine-containing polymer chitosan. To effectively package the enzyme and sorbent, tyrosinase was immobilized between two chitosan gel films. The entrapment of tyrosinase between the films led to little loss of activity during immobilization, while tyrosinase leakage during incubation was limited. The chitosan gelsmore » rapidly adsorb the tyrosinase-generated product(s) of phenol oxidation while the capacity of the gels is substantially greater than the capacity of chitosan flakes. The performance of tyrosinase-containing chitosan gels significantly depends on the ratio of tyrosinase-to-chitosan. High tyrosinase-to-chitosan ratios result in less efficient use of tyrosinase, presumably due to suicide inactivation. However, the efficiency of chitosan use increases with increased tyrosinase-to-chitosan ratios.« less

ZnCl 2- and NH 4Cl-hydroponics gel electrolytes for zinc-carbon batteries

NASA Astrophysics Data System (ADS)

Khalid, N. H.; Ismail, Y. M. Baba; Mohamad, A. A.

Absorbency testing is used to determine the percentage of ZnCl 2 or NH 4Cl solution absorbed by a hydroponics gel (HPG). It is found that the absorbency of ZnCl 2 or NH 4Cl solution decreases with increasing solution concentration. The conductivity of ZnCl 2- and NH 4Cl-HPG electrolytes is dependent on the solution concentration. A mixture of salt solution with HPG yields excellent gel polymer electrolytes with conductivities of 0.026 and 0.104 S cm -1 at 3 M ZnCl 2 and 7 M NH 4Cl, respectively. These gel electrolytes are then used to produce zinc-carbon cells. The fabricated cells give capacities of 8.8 and 10.0 mAh, have an internal resistance of 25.4 and 19.8 Ω, a maximum power density of 12.7 and 12.2 mW cm -2, and a short-circuit current density of 29.1 and 33.9 mA cm -2 for ZnCl 2- and NH 4Cl-HPG electrolytes, respectively.

In situ gel-to-crystal transition and synthesis of metal nanoparticles obtained by fluorination of a cyclic β-aminoalcohol gelator.

PubMed

Xu, Yang; Kang, Chuanqing; Chen, Yu; Bian, Zheng; Qiu, Xuepeng; Gao, Lianxun; Meng, Qingxin

2012-12-21

A new fluorinated version of a cyclic β-aminoalcohol gelator derived from 1,2,3,4-tetrahydroisoquinoline is presented. The gelator is able to gel various nonprotic solvents through OH⋅⋅⋅N hydrogen bonds and additional CH⋅⋅⋅F interactions due to the introduction of fluorine. A bimolecular lamellar structure is formed in the gel phase, which partly preserves the pattern of molecular organization in the single crystal. The racemate of the chiral gelator shows lower gelation ability than its enantiomer because of a higher tendency to form microcrystals, as shown by X-ray diffraction analysis. The influence of fluorination on the self-assembly of the gelator and the properties of the gel was investigated in comparison to the original fluorine-free gel system. The introduction of fluorine brings two new features. The first is good recognition of o-xylene by the gelator, which induces an in situ transition from gels of o-xylene and of an o-xylene/toluene mixture to identical single crystals with unique tubular architecture. The second is the enhanced stability of the toluene gel towards ions, including quaternary ammonium salts, which enables the preparation of a stable toluene gel in the presence of chloroaurate or chloroplatinate. The gel system can be used as a template for the synthesis of spherical gold nanoparticles with a diameter of 5 to 9 nm and wormlike platinum nanostructures with a diameter of 2 to 3 nm and a length of 5 to 12 nm. This is the first example of a synthesis of platinum nanoparticles in an organogel medium. Therefore, the appropriate introduction of a fluorine atom and corresponding nonbonding interactions into a known gelator to tune the properties and functions of a gel is a simple and effective tactic for design of a gel system with specific targets. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

High resolution clear native electrophoresis for in-gel functional assays and fluorescence studies of membrane protein complexes.

PubMed

Wittig, Ilka; Karas, Michael; Schägger, Hermann

2007-07-01

Clear native electrophoresis and blue native electrophoresis are microscale techniques for the isolation of membrane protein complexes. The Coomassie Blue G-250 dye, used in blue native electrophoresis, interferes with in-gel fluorescence detection and in-gel catalytic activity assays. This problem can be overcome by omitting the dye in clear native electrophoresis. However, clear native electrophoresis suffers from enhanced protein aggregation and broadening of protein bands during electrophoresis and therefore has been used rarely. To preserve the advantages of both electrophoresis techniques we substituted Coomassie dye in the cathode buffer of blue native electrophoresis by non-colored mixtures of anionic and neutral detergents. Like Coomassie dye, these mixed micelles imposed a charge shift on the membrane proteins to enhance their anodic migration and improved membrane protein solubility during electrophoresis. This improved clear native electrophoresis offers a high resolution of membrane protein complexes comparable to that of blue native electrophoresis. We demonstrate the superiority of high resolution clear native electrophoresis for in-gel catalytic activity assays of mitochondrial complexes I-V. We present the first in-gel histochemical staining protocol for respiratory complex III. Moreover we demonstrate the special advantages of high resolution clear native electrophoresis for in-gel detection of fluorescent labeled proteins labeled by reactive fluorescent dyes and tagged by fluorescent proteins. The advantages of high resolution clear native electrophoresis make this technique superior for functional proteomics analyses.

Long-term stability of glucose: glycolysis inhibitor vs. gel barrier tubes.

PubMed

Winter, Theresa; Hannemann, Anke; Suchsland, Juliane; Nauck, Matthias; Petersmann, Astrid

2018-03-12

Measuring the glucose concentration in whole blood samples is critical due to unsatisfactory glycolysis inhibition. Previous studies showed that Terumo tubes were superior, but they were taken off the European market in 2016 and alternatives were required. This initiated the present evaluation of glucose stability in five available tube types. Venous blood samples were collected from 61 healthy volunteers to test tubes supplied by Terumo (two sets), Greiner FC-Mix, BD FX-Mixture and BD serum. After sampling, the contents were thoroughly mixed and centrifuged within an hour. The glucose concentrations were determined and the samples resuspended except for BD serum tubes (gel barrier). The first 30 samples were stored at room temperature and the remaining 31 at 4°C. After 24, 48, 72 and 96 h, all tubes were (re)centrifuged, and glucose concentration measurements were repeated. Changes in glucose concentrations over time differed significantly between the investigated tube types and to a certain extent between the two storing conditions. Glycolysis was most evident in the BD FX-mixture tubes. Good glucose stability was observed in samples retrieved form BD serum and Greiner tubes. The stability in both Terumo tubes was comparable to that in other studies. Although Greiner and both Terumo tubes are supposed to contain the same glycolysis inhibitor, glucose stability differed between these tubes. We showed that Greiner is an acceptable alternative to Terumo and that glucose in serum that was rapidly separated from corpuscles by a gel barrier is stable for an extended time.

Agar-based bridges as biocompatible candidates to provide guide cues in spinal cord injury repair.

PubMed

Martín-López, Eduardo; Darder, Margarita; Ruiz-Hitzky, Eduardo; Nieto Sampedro, Manuel

2013-01-01

Spinal bridge implants are strategic to provide growth surfaces for axonal regeneration after spinal cord injuries. The design of an appropriate substrate, one that is suitable for implantation, must involve careful testing of the biomaterial properties both in vitro and in vivo. The goal of this work was to test the structure, stability and biological response after spinal bridges implantation of several biopolymers, composed of mixtures of agar (AG), as structural matrix scaffold, with κ-carrageenan (Kc), gelatin (G), xanthan gum (Xn) and polysulfone (PS). Biopolymer structures were studied by environmental scanning electron microscopy, whereas the stability of gels was analyzed by in vitro degradation and swelling tests. The biocompatibility of these materials and their ability to promote cell growth and axonal regeneration were studied by implantation of spinal bridges containing empty linear channels in an acute rat spinal cord transection model at thoracic level (T8). All gel mixtures gave rise to porous structures and they were stables to degradation, excepting the AG+G mixture. Spinal bridges constructed from all mixtures were implanted during a month in adult rats. After this time a low host reaction occurred to all bridge materials as well as neurite and cell ingrowths through the empty channels. Neurites within the bridges were mostly peripheral sensory fibers such as those positive for CGRP, whereas there was a lack of regeneration of central axons crossing from the spinal tissue to bridges. Many of these neurites established closed contacts with non-myelin Schwann cells. The histological analysis revealed a high accumulation of collagen fibers within the channels. Unexpected was the apparent loss of channels linearity which affected the growth of neurites and cells, indicating the need for additional regeneration strategies and vertebrae bridge fixing.

Utilization of SRS pond ash in controlled low strength material. Technical report

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

Langton, C.A.; Rajendran, N.

1995-12-01

Design mixes for Controlled Low Strength Material (CLSM) were developed which incorporate pond ashes (fly ashes) from the A-Area Ash Pile, the old F-Area Ash Basin and the D-Area Ash Basin. CLSM is a pumpable, flowable, excavatable backfill used in a variety of construction applications at SRS. Results indicate that CLSM which meets all of the SRS design specifications for backfill, can be made with the A-, D-, and F-Area pond ashes. Formulations for the design mixes are provided in this report. Use of the pond ashes may result in a cost savings for CLSM used at SRS and willmore » utilize a by-product waste material, thereby decreasing the amount of material requiring disposal.« less

Switching wormlike micelles of selenium-containing surfactant using redox reaction.

PubMed

Zhang, Yongmin; Kong, Weiwei; Wang, Cheng; An, Pengyun; Fang, Yun; Feng, Yujun; Qin, Zhirong; Liu, Xuefeng

2015-10-14

A novel redox-switchable wormlike micellar system was developed based on a mixture of selenium-containing zwitterionic surfactant and commercially available anionic surfactant sodium dodecyl sulfate, which reversibly and quickly responds to H2O2 and vitamin C, and shows circulatory gel/sol transition, reflecting changes in aggregate morphology from entangled worms to vesicles.

A multi-channel gel electrophoresis and continuous fraction collection apparatus for high throughput protein separation and characterization

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

Choi, Megan; Nordmeyer, Robert A.; Cornell, Earl

2009-10-02

To facilitate a direct interface between protein separation by PAGE and protein identification by mass spectrometry, we developed a multichannel system that continuously collects fractions as protein bands migrate off the bottom of gel electrophoresis columns. The device was constructed using several short linear gel columns, each of a different percent acrylamide, to achieve a separation power similar to that of a long gradient gel. A Counter Free-Flow elution technique then allows continuous and simultaneous fraction collection from multiple channels at low cost. We demonstrate that rapid, high-resolution separation of a complex protein mixture can be achieved on this systemmore » using SDS-PAGE. In a 2.5 h electrophoresis run, for example, each sample was separated and eluted into 48-96 fractions over a mass range of 10-150 kDa; sample recovery rates were 50percent or higher; each channel was loaded with up to 0.3 mg of protein in 0.4 mL; and a purified band was eluted in two to three fractions (200 L/fraction). Similar results were obtained when running native gel electrophoresis, but protein aggregation limited the loading capacity to about 50 g per channel and reduced resolution.« less

Obtention and characterization of dried gels prepared with whey proteins, honey and hydrocolloids mixture.

PubMed

Rodriguez, Ana C; Torrez Irigoyen, Martín R; Navarro, Alba S; Yamul, Diego K

2017-11-01

Large amounts of honey and liquid whey derived from the dairy industry are produced in Argentina. Honey is exported in bulk and whey is transformed into whey protein concentrates and isolates. The objective of this work was to investigate the effect of pH, composition and storage time on the properties of dried gels with honey, whey proteins and hydrocolloids. Color properties varied according to pH and composition. The fracture stress of dried gels prepared with corn starch was higher than that of gels prepared with guar gum in all conditions assayed. Young's modulus was higher at pH 7 for both compositions and increased with storage time. Rubbery characteristics were found in dried gels with guar gum, while both corn starch and guar gum made the microstructure rougher. Multivariate analysis showed that samples could be grouped by pH. Panelists preferred pH 7 products over acidic ones, and no significant differences in sensory properties were found using either corn starch or guar gum in the formulation. The results demonstrated that it is possible to generate a new product, which may open new applications for honey and whey in food formulations. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Evaluation of synovium-derived mesenchymal stem cells and 3D printed nanocomposite scaffolds for tissue engineering

NASA Astrophysics Data System (ADS)

Pan, Jian-Feng; Li, Shuo; Guo, Chang-An; Xu, Du-Liang; Zhang, Feng; Yan, Zuo-Qin; Mo, Xiu-Mei

2015-08-01

Stem cells and scaffolds play a very important role in tissue engineering. Here, we isolated synovium-derived mesenchymal stem cells (SMSCs) from synovial membrane tissue and characterized stem-cell properties. Gelatin nanoparticles (NP) were prepared using a two-step desolvation method and then pre-mixed into different host matrix (silk fibroin (SF), gelatin (Gel), or SF-Gel mixture) to generate various 3D printed nanocomposite scaffolds (NP/SF, NP/SF-Gel, NP/Gel-1, and NP/Gel-2). The microstructure was examined by scanning electron microscopy. Biocompatibility assessment was performed through CCK-8 assay by coculturing with SMSCs at 1, 3, 7 and 14 days. According to the results, SMSCs are similar to other MSCs in their surface epitope expression, which are negative for CD45 and positive for CD44, CD90, and CD105. After incubation in lineage-specific medium, SMSCs could differentiate into chondrocytes, osteocytes and adipocytes. 3D printed nanocomposite scaffolds exhibited a good biocompatibility in the process of coculturing with SMSCs and had no negative effect on cell behavior. The study provides a strategy to obtain SMSCs and fabricate 3D printed nanocomposite scaffolds, the combination of which could be used for practical applications in tissue engineering.

Development of an analytical technique for the detection of alteration minerals formed in bentonite by reaction with alkaline solutions

NASA Astrophysics Data System (ADS)

Sakamoto, H.; Shibata, M.; Owada, H.; Kaneko, M.; Kuno, Y.; Asano, H.

A multibarrier system consisting of cement-based backfill, structures and support materials, and a bentonite-based buffer material has been studied for the TRU waste disposal concept being developed in Japan, the aim being to restrict the migration of radionuclides. Concern regarding bentonite-based materials in this disposal environment relates to long-term alteration under hyper-alkaline conditions due to the presence of cementitious materials. In tests simulating the interaction between bentonite and cement, formation of secondary minerals due to alteration reactions under the conditions expected for geological disposal of TRU waste (equilibrated water with cement at low liquid/solid ratio) has not been observed, although alteration was observed under extremely hyper-alkaline conditions with high temperatures. This was considered to be due to the fact that analysis of C-S-H gel formed at the interface as a secondary mineral was difficult using XRD, because of its low crystallinity and low content. This paper describes an analytical technique for the characterization of C-S-H gel using a heavy liquid separation method which separates C-S-H gel from Kunigel V1 bentonite (bentonite produced in Japan) based on the difference in specific gravity between the crystalline minerals constituting Kunigel V1 and the secondary C-S-H gel. For development of C-S-H gel separation methods, simulated alteration samples were prepared by mixing 990 mg of unaltered Kunigel V1 and 10 mg of C-S-H gel synthesized using pure chemicals at a ratio of Ca/Si = 1.2. The simulated alteration samples were dispersed in bromoform-methanol mixtures with specific gravities ranging from 2.00 to 2.57 g/cm 3 and subjected to centrifuge separation to recover the light density fraction. Subsequent XRD analysis to identify the minerals was complemented by dissolution in 0.6 N hydrochloric acid to measure the Ca and Si contents. The primary peak (2 θ = 29.4°, Cu Kα) and secondary peaks (2 θ = 32.1° and 50.1°, Cu Kα) of the C-S-H gel, which could not be distinguished before the heavy liquid separation, were clearly identified by XRD after separation. The result of the analyses of the light density fraction indicates highest recovery of C-S-H gel and least inclusion of bentonite for separation using heavy liquid with a specific gravity of 2.10 g/cm 3. The traces of bentonite minerals included in the suspension were identified to be montmorillonite, quartz, clinoptilolite, and calcite. The separation technique was also tested for Ca-bentonite prepared by passing a calcium hydroxide solution through a bentonite (Kunigel V1)-silica sand mixture. The results indicated that the technique would also be applicable to separation of C-S-H gel from Ca-bentonite.

Three-Phase Coexistence in Colloidal Rod-Plate Mixtures.

PubMed

Woolston, Phillip; van Duijneveldt, Jeroen S

2015-09-01

Aqueous suspensions of clay particles, such as montmorillonite (MMT) platelets and sepiolite (Sep) rods, tend to form gels at concentrations around 1 vol %. For Sep rods, adsorbing sodium polyacrylate to the surface allows for an isotropic-nematic phase separation to be seen instead. Here, MMT is added to such Sep suspensions, resulting in a complex phase behavior. Across a range of clay concentrations, separation into three phases is observed: a lower, nematic phase dominated by Sep rods, a MMT-rich middle layer, which is weakly birefringent and probably a gel, and a dilute top phase. Analysis of phase volumes suggests that the middle layer may contain as much as 6 vol % MMT.

[Deceleration of cataract development in rats under the action of N-acetylcarnosine and D-pantethine mixture].

PubMed

Avetisov, S É; Sheremet, N L; Muranov, K O; Polianskiĭ, N B; Polunin, G S; Ostrovskiĭ, M A

2014-01-01

The effect of a mixture of N-acetylcarnosine and D-pantethine (1 : 1, m/m) on UV-A induced cataract in rats was studied. It is shown that instillation of a 5% mixture into the eyes or intraperitoneal injections (25 or 150 mg/kg) inhibit the formation of cataracts, starting from 82nd day of the experiment (p < 0.03), after which the protective effect of the mixture significantly increases (p = 0.0003). UV-A irradiation significantly (p < 0.01) increased the content of water-insoluble proteins in the lens. The use of the mixture of N-Acetylcarnosine and D-pantethine prevented (p < 0.001) an increase in the content of water-insoluble proteins caused by UV-A irradiation. Gel permeation chromatography data showed that, in the control group, water insoluble proteins consist of 3 fractions (40 kDa, 100 - 200 kDa, and1000 kDa). UV-A irradiation reduced the amount of protein in fraction 1 and increases the amount of protein in the fractions 2 and 3. The use of the mixture of N-acetylcarnosine and D-pantethine reduced the effects of UV-A light. The authors attribute the effect of the N-acetylcarnosine and D-pantethine mixture to their chaperone-like properties.

Sol-gel derived C-SiC composites and protective coatings for sustained durability in the space environment

NASA Astrophysics Data System (ADS)

Haruvy, Yair; Liedtke, Volker

2003-09-01

Composites and coatings were produced via the fast sol-gel process of a mixture of alkoxysilane precursors. The composites were comprised of carbon fibers, fabrics, or their precursors as reinforcement, and sol-gel-derived silicon carbide as matrix, aiming at high-temperature stable ceramics that can be utilized for re-entry structures. The protective coatings were comprised of fluorine-rich sol-gel derived resins, which exhibit high flexibility and coherence to provide sustained ATOX protection necessary for LEO space-exposed elements. For producing the composites, the sol-gel-derived resin is cast onto the reinforcement fibers/fabrics mat (carbon or its precursors) to produce a 'green' composite that is being cured. The 'green' composite is converted into a C-SiC composite via a gradual heat-pressure process under inert atmosphere, during which the organic substituents on the silicon atoms undergo internal oxidative pyrolysis via the schematic reaction: (SiRO3/2)n -> SiC + CO2 + H2O. The composition of the resultant silicon-oxi-carbide is tailorable via modifying the composition of the sol-gel reactants. The reinforcement, when made of carbon precursors, is converted into carbon during the heat-and-pressure processing as well. The C-SiC composites thus derived exhibit superior thermal stability and comparable thermal conductivity, combined with good mechanical strength features and failure resistance, which render them greatly applicable for re-entry shielding, heat-exchange pipes, and the like. Fluorine rich sol-gel derived coatings were developed as well, via the use of HF rich sol-gel process. These coatings provide oxidation-protection via the silica formation process, together with flexibility that allows 18,000 repetitive folding of the coating without cracking.

Low density microcellular foams

DOEpatents

LeMay, James D.

1992-01-01

Disclosed is a process of producing microcellular from which comprises the steps of: (a) selecting a multifunctional epoxy oligomer resin; (b) mixing said epoxy resin with a non-reactive diluent to form a resin-diluent mixture; (c) forming a diluent containing cross-linked epoxy gel from said resin-diluent mixture; (d) replacing said diluent with a solvent therefore; (e) replacing said solvent with liquid carbon dioxide; and (f) vaporizing off said liquid carbon dioxide under supercritical conditions, whereby a foam having a density in the range of 35-150 mg/cc and cell diameters less than about 1 .mu.m is produced. Also disclosed are the foams produced by the process.

Low density microcellular foams

DOEpatents

LeMay, J.D.

1991-11-19

Disclosed is a process of producing microcellular foam which comprises the steps of: (a) selecting a multifunctional epoxy oligomer resin; (b) mixing said epoxy resin with a non-reactive diluent to form a resin-diluent mixture; (c) forming a diluent containing cross-linked epoxy gel from said resin-diluent mixture; (d) replacing said diluent with a solvent therefore; (e) replacing said solvent with liquid carbon dioxide; and (f) vaporizing off said liquid carbon dioxide under supercritical conditions, whereby a foam having a density in the range of 35-150 mg/cc and cell diameters less than about 1 [mu]m is produced. Also disclosed are the foams produced by the process. 8 figures.

Low density microcellular foams

DOEpatents

LeMay, James D.

1991-01-01

Disclosed is a process of producing microcellular foam which comprises the steps of: (a) selecting a multifunctional epoxy oligomer resin; (b) mixing said epoxy resin with a non-reactive diluent to form a resin-diluent mixture; (c) forming a diluent containing cross-linked epoxy gel from said resin-diluent mixture; (d) replacing said diluent with a solvent therefore; (e) replacing said solvent with liquid carbon dioxide; and (f) vaporizing off said liquid carbon dioxide under supercritical conditions, whereby a foam having a density in the range of 35-150 mg/cc and cell diameters less than about 1 .mu.m is produced. Also disclosed are the foams produced by the process.

Sol-gel type synthesis of Bi.sub.2 (Sr,Ta.sub.2)O.sub.9 using an acetate based system

DOEpatents

Boyle, Timothy J.

1997-01-01

A method of forming a layered-perovskite bismuth-strontium-tantalum oxide (SBT) ferroelectric material is performed by dissolving a bismuth compound in a first solvent to form a first solution, mixing a strontium compound and a tantalum compound to form a binary mixture, dissolving the binary mixture in a second solvent to form a second solution, mixing the first solution with the second solution to form a SBT precursor solution, evaporating the first and second solvents to form a SBT precursor material and subsequently sintering said SBT precursor material in the presence of oxygen.

Sol-gel type synthesis of Bi{sub 2}(Sr,Ta{sub 2})O{sub 9} using an acetate based system

DOEpatents

Boyle, T.J.

1997-11-04

A method of forming a layered-perovskite bismuth-strontium-tantalum oxide (SBT) ferroelectric material is performed by dissolving a bismuth compound in a first solvent to form a first solution, mixing a strontium compound and a tantalum compound to form a binary mixture, dissolving the binary mixture in a second solvent to form a second solution, mixing the first solution with the second solution to form a SBT precursor solution, evaporating the first and second solvents to form a SBT precursor material and subsequently sintering said SBT precursor material in the presence of oxygen. 6 figs.

Tetraethyl orthosilicate-based glass composition and method

DOEpatents

Wicks, G.G.; Livingston, R.R.; Baylor, L.C.; Whitaker, M.J.; O`Rourke, P.E.

1997-06-10

A tetraethyl orthosilicate-based, sol-gel glass composition with additives selected for various applications is described. The composition is made by mixing ethanol, water, and tetraethyl orthosilicate, adjusting the pH into the acid range, and aging the mixture at room temperature. The additives, such as an optical indicator, filler, or catalyst, are then added to the mixture to form the composition which can be applied to a substrate before curing. If the additive is an indicator, the light-absorbing characteristics of which vary upon contact with a particular analyte, the indicator can be applied to a lens, optical fiber, reagent strip, or flow cell for use in chemical analysis. Alternatively, an additive such as alumina particles is blended into the mixture to form a filler composition for patching cracks in metal, glass, or ceramic piping. 12 figs.

Synergistic in vitro and in vivo antimicrobial effect of a mixture of ZnO nanoparticles and Lactobacillus fermentation liquor.

PubMed

Kuang, Huijuan; Yang, Lin; Shah, Nagendra P; Aguilar, Zoraida P; Wang, Lijun; Xu, Hengyi; Wei, Hua

2016-04-01

In this study, we investigated the antibacterial activity of ZnO nanoparticles (NPs) and Lactobacillus-fermentation liquor (LFL) against two pathogenic bacteria in vitro and in vivo. Bactericidal tests were performed on solid agar plates and quantitative real-time PCR (qPCR), and denaturing gradient gel electrophoresis (DGGE) techniques were used to examine the antibacterial activity of the mixture of ZnO NPs and LFL in vivo. The results showed that the mixture exhibited higher antibacterial activity against Salmonella typhimurium in vitro in comparison with ZnO NPs alone. The results showed that ZnO NPs and LFL significantly enhanced microbial diversity in mouse intestine which suggested a synergistic antibacterial activity against the tested pathogenic bacteria that could be used for the control of the spread and persistence of bacterial infections.

Development of a biodegradable tissue adhesive based on functionalized 1,2-ethylene glycol bis(dilactic acid). II.

PubMed

Rohm, Henning W; Lurtz, Claudia; Wegmann, Juergen; Odermatt, Erich K; Behrend, Detlef; Schmitz, Klaus-Peter; Sternberg, Katrin

2011-04-01

In body regions where damage and bleeding must be avoided, a substitute for mechanical tissue fixation by sutures or staplers is needed. Since tissue adhesives provide easy and fast handling they are a promising alternative. The present study reports the development and analysis of a tissue adhesive that consists of two adhesive components: hexamethylene diisocyanate (HDI) functionalized 1,2-ethylene glycol bis(dilactic acid) (ELA-NCO) and chitosan chloride. This composition was chosen based on preliminary studies on several chain elongation agents. The present study evaluates this adhesive system by IR-spectroscopy, tensile tests, and gel point measurements in comparison to fibrin glue. The system's in vitro biocompatibility was tested with mouse fibroblasts (L929) according to ISO 10993-5. Furthermore, an implantation study was performed in SPF-Wistar rats. The adhesive strength of manually applied mixtures or mixtures applied by double chamber syringes with a mixing extruder was determined to be significantly higher than that of fibrin glue on bovine muscle tissue at 37°C. Tensile strength increased further when exposure time of the adhesive was increased from 10 min to 48 h. The rheological gel point determination showed that the mixture of ELA-NCO/DMSO and chitosan chloride offers a time window large enough to readjust the fused joint during surgery, as opposed to fibrin glue. Additionally, the in vitro and in vivo biocompatibility studies of the adhesive system revealed no toxic effects on the surrounding tissue. Copyright © 2010 Wiley Periodicals, Inc.

Fabrication and physical and biological properties of fibrin gel derived from human plasma.

PubMed

Zhao, Haiguang; Ma, Lie; Zhou, Jie; Mao, Zhengwei; Gao, Changyou; Shen, Jiacong

2008-03-01

The fast development of tissue engineering and regenerative medicine drives the old biomaterials, for example, fibrin glue, to find new applications in these areas. Aiming at developing a commercially available hydrogel for cell entrapment and delivery, in this study we optimized the fabrication and gelation conditions of fibrin gel. Fibrinogen was isolated from human plasma by a freeze-thaw circle. Gelation of the fibrinogen was accomplished by mixing with thrombin. Absorbance of the fibrinogen/thrombin mixture at 550 nm as a function of reaction time was monitored by UV-VIS spectroscopy. It was found that the clotting time is significantly influenced by the thrombin concentration and the temperature, while less influenced by the fibrinogen concentration. After freeze-drying, the fibrin gel was characterized by scanning electron microscopy (SEM), revealing fibrous microstructure. Thermal gravimetric analysis found that the degradation temperature of the crosslinked fibrin gel starts from 288 degrees C, which is about 30 degrees C higher than that of the fibrinogen. The hydrogel has an initial water-uptake ratio of approximately 50, decreased to 30-40 after incubation in water for 11 h depending on the thrombin concentration. The fibrin gels lost their weights in PBS very rapidly, while slowly in DMEM/fetal bovine serum and DMEM. In vitro cell culture found that human fibroblasts could normally proliferate in the fibrin gel with spreading morphology. In conclusion, the fibrin gel containing higher concentration of fibrinogen (20 mg ml(-1)) and thrombin (5 U ml(-1)) has suitable gelation time and handling properties, and thus is applicable as a delivery vehicle for cells such as fibroblasts.

Fabrication and physical and biological properties of fibrin gel derived from human plasma

NASA Astrophysics Data System (ADS)

Zhao, Haiguang; Ma, Lie; Zhou, Jie; Mao, Zhengwei; Gao, Changyou; Shen, Jiacong

2008-03-01

The fast development of tissue engineering and regenerative medicine drives the old biomaterials, for example, fibrin glue, to find new applications in these areas. Aiming at developing a commercially available hydrogel for cell entrapment and delivery, in this study we optimized the fabrication and gelation conditions of fibrin gel. Fibrinogen was isolated from human plasma by a freeze-thaw circle. Gelation of the fibrinogen was accomplished by mixing with thrombin. Absorbance of the fibrinogen/thrombin mixture at 550 nm as a function of reaction time was monitored by UV-VIS spectroscopy. It was found that the clotting time is significantly influenced by the thrombin concentration and the temperature, while less influenced by the fibrinogen concentration. After freeze-drying, the fibrin gel was characterized by scanning electron microscopy (SEM), revealing fibrous microstructure. Thermal gravimetric analysis found that the degradation temperature of the crosslinked fibrin gel starts from 288 °C, which is about 30 °C higher than that of the fibrinogen. The hydrogel has an initial water-uptake ratio of ~50, decreased to 30-40 after incubation in water for 11 h depending on the thrombin concentration. The fibrin gels lost their weights in PBS very rapidly, while slowly in DMEM/fetal bovine serum and DMEM. In vitro cell culture found that human fibroblasts could normally proliferate in the fibrin gel with spreading morphology. In conclusion, the fibrin gel containing higher concentration of fibrinogen (20 mg ml-1) and thrombin (5 U ml-1) has suitable gelation time and handling properties, and thus is applicable as a delivery vehicle for cells such as fibroblasts.

Role of 1% alendronate gel as adjunct to mechanical therapy in the treatment of chronic periodontitis among smokers.

PubMed

Sharma, Anuj; Raman, Achala; Pradeep, Avani Raju

2017-01-01

Alendronate (ALN) inhibits osteoclastic bone resorption and triggers osteostimulative properties both in vivo and in vitro, as shown by increase in matrix formation. This study aimed to explore the efficacy of 1% ALN gel as local drug delivery (LDD) in adjunct to scaling and root planing (SRP) for the treatment of chronic periodontitis among smokers. 75 intrabony defects were treated in 46 male smokers either with 1% ALN gel or placebo gel. ALN gel was prepared by adding ALN into carbopol-distilled water mixture. Clinical parameters [modified sulcus bleeding index, plaque index, probing depth (PD), and periodontal attachment level (PAL)] were recorded at baseline, at 2 months, and at 6 months, while radiographic parameters were recorded at baseline and at 6 months. Defect fill at baseline and at 6 months was calculated on standardized radiographs by using the image analysis software. Mean PD reduction and mean PAL gain were found to be greater in the ALN group than in the placebo group, both at 2 and 6 months. Furthermore, a significantly greater mean percentage of bone fill was found in the ALN group (41.05±11.40%) compared to the placebo group (2.5±0.93%). The results of this study showed 1% ALN stimulated a significant increase in PD reduction, PAL gain, and an improved bone fill compared to placebo gel in chronic periodontitis among smokers. Thus, 1% ALN, along with SRP, is effective in the treatment of chronic periodontitis in smokers.

Blue light emission from trivalent cerium doped in sol-gel silica glass

NASA Astrophysics Data System (ADS)

Tokumitsu, Seika; Murakami, Yukon; Oda, Hisaya; Kawabe, Yutaka

2017-02-01

Rare earths in glass matrices are promising for active optical devices as amplifiers and lasers. Emission originating from d-f transitions in sol-gel glass has not been studied very often, while those based on f-f transitions were widely utilized. However, d-f emission in rare earths is very important because of their strong oscillator strength and broad emission widths suitable for the application to scintillators and solid-state lasers. Co-doping of aluminum in sol-gel synthesis was known to be effective for the emission enhancement of trivalent terbium and europium. Recently, we applied aluminum co-doping to cerium and europium systems in sol-gel glass to succeed in the observation of strong blue light emission originating from d-f transitions. Glass samples were prepared with conventional sol-gel process where tetramethylorthosilicate was hydrolyzed in the mixture of water, ethanol and dimethylformamide with nitric acid catalyst. After adding cerium nitrate and aluminum nitrate, the solution experienced drying followed by calcination at 1,050°C under air environment. When molar ratio of cerium to silicon was adjusted at 0.1% and Al concentration was varied in 0.1 2.0%, transparent glass products showed bright and broad blue photoluminescence under UV illumination. The fluorescence lifetimes were found to be about 50 90 ns, indicating that the emission was due to d-f transitions. Considering the simplicity of the process, blue phosphors based on sol-gel glass will be very promising for future applications.

Influence of surfactants on the effectiveness of bleaching gels.

PubMed

Caneppele, Taciana Marco Ferraz; Torres, Carlos Rocha Gomes

2011-02-01

This study evaluated the influence of surfactants on the effectiveness of 35% hydrogen peroxide (HP) and 10% carbamide peroxide (CP) bleaching gels. One hundred and forty bovine teeth were used, which were stained by immersion in a coffee, red wine, and tobacco mixture for 7 days. At the end of this process, the color measurement at baseline was taken with the Vita Easyshade spectrophotometer. The teeth were divided into seven groups: (a) negative control (NC), (b) positive control for HP (PC-35), (c) HP + Tween 20 (T20-35), (d) HP + laurel sodium sulfate (LSS-35), (e) positive control for CP (PC-10), (f) CP + Tween 20 (T20-10), and (g) CP + laurel sodium sulfate (LSS-10). Group NC was kept in artificial saliva for 21 days. Groups PC-35, T20-35, and LSS 35 received three applications of bleaching gel for 10 min; the process was repeated after 7 days. Groups PC-10, T20-10, and LSS-10 received the gel for 8 h per day for 14 days. After the bleaching process, the final color was measured. The analysis of variance and Tukey tests showed statistically significant differences for the parameters of ∆L, ∆b, and ∆E of the HP gels with surfactant and positive control group (PC-35). Within the limits of this in vitro study, the addition of surfactants to HP bleaching gel increased the bleaching effectiveness.

Composition for absorbing hydrogen from gas mixtures

DOEpatents

Heung, Leung K.; Wicks, George G.; Lee, Myung W.

1999-01-01

A hydrogen storage composition is provided which defines a physical sol-gel matrix having an average pore size of less than 3.5 angstroms which effectively excludes gaseous metal hydride poisons while permitting hydrogen gas to enter. The composition is useful for separating hydrogen gas from diverse gas streams which may have contaminants that would otherwise render the hydrogen absorbing material inactive.

Method of Preparing Monoclinic BaO.Al2O3.2SiO2

DTIC Science & Technology

Monoclinic celsian (BaO.Al2O3.2SiO2) is produced by heating a stoichiometric, powder mixture of BaCO3 (or BaC2O4), Al2O3, and SiO2 (preferably SiO2 gel) with monoclinic celsian seeds at from 1250 deg C to 1500 deg C.

Weathering Performance of Wood Coated with a Combination of Alkoxysilanes and Rutile TiO2 Heirarchical Nanostructures

Treesearch

Rongbo Zheng; Mandla A. Tshabalala; Qingyu Li; Hongyan Wang

2015-01-01

The weathering performance of wood coated with a combination of rutile TiO2 hierarchicalnanostructures and a sol-gel deposit of alkoxysilanes was determined by exposing three sets of specimens to UV light and water spray. The first set consisted of specimens coated with a mixture of methyltrimethoxysilane (MTMOS) and hexadecyltrimethoxysilane (...

Treating Fibrous Insulation to Reduce Thermal Conductivity

NASA Technical Reports Server (NTRS)

Zinn, Alfred; Tarkanian, Ryan

2009-01-01

A chemical treatment reduces the convective and radiative contributions to the effective thermal conductivity of porous fibrous thermal-insulation tile. The net effect of the treatment is to coat the surfaces of fibers with a mixture of transition-metal oxides (TMOs) without filling the pores. The TMO coats reduce the cross-sectional areas available for convection while absorbing and scattering thermal radiation in the pores, thereby rendering the tile largely opaque to thermal radiation. The treatment involves a sol-gel process: A solution containing a mixture of transition-metal-oxide-precursor salts plus a gelling agent (e.g., tetraethylorthosilicate) is partially cured, then, before it visibly gels, is used to impregnate the tile. The solution in the tile is gelled, then dried, and then the tile is fired to convert the precursor salts to the desired mixed TMO phases. The amounts of the various TMOs ultimately incorporated into the tile can be tailored via the concentrations of salts in the solution, and the impregnation depth can be tailored via the viscosity of the solution and/or the volume of the solution relative to that of the tile. The amounts of the TMOs determine the absorption and scattering spectra.

Controlled release from a composite silicone/hydrogel membrane.

PubMed

Hu, Z; Wang, C; Nelson, K D; Eberhart, R C

2000-01-01

To enhance the drug uptake and release capacity of silicone rubber (SR), N-isopropylacrylamide (NIPA) hydrogel particles have been incorporated into a SR membrane. The NIPA particles were thoroughly blended with uncured SR with a certain ratio at room temperature. The mixture was then cast in a Petri dish to 1 mm thickness and cured 10 hours at 90 degrees C. The SR/NIPA composite gel can absorb water approximately equal to its dry weight. Brilliant blue, used as a mock drug, was loaded into the composite gel. Drug release increased exponentially to a final value that is temperature dependent: low at T> =34 degrees C, and high at T< 34 degrees C. This finding is because the hydrophobicity of NIPA changes with temperature. Pulsed release in response to temperature switching between 20 and 39 degrees C has been achieved. Drug uptake and release capability strongly depends upon the structure of the composite gel. The optimal range of NIPA composition is between 75 and 87% by volume. In the cited range, the NIPA particles form an interconnected network that provides a channel for diffusion of drug solution. The SR/NIPA composite gel has promising attributes as a wound dressing and other uses.

Peptide-based ambidextrous bifunctional gelator: applications in oil spill recovery and removal of toxic organic dyes for waste water management.

PubMed

Basu, Kingshuk; Nandi, Nibedita; Mondal, Biplab; Dehsorkhi, Ashkan; Hamley, Ian W; Banerjee, Arindam

2017-12-06

A low molecular weight peptide-based ambidextrous gelator molecule has been discovered for efficient control of water pollution. The gelator molecules can gel various organic solvents with diverse polarity, e.g. n -hexane, n -octane, petroleum ether, petrol, diesel, aromatic solvents like chlorobenzene, toluene, benzene, o -xylene and even aqueous phosphate buffer of pH 7.5. These gels have been thoroughly characterized using various techniques including field emission scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray powder diffraction analysis, small angle X-ray scattering and rheological experiments. Interestingly, hydrogel obtained from the gelator molecule has been found to absorb toxic organic dyes (both cationic and anionic dyes) from dye-contaminated water. The gelator molecule can be reused for several cycles, indicating its possible future use in waste water management. Moreover, this gelator can selectively gel petrol, diesel, pump oil from an oil-water mixture in the presence of a carrier solvent, ethyl acetate, suggesting its efficient application for oil spill recovery. These results indicate that the peptide-based ambidextrous gelator produces soft materials (gels) with dual function: (i) removal of toxic organic dyes in waste water treatment and (ii) oil spill recovery.

Determining equilibrium osmolarity in poly(ethylene glycol)/chondrotin sulfate gels mimicking articular cartilage.

PubMed

Sircar, S; Aisenbrey, E; Bryant, S J; Bortz, D M

2015-01-07

We present an experimentally guided, multi-phase, multi-species polyelectrolyte gel model to make qualitative predictions on the equilibrium electro-chemical properties of articular cartilage. The mixture theory consists of two different types of polymers: poly(ethylene gylcol) (PEG), chondrotin sulfate (ChS), water (acting as solvent) and several different ions: H(+), Na(+), Cl(-). The polymer chains have covalent cross-links whose effect on the swelling kinetics is modeled via Doi rubber elasticity theory. Numerical studies on equilibrium polymer volume fraction and net osmolarity (difference in the solute concentration across the gel) show a complex interplay between ionic bath concentrations, pH, cross-link fraction and the average charge per monomer. Generally speaking, swelling is aided due to a higher average charge per monomer (or a higher particle fraction of ChS, the charged component of the polymer), low solute concentration in the bath, a high pH or a low cross-link fraction. A peculiar case arises at higher values of cross-link fraction, where it is observed that increasing the average charge per monomer leads to gel deswelling. Copyright © 2014 Elsevier Ltd. All rights reserved.

Improvement of proteolytic efficiency towards low-level proteins by an antifouling surface of alumina gel in a microchannel.

PubMed

Liu, Yun; Wang, Huixiang; Liu, Qingping; Qu, Haiyun; Liu, Baohong; Yang, Pengyuan

2010-11-07

A microfluidic reactor has been developed for rapid enhancement of protein digestion by constructing an alumina network within a poly(ethylene terephthalate) (PET) microchannel. Trypsin is stably immobilized in a sol-gel network on the PET channel surface after pretreatment, which produces a protein-resistant interface to reduce memory effects, as characterized by X-ray fluorescence spectrometry and electroosmotic flow. The gel-derived network within a microchannel provides a large surface-to-volume ratio stationary phase for highly efficient proteolysis of proteins existing both at a low level and in complex extracts. The maximum reaction rate of the encapsulated trypsin reactor, measured by kinetic analysis, is much faster than in bulk solution. Due to the microscopic confinement effect, high levels of enzyme entrapment and the biocompatible microenvironment provided by the alumina gel network, the low-level proteins can be efficiently digested using such a microreactor within a very short residence time of a few seconds. The on-chip microreactor is further applied to the identification of a mixture of proteins extracted from normal mouse liver cytoplasm sample via integration with 2D-LC-ESI-MS/MS to show its potential application for large-scale protein identification.

Exploring the dynamics of phase separation in colloid-polymer mixtures with long range attraction.

PubMed

Sabin, Juan; Bailey, Arthur E; Frisken, Barbara J

2016-06-28

We have studied the kinetics of phase separation and gel formation in a low-dispersity colloid - non-adsorbing polymer system with long range attraction using small-angle light scattering. This system exhibits two-phase and three-phase coexistence of gas, liquid and crystal phases when the strength of attraction is between 2 and 4kBT and gel phases when the strength of attraction is increased. For those samples that undergo macroscopic phase separation, whether to gas-crystal, gas-liquid or gas-liquid-crystal coexistence, we observe dynamic scaling of the structure factor and growth of a characteristic length scale that behaves as expected for phase separation in fluids. In samples that gel, the power law associated with the growth of the dominant length scale is not equal to 1/3, but appears to depend mainly on the strength of attraction, decreasing from 1/3 for samples near the coexistence region to 1/27 at 8kBT, over a wide range of colloid and polymer concentrations.

DIGE Analysis Software and Protein Identification Approaches.

PubMed

Hmmier, Abduladim; Dowling, Paul

2018-01-01

DIGE is a high-resolution two-dimensional gel electrophoresis method, with excellent dynamic range obtained by fluorescent tag labeling of protein samples. Scanned images of DIGE gels show thousands of protein spots, each spot representing a single or a group of protein isoforms. By using commercially available software, each protein spot is defined by an outline, which is digitized and correlated with the quantity of proteins present in each spot. Software packages include DeCyder, SameSpots, and Dymension 3. In addition, proteins of interest can be excised from post-stained gels and identified with conventional mass spectrometry techniques. High-throughput mass spectrometry is performed using sophisticated instrumentation including matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF), MALDI-TOF/TOF, and liquid chromatography tandem mass spectrometry (LC-MS/MS). Tandem MS (MALDI-TOF/TOF or LC-MS/MS), analyzes fragmented peptides, resulting in amino acid sequence information, especially useful when protein spots are low abundant or where a mixture of proteins is present.

Characterization of an alkaline protease associated with a granulosis virus of Plodia interpunctella.

PubMed

Tweeten, K A; Bulla, L A; Consigli, R A

1978-06-01

An alkaline protease was found to be associated with the granulosis virus of the Indian meal moth. Plodia interpunctella. The protease was located within the protein matrix of the occluded virus and hydrolyzed the major constituent of this matrix, a 28,000-dalton protein (granulin), to a mixture of polypeptides ranging in molecular weight from 10,000 to 27,000. A rapid, sensitive assay for the protease was developed using radioactively labeled granulosis virus as substrate. With this assay, the proteolytic activity could be detected by measuring the release of acid-soluble peptides from the labeled virus. The protease had a pH optimum of 10.5 and a temperature optimum of 40 degrees C and was inhibited by diisopropyl phosphorofluoridate, phenylmethylsulfonyl fluoride, and L-(1-tosylamido-2-phenyl) ethyl chloromethyl ketone. Purification of the protease from matrix protein was achieved by anion-exchange and gel permeation chromatography. The molecular weight of the isolated protease, determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and gel filtration, was approximately 14,000.

Light-weight black ceramic insulation

NASA Technical Reports Server (NTRS)

Hsu, Ming-Ta S. (Inventor); Chen, Timothy S. (Inventor)

2003-01-01

Ultra-high temperature, light-weight, black ceramic insulation having a density ranging from about 0.12 g/cc. to 0.6 g/cc. such as ceramic tile is obtained by pyrolyzing siloxane gels derived from the reaction of at least one organo dialkoxy silane and at least one tetralkoxy silane in an acid or base liquid medium. The reaction mixture of the tetra- and dialkoxy silanes also may contain an effective amount of a mono- or trialkoxy silane to obtain the siloxane gels. The siloxane gels are dried at ambient temperatures and pressures to form siloxane ceramic precursors without significant shrinkage. The siloxane ceramic precursors are subsequently pyrolyzed, in an inert atmosphere, to form the black ceramic insulation comprising atoms of silicon, carbon and oxygen. The ceramic insulation can be characterized as a porous, uniform ceramic tile resistant to oxidation at temperatures ranging as high as 1700.degree. C., and particularly useful as lightweight tiles for spacecraft and other high-temperature insulation applications.

Effect of pulverized fuel ash and CO{sub 2} curing on the water resistance of magnesium oxychloride cement (MOC)

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

He, Pingping; Poon, Chi Sun, E-mail: cecspoon@polyu.edu.hk; Tsang, Daniel C.W.

This paper presents a study on the use of pulverized fuel ash (PFA) to improve the water resistance of magnesium oxychloride cement (MOC). Strength retention coefficients and volume stability were tested to evaluate the water resistance of MOC, in which the addition of PFA resulted in a remarkable improvement. The characterization of hydration products before and after water immersion was carried out using quantitative X-ray diffraction (QXRD), thermogravimetric (TG), Fourier-transformed infrared spectroscopy (FTIR) and scanning electron microscope (SEM). With the Q-XRD analysis, it was shown that the addition of PFA could result in the great increase of the amount ofmore » amorphous phase during air curing. This amorphous gel was identified as a mixture of magnesium-chloride-silicate-hydrate gel (M-Cl-S-H gel) and magnesium-chloride-hydrate gel (M-Cl-H gel) by elemental mapping scanning. It suggested that PFA could not only react with MOC to form M-Cl-S-H gel, but also change the morphology of magnesium oxychloride. The generation of insoluble M-Cl-S-H gel and M-Cl-H gel and densification of the microstructure contributed to the improvement of the water resistance of MOC. The MOC mortar expanded during air curing due to the hydration of excess MgO. Water immersion led to more expansion of MOC mortar as a result of the continuously hydration of excess MgO and the formation of Mg(OH){sub 2}. Adding PFA could increase the expansion of MOC mortar during air curing, which may because the amorphous gel could remain more water and benefit to the hydration of MgO. While, the addition of PFA could decrease the expansion of cement mortar during water immersion perhaps due to the reduction of the content of excess MgO and the insoluble amorphous-gel-layer that protect the MgO from hydration. Moreover, CO{sub 2} curing could further improve the performance of the PFA-blended MOC due to the formation of a higher content of amorphous gel.« less

Lamellar biogels comprising fluid membranes with a newly synthesized class of polyethylene glycol-surfactants

NASA Astrophysics Data System (ADS)

Warriner, Heidi E.; Davidson, Patrick; Slack, Nelle L.; Schellhorn, Matthias; Eiselt, Petra; Idziak, Stefan H. J.; Schmidt, Hans-Werner; Safinya, Cyrus R.

1997-09-01

A series of four polymer-surfactant macromolecules, each consisting of a double-chain hydrophobic moiety attached onto a monofunctional polyethylene glycol (PEG) polymer chain, were synthesized in order to study their effect upon the fluid lamellar liquid crystalline (Lα) phase of the dimyristoylphosphatidylcholine/pentanol/water system. The main finding of this study is that the addition of these compounds induces a new lamellar gel, called Lα,g. We have determined the phase diagrams as a function of PEG-surfactant concentration, cPEG, and weight fraction water, ΦW. All phase diagrams are qualitatively similar and show the existence of the gel. Unlike more common polymer physical gels, this gel can be induced either by increasing cPEG or by adding water at constant cPEG. In particular, less polymer is required for gelation as water concentration increases. Moreover, the gel phase is attained at concentrations of PEG-surfactant far below that required for classical polymer gels and is stable at temperatures comparable to the lower critical solution temperature of free PEG-water mixtures. Small angle x-ray experiments demonstrate the lamellar structure of the gel phase, while wide angle x-ray scattering experiments prove that the structure is Lα, not Lβ' (a common chain-ordered phase which is also a gel). The rheological behavior of the Lα,g phase demonstrates the existence of three dimensional elastic properties. Polarized light microscopy of Lα,g samples reveals that the Lα,g is induced by a proliferation of defect structures, including whispy lines, spherulitic defects, and a nematiclike Schlieren texture. We propose a model of topological defects created by the aggregation of PEG-surfactant into highly curved regions within the membranes. This model accounts for both the inverse relationship between ΦW and cPEG observed along the gel transition line and the scaling dependence of the interlayer spacing at the gel transition with the PEG molecular weight. These Lα hydrogels could serve as the matrix for membrane-anchored peptides, proteins or other drug molecules, creating a "bioactive gel" with mechanical stability deriving from the polymer-lipid minority component.

Modification of wheat starch with succinic acid/acetanhydride and azelaic acid/acetanhydride mixtures. II. Chemical and physical properties.

PubMed

Ačkar, Durđica; Subarić, Drago; Babić, Jurislav; Miličević, Borislav; Jozinović, Antun

2014-08-01

The aim of this research was to investigate the influence of modification with succinic acid/acetanhydride and azelaic acid/acetanhydride mixtures on chemical and physical properties of wheat starch. Starch was isolated from two wheat varieties and modified with mixtures of succinic acid and acetanhydride and azelaic acid and acetanhydride in 4, 6 and 8% (w/w). Total starch content, resistant starch content, degree of modification, changes in FT-IR spectra, colour, gel texture and freeze-thaw stability were determined. Results showed that resistant starch content increased by both investigated modifications, and degree of modification increased proportionally to amount of reagents used. FT-IR analysis of modified starches showed peak around 1,740 cm(-1), characteristic for carbonyl group of ester. Total colour difference caused by modifications was detectable by trained people. Adhesiveness significantly increased, while freeze-thaw stability decreased by both investigated modifications.

Development of a new continuous process for mixing of complex non-Newtonian fluids

NASA Astrophysics Data System (ADS)

Migliozzi, Simona; Mazzei, Luca; Sochon, Bob; Angeli, Panagiota; Thames Multiphase Team; Coral Project Collaboration

2017-11-01

Design of new continuous mixing operations poses many challenges, especially when dealing with highly viscous non-Newtonian fluids. Knowledge of complex rheological behaviour of the working mixture is crucial for development of an efficient process. In this work, we investigate the mixing performance of two different static mixers and the effects of the mixture rheology on the manufacturing of novel non-aqueous-based oral care products using experimental and computational fluid dynamic methods. The two liquid phases employed, i.e. a carbomer suspension in polyethylene glycol and glycerol, start to form a gel when they mix. We studied the structure evolution of the liquid mixture using time-resolved rheometry and we obtained viscosity rheograms at different phase ratios from pressure drop measurements in a customized mini-channel. The numerical results and rheological model were validated with experimental measurements carried out in a specifically designed setup. EPSRS-CORAL.

Composition and method for self-assembly and mineralization of peptide-amphiphiles

DOEpatents

Stupp, Samuel I [Chicago, IL; Beniash, Elia [Newton, MA; Hartgerink, Jeffrey D [Pearland, TX

2012-02-28

The present invention is directed to a composition useful for making homogeneously mineralized self assembled peptide-amphiphile nanofibers and nanofiber gels. The composition is generally a solution comprised of a positively or negatively charged peptide-amphiphile and a like signed ion from the mineral. Mixing this solution with a second solution containing a dissolved counter-ion of the mineral and/or a second oppositely charged peptide amphiphile, results in the rapid self assembly of the peptide-amphiphiles into a nanofiber gel and templated mineralization of the ions. Templated mineralization of the initially dissolved mineral cations and anions in the mixture occurs with preferential orientation of the mineral crystals along the fiber surfaces within the nanofiber gel. One advantage of the present invention is that it results in homogenous growth of the mineral throughout the nanofiber gel. Another advantage of the present invention is that the nanofiber gel formation and mineralization reactions occur in a single mixing step and under substantially neutral or physiological pH conditions. These homogeneous nanostructured composite materials are useful for medical applications especially the regeneration of damaged bone in mammals. This invention is directed to the synthesis of peptide-amphiphiles with more than one amphiphilic moment and to supramolecular compositions comprised of such multi-dimensional peptide-amphiphiles. Supramolecular compositions can be formed by self assembly of multi-dimensional peptide-amphiphiles by mixing them with a solution comprising a monovalent cation.

Composition and method for self-assembly and mineralization of peptide amphiphiles

DOEpatents

Stupp, Samuel I [Chicago, IL; Beniash, Elia [Newton, MA; Hartgerink, Jeffrey D [Houston, TX

2009-06-30

The present invention is directed to a composition useful for making homogeneously mineralized self assembled peptide-amphiphile nanofibers and nanofiber gels. The composition is generally a solution comprised of a positively or negatively charged peptide-amphiphile and a like signed ion from the mineral. Mixing this solution with a second solution containing a dissolved counter-ion of the mineral and/or a second oppositely charged peptide amphiphile, results in the rapid self assembly of the peptide-amphiphiles into a nanofiber gel and templated mineralization of the ions. Templated mineralization of the initially dissolved mineral cations and anions in the mixture occurs with preferential orientation of the mineral crystals along the fiber surfaces within the nanofiber gel. One advantage of the present invention is that it results in homogenous growth of the mineral throughout the nanofiber gel. Another advantage of the present invention is that the nanofiber gel formation and mineralization reactions occur in a single mixing step and under substantially neutral or physiological pH conditions. These homogeneous nanostructured composite materials are useful for medical applications especially the regeneration of damaged bone in mammals. This invention is directed to the synthesis of peptide-amphiphiles with more than one amphiphilic moment and to supramolecular compositions comprised of such multi-dimensional peptide-amphiphiles. Supramolecular compositions can be formed by self assembly of multi-dimensional peptide-amphiphiles by mixing them with a solution comprising a monovalent cation.

Characterisation of rheology and microstructures of κ-carrageenan in ethanol-water mixtures.

PubMed

Yang, Zhi; Yang, Huijuan; Yang, Hongshun

2018-05-01

The effects of ethanol (up to 20 wt%) on the rheological properties and structural characteristics of κ-carrageenan gel were investigated by Field Emission Scanning Electron Microscopy (FESEM) and Small Angle X-ray Scattering (SAXS). Both the sol-gel and gel-sol transition temperatures shifted to higher degree (from 36.8 ± 0.5 to 52.5 ± 1.4 °C and from 51.2 ± 0.6 to 67.0 ± 0.5 °C, respectively) upon 20 wt% ethanol addition (P < 0.05). The critical relaxation exponent n and the critical gel strength S g obtained from Winter-Chambon criterion decreased and increased, respectively as the ethanol concentration increased. The κ-carrageenan gel was formed due to the formation of fibrillar networks, and the fibrillar density increased upon ethanol addition via FESEM. Moreover, upon 20 wt% ethanol addition, the average radius of gyration of κ-carrageenan strand increased from 1.18 ± 0.03 of control to 1.55 ± 0.02 nm by SAXS. A mechanism underlying the effect of ethanol on the κ-carrageenan gelation was proposed based on coil to double helix transition followed by the helix aggregation. Copyright © 2018 Elsevier Ltd. All rights reserved.

Methods for and products of processing nanostructure nitride, carbonitride and oxycarbonitride electrode power materials by utilizing sol gel technology for supercapacitor applications

DOEpatents

Huang, Yuhong; Wei, Oiang; Chu, Chung-tse; Zheng, Haixing

2001-01-01

Metal nitride, carbonitride, and oxycarbonitride powder with high surface area (up to 150 m.sup.2 /g) is prepared by using sol-gel process. The metal organic precursor, alkoxides or amides, is synthesized firstly. The metal organic precursor is modified by using unhydrolyzable organic ligands or templates. A wet gel is formed then by hydrolysis and condensation process. The solvent in the wet gel is then be removed supercritically to form porous amorphous hydroxide. This porous hydroxide materials is sintered to 725.degree. C. under the ammonia flow and porous nitride powder is formed. The other way to obtain high surface area nitride, carbonitride, and oxycarbonitride powder is to pyrolyze polymerized templated metal amides aerogel in an inert atmosphere. The electrochemical capacitors are prepared by using sol-gel prepared nitride, carbonitride, and oxycarbonitride powder. Two methods are used to assemble the capacitors. Electrode is formed either by pressing the mixture of nitride powder and binder to a foil, or by depositing electrode coating onto metal current collector. The binder or coating is converted into a continuous network of electrode material after thermal treatment to provide enhanced energy and power density. Liquid electrolyte is soaked into porous electrode. The electrochemical capacitor assembly further has a porous separator layer between two electrodes/electrolyte and forming a unit cell.

Continuous flow immobilized enzyme reactor-tandem mass spectrometry for screening of AChE inhibitors in complex mixtures.

PubMed

Forsberg, Erica M; Green, James R A; Brennan, John D

2011-07-01

A method is described for identifying bioactive compounds in complex mixtures based on the use of capillary-scale monolithic enzyme-reactor columns for rapid screening of enzyme activity. A two-channel nanoLC system was used to continuously infuse substrate coupled with automated injections of substrate/small molecule mixtures, optionally containing the chromogenic Ellman reagent, through sol-gel derived acetylcholinesterase (AChE) doped monolithic columns. This is the first report of AChE encapsulated in monolithic silica for use as an immobilized enzyme reactor (IMER), and the first use of such IMERs for mixture screening. AChE IMER columns were optimized to allow rapid functional screening of compound mixtures based on changes in the product absorbance or the ratio of mass spectrometric peaks for product and substrate ions in the eluent. The assay had robust performance and produced a Z' factor of 0.77 in the presence of 2% (v/v) DMSO. A series of 52 mixtures consisting of 1040 compounds from the Canadian Compound Collection of bioactives was screened and two known inhibitors, physostigmine and 9-aminoacridine, were identified from active mixtures by manual deconvolution. The activity of the compounds was confirmed using the enzyme reactor format, which allowed determination of both IC(50) and K(I) values. Screening results were found to correlate well with a recently published fluorescence-based microarray screening assay for AChE inhibitors.

Method for producing microcomposite powders using a soap solution

DOEpatents

Maginnis, Michael A.; Robinson, David A.

1996-01-01

A method for producing microcomposite powders for use in superconducting and non-superconducting applications. A particular method to produce microcomposite powders for use in superconducting applications includes the steps of: (a) preparing a solution including ammonium soap; (b) dissolving a preselected amount of a soluble metallic such as silver nitrate in the solution including ammonium soap to form a first solution; (c) adding a primary phase material such as a single phase YBC superconducting material in particle form to the first solution; (d) preparing a second solution formed from a mixture of a weak acid and an alkyl-mono-ether; (e) adding the second solution to the first solution to form a resultant mixture; (f) allowing the resultant mixture to set until the resultant mixture begins to cloud and thicken into a gel precipitating around individual particles of the primary phase material; (g) thereafter drying the resultant mixture to form a YBC superconducting material/silver nitrate precursor powder; and (h) calcining the YBC superconducting material/silver nitrate precursor powder to convert the silver nitrate to silver and thereby form a YBC/silver microcomposite powder wherein the silver is substantially uniformly dispersed in the matrix of the YBC material.

Fabrication of microfibrillated cellulose gel from waste pulp sludge via mild maceration combined with mechanical shearing

Treesearch

Nusheng Chen; Junyong Zhu; Zhaohui Tong

2016-01-01

This article describes a facile route, which combines mild maceration of waste pulp sludge and a mechanical shearing process, to prepare microfibrillated cellulose (MFC) with a high storage modulus. In the maceration, the mixture of glacial acetic acid and hydrogen peroxide was used to extract cellulose from never-dried waste pulp sludge. Then, two different mechanical...

Simple Cloud Chambers Using a Freezing Mixture of Ice and Cooking Salt

ERIC Educational Resources Information Center

Yoshinaga, Kyohei; Kubota, Miki; Kamata, Masahiro

2015-01-01

We have developed much simpler cloud chambers that use only ice and cooking salt instead of the dry ice or ice gel pack needed for the cloud chambers produced in our previous work. The observed alpha-ray particle tracks are as clear as those observed using our previous cloud chambers. The tracks can be observed continuously for about 20?min, and…

Role of 1% alendronate gel as adjunct to mechanical therapy in the treatment of chronic periodontitis among smokers

PubMed Central

SHARMA, Anuj; RAMAN, Achala; PRADEEP, Avani Raju

2017-01-01

Abstract Objective Alendronate (ALN) inhibits osteoclastic bone resorption and triggers osteostimulative properties both in vivo and in vitro, as shown by increase in matrix formation. This study aimed to explore the efficacy of 1% ALN gel as local drug delivery (LDD) in adjunct to scaling and root planing (SRP) for the treatment of chronic periodontitis among smokers. Material and Methods 75 intrabony defects were treated in 46 male smokers either with 1% ALN gel or placebo gel. ALN gel was prepared by adding ALN into carbopol-distilled water mixture. Clinical parameters [modified sulcus bleeding index, plaque index, probing depth (PD), and periodontal attachment level (PAL)] were recorded at baseline, at 2 months, and at 6 months, while radiographic parameters were recorded at baseline and at 6 months. Defect fill at baseline and at 6 months was calculated on standardized radiographs by using the image analysis software. Results Mean PD reduction and mean PAL gain were found to be greater in the ALN group than in the placebo group, both at 2 and 6 months. Furthermore, a significantly greater mean percentage of bone fill was found in the ALN group (41.05±11.40%) compared to the placebo group (2.5±0.93%). Conclusions The results of this study showed 1% ALN stimulated a significant increase in PD reduction, PAL gain, and an improved bone fill compared to placebo gel in chronic periodontitis among smokers. Thus, 1% ALN, along with SRP, is effective in the treatment of chronic periodontitis in smokers. PMID:28678942

The value of automated gel column agglutination technology in the identification of true inherited D blood types in massively transfused patients.

PubMed

Summers, Thomas; Johnson, Viviana V; Stephan, John P; Johnson, Gloria J; Leonard, George

2009-08-01

Massive transfusion of D- trauma patients in the combat setting involves the use of D+ red blood cells (RBCs) or whole blood along with suboptimal pretransfusion test result documentation. This presents challenges to the transfusion service of tertiary care military hospitals who ultimately receive these casualties because initial D typing results may only reflect the transfused RBCs. After patients are stabilized, mixed-field reaction results on D typing indicate the patient's true inherited D phenotype. This case series illustrates the utility of automated gel column agglutination in detecting mixed-field reactions in these patients. The transfusion service test results, including the automated gel column agglutination D typing results, of four massively transfused D- patients transfused D+ RBCs is presented. To test the sensitivity of the automated gel column agglutination method in detecting mixed-field agglutination reactions, a comparative analysis of three automated technologies using predetermined mixtures of D+ and D- RBCs is also presented. The automated gel column agglutination method detected mixed-field agglutination in D typing in all four patients and in the three prepared control specimens. The automated microwell tube method identified one of the three prepared control specimens as indeterminate, which was subsequently manually confirmed as a mixed-field reaction. The automated solid-phase method was unable to detect any mixed fields. The automated gel column agglutination method provides a sensitive means for detecting mixed-field agglutination reactions in the determination of the true inherited D phenotype of combat casualties transfused massive amounts of D+ RBCs.

Solution-processable electrochemiluminescent ion gels for flexible, low-voltage, emissive displays on plastic.

PubMed

Moon, Hong Chul; Lodge, Timothy P; Frisbie, C Daniel

2014-03-05

Ion gels comprising ABA triblock copolymers and ionic liquids have received much attention as functional materials in numerous applications, especially as gate dielectrics in organic transistors. Here we have expanded the functionality of ion gels by demonstrating low-voltage, flexible electrochemiluminescent (ECL) devices using patterned ion gels containing redox-active luminophores. The ECL devices consisted only of a 30 μm thick emissive gel and two electrodes and were fabricated on indium tin oxide-coated substrates (e.g., polyester) simply by solution-casting the ECL gel and brush-painting a top Ag electrode. The triblock copolymer employed in the gel was polystyrene-block-poly(methyl methacrylate)-block-polystyrene, where the solvophobic polystyrene end blocks associate into micellar cross-links in the versatile ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMI][TFSI]). An ECL gel containing ~6.25 wt % Ru(bpy)3Cl2 (relative to [EMI][TFSI]) as the luminophore turned on at an AC peak-to-peak voltage as low as 2.6 V (i.e., -1.3 to +1.3 V) and showed a relatively rapid response (sub-ms). The wavelength of maximum emission was 610 nm (red-orange). With the use of an iridium(III) complex, Ir(diFppy)2(bpy)PF6 [diFppy = 2-(2',4'-difluorophenyl)pyridine; bpy = 2,2'-bipyridyl], the emitting color was tuned to a maximum wavelength of 540 nm (green). Moreover, when a blended luminophore system containing a 60:40 mixture of Ru(bpy)3(2+) and Ir(diFppy)2(bpy)(+) was used in the emissive layer, the luminance of red-orange-colored light was enhanced by a factor of 2, which is explained by the generation of the additional excited state Ru(bpy)3(2+)* by a coreactant pathway with Ir(diFppy)2(bpy)(+)* in addition to the usual annihilation pathway. This is the first time that enhanced ECL has been achieved in ion gels (or ionic liquids) using a coreactant. Overall, the results indicate that ECL ion gels are attractive multifunctional materials for printed electronics.

Structure of phospholipid-cholesterol membranes: an x-ray diffraction study.

PubMed

Karmakar, Sanat; Raghunathan, V A

2005-06-01

We have studied the phase behavior of mixtures of cholesterol with dipalmitoyl phosphatidylcholine (DPPC), dimyristoyl phosphatidylcholine (DMPC), and dilauroyl phosphatidylethanolamine (DLPE), using x-ray diffraction techniques. Phosphatidylcholine (PC)-cholesterol mixtures are found to exhibit a modulated phase for cholesterol concentrations around 15 mol % at temperatures below the chain melting transition. Lowering the relative humidity from 98% to 75% increases the temperature range over which it exists. An electron density map of this phase in DPPC-cholesterol mixtures, calculated from the x-ray diffraction data, shows bilayers with a periodic height modulation, as in the ripple phase observed in many PCs in between the main- and pretransitions. However, these two phases differ in many aspects, such as the dependence of the modulation wavelength on the cholesterol content and thermodynamic stability at reduced humidities. This modulated phase is found to be absent in DLPE-cholesterol mixtures. At higher cholesterol contents the gel phase does not occur in any of these three systems, and the fluid lamellar phase is observed down to the lowest temperature studied (5 degrees C).

Development of mesoporous structures of composite silica particles with various organic functional groups in the presence and absence of ammonia catalyst

NASA Astrophysics Data System (ADS)

Park, Tae Jae; Jung, Gyu Il; Kim, Euk Hyun; Koo, Sang Man

2017-06-01

Development of mesoporous structures of composite silica particles with various organic functional groups was investigated by using a two-step process, consisting of one-pot sol-gel process in the presence and absence of ammonium hydroxide and a selective dissolution process with an ethanol-water mixture. Five different organosilanes, including methyltrimethoxysilane (MTMS), 3-mercaptopropyltrimethoxysilane (MPTMS), phenyltrimethoxysilane (PTMS), vinyltrimethoxysilane (VTMS), and 3-aminopropyltrimethoxysilane (APTMS) were employed. The mesoporous (organically modified silica) ORMOSIL particles were obtained even in the absence of ammonium hydroxide when the reaction mixture contained APTMS. The morphology of the particles, however, were different from those prepared with ammonia catalyst and the same organosilane mixtures, probably because the overall hydrolysis/condensation rates became slower. Co-existence of APTMS and VTMS was essential to prepare mesoporous particles from ternary organosilane mixtures. The work presented here demonstrates that organosilica particles with desired functionality and desired mesoporous structures can be obtained by selecting proper types of organosilane monomers and performing a facile and mild process either with or without ammonium hydroxide.

Composite gel polymer electrolyte for lithium ion batteries

NASA Astrophysics Data System (ADS)

Naderi, Roya

Composite gel polymer electrolyte (CGPE) films, consisting of poly (vinylidene fluoride-hexafluoropropylene) (PVdF-HFP) as the membrane, DMF and PC as solvent and plasticizing agent, mixture of charge modified TiO2 and SiO 2 nano particles as ionic conductors, and LiClO4+LiPF 6 as lithium salts were fabricated. Following the work done by Li et al., CGPE was coated on an O2-plasma treated trilayer polypropylene-polyethylene-polypropylene membrane separator using solution casting technique in order to improve the adhesive properties of gel polymer electrolyte to the separator membrane and its respective ionic conductivity due to decreasing the bulk resistance. In acidic CGPE with, the mixture of acid treated TiO2 and neutral SiO2 nano particles played the role of the charge modified nano fillers with enhanced hydroxyl groups. Likely, the mixture of neutral TiO 2 nano particles with basic SiO2 prepared through the hydrolization of tetraethyl orthosilicate (TEOS) provided a more basic environment due to the residues of NH4OH (Ammonium hydroxide) catalyst. The O2 plasma treated separator was coated with the solution of PVDF-HFP: modified nano fillers: Organic solvents with the mixture ratio of 0.1:0.01:1. After the evaporation of the organic solvents, the dried coated separator was soaked in PC-LiClO4+LiPF6 in EC: DMC:DEC (4:2:4 in volume) solution (300% wt. of PVDF-HFP) to form the final CGPE. Lim et al. has reported the enhanced ionic conductivity of 9.78*10-5 Scm-1 in an acidic composite polystyrene-Al2O3 solid electrolyte system with compared to that of basic and neutral in which the ionic conductivity undergoes an ion hopping process in solid interface rather than a segmental movement of ions through the plasticized polymer chain . Half-cells with graphite anode and Li metal as reference electrode were then assembled and the electrochemical measurements and morphology examinations were successfully carried out. Half cells demonstrated a considerable change in their electrochemical performance upon the enhancement of acidic properties of the CGPE, gaining the reversible specific capacity of 314 mAh.g-1 in acidic CGPE vs. 247 mAh.g-1 in basic CGPE C/20 after 33 cycles. The CGPE exhibited submicron pore size while the ionic conductivities were in order of 10-3 and 10-5 Scm-1 with and without modified nano-fillers respectively.

Comparison of Different IMAC Techniques Used for Enrichment of Phosphorylated Peptides

PubMed Central

Kånge, Rikard; Selditz, Ulrike; Granberg, Maria; Lindberg, Ulrika; Ekstrand, Gunnar; Ek, Bo; Gustafsson, Magnus

2005-01-01

Four commercially available immobilized metal ion affinity chromatography (IMAC) methods for phosphopeptide enrichment were compared using small volumes and concentrations of phosphopeptide mixtures with or without extra-added bovine serum albumin (BSA) nonphosphorylated peptides. Addition of abundant tryptic BSA peptides to the phosphopeptide mixture increases the demand for selective IMAC capture. While SwellGel gallium Discs, IPAC Metal Chelating Resin, and ZipTipMC Pipette Tips allow for the possibility of enriching phosphopeptides, the Gyrolab MALDI IMAC1 also presents the possibility of verifying existing phosphopeptides after a dephosphorylation step. Phosphate-containing peptides are identified through a mass shift between phosphorylated and dephosphorylated spectra of 80 Da (or multiples of 80 Da). This verification is useful if the degree of phosphorylation is low in the sample or if the ionization is unfavorable, which often is the case for phosphopeptides. A peptide mixture in which phosphorylated serine, threonine, and tyrosine were represented was diluted in steps and thereafter enriched using the four different IMAC methods prior to analyses with matrix assisted laser desorption/ionization mass spectrometry. The enrichment of phosphopeptides using SwellGel Gallium Discs or Gyrolab MALDI IMAC1 was not significantly affected by the addition of abundant BSA peptides added to the sample mixture, and the achieved detection limits using these techniques were also the lowest. All four of the included phosphopeptides were detected by MALDI-MS only after enrichment using the Gyrolab MALDI IMAC1 compact disc (CD) and detection down to low femtomole levels was possible. Furthermore, selectivity, reproducibility, and detection for a number of other phosphopeptides using the IMAC CD are reported herein. For example, two phosphopeptides sent out in a worldwide survey performed by the Proteomics Research Group (PRG03) of the Association of Biomolecular Resource Facilities (ABRF) were detected and verified by means of the 80 Da mass shift achieved by on-column dephosphorylation. PMID:16030316

Integration of isoelectric focusing with parallel sodium dodecyl sulfate gel electrophoresis for multidimensional protein separations in a plastic microfluidic [correction of microfludic] network.

PubMed

Li, Yan; Buch, Jesse S; Rosenberger, Frederick; DeVoe, Don L; Lee, Cheng S

2004-02-01

An integrated protein concentration/separation system, combining non-native isoelectric focusing (IEF) with sodium dodecyl sulfate (SDS) gel electrophoresis on a polymer microfluidic chip, is reported. The system provides significant analyte concentration and extremely high resolving power for separated protein mixtures. The ability to introduce and isolate multiple separation media in a plastic microfluidic network is one of two key requirements for achieving multidimensional protein separations. The second requirement lies in the quantitative transfer of focused proteins from the first to second separation dimensions without significant loss in the resolution acquired from the first dimension. Rather than sequentially sampling protein analytes eluted from IEF, focused proteins are electrokinetically transferred into an array of orthogonal microchannels and further resolved by SDS gel electrophoresis in a parallel and high-throughput format. Resolved protein analytes are monitored using noncovalent, environment-sensitive, fluorescent probes such as Sypro Red. In comparison with covalently labeling proteins, the use of Sypro staining during electrophoretic separations not only presents a generic detection approach for the analysis of complex protein mixtures such as cell lysates but also avoids additional introduction of protein microheterogeneity as the result of labeling reaction. A comprehensive 2-D protein separation is completed in less than 10 min with an overall peak capacity of approximately 1700 using a chip with planar dimensions of as small as 2 cm x 3 cm. Significant enhancement in the peak capacity can be realized by simply raising the density of microchannels in the array, thereby increasing the number of IEF fractions further analyzed in the size-based separation dimension.

Oriented 1,2-dimyristoyl-sn-glycero-3-phosphorylcholine/ganglioside membranes: a Fourier transform infrared attenuated total reflection spectroscopic study. Band assignments; orientational, hydrational, and phase behavior; and effects of Ca2+ binding.

PubMed

Müller, E; Giehl, A; Schwarzmann, G; Sandhoff, K; Blume, A

1996-09-01

Fourier transform infrared (FTIR) attenuated total reflection (ATR) spectroscopy was used to elucidate the hydration behavior and molecular order of phospholipid/ganglioside bilayers. We examined dry and hydrated films of the gangliosides GM1, deacetyl-GM1, lyso-GM1, deacetyllyso-GM1, and GM3 and oriented mixed films of these gangliosides with 1,2-dimyristoyl-sn-glycero-3-phosphorylcholine (DMPC) using polarized light. Analysis of the amide I frequencies reveals that the amide groups are involved in intermolecular interactions via hydrogen bonds of varying strengths. The tilt angle of the acyl chains of the lipids in mixed films was determined as a function of ganglioside structure. Deacetylation of the sialic acid in the headgroup has a stronger influence on the tilt angle than the removal of the ganglioside fatty acid. The phase behavior was examined by FTIR ATR spectroscopy and by differential scanning calorimetry (DSC) measurements on lipid suspensions. At the same molar concentration, lyso-gangliosides have less effect on changes of transition temperature compared to the double-chain analogs. Distinct differences in the amide band shapes were observed between mixtures with lyso-gangliosides and normal double-chain gangliosides. Determined from the dicroic ratio RATR, the orientation of the COO- group in all DMPC/ganglioside mixtures was found to be relatively fixed with respect to the membrane normal. In 4:1 mixtures of DMPC with GM1 and deacetyl-GM1, the binding of Ca2+ leads to a slight decrease in chain tilt in the gel phase, probably caused by a dehydration of the membrane-water interface. In mixtures of DMPC with GM3 and deacetyl-lyso-GM1, a slight increase in chain tilt is observed. The chain tilt in DMPC/lyso-GM1 mixtures is unchanged. Analysis of the COO- band reveals that Ca2+ does not bind to the carboxylate group of the sialic acid of GM1 and deacetyl-GM1, the mixtures in which a decrease in chain tilt was observed. Binding to the sialic acid was only observed for mixtures of DMPC with GM3, lyso-GM1, and deacetyl-lyso-GM1. Ca2+ obviously accumulates at the bilayer-water interface and leads to partial dehydration of the headgroup region in the gel as well as in the liquid-crystalline phase. This can be concluded from the changes in the amide I band shapes. With the exception of DMPC/deacetyl-GM1, the effects on the ester C==O bands are small. The addition of Ca2+ has minor effects on the phase behavior, with the exception of the DMPC/GM1 mixture.

Studies on the effect of dispersoid(ZrO2) in PVdF-co-HFP based gel polymer electrolytes

NASA Astrophysics Data System (ADS)

Sivakumar, M.; Subadevi, R.; Muthupradeepa, R.

2013-06-01

Gel polymer electrolytes containing poly(vinylidenefluoride-co-hexafluoropropylene) (P(VdF-co-HFP)) / Lithium bis(trifluoromethane sulfon)imide (LiTFSI) / mixture of ethylene carbonate and propylene carbonate (EC+PC) with different concendration of ZrO2 has been prepared using the solution casting technique. The conductivity of the prepared electrolyte sample has been determined by AC impedance technique in the range 303-353K. The temperature dependent ionic conductivity plot seems to obey VTF relation. The maximum ionic conductivity value of 4.46 × 10-3S/cm has been obtained for PVdF-co-HFP(32%) - LiTFSI(8%) - EC+PC (60%) + ZrO2(6wt%) based polymer electrolyte. The surface morphology of the prepared electrolyte sample has been studied using SEM.

Selection of new Kynar-based electrolytes for lithium-ion batteries

NASA Astrophysics Data System (ADS)

Christie, Alasdair M.; Christie, Lynn; Vincent, Colin A.

New electrolyte solution compositions have been identified for use in lithium-ion batteries after gelling with an appropriate quantity of Kynar polymer. Since the Li + conducting medium is largely the liquid electrolyte component, the assessment of these solutions as suitable lithium-ion cell candidates were investigated before adding the polymer. Selected electrolyte solutions were then used in the preparation of polymer gels. The specific conductivities of Kynar-based gels were determined as a function of salt concentration and polymer concentration. Optimised self-supporting polymer films, based on mixtures of ethylene carbonate (EC), ethylmethyl carbonate (EMC) and lithium hexafluorophosphate (LiPF 6) or lithium tetrafluoroborate (LiBF 4), showed good high current density cycling performance when used as separators in coke and Li 1- xMn 2O 4 (spinel) half-cells.

A Polymer Electrolyte for Dye-Sensitized Solar Cells Based on a Poly(Polyvinylidenefluoride-Co-Hexafluoropropylene)/Hydroxypropyl Methyl Cellulose Blend

NASA Astrophysics Data System (ADS)

Won, Lee Ji; Kim, Jae Hong; Thogiti, Suresh

2018-05-01

A novel polymer blend electrolyte for dye-sensitized solar cells (DSSCs) was synthesized by quasi-solidifying a liquid-based electrolyte containing an iodide/triiodide redox couple and supporting salts with a mixture of poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) and indigenous hydroxypropyl methyl cellulose (HPMC). A high ionic conductivity of 8.8 × 10-4 S cm-1 was achieved after introducing 5 wt% of HPMC with respect to the weight of PVDH-HFP. DSSCs were fabricated using gel polymer blend electrolytes, and the J-V characteristics of the fabricated devices were analyzed. Under optimal conditions, the photovoltaic conversion efficiency of cells with the novel HPMC-blended gel electrolyte (5.34%) was significantly greater than that of cells without HPMC (3.97%).

Isolation and characterization of the CNBr peptides from the proteolytically derived N-terminal fragment of ovine opsin.

PubMed Central

Brett, M; Findlay, J B

1983-01-01

Ovine rhodopsin may be cleaved in situ by Staphylococcus aureus V8 proteinase into two membrane-bound fragments designated V8-L (27 000 mol.wt.) and V8-S (12 000 mol.wt.). After purification of the proteolysed complex by affinity chromatography in detergent using concanavalin A immobilized on Sepharose 4B, the two polypeptide fragments may be separated by gel-permeation chromatography on Sephadex LH-60. Digestion of the N-terminal-derived V8-L fragment with CNBr in 70% (v/v) trifluoroacetic acid resulted in a peptide mixture that could be fractionated by procedures involving gel-permeation chromatography in organic and aqueous solvents and the use of differential solubility. The complete or partial sequences of all ten peptides are reported. PMID:6224479

Studies on lectins. XXXII. Application of affinity electrophoresis to the study of the interaction of lectins and their derivatives with sugars.

PubMed

Horejsí, V; Tichá, M; Kocourek, J

1977-09-29

Affinity electrophoresis was used to study the sugar binding heterogeneity of lectins or their derivatives. Commercial and demetallized preparations of concanavalin A could be resolved by affinity electrophoresis into three components with different affinity to immobilized sugar. Similarly the Vicia cracca lectin obtained by affinity chromatography behaved on affinity gels as a mixture of active and inactive molecular species. Affinity electrophoresis has shown that the nonhemagglutinating acetylated lentil lectin and photo-oxidized or sulfenylated pea lectin retain their sugar binding properties; dissociation constants of saccharide complexes of these derivatives are similar to those of native lectins. The presence of specific immobilized sugar in the affinity gel improved the resolution of isolectins from Dolichos biflorus and Ricinus communis seeds.

Cadmium-Aluminum Layered Double Hydroxide Microspheres for Photocatalytic CO2 Reduction.

PubMed

Saliba, Daniel; Ezzeddine, Alaa; Sougrat, Rachid; Khashab, Niveen M; Hmadeh, Mohamad; Al-Ghoul, Mazen

2016-04-21

We report the synthesis of cadmium-aluminum layered double hydroxide (CdAl LDH) using the reaction-diffusion framework. As the hydroxide anions diffuse into an agar gel matrix containing the mixture of aluminum and cadmium salts at a given ratio, they react to give the LDH. The LDH self-assembles inside the pores of the gel matrix into a unique spherical-porous shaped microstructure. The internal and external morphologies of the particles are studied by electron microscopy and tomography revealing interconnected channels and a high surface area. This material is shown to exhibit a promising performance in the photoreduction of carbon dioxide using solar light. Moreover, the palladium-decorated version shows a significant improvement in its reduction potential at room temperature. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fracturing fluid cleanup by controlled release of enzymes from polyelectrolyte complex nanoparticles

NASA Astrophysics Data System (ADS)

Barati Ghahfarokhi, Reza

Guar-based polymer gels are used in the oil and gas industry to viscosify fluids used in hydraulic fracturing of production wells, in order to reduce leak-off of fluids and pressure, and improve the transport of proppants. After fracturing, the gel and associated filter cake must be degraded to very low viscosities using breakers to recover the hydraulic conductivity of the well. Enzymes are widely used to achieve this but injecting high concentrations of enzyme may result in premature degradation, or failure to gel; denaturation of enzymes at alkaline pH and high temperature conditions can also limit their applicability. In this study, application of polyelectrolyte nanoparticles for entrapping, carrying, releasing and protecting enzymes for fracturing fluids was examined. The objective of this research is to develop nano-sized carriers capable of carrying the enzymes to the filter cake, delaying the release of enzyme and protecting the enzyme against pH and temperature conditions inhospitable to native enzyme. Polyethylenimine-dextran sulfate (PEI-DS) polyelectrolyte complexes (PECs) were used to entrap two enzymes commonly used in the oil industry in order to obtain delayed release and to protect the enzyme from conditions inhospitable to native enzyme. Stability and reproducibility of PEC nanoparticles was assured over time. An activity measurement method was used to measure the entrapment efficiency of enzyme using PEC nanoparticles. This method was confirmed using a concentration measurement method (SDS-PAGE). Entrapment efficiencies of pectinase and a commercial high-temperature enzyme mixture in polyelectrolyte complex nanoparticles were maximized. Degradation, as revealed by reduction in viscoelastic moduli of borate-crosslinked hydroxypropyl guar (HPG) gel by commercial enzyme loaded in polyelectrolyte nanoparticles, was delayed, compared to equivalent systems where the enzyme mixture was not entrapped. This indicates that PEC nanoparticles delay the activity of enzymes by entrapping them. It was also observed that control PEC nanoparticles decreased both viscoelastic moduli, but with a slower rate compared to the PEC nanoparticles loaded with enzyme. Preparation shear and applied shear showed no significant effect on activity of enzyme-loaded PEC nanoparticles mixed with HPG solutions. However, fast addition of chemicals during the preparations showed smaller particle size compared to the drop-wise method. PEC nanoparticles (PECNPs) also protected both enzymes from denaturation at elevated temperature and pH. Following preparation, enzyme-loaded PEC nanoparticles were mixed with borate crosslinked HPG and the mixture was injected through a shear loop. Pectinase-loaded nanoparticles mixed with gelled HPG showed no sensitivity to shear applied along the shear loop at 25 °C. However, EL2X-loaded PEC nanoparticles showed sensitivity to shear applied along the shear loop at 40 °C. Filter cake was formed and degraded in a fluid loss cell for borate crosslinked HPG solutions mixed with either enzymes or enzyme-loaded PEC nanoparticles. Cleanup slopes of filter cake degraded using enzyme-loaded PEC nanoparticles and systems with enzymes mixed with HPG gel were significantly higher than for the filter cake formed with HPG gel mixed with no enzyme. In a different application, enzyme-loaded PEC nanoparticles showed significantly slower reduction in viscosity of HPG solution over time compared to the HPG systems mixed with enzyme. Increasing the viscosity of low concentration HPG, used as slick-water, decreases the proppant settling velocity. This is of specific interest in fracturing fluids used for unconventional reservoirs.

Studies of Biosilicification; The Role of Proteins, Carbohydrates and Model Compounds in Structure Control

DTIC Science & Technology

2005-12-31

No. carbons Pore volume data. Resolution of complex monosaccharide mixtures from plant cell wall isolates by high pH anion exchange chromatography. To...interwoven polysaccharide chains embedded in a gel matrix of galacturonic acid rich polysaccharides connected by calcium bridges. This network also...picomolar levels). Also, it allows the determination of intact monosaccharides without pre or post column derivatisation, decreasing the time of

Selection of imprinted nanoparticles by affinity chromatography.

PubMed

Guerreiro, António R; Chianella, Iva; Piletska, Elena; Whitcombe, Michael J; Piletsky, Sergey A

2009-04-15

Soluble molecularly imprinted nanoparticles were synthesised via iniferter initiated polymerisation and separated by size via gel permeation chromatography. Subsequent fractionation of these particles by affinity chromatography allowed the separation of high affinity fractions from the mixture of nanoparticles. Fractions selected this way possess affinity similar to that of natural antibodies (K(d) 6.6x10(-8)) M and were also able to discriminate between related functional analogues of the template.

Fate of a metal-resistant inoculum in contaminated and pristine soils assessed by denaturing gradient gel electrophoresis

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

Stephen, J.R.; Chang, Y.J.; MacNaughton, S.J.

Cesium, cadmium, cobalt, and strontium are four contaminants frequently found in soils at biotoxic levels. Introduction of certain nongenetically modified bacteria has been frequently suggested as a method for the immobilization of heavy metal contaminants in soil, thereby reducing runoff and bioavailability. In this study, the authors have used the polymerase chain reaction (PCR) and denaturing gradient gel electrophoresis (DGGE) to track the survival of the five bacterial species added to soil microcosms with and without the addition of a mixture of these metals. The PCR primers targeted conserved regions of the 165 rDNA molecular present in all bacteria. Themore » reaction products were shown to reflect the relative abundance of the bacteria both in mixtures of pure cultures and against a background of all the eubacterial species present in the soil following inoculation. Three of the species (Pseudomonas aeruginosa FRD-1, Shewanella putrifaciens 200, and Desulfovibrio vulgaris Hildenborough) decreased rapidly following inoculation into both soils. The proportion of Alcaligenes eutrophus CH34 remained at a constant level throughout the 8-week experiment in both soil treatments. Sphingomonas aromaticivorans B0695 showed toxic metal-dependent survival in that its relative abundance dropped rapidly in pristine soil but remained at approximately inoculation levels throughout the experiment in contaminated microcosms.« less

Chemical Transformations in Proto-Cytoplasmic Media. Phosphorus Coupling in the Silica Hydrogel Phase

PubMed Central

Gorrell, Ian B.; Henderson, Timothy W.; Albdeery, Kamal; Savage, Philip M.; Kee, Terence P.

2017-01-01

It has been proposed that prebiotic chemical studies on the emergence of primitive life would be most relevant when performed in a hydrogel, rather than an aqueous, environment. In this paper we describe the ambient temperature coupling of phosphorus oxyacids [Pi] mediated by Fe(II) under aerobic conditions within a silica hydrogel (SHG) environment. We have chosen to examine SHGs as they have considerable geological precedence as key phases in silicification en route to rock formation. Following a description of the preparation and characterization studies on our SHG formulations, coupling experiments between Pi species are described across multiple permutations of (i) Pi compound; (ii) gel formulation; (iii) metal salt additive; and (iv) pH-modifying agent. The results suggest that successful Pi coupling, indicated by observation of pyrophosphate [PPi(V)] via 31P-NMR spectroscopy, takes place when the following components are present: (i) a mixture of mixture of Pi(III) and Pi(V) or pure PPi(III– V); (ii) Fe(II); (iii) acetic or formic acid (not hydrochloric acid); (iv) aerobic conditions or the presence of H2O2 as an oxidant; and (v) the presence of a gel system. On the basis of these, and aqueous control reactions, we suggest mechanistic possibilities. PMID:29156594

Photocatalytic degradation of mixed gaseous carbonyl compounds at low level on adsorptive TiO2/SiO2 photocatalyst using a fluidized bed reactor.

PubMed

Zhang, Maolin; An, Taicheng; Fu, Jiamo; Sheng, Guoying; Wang, Xinming; Hu, Xiaohong; Ding, Xuejun

2006-06-01

An adsorptive silica-supported titania photocatalyst TiO(2)/SiO(2) was prepared by using nanosized titania (anatase) immobilized on silica gel by the sol-gel technique with the titanium tetra isopropoxide as the main raw material and acetic acid as the acid catalyst. Meanwhile the structure and properties of the TiO(2)/SiO(2) photocatalyst were studied by means of many modern analysis techniques such as TEM, XRD, and BET. Gas-solid heterogeneous photocatalytic decomposition of four carbonyl compounds mixture at low concentration levels over ultraviolet irradiated TiO(2)/SiO(2) photocatalyst were carried out with high degradation efficiencies in a coaxial triple-cylinder-type fluidized bed photocatalytic reactor, which provided efficient continuous contact of ultraviolet photons, silica-supported titania photocatalyst, and gaseous reactants. Experimental results showed that the photocatalyst had a high adsorption performance and a good photocatalytic activity for four carbonyl compounds mixture. Some factors influencing the photocatalytic decomposition of the mixed carbonyl compounds, i.e. the gas flowrate, relative humidity, concentration of oxygen, and illumination time, were discussed in detail. It is found that the photocatalytic reaction rate of four carbonyl compounds decreased in this order: propionaldehyde, acetone, acetaldehyde and formaldehyde.

Effect of reaction solvent on hydroxyapatite synthesis in sol-gel process

NASA Astrophysics Data System (ADS)

Nazeer, Muhammad Anwaar; Yilgor, Emel; Yagci, Mustafa Baris; Unal, Ugur; Yilgor, Iskender

2017-12-01

Synthesis of hydroxyapatite (HA) through sol-gel process in different solvent systems is reported. Calcium nitrate tetrahydrate (CNTH) and diammonium hydrogen phosphate (DAHP) were used as calcium and phosphorus precursors, respectively. Three different synthesis reactions were carried out by changing the solvent media, while keeping all other process parameters constant. A measure of 0.5 M aqueous DAHP solution was used in all reactions while CNTH was dissolved in distilled water, tetrahydrofuran (THF) and N,N-dimethylformamide (DMF) at a concentration of 0.5 M. Ammonia solution (28-30%) was used to maintain the pH of the reaction mixtures in the 10-12 range. All reactions were carried out at 40 ± 2°C for 4 h. Upon completion of the reactions, products were filtered, washed and calcined at 500°C for 2 h. It was clearly demonstrated through various techniques that the dielectric constant and polarity of the solvent mixture strongly influence the chemical structure and morphological properties of calcium phosphate synthesized. Water-based reaction medium, with highest dielectric constant, mainly produced β-calcium pyrophosphate (β-CPF) with a minor amount of HA. DMF/water system yielded HA as the major phase with a very minor amount of β-CPF. THF/water solvent system with the lowest dielectric constant resulted in the formation of pure HA.

Relationship between sol-gel conditions and enzyme stability: a case study with β-galactosidase/silica biocatalyst for whey hydrolysis.

PubMed

Escobar, Sindy; Bernal, Claudia; Mesa, Monica

2015-01-01

The sol-gel process has been very useful for preparing active and stable biocatalysts, with the possibility of being reused. Especially those based on silica are well known. However, the study of the enzyme behavior during this process is not well understood until now and more, if the surfactant is involved in the synthesis mixture. This work is devoted to the encapsulation of β-galactosidase from Bacillus circulans in silica by sol-gel process, assisted by non-ionic Triton X-100 surfactant. The correlation between enzyme activity results for the β-galactosidase in three different environments (soluble in buffered aqueous reference solution, in the silica sol, and entrapment on the silica matrix) explains the enzyme behavior under stress conditions offered by the silica sol composition and gelation conditions. A stable β-galactosidase/silica biocatalyst is obtained using sodium silicate, which is a cheap source of silica, in the presence of non-ionic Triton X-100, which avoids the enzyme deactivation, even at 40 °C. The obtained biocatalyst is used in the whey hydrolysis for obtaining high value products from this waste. The preservation of the enzyme stability, which is one of the most important challenges on the enzyme immobilization through the silica sol-gel, is achieved in this study.

Sol-gel method for encapsulating molecules

DOEpatents

Brinker, C. Jeffrey; Ashley, Carol S.; Bhatia, Rimple; Singh, Anup K.

2002-01-01

A method for encapsulating organic molecules, and in particular, biomolecules using sol-gel chemistry. A silica sol is prepared from an aqueous alkali metal silicate solution, such as a mixture of silicon dioxide and sodium or potassium oxide in water. The pH is adjusted to a suitably low value to stabilize the sol by minimizing the rate of siloxane condensation, thereby allowing storage stability of the sol prior to gelation. The organic molecules, generally in solution, is then added with the organic molecules being encapsulated in the sol matrix. After aging, either a thin film can be prepared or a gel can be formed with the encapsulated molecules. Depending upon the acid used, pH, and other processing conditions, the gelation time can be from one minute up to several days. In the method of the present invention, no alcohols are generated as by-products during the sol-gel and encapsulation steps. The organic molecules can be added at any desired pH value, where the pH value is generally chosen to achieve the desired reactivity of the organic molecules. The method of the present invention thereby presents a sufficiently mild encapsulation method to retain a significant portion of the activity of the biomolecules, compared with the activity of the biomolecules in free solution.

Hydration of Hybrid Alkaline Cement Containing a Very Large Proportion of Fly Ash: A Descriptive Model

PubMed Central

Garcia-Lodeiro, Inés; Donatello, Shane; Fernández-Jiménez, Ana; Palomo, Ángel

2016-01-01

In hybrid alkaline fly ash cements, a new generation of binders, hydration, is characterized by features found in both ordinary portland cement (OPC) hydration and the alkali activation of fly ash (AAFA). Hybrid alkaline fly ash cements typically have a high fly ash (70 wt % to 80 wt %) and low clinker (20 wt % to 30 wt %) content. The clinker component favors curing at ambient temperature. A hydration mechanism is proposed based on the authors’ research on these hybrid binders over the last five years. The mechanisms for OPC hydration and FA alkaline activation are summarized by way of reference. In hybrid systems, fly ash activity is visible at very early ages, when two types of gel are formed: C–S–H from the OPC and N–A–S–H from the fly ash. In their mutual presence, these gels tend to evolve, respectively, into C–A–S–H and (N,C)–A–S–H. The use of activators with different degrees of alkalinity has a direct impact on reaction kinetics but does not modify the main final products, a mixture of C–A–S–H and (N,C)–A–S–H gels. The proportion of each gel in the mix does, however, depend on the alkalinity generated in the medium. PMID:28773728

Nanoemulsion-based gel formulations of COX-2 inhibitors for enhanced efficacy in inflammatory conditions

NASA Astrophysics Data System (ADS)

Lala, R. R.; Awari, N. G.

2014-02-01

In the present study, we have investigated the potential of a nanoemulsion (thermodynamically stable transparent dispersions of oil and water having a droplet size <200 nm) formulation for the topical delivery of COX-2 inhibitors using etoricoxib as a model drug. Various oil-in-water nanoemulsions were prepared by the spontaneous emulsification method. The nanoemulsion area was identified by constructing pseudo-ternary phase diagrams. The prepared nanoemulsions were subjected to thermodynamic stability testing. Those that passed these tests were characterized for viscosity, droplet size and differential scanning calorimetry. Topical permeation of etoricoxib through porcine abdominal skin was estimated using the Franz diffusion cell. The ex vivo skin permeation profile of optimized formulations was compared with that of etoricoxib conventional gel. A significant increase in permeability was observed in optimized nanoemulsion formulations consisting of 2 % w/w of etoricoxib, 20 % w/w of Triacetin, 38 % w/w of a surfactant mixture (Cremophor RH 40:Transcutol P), and 42 % w/w of water. The anti-inflammatory effects of this formulation on carrageenan-induced paw edema in rats showed a significant increase in the percent inhibition value (84.61 % with the nanoemulsion gel and 92.30 % with the nanoemulsion) as compared with the conventional gel (69.23 %) after 6 h when compared with etoricoxib conventional gel. These results suggest that nanoemulsions can serve as potential vehicles for improved transdermal delivery of anti-inflammatory agents such as etoricoxib.

Development and stability evaluation of olive oil nanoemulsion using sucrose monoester laurate

NASA Astrophysics Data System (ADS)

Eid, Ahmad M. M.; Baie, Saringat Haji; Arafat, Osama

2012-11-01

Nanoemulsion is a type of emulsion that consists of fine oil-in-water dispersions, with the droplets covering the size range of 20-200 nm. It can be achieved through emulsification process. One of the processes is through low energy emulsification method. Olive oil was chosen in this study due to its efficiency in treating skin problem. Olive oil nanophase gel (NPG) formulations were performed through various ratios of olive oil, sucrose laurate and glycerin. The particle sizes and stability of the prepared olive oil nanophase gel were evaluated and the optimal formulation was then selected for the development of olive oil nanoemulsion. This study proved that the composition of oil and surfactant play an important roles in influencing the nanophase gel droplet size. Nanophase gels containing olive oil in the concentration of 50 and 60 % show good stability at 4 °C and room temperature while it was less stable at 40 °C. Olive oil nanophase gels in the concentration of 50 % and 60 % with sucrose laurate 25 % in each formulation were good candidates to prepare nanoemulsion because they have the suitable droplets size and Polydispersing Index (PDI) when compared to other formulations. A mixture of NPG 50 % and water in the ratio of 40:60 and NPG 60 % and water in the ratio of 33.3:66.7 were used to produce nanoemulsions containing 20 % of oil with negative values of zeta potential (>60) which indicate the good stability of the nanoemulsions.

The impact of the concentration of casein micelles and whey protein-stabilized fat globules on the rennet-induced gelation of milk.

PubMed

Gaygadzhiev, Zafir; Corredig, Milena; Alexander, Marcela

2009-02-01

The rennet-induced aggregation of skim milk recombined with whey protein-stabilized emulsion droplets was studied using diffusing wave spectroscopy (DSW) and small deformation rheology. The effect of different volume fractions of casein micelles and fat globules was investigated by observing changes in turbidity (1/l*), apparent radius, elastic modulus and mean square displacement (MSD), in addition to confocal imaging of the gels. Skim milk containing different concentration of casein micelles showed comparable light-scattering profiles; a higher volume fraction of caseins led to the development of more elastic gels. By following the development of 1/l* in recombined milks, it was possible to describe the behaviour of the fat globules during the initial stages of rennet coagulation. Increasing the volume fraction of fat globules showed a significant increase in gel elasticity, caused by flocculation of the oil droplets. The presence of flocculated oil globules within the gel structure was confirmed by confocal microscopy observations. Moreover, a lower degree of kappa-casein hydrolysis was needed to initiate casein micelles aggregation in milk containing whey protein-stabilized oil droplets compared to skim milk. This study for the first time clearly describes the impact of a mixture of casein micelles and whey protein-stabilized fat globules on the pre-gelation stages of rennet coagulation, and further highlights the importance of the flocculation state of the emulsion droplets in affecting the structure formation of the gel.

Production of cerium dioxide microspheres by an internal gelation sol–gel method

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

Katalenich, Jeffrey A.

An internal gelation sol-gel technique was used to prepare cerium dioxide microspheres with uniform diameters near 100 µm. In this process, chilled aqueous solutions containing cerium, hexamethylenetetramine (HMTA), and urea are transformed into a solid gel by heat addition and are subsequently washed, dried, and sintered to produce pure cerium dioxide. Cerous nitrate and ceric ammonium nitrate solutions were compared for their usefulness in microsphere production. Gelation experiments were performed with both cerous nitrate and ceric ammonium nitrate to determine desirable concentrations of cerium, HMTA, and urea in feed solutions as well as the necessary quantity of ammonium hydroxide addedmore » to cerium solutions. Analysis of the pH before and after sample gelation was found to provide a quantitative metric for optimal parameter selection along with subjective evaluations of gel qualities. The time necessary for chilled solutions to gel upon inserting into a hot water bath was determined for samples with a variety of parameters and also used to determine desirable formulations for microsphere production. A technique for choosing the optimal mixture of ceric ammonium nitrate, HMTA, and urea was determined using gelation experiments and used to produce microspheres by dispersion of the feed solution into heated silicone oil. Gelled spheres were washed to remove excess reactants and reaction products before being dried and sintered. X-ray diffraction of air-dried microspheres, sintered microspheres, and commercial CeO 2 powders indicated that air-dried and sintered spheres were pure CeO 2.« less

Method of cell transplantation promoting the organization of intraarterial thrombus.

PubMed

Hirano, Koji; Shimono, Takatsugu; Imanaka-Yoshida, Kyoko; Miyamoto, Keiichi; Fujinaga, Kazuya; Kajimoto, Masaki; Miyake, Yoichiro; Nishikawa, Masakatsu; Yoshida, Toshimichi; Uchida, Atsumasa; Shimpo, Hideto; Yada, Isao; Hirata, Hitoshi

2005-08-30

Endovascular aortic repairs have been developed as less invasive treatments for aortic aneurysms. Some aneurismal cavities, however, remain without organization, causing a re-expansion of the aneurysms. We studied cell transplantation into the aneurismal sac to promote the organization of thrombus for the complete healing of aneurysms. Skin fibroblasts and skeletal myoblasts were isolated from rats for cell transplantation. An intraarterial thrombus model was made by ligation of the carotid artery. Culture medium (medium group, n=11), collagen gel (gel group, n=11), fibroblasts with collagen gel (F group, n=15), myoblasts with collagen gel (M group, n=12), or mixture of fibroblasts and myoblasts with collagen gel (F+M group, n=14) were injected into the thrombus. After 28 days, histologically, the arterial lumens of the F and M groups were partly filled with fibrous tissues, whereas in the F+M group organization was almost completed and luminal sizes diminished. Immunohistochemical staining demonstrated that alpha-smooth muscle actin-positive cells were more abundantly contained in the organized area of the F+M group than in the other groups. We also analyzed cellular function in vitro with immunofluorescence; coculture of fibroblasts and myoblasts showed that the fraction of alpha-smooth muscle actin-positive fibroblasts increased. This phenomenon accounts for the rapid organization of thrombus in the F+M group in vivo. Cell transplantation accelerated thrombus organization. Especially, myoblasts enhanced differentiation of fibroblasts into myofibroblasts, contributing to rapid thrombus organization. Cell transplantation into unorganized spaces seems applicable to endovascular treatment of aneurysms.

The Hb A variant (beta73 Asp-->Leu) disrupts Hb S polymerization by a novel mechanism.

PubMed

Adachi, Kazuhiko; Ding, Min; Surrey, Saul; Rotter, Maria; Aprelev, Alexey; Zakharov, Mikhail; Weng, Weijun; Ferrone, Frank A

2006-09-22

Polymerization of a 1:1 mixture of hemoglobin S (Hb S) and the artificial mutant HbAbeta73Leu produces a dramatic morphological change in the polymer domains in 1.0 M phosphate buffer that are a characteristic feature of polymer formation. Instead of feathery domains with quasi 2-fold symmetry that characterize polymerization of Hb S and all previously known mixtures such as Hb A/S and Hb F/S mixtures, these domains are compact structures of quasi-spherical symmetry. Solubility of Hb S/Abeta73Leu mixtures was similar to that of Hb S/F mixtures. Kinetics of polymerization indicated that homogeneous nucleation rates of Hb S/Abeta73Leu mixtures were the same as those of Hb S/F mixtures, while exponential polymer growth (B) of Hb S/Abeta73Leu mixtures were about three times slower than those of Hb S/F mixtures. Differential interference contrast (DIC) image analysis also showed that fibers in the mixture appear to elongate between three and five times more slowly than in equivalent Hb S/F mixtures by direct measurements of exponential growth of mass of polymer in a domain. We propose that these results of Hb S/Abeta73Leu mixtures arise from a non-productive binding of the hybrid species of this mixture to the end of the growing polymer. This "cap" prohibits growth of polymers, but by nature is temporary, so that the net effect is a lowered growth rate of polymers. Such a cap is consistent with known features of the structure of the Hb S polymer. Domains would be more spherulitic because slower growth provides more opportunity for fiber bending to spread domains from their initial 2-fold symmetry. Moreover, since monomer depletion proceeds more slowly in this mixture, more homogeneous nucleation events occur, and the resulting gel has a far more granular character than normally seen in mixtures of non-polymerizing hemoglobins with Hb S. This mixture is likely to be less stiff than polymerized mixtures of other hybrids such as Hb S with HbF, potentially providing a novel approach to therapy.

Coal-oil slurry preparation

DOEpatents

Tao, John C.

1983-01-01

A pumpable slurry of pulverized coal in a coal-derived hydrocarbon oil carrier which slurry is useful as a low-ash, low-sulfur clean fuel, is produced from a high sulfur-containing coal. The initial pulverized coal is separated by gravity differentiation into (1) a high density refuse fraction containing the major portion of non-coal mineral products and sulfur, (2) a lowest density fraction of low sulfur content and (3) a middlings fraction of intermediate sulfur and ash content. The refuse fraction (1) is gasified by partial combustion producing a crude gas product from which a hydrogen stream is separated for use in hydrogenative liquefaction of the middlings fraction (3). The lowest density fraction (2) is mixed with the liquefied coal product to provide the desired fuel slurry. Preferably there is also separately recovered from the coal liquefaction LPG and pipeline gas.

Case study, comparison of trial burn results from similar sulfuric acid regeneration plants

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

Milaszewski, M.; Johns, T.; Dickerson, W.F.

The primary business of Rhodia Eco Services (Rhodia) is the regeneration of sulfuric acid. Sulfuric acid regeneration requires thermal decomposition of acid to sulfur dioxide, and remaking the acid through chemical reaction. The sulfuric acid regeneration furnace is the ideal place to process pumpable wastes for energy recovery and for thermal destruction. Rhodia is regulated by the Boiler and Industrial Furnace (BIF) regulations (40 CFR 266, Subpart H). The Hammond, Indiana plant is an interim status BIF facility and the Houston, Texas facility is renewing its RCRA incineration permit as a BIF facility. Both plants have conducted BIF Trial Burnsmore » with very similar results. The performance levels demonstrated were at levels better than RCRA/BIF standards for destruction and removal efficiency, metal, HCl/Cl, particulate, dioxin/furan, and organic emissions.« less

Development and Validation of a High-Performance Thin-Layer Chromatographic Method for the Simultaneous Determination of Two Binary Mixtures Containing Ketorolac Tromethamine with Phenylephrine Hydrochloride and with Febuxostat

PubMed Central

El Yazbi, Fawzy A.; Hassan, Ekram M.; Khamis, Essam F.; Ragab, Marwa A.A.; Hamdy, Mohamed M.A.

2016-01-01

A validated and highly selective high-performance thin-layer chromatography (HPTLC) method was developed for the determination of ketorolac tromethamine (KTC) with phenylephrine hydrochloride (PHE) (Mixture 1) and with febuxostat (FBX) (Mixture 2) in bulk drug and in combined dosage forms. The proposed method was based on HPTLC separation of the drugs followed by densitometric measurements of their spots at 273 and 320 nm for Mixtures 1 and 2, respectively. The separation was carried out on Merck HPTLC aluminum sheets of silica gel 60 F254 using chloroform–methanol–ammonia (7:3:0.1, v/v) and (7.5:2.5:0.1, v/v) as mobile phase for KTC/PHE and KTC/FBX mixtures, respectively. Linear regression lines were obtained over the concentration ranges 0.20–0.60 and 0.60–1.95 µg band−1 for KTC and PHE (Mixture 1), respectively, and 0.10–1.00 and 0.25–2.50 µg band−1 for KTC and FBX (Mixture 2), respectively, with correlation coefficients higher than 0.999. The method was successfully applied to the analysis of the two drugs in their synthetic mixtures and in their dosage forms. The mean percentage recoveries were in the range of 98–102%, and the RSD did not exceed 2%. The method was validated according to ICH guidelines and showed good performances in terms of linearity, sensitivity, precision, accuracy and stability. PMID:26847918

The low temperature synthesis, characterization and properties of ferroelectrics

NASA Astrophysics Data System (ADS)

Xu, Jie

2000-10-01

PZT 50:50 xerogels prepared by two different sol-gel routes crystallized in a similar fashion to give a mixture of tetragonal and rhombohedral at high temperature (1000°C). Both the diffraction and EXAFS data suggest that the compositional inhomogeneity of the samples prepared by the two routes is similar. The crystallization of CZT gels is complicated. Crystalline CaCO 3 was always detected in the dry gels regardless of the sample composition and preparation methods. At intermediate temperatures a fluorite related phase was always formed and it transformed to perovskite at higher temperatures. The EXAFS data suggest that perovskite CZT samples prepared using alkoxide sol-gel chemistry may not be random solid solutions. All the solution processed ZrTiO4 materials crystallized in the range 600--700°C. The KTN samples prepared using a conventional alkoxide sol-gel route crystallized completely to perovskite at lower temperatures than those prepared using prehydrolyzed precursors. The EXAFS data for the KTN samples prepared using a conventional alkoxide sol-gel route are consistent with a random distribution of tantalum and niobium in the solid solution. However, materials prepared using the inhomogeneous sol-gel route and by the direct reaction of mixed oxides were shown to be compositionally inhomogeneous. The heterogeneity could not be removed by regrinding and heating the mixed oxide samples several times. K2Ta4-xNbxO11 (x = 0, 2, 4) samples were prepared using alkoxide sol-gel chemistry and their crystallization was examined by powder X-ray diffraction. A Rietveld structure analysis of the pyrochlore formed from a gel with bulk composition K2Ta 2Nb2O11 indicated that it was rich in potassium relative to the bulk sample. On heating to high temperatures tetragonal tungsten bronzes were formed. A Rietveld analysis was also performed for K2Ta 2Nb2O11 with tetragonal tungsten bronze structure. The defect pyrochlores "AgTaO3" and GaTaO 3 were synthesized by ion-exchange using pyrochlore KTaO3 as a starting material. The structures of the pyrochlores were examined using the Rietveld method. The pyrochlore-to-perovskite transformations were also explored.

Phase diagram of a reentrant gel of patchy particles

NASA Astrophysics Data System (ADS)

Roldán-Vargas, Sándalo; Smallenburg, Frank; Kob, Walter; Sciortino, Francesco

2013-12-01

We study the phase diagram of a binary mixture of patchy particles which has been designed to form a reversible gel. For this we perform Monte Carlo and molecular dynamics simulations to investigate the thermodynamics of such a system and compare our numerical results with predictions based on the analytical parameter-free Wertheim theory. We explore a wide range of the temperature-density-composition space that defines the three-dimensional phase diagram of the system. As a result, we delimit the region of thermodynamic stability of the fluid. We find that for a large region of the phase diagram the Wertheim theory is able to give a quantitative description of the system. For higher densities, our simulations show that the system is crystallizing into a BCC structure. Finally, we study the relaxation dynamics of the system by means of the density and temperature dependences of the diffusion coefficient. We show that there exists a density range where the system passes reversibly from a gel to a fluid upon both heating and cooling, encountering neither demixing nor phase separation.

Flexible bilayers with spontaneous curvature lead to lamellar gels and spontaneous vesicles

PubMed Central

Coldren, Bret A.; Warriner, Heidi; van Zanten, Ryan; Zasadzinski, Joseph A.; Sirota, Eric B.

2006-01-01

Mixtures of cetyltrimethylammonium tosylate (CTAT) and sodium dodecylbenzene sulfonate (SDBS) in water form a fluid lamellar phase at ≤40 wt % water but surprisingly turn into viscous gels at higher water fractions. The gels are characterized by spherulite and other bilayer defects consistent with a low bending elasticity, κ ∼ kBT, and a nonzero spontaneous curvature. Caillé analysis of the small-angle x-ray line shape confirms that for 7:3 wt:wt CTAT:SDBS bilayers at 50% water, κ = 0.62 ± 0.09 kBT and κ̄ = −0.9 ± 0.2 kBT. For 13:7 wt:wt CTAT:SDBS bilayers, the measured bending elasticity decreases with increasing water dilution in good agreement with predictions based on renormalization theory, giving κo = 0.28 kBT. These results show that surfactant mixing is sufficient to make κ ∼ kBT, which promotes strong, Helfrich-type repulsion between bilayers that can dominate the van der Waals attraction. These are necessary conditions for spontaneous vesicles formed at even higher water fractions to be equilibrium structures. PMID:16467142

A new validated method for the simultaneous determination of benzocaine, propylparaben and benzyl alcohol in a bioadhesive gel by HPLC.

PubMed

Pérez-Lozano, P; García-Montoya, E; Orriols, A; Miñarro, M; Ticó, J R; Suñé-Negre, J M

2005-10-04

A new HPLC-RP method has been developed and validated for the simultaneous determination of benzocaine, two preservatives (propylparaben (nipasol) and benzyl alcohol) and degradation products of benzocaine in a semisolid pharmaceutical dosage form (benzocaine gel). The method uses a Nucleosil 120 C18 column and gradient elution. The mobile phase consisted of a mixture of methanol and glacial acetic acid (10%, v/v) at different proportion according to a time-schedule programme, pumped at a flow rate of 2.0 ml min(-1). The DAD detector was set at 258 nm. The validation study was carried out fulfilling the ICH guidelines in order to prove that the new analytical method, meets the reliability characteristics, and these characteristics showed the capacity of analytical method to keep, throughout the time, the fundamental criteria for validation: selectivity, linearity, precision, accuracy and sensitivity. The method was applied during the quality control of benzocaine gel in order to quantify the drug (benzocaine), preservatives and degraded products and proved to be suitable for rapid and reliable quality control method.

Selective digestion of Ba2+/Ca2+ alginate gel microdroplets for single-cell handling

NASA Astrophysics Data System (ADS)

Odaka, Masao; Hattori, Akihiro; Matsuura, Kenji; Yasuda, Kenji

2018-06-01

Cells encapsuled by polymer microdroplets are an effective platform for the identification and separation of individual cells for single-cell-based analysis. However, a key challenge is to maintain and release the captured cells in the microdroplets selectively, nondestructively, and noninvasively. We developed a simple method of encapsulating cells in alginate microdroplets having different digestion characteristics. Cells were diluted with an alginate polymer of sol state and encapsulated into microdroplets with Ba2+ and Ca2+ by a spray method. When a chelating buffer was applied, alginate gel microdroplets were digested according to the difference in chelating efficiency of linkage-divalent cations; hence, two types of alginate microdroplets were formed. Moreover, we examined the capability of the alginate gel to exchange linkage-divalent cations and found that both Ca2+ exchange in Ba-alginate microdroplets and Ba2+ exchange in Ca-alginate microdroplets occurred. These results indicate that the potential applications of a mixture of alginate microdroplets with different divalent cations control the selective digestion of microdroplets to improve the high-throughput, high-content microdroplet-based separation, analysis, or storage of single cells.

Effect of gellan gum on the thermogelation property and drug release profile of Poloxamer 407 based ophthalmic formulation.

PubMed

Dewan, Mitali; Sarkar, Gunjan; Bhowmik, Manas; Das, Beauty; Chattoapadhyay, Atis Kumar; Rana, Dipak; Chattopadhyay, Dipankar

2017-09-01

The effect of gellan gum on the gelation behavior and in-vitro release of a specific drug named pilocarpine hydrochloride from different ophthalmic formulations based on poloxamer 407 is examined. The mixture of 0.3wt% gellan gum and 18wt% poloxamer (PM) solutions show a considerable increase in gel strength in physiological condition. Gel dissolution rate from PM based formulation is significantly decreased due to the addition of gellan gum. FTIR spectra analysis witnesses an interaction in between OH groups of two polymers which accounts for lowering in gelation temperature of PM-gellan gum based formulations. It is also observed from the cryo-SEM study that the pore size of PM gel decreases with an addition of gellan gum and in-vitro release studies indicate that PM-gellan gum based formulation retain drug better than the PM solution alone. Therefore, the developed formulation has the potential to be utilized as an in-situ ophthalmic drug carrier. Copyright © 2017 Elsevier B.V. All rights reserved.

A Novel Universal Primer-Multiplex-PCR Method with Sequencing Gel Electrophoresis Analysis

PubMed Central

Huang, Kunlun; Zhang, Nan; Yuan, Yanfang; Shang, Ying; Luo, Yunbo

2012-01-01

In this study, a novel universal primer-multiplex-PCR (UP-M-PCR) method adding a universal primer (UP) in the multiplex PCR reaction system was described. A universal adapter was designed in the 5′-end of each specific primer pairs which matched with the specific DNA sequences for each template and also used as the universal primer (UP). PCR products were analyzed on sequencing gel electrophoresis (SGE) which had the advantage of exhibiting extraordinary resolution. This method overcame the disadvantages rooted deeply in conventional multiplex PCR such as complex manipulation, lower sensitivity, self-inhibition and amplification disparity resulting from different primers, and it got a high specificity and had a low detection limit of 0.1 ng for single kind of crops when screening the presence of genetically modified (GM) crops in mixture samples. The novel developed multiplex PCR assay with sequencing gel electrophoresis analysis will be useful in many fields, such as verifying the GM status of a sample irrespective of the crop and GM trait and so on. PMID:22272223

Solid-gel precursor solutions and methods for the fabrication of polymetallicsiloxane coating films

DOEpatents

Sugama, Toshifumi

1992-01-01

Solutions and preparation methods necessary for the fabrication of metal oxide cross-linked polysiloxane coating films are disclosed. The films are useful in provide heat resistance against oxidation, wear resistance, thermal insulation, and corrosion resistance of substrates. The sol-gel precursor solution comprises a mixture of a monomeric organoalkoxysilane, a metal alkoxide M(OR).sub.n (wherein M is Ti, Zr, Ge or Al; R is CH.sub.3, C.sub.2 H.sub.5 or C.sub.3 H.sub.7 ; and n is 3 or 4), methanol, water, HCl and NaOH. The invention provides a sol-gel solution, and a method of use thereof, which can be applied and processed at low temperatures (i.e., <1000.degree. C.). The substrate can be coated by immersing it in the above mentioned solution at ambient temperature. The substrate is then withdrawn from the solution. Next, the coated substrate is heated for a time sufficient and at a temperature sufficient to yield a solid coating. The coated substrate is then heated for a time sufficient, and temperature sufficient to produce a polymetallicsiloxane coating.

Solid-gel precursor solutions and methods for the fabrication of polymetallicsiloxane coating films

DOEpatents

Sugama, Toshifumi

1993-01-01

Solutions and preparation methods necessary for the fabrication of metal oxide cross-linked polysiloxane coating films are disclosed. The films are useful in provide heat resistance against oxidation, wear resistance, thermal insulation, and corrosion resistance of substrates. The sol-gel precursor solution comprises a mixture of a monomeric organoalkoxysilane, a metal alkoxide M(OR).sub.n (wherein M is Ti, Zr, Ge or Al; R is CH.sub.3, C.sub.2 H.sub.5 or C.sub.3 H.sub.7 ; and n is 3 or 4), methanol, water, HCl and NaOH. The invention provides a sol-gel solution, and a method of use thereof, which can be applied and processed at low temperatures (i.e., <1000.degree. C.). The substrate can be coated by immersing it in the above mentioned solution at ambient temperature. The substrate is then withdrawn from the solution. Next, the coated substrate is heated for a time sufficient and at a temperature sufficient to yield a solid coating. The coated substrate is then heated for a time sufficient, and temperature sufficient to produce a polymetallicsiloxane coating.

Solid-gel precursor solutions and methods for the fabrication of polymetallicsiloxane coating films

DOEpatents

Toshifumi Sugama.

1993-04-06

Solutions and preparation methods necessary for the fabrication of metal oxide cross-linked polysiloxane coating films are disclosed. The films are useful in provide heat resistance against oxidation, wear resistance, thermal insulation, and corrosion resistance of substrates. The sol-gel precursor solution comprises a mixture of a monomeric organoalkoxysilane, a metal alkoxide M(OR)[sub n] (wherein M is Ti, Zr, Ge or Al; R is CH[sub 3], C[sub 2]H[sub 5] or C[sub 3]H[sub 7]; and n is 3 or 4), methanol, water, HCl and NaOH. The invention provides a sol-gel solution, and a method of use thereof, which can be applied and processed at low temperatures (i.e., < 1,000 C.). The substrate can be coated by immersing it in the above mentioned solution at ambient temperature. The substrate is then withdrawn from the solution. Next, the coated substrate is heated for a time sufficient and at a temperature sufficient to yield a solid coating. The coated substrate is then heated for a time sufficient, and temperature sufficient to produce a polymetallicsiloxane coating.

Supramolecular Phase-Selective Gelation by Peptides Bearing Side-Chain Azobenzenes: Effect of Ultrasound and Potential for Dye Removal and Oil Spill Remediation

PubMed Central

Bachl, Jürgen; Oehm, Stefan; Mayr, Judith; Cativiela, Carlos; Marrero-Tellado, José Juan; Díaz Díaz, David

2015-01-01

Phase selective gelation (PSG) of organic phases from their non-miscible mixtures with water was achieved using tetrapeptides bearing a side-chain azobenzene moiety. The presence of the chromophore allowed PSG at the same concentration as the minimum gelation concentration (MGC) necessary to obtain the gels in pure organic phases. Remarkably, the presence of the water phase during PSG did not impact the thermal, mechanical, and morphological properties of the corresponding organogels. In the case of miscible oil/water mixtures, the entire mixture was gelled, resulting in the formation of quasi-hydrogels. Importantly, PSG could be triggered at room temperature by ultrasound treatment of the mixture or by adding ultrasound-aided concentrated solution of the peptide in an oil-phase to a mixture of the same oil and water. Moreover, the PSG was not affected by the presence of salts or impurities existing in water from natural sources. The process could be scaled-up, and the oil phases (e.g., aromatic solvents, gasoline, diesel fuel) recovered almost quantitatively after a simple distillation process, which also allowed the recovery and reuse of the gelator. Finally, these peptidic gelators could be used to quantitatively remove toxic dyes from aqueous solutions. PMID:26006247

Oxalyl retro-peptide gelators. Synthesis, gelation properties and stereochemical effects

PubMed Central

Makarević, Janja; Jokić, Milan; Frkanec, Leo; Čaplar, Vesna; Šijaković Vujičić, Nataša

2010-01-01

Summary In this work we report on gelation properties, self-assembly motifs, chirality effects and morphological characteristics of gels formed by chiral retro-dipeptidic gelators in the form of terminal diacids (1a–5a) and their dimethyl ester (1b–5b) and dicarboxamide (1c–5c) derivatives. Terminal free acid retro-dipeptides (S,S)-bis(LeuLeu) 1a, (S,S)-bis(PhgPhg) 3a and (S,S)-bis(PhePhe) 5a showed moderate to excellent gelation of highly polar water/DMSO and water/DMF solvent mixtures. Retro-peptides incorporating different amino acids (S,S)-(LeuPhg) 2a and (S,S)-(PhgLeu) 4a showed no or very weak gelation. Different gelation effectiveness was found for racemic and single enantiomer gelators. The heterochiral (S,R)-1c diastereoisomer is capable of immobilizing up to 10 and 4 times larger volumes of dichloromethane/DMSO and toluene/DMSO solvent mixtures compared to homochiral (S,S)-1c. Based on the results of 1H NMR, FTIR, CD investigations, molecular modeling and XRPD studies of diasteroisomeric diesters (S,S)-1b/(S,R)-1b and diacids (S,S)-1b/(S,R)-1a, a basic packing model in their gel aggregates is proposed. The intermolecular hydrogen bonding between extended gelator molecules utilizing both, the oxalamide and peptidic units and layered organization were identified as the most likely motifs appearing in the gel aggregates. Molecular modeling studies of (S,S)- 1a/(S,R)-1a and (S,S)-1b/(S,R)- 1b diasteroisomeric pairs revealed a decisive stereochemical influence yielding distinctly different low energy conformations: those of (S,R)-diastereoisomers with lipophilic i-Bu groups and polar carboxylic acid or ester groups located on the opposite sides of the oxalamide plane resembling bola amphiphilic structures and those of (S,S)-diasteroisomers possessing the same groups located at both sides of the oxalamide plane. Such conformational characteristics were found to strongly influence both, gelator effectiveness and morphological characteristics of gel aggregates. PMID:21085503

Oxalyl retro-peptide gelators. Synthesis, gelation properties and stereochemical effects.

PubMed

Makarević, Janja; Jokić, Milan; Frkanec, Leo; Caplar, Vesna; Sijaković Vujičić, Nataša; Zinić, Mladen

2010-10-04

In this work we report on gelation properties, self-assembly motifs, chirality effects and morphological characteristics of gels formed by chiral retro-dipeptidic gelators in the form of terminal diacids (1a-5a) and their dimethyl ester (1b-5b) and dicarboxamide (1c-5c) derivatives. Terminal free acid retro-dipeptides (S,S)-bis(LeuLeu) 1a, (S,S)-bis(PhgPhg) 3a and (S,S)-bis(PhePhe) 5a showed moderate to excellent gelation of highly polar water/DMSO and water/DMF solvent mixtures. Retro-peptides incorporating different amino acids (S,S)-(LeuPhg) 2a and (S,S)-(PhgLeu) 4a showed no or very weak gelation. Different gelation effectiveness was found for racemic and single enantiomer gelators. The heterochiral (S,R)-1c diastereoisomer is capable of immobilizing up to 10 and 4 times larger volumes of dichloromethane/DMSO and toluene/DMSO solvent mixtures compared to homochiral (S,S)-1c. Based on the results of (1)H NMR, FTIR, CD investigations, molecular modeling and XRPD studies of diasteroisomeric diesters (S,S)-1b/(S,R)-1b and diacids (S,S)-1b/(S,R)-1a, a basic packing model in their gel aggregates is proposed. The intermolecular hydrogen bonding between extended gelator molecules utilizing both, the oxalamide and peptidic units and layered organization were identified as the most likely motifs appearing in the gel aggregates. Molecular modeling studies of (S,S)-1a/(S,R)-1a and (S,S)-1b/(S,R)-1b diasteroisomeric pairs revealed a decisive stereochemical influence yielding distinctly different low energy conformations: those of (S,R)-diastereoisomers with lipophilic i-Bu groups and polar carboxylic acid or ester groups located on the opposite sides of the oxalamide plane resembling bola amphiphilic structures and those of (S,S)-diasteroisomers possessing the same groups located at both sides of the oxalamide plane. Such conformational characteristics were found to strongly influence both, gelator effectiveness and morphological characteristics of gel aggregates.

Fabrication and Evaluation of Graphite Fiber-Reinforced Polyimide Composite Tube Forms Using Modified Resin Transfer Molding

NASA Technical Reports Server (NTRS)

Exum, Daniel B.; Ilias, S.; Avva, V. S.; Sadler, Bob

1997-01-01

The techniques necessary for the fabrication of a complex three-dimensional tubular form using a PMR-type resin have been developed to allow for the construction of several tubes with good physical and mechanical properties. Employing established resin transfer molding practices, the relatively non-hazardous AMB-21 in acetone formulation was used to successfully impregnate four layers of AS4 braided graphite fiber preform previously loaded around an aluminum cylindrical core in an enclosed mold cavity. Using heat and vacuum, the solvent was evaporated to form a prepreg followed by a partial imidization and removal of condensation products. The aluminum core was replaced by a silicone rubber bladder and the cure cycle continued to the final stage of 550 F with a bladder internal pressure of 200 lbs/sq in while simultaneously applying a strong vacuum to the prepreg for removal of any additional imidization products. A combination of several modifications to the standard resin transfer molding methodology enabled the mold to 'breathe', allowing the imidization products a pathway for escape. AMB-21 resin was chosen because of the carcinogenic nature of the primary commercial polyimide PMR-15. The AMB-21 resin was formulated using commercially available monomers or monomer precursors and dissolved in a mixture of methyl alcohol and acetone. The viscosity of the resulting monomer solution was checked by use of a Brookfield rheometer and adjusted by adding acetone to an easily pumpable viscosity of about 600 cP. In addition, several types of chromatographic and thermal analyses were of the braids, and excess handling of the preforms broke some of the microscopic fibers, needlessly decreasing the strength of the finished part. In addition, three dimensional braided preforms with fibers along the length of the tube will be significantly stronger in tension than the braided preforms used in this study.

Enhancing the Thermotolerance of Entomopathogenic Isaria fumosorosea SFP-198 Conidial Powder by Controlling the Moisture Content Using Drying and Adjuvants

PubMed Central

Lee, Se Jin; Lee, Hyang Burm

2014-01-01

Entomopathogenic fungi are promising pest-control agents but their industrial applicability is limited by their thermosusceptibility. With an aim to increase the thermotolerance of Isaria fumosorosea SFP-198, moisture absorbents were added to dried conidial powder, and the relationship between its water potential and thermotolerance was investigated. Mycotized rice grains were dried at 10℃, 20℃, 30℃, and 40℃ and the drying effect of each temperature for 24, 48, 96, and 140 hr was determined. Drying for 48 hr at 10℃ and 20℃ reduced the moisture content to < 5% without any significant loss of conidial thermotolerance, but drying at 30℃ and 40℃ reduced both moisture content and conidial thermotolerance. To maintain thermotolerance during storage, moisture absorbents, such as calcium chloride, silica gel, magnesium sulfate, white carbon, and sodium sulfate were individually added to previously dried-conidial powder at 10% (w/w). These mixtures was then stored at room temperature for 30 days and subjected to 50℃ for 2 hr. The white carbon mixture had the highest conidial thermotolerance, followed by silica gel, magnesium sulfate, and then the other absorbents. A significant correlation between the water potential and conidial thermotolerance was observed in all conidia-absorbent mixtures tested in this study (r = -0.945). Conidial thermotolerance in wet conditions was evaluated by adding moisturized white carbon (0~20% H2O) to conidia to mimic wet conditions. Notably, the conidia still maintained their thermotolerance under these conditions. Thus, it is evident that conidial thermotolerance can be maintained by drying mycotized rice grains at low temperatures and adding a moisture absorbent, such as white carbon. PMID:24808736

Proteomic studies in zebrafish liver cells exposed to the brominated flame retardants HBCD and TBBPA.

PubMed

Kling, Peter; Förlin, Lars

2009-10-01

Proteomic effect screening in zebrafish liver cells was performed to generate hypotheses regarding single and mixed exposure to the BFRs HBCD and TBBPA. Responses at sublethal exposure were analysed by two-dimensional gel electrophoresis followed by MALDI-TOF and FT-ICR protein identification. Mixing of HBCD and TBBPA at sublethal doses of individual substances seemed to increase toxicity. Proteomic analyses revealed distinct exposure-specific and overlapping responses suggesting novel mechanisms with regard to HBCD and TBBPA exposure. While distinct HBCD responses were related to decreased protein metabolism, TBBPA revealed effects related to protein folding and NADPH production. Overlapping responses suggest increased gluconeogenesis (GAPDH and aldolase) while distinct mixture effects suggest a pronounced NADPH production and changes in proteins related to cell cycle control (prohibitin and crk-like oncogene). We conclude that mixtures containing HBCD and TBBPA may result in unexpected effects highlighting proteomics as a sensitive tool for detecting and hypothesis generation of mixture effects.

Encyclopedia of Explosives and Related Items. Volume 6

DTIC Science & Technology

1974-01-01

guns metal clad steel jacket, contg 10 grains of Similar unsatisfactory "cook-off’ prema- compressed incendiary mixture IM**11, de - tures were obtd...which essentially dampens the ex- tremely high pressures and provides the de - k sired distribution of forces to the metal part for forming. The metal ...flammable liquid or 1) Stationary type: gel contained in a strong metal reservoir is a) German Flammenwerfer contained 45 put under heavy pressure by

Army Logistician. Volume 35, Issue 5, September-October 2003

DTIC Science & Technology

2003-10-01

Report Documentation Page Form ApprovedOMB No. 0704-0188 Public reporting burden for the collection of information is estimated to average 1 hour per...and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information...designed to deliver performance-enhancing natu- ral food elements to troops in the field. The gel con- tains a mixture of glucose and maltodextrin —a

Generation of Soluble Receptor Activator of NF-kappa B Ligand is Critical for Osteolytic Bone Metastasis

DTIC Science & Technology

2009-10-01

differentiation and activation of osteoclast precursors. Targeting RANKL expression with antisense oligonucleotides (RANKL- ASO ) decreased RANKL expression and...1,175 Ci/mmol at 10 mCi/mL). Two microliters of the reaction mixture were separated on a 12% SDS-polyacrylamide gel and subsequently visualized...OPG), a decoy receptor for RANKL, at the TB-interface was also increased. Targeting RANKL expression with antisense oligonucleotides (RANKL- ASO

The Impact of HA Oligomer Content on Physical, Mechanical, and Biologic Properties of Divinyl Sulfone-Crosslinked HA Hydrogels

PubMed Central

Ibrahim, Samir; Kang, Qian K; Ramamurthi, Anand

2009-01-01

In recent studies, we showed that exogenous hyaluronic acid oligomers (HA-o) stimulate functional endothelialization, though native long-chain HA is more bioinert and possibly more biocompatible. Thus, in this study, hydrogels containing high molecular weight (HMW) HA (1×106 Da) and HA oligomer mixtures (HA-o: 0.75–10 kDa) were created by crosslinking with divinyl sulfone (DVS). The incorporation of HA oligomers was found to compromise the physical and mechanical properties of the gels (rheology, apparent crosslinking density, swelling ratio, degradation) and to very mildly enhance inflammatory cell recruitment in vivo; increasing the DVS crosslinker content within the gels in general, had the opposite effect, though the relatively high concentration of DVS within these gels (necessary to create a solid gel) also stimulated a mild sub-cutaneous inflammatory response in vivo and VCAM-1 expression by ECs cultured atop; ICAM-expression levels remained very low irrespective extent of DVS crosslinking or HA-o content. The greatest EC attachment and proliferation (MTT assay) was observed on gels that contained the highest amount of HA-o. The study shows that the beneficial EC response to HA oligomers and biocompatibility of HA is mostly unaltered by their chemical derivatization and crosslinking into a hydrogel. However, the study also demonstrates that the relatively high concentrations of DVS, necessary to create solid gels, compromises their biocompatibility. Moreover, the poor mechanics of even these heavily crosslinked gels, in the context of vascular implantation, necessitates the investigation of other, more appropriate crosslinking agents. Alternately, the outcomes of this study may be used to guide an approach based on chemical immobilization and controlled surface-presentation of both bioactive HA oligomers and more biocompatible HMW HAon synthetic or tissue engineered grafts already in use, without the use of a crosslinker, so that improved, predictable, and functional endothelialization can be achieved, and the need to create a mechanically compliant biomaterial for standalone use, circumvented. PMID:20186732

Three-dimensional printing fiber reinforced hydrogel composites.

PubMed

Bakarich, Shannon E; Gorkin, Robert; in het Panhuis, Marc; Spinks, Geoffrey M

2014-09-24

An additive manufacturing process that combines digital modeling and 3D printing was used to prepare fiber reinforced hydrogels in a single-step process. The composite materials were fabricated by selectively pattering a combination of alginate/acrylamide gel precursor solution and an epoxy based UV-curable adhesive (Emax 904 Gel-SC) with an extrusion printer. UV irradiation was used to cure the two inks into a single composite material. Spatial control of fiber distribution within the digital models allowed for the fabrication of a series of materials with a spectrum of swelling behavior and mechanical properties with physical characteristics ranging from soft and wet to hard and dry. A comparison with the "rule of mixtures" was used to show that the swollen composite materials adhere to standard composite theory. A prototype meniscus cartilage was prepared to illustrate the potential application in bioengineering.

The impact of the molecular weight of dextran on formation of whey protein isolate (WPI)-dextran conjugates in fibers produced by needleless electrospinning after annealing.

PubMed

Turan, Deniz; Gibis, Monika; Gunes, Gurbuz; Baier, Stefan K; Weiss, Jochen

2018-04-25

The conjugation reaction of electrospun fibers of a mixture of whey protein isolate (WPI) and dextran using different molecular weights (40, 70, and 100 kDa) and mixing ratios was studied. This study includes the electrospinnability of a mixture of WPI and dextran, and the conjugation reaction between them via the initial stage of the Maillard reaction. The WPI-dextran fibers were characterized using optical and transmission electron microscopy. The covalent attachment of dextran to WPI was confirmed using sodium-dodecyl-sulfate-polyacrylamide gel-electrophoresis with protein and glycoprotein staining. Both 70 and 100 kDa of dextran and WPI at mixing ratios of 2 : 1 and 3 : 1 in phosphate buffer (30 mM, pH 6.5) were electrospun using needleless electrospinning. The solution concentration of the mixture was 50 wt% (33.3/37.5 wt% for dextran/16.5/12.5 wt% for WPI). The optimal conjugation conditions chosen from the experiments were a mixture of dextran (70 kDa)-WPI at 3 : 1 (75% relative humidity, 60 °C, 48 h).

Induced nanoparticle aggregation for short nucleic acid quantification by depletion isotachophoresis.

PubMed

Marczak, Steven; Senapati, Satyajyoti; Slouka, Zdenek; Chang, Hsueh-Chia

2016-12-15

A rapid (<20min) gel-membrane biochip platform for the detection and quantification of short nucleic acids is presented based on a sandwich assay with probe-functionalized gold nanoparticles and their separation into concentrated bands by depletion-generated gel isotachophoresis. The platform sequentially exploits the enrichment and depletion phenomena of an ion-selective cation-exchange membrane created under an applied electric field. Enrichment is used to concentrate the nanoparticles and targets at a localized position at the gel-membrane interface for rapid hybridization. The depletion generates an isotachophoretic zone without the need for different conductivity buffers, and is used to separate linked nanoparticles from isolated ones in the gel medium and then by field-enhanced aggregation of only the linked particles at the depletion front. The selective field-induced aggregation of the linked nanoparticles during the subsequent depletion step produces two lateral-flow like bands within 1cm for easy visualization and quantification as the aggregates have negligible electrophoretic mobility in the gel and the isolated nanoparticles are isotachophoretically packed against the migrating depletion front. The detection limit for 69-base single-stranded DNA targets is 10 pM (about 10 million copies for our sample volume) with high selectivity against nontargets and a three decade linear range for quantification. The selectivity and signal intensity are maintained in heterogeneous mixtures where the nontargets outnumber the targets 10,000 to 1. The selective field-induced aggregation of DNA-linked nanoparticles at the ion depletion front is attributed to their trailing position at the isotachophoretic front with a large field gradient. Copyright © 2016 Elsevier B.V. All rights reserved.

Comparative study between three analgesic agents for the pain management during extracorporeal shock wave lithotripsy.

PubMed

Liu, Jianjun; Zang, Yun-Jiang

2013-09-26

To compare the clinical efficacy between locally applied diclofenac diethylamine gel, EMLA cream and systemically given diclofenac sodium for the pain relief during extracorporeal shock wave lithotripsy (SWL) using Dornier Delta Compact Lithotripter. One hundred five patients with renal stones were randomly divided in to 3 groups. Group A was given intramuscular diclofenac sodium (1 mg/kg), 45 minutes before the procedure. In group B, 10 gm of eutectic mixture of local anesthetic (EMLA) cream and in group C, 15 gm of diclofenac diethylamine gel was applied locally 45 minutes before the procedure. Ten-score linear and visual analogue scale (VAS) was used to assess the severity of pain during the procedure. Analysis of variance (ANOVA) test was used to compare various parameters and analyzed statistically. All the three groups were not statistically different with respect to age, weight, stone size, number of shock wave delivered and maximum voltage used (P > .05). The mean pain score in group A was 4.48, in group B was 3.60 and in group C was 3.95, which were not significantly different (P = 1.34). Complication like skin lesion was found only in injection diclofenac sodium group whereas cold sensation at the local site was typically found in diclofenac diethylamine gel group. Although not statistically significant, the mean pain score in locally applied analgesic agents (EMLA and diclofenac diethylamine gel) is lower as compared to intramuscularly given diclofenac sodium. Among these two locally acting drugs, diclofenac diethylamine gel is an equally effective alternative to EMLA.

A novel poloxamers/hyaluronic acid in situ forming hydrogel for drug delivery: rheological, mucoadhesive and in vitro release properties.

PubMed

Mayol, Laura; Quaglia, Fabiana; Borzacchiello, Assunta; Ambrosio, Luigi; La Rotonda, Maria I

2008-09-01

The influence of hyaluronic acid (HA) on the gelation properties of poloxamers blends has been studied with the aim of engineering thermosensitive and mucoadhesive polymeric platforms for drug delivery. The gelation temperature (T(gel)), viscoelastic properties and mucoadhesive force of the systems were investigated and optimised by means of rheological analyses. Poloxamers micellar diameter was evaluated by photon correlation spectroscopy (PCS). Moreover in order to explore the feasibility of these platforms for drug delivery, the optimised systems were loaded with acyclovir and its release properties studied in vitro. By formulating poloxamers/HA platforms, at specific concentrations, it was possible to obtain a thermoreversible gel with a T(gel) close to body temperature. The addition of HA did not hamper the self assembling process of poloxamers just delaying the gelation temperature of few Celsius degrees. Furthermore, HA presence led to a strong increase of the poloxamer rheological properties thus indicating possible HA interactions with micelles through secondary bonds, such as hydrogen ones, which reinforce the gel structure. These interactions could also explain PCS results which show, in systems containing HA, aggregates with hydrodynamic diameters much higher than those of poloxamer micelles. Mucoadhesion experiments showed a rheological synergism between poloxamers/HA gels and mucin dispersion which led to a change of the flow behaviour from a quite Newtonian one of the separate solutions to a pseudoplastic one of their mixture. In vitro release experiments indicated that the optimised platform was able to prolong and control acyclovir release for more than 6h.

Formulation and evaluation of in situ gelling systems for intranasal administration of gastrodin.

PubMed

Cai, Zheng; Song, Xiangrong; Sun, Feng; Yang, Zhaoxiang; Hou, Shixiang; Liu, Zhongqiu

2011-12-01

Gastrodin is the major bioactive constituent of the traditional Chinese drug "Tianma." It is used in the treatment of some nervous system diseases and can be transported to the brain via intranasal administration. In the current paper, the development of a novel ion-activated in situ gelling system for the nasal delivery of gastrodin is discussed. An in situ perfusion model was used to determine the absorption-rate constant of gastrodin through rat nasal mucosa. The optimal formulation was determined by measuring the critical cation concentration, anti-dilution capacity, gel expansion coefficient, water-holding capacity, and adhesive capacity. The best formulation consisted of 10% gastrodin, 0.5% deacetylated gellan gum as the gelatinizer, and 0.03% ethylparaben as the preservative. The rheological properties of gastrodin nasal in situ gels were also investigated. The viscosity and elasticity sharply increased at temperatures below 25°C. When physiological concentrations of cations were added into the preparation, the mixture gelled into a semi-solid. The results of an accelerated stability test show that gastrodin nasal in situ gels can be stable for more than 2 years. Mucociliary toxicity was evaluated using the in situ toad palate model and the rat nasal mucociliary method; both models demonstrated no measurable ciliotoxicity. Pharmacodynamic studies suggest that similar acesodyne and sedative effects were induced following intranasal administration of 50 mg/kg gastrodin nasal in situ gels or oral administration of 100 mg/kg gastrodin solution. The in situ gel preparation is a safe and effective nasal delivery system for gastrodin.

Protecting chickens against coccidiosis in floor pens by administering Eimeria oocysts using gel beads or spray vaccination.

PubMed

Jenkins, Mark C; Parker, Carolyn; O'Brien, Celia; Persyn, Joseph; Barlow, Darren; Miska, Katarzyna; Fetterer, Raymond

2013-09-01

Control of avian coccidiosis is increasingly being achieved by the administration of low doses of Eimeria oocysts to newly hatched chicks. The purpose of this study was to test the efficacy of gel beads containing a mixture of Eimeria acervulina, Eimeria maxima, and Eimeria tenella oocysts as a vaccine to protect broilers raised in contact with litter. Newly hatched chicks were either sprayed with an aqueous suspension of Eimeria oocysts or were allowed to ingest feed containing Eimeria oocysts-incorporated gel beads. Control, 1-day-old chicks were given an equivalent number of Eimeria oocysts (10(3) total) by oral gavage or received no vaccine (nonimmunized controls). All chicks were raised in floor-pen cages in direct contact with litter. At 4 wk of age, all chickens and a control nonimmunized group received a high-dose E. acervulina, E. maxima, and E. tenella challenge infection. Chickens immunized with Eimeria oocysts in gel beads or by spray vaccination displayed significantly (P < 0.05) greater weight gain (WG) compared to nonimmunized controls. Feed conversion ratio (FCR) also showed a significant (P < 0.05) improvement in both groups relative to nonimmunized controls. Moreover, WG and FCR in both groups was not significantly different (P > 0.05) from chickens immunized by oral gavage or from nonimmunized, noninfected controls. Oocyst excretion after Eimeria challenge by all immunized groups was about 10-fold less than in nonimmunized controls. These findings indicate that immunization efficacy of gel beads and spray vaccination is improved by raising immunized chicks in contact with litter.

Investigation on characteristics of 3D printing using Nostoc sphaeroides biomass.

PubMed

An, Yan-Jun; Guo, Chao-Fan; Zhang, Min; Zhong, Ze-Ping

2018-06-27

Gel-like constructs can be produced using an extrusion-based 3D food printing (3D-FP) technique. Nostoc sphaeroides biomass is a natural gel material. Considering its good nutrition and rheological properties, these algae were chosen in this study as supply material (ink) for 3D-FP. With this gel material, the extrusion-based 3D printing system was set as a model, and the printing behavior was investigated. Furthermore, the 3D-FP mechanisms were explained through low-field nuclear magnetic resonance and rheological measurements. Results indicated that although fresh biomass gel was printable, nonuniformity and instability occurred during printing. Blanched inks showed nonsmooth printing behavior, which was associated with a decrease in elasticity and viscosity. The printability was improved by increasing the rehydration time to 24 h when rehydrated powder was used. Increasing the rehydration time increased the water-binding degree. Pre-gelatinized potato starch was added to the mixture at ratios ranging from 1 to 100 g kg -1 . The best printing outcome was observed at 40 g kg -1 potato starch. We emphasize that elasticity and viscosity balance is an essential parameter to achieve printability. The strategies adopted in this work provide new insights into the development of personalized food regarding texture and nutritional additive content. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Further development of an electroosmotic medium pump system for preparative disk gel electrophoresis.

PubMed

Hayakawa, Mitsuo; Hosogi, Yumiko; Takiguchi, Hisashi; Shiroza, Teruaki; Shibata, Yasuko; Hiratsuka, Koichi; Kiyama-Kishikawa, Michiko; Hamajima, Susumu; Abiko, Yoshimitsu

2003-02-01

A simple and practical 6.8-cm-diameter (36.30-cm(2) cross-sectional-area) preparative disk gel electrophoresis device, based on the design of M. Hayakawa et al. (Anal. Biochem. 288 (2001) 168), in which the elution buffer is driven by an electroosmotic buffer flow through the membrane into the elution chamber from the anode chamber was constructed. We have found that the dialysis membranes employed provide suitable flow rates for the elution buffer, similar to those of an earlier 3.6-cm-diameter device, resulting in the prevention of excess eluate dilution. The efficiency of this device was demonstrated by the fractionation of a bovine serum albumin (BSA) Cohn V fraction into monomer, dimer, and oligomer components using nondenaturing polyacrylamide gel electrophoresis (native-PAGE). The maximum protein concentration of the eluate achieved was 133 mg/ml of BSA monomer, which required a dilution of the eluate for subsequent analytical PAGE performance. As a practical example, the two-dimensional fractionation of soluble dipeptidyl peptidase IV (sDPP IV) from 50 ml fetal bovine serum (3.20 g protein) per gel is presented. The sDPP IV enzyme protein was recovered in a relatively short time, utilizing a 6.5% T native-PAGE and subsequential sodium dodecyl sulfate-PAGE system. This device enhances the possibility of continuous electrophoretic fractionation of complex protein mixtures on a preparative scale. Copyright 2003 Elsevier Science (USA)

Zoological effects of variations in atmospheric oxygen levels

NASA Technical Reports Server (NTRS)

Kloek, G.

1982-01-01

The role of certain gene enzymes in survival in modified atmospheres was examined. Chromosome morphology was studied. Mortality and life span were measured. Equipment to deliver various gas mixtures to the flies was designed and fabricated. To study the gene enzymes a technique called starch gel electrophoresis was needed. Equipment and supplies for this work and the study of chromosome morphology was available on the market, although some of the equipment was fabricated to save the project money.

Microemulsion and Sol-Gel Synthesized ZrO₂-MgO Catalysts for the Liquid-Phase Dehydration of Xylose to Furfural.

PubMed

Parejas, Almudena; Montes, Vicente; Hidalgo-Carrillo, Jesús; Sánchez-López, Elena; Marinas, Alberto; Urbano, Francisco J

2017-12-18

Two series of catalysts were prepared by sol-gel and microemulsion synthetic procedure (SG and ME, respectively). Each series includes both pure Mg and Zr solids as well as Mg-Zr mixed solids with 25%, 50% and 75% nominal Zr content. The whole set of catalysts was characterized from thermal, structural and surface chemical points of view and subsequently applied to the liquid-phase xylose dehydration to furfural. Reactions were carried out in either a high-pressure autoclave or in an atmospheric pressure multi-reactor under a biphasic (organic/water) reaction mixture. Butan-2-ol and toluene were essayed as organic solvents. Catalysts prepared by microemulsion retained part of the surfactant used in the synthetic procedure, mainly associated with the Zr part of the solid. The MgZr-SG solid presented the highest surface acidity while the Mg3Zr-SG one exhibited the highest surface basicity among mixed systems. Xylose dehydration in the high-pressure system and with toluene/water solvent mixture led to the highest furfural yield. Moreover, the yield of furfural increases with the Zr content of the catalyst. Therefore, the catalysts constituted of pure ZrO₂ (especially Zr-SG) are the most suitable to carry out the process under study although MgZr mixed solids could be also suitable for overall processes with additional reaction steps.

Sol-gel analogous aminolysis-ammonolysis of chlorosilanes to chlorine-free Si/(C)/N-materials.

PubMed

Wiltzsch, Conny; Wagler, Jörg; Roewer, Gerhard; Kroke, Edwin

2009-07-28

Large amounts of chlorosilanes, especially SiCl4 and CH3SiCl3, are produced as side-products of the industrial fabrication of solar or electronic grade silicon and the Müller-Rochow process. It was a goal of the present study to transform these compounds into useful chlorine-free precursors for Si/(C)/N ceramics via a sol-gel analogous liquid processing route. Chlorine substitution of the chlorosilanes (mixtures) with diethylamine did not yield chlorine-free products, complete reactions are only possible with lithium diethylamide. However, aminolyses with n-propylamine were successful. Transamination with ammonia was not possible with diethylaminosilanes but was with n-propylaminosilanes in various solvents. This result was attributed to steric reasons and polar interactions of the N-H groups. Colourless solid or liquid polysilazanes were obtained, depending on the silane (mixture) and the solvent. Transamination reactions of CH3Si(NH-n-Pr)3 in chloroform reproducibly yielded a cage-like oligosilazane of the composition (CH3)9Si9(NH)12N. Single crystal X-ray structure analysis revealed a seven-cyclic cluster containing four six- and three ten-membered silazane rings. This unique silazane cage as well as the other aminosilanes and the silazanes were comprehensively characterised using multi-nuclear solid state and solution NMR, elemental analyses and thermal gravimetry (TGA).

Mixing a sol and a precipitate of block copolymers with different block ratios leads to an injectable hydrogel.

PubMed

Yu, Lin; Zhang, Zheng; Zhang, Huan; Ding, Jiandong

2009-06-08

A facile method to obtain a thermoreversible physical hydrogel was found by simply mixing an aqueous sol of a block copolymer with a precipitate of a similar copolymer but with a different block ratio. Two ABA-type triblock copolymers poly(D,L-lactic acid-co-glycolic acid)-B-poly(ethylene glycol)-B-poly(D,L-lactic acid-co-glycolic acid) (PLGA-PEG-PLGA) were synthesized. One sample in water was a sol in a broad temperature region, while the other in water was just a precipitate. The mixture of these two samples with a certain mix ratio underwent, however, a sol-to-gel-to-precipitate transition upon an increase of temperature. A dramatic tuning of the sol-gel transition temperature was conveniently achieved by merely varying mix ratio, even in the case of a similar molecular weight. Our study indicates that the balance of hydrophobicity and hydrophilicity within this sort of amphiphilic copolymers is critical to the inverse thermal gelation in water resulting from aggregation of micelles. The availability of encapsulation and sustained release of lysozyme, a model protein by the thermogelling systems was confirmed. This "mix" method provides a very convenient approach to design injectable thermogelling biomaterials with a broad adjustable window, and the novel copolymer mixture platform is potentially used in drug delivery and other biomedical applications.

Coordination Polymer Gels with Modular Nanomorphologies, Tunable Emissions, and Stimuli-Responsive Behavior Based on an Amphiphilic Tripodal Gelator.

PubMed

Sutar, Papri; Maji, Tapas Kumar

2017-08-21

The recent upsurge in research on coordination polymer gels (CPGs) stems from their synthetic modularity, nanoscale processability, and versatile functionalities. Here we report self-assembly of an amphiphilic, tripodal low-molecular weight gelator (L) that consists of 4,4',4-[1,3,5-phenyl-tri(methoxy)]-tris-benzene core and 2,2':6',2″-terpyridyl termini, with different metal ions toward the formation of CPGs that show controllable nanomorphologies, tunable emission, and stimuli-responsive behaviors. L can also act as a selective chemosensor for Zn II with very low limit of detection (0.18 ppm) in aqueous medium. Coordination-driven self-assembly of L with Zn II in H 2 O/MeOH solvent mixture results in a coordination polymer hydrogel (ZnL) that exhibits sheet like morphology and charge-transfer emission. On the other hand, coordination of L with Tb III and Eu III in CHCl 3 /tetrahydrofuran solvent mixture results in green- and red-emissive CPGs, respectively, with nanotubular morphology. Moreover, precise stoichiometric control of L/Eu III /Tb III ratio leads to the formation of bimetallic CPGs that show emissions over a broad spectral range, including white-light-emission. We also explore the multistimuli responsive properties of the white-light-emitting CPG by exploiting the dynamics of Ln III -tpy coordination.

Amphipathic peptide affects the lateral domain organization of lipid bilayers.

PubMed

Polozov, I V; Polozova, A I; Molotkovsky, J G; Epand, R M

1997-09-04

Using lipid-specific fluorescent probes, we studied the effects of amphipathic helical, membrane active peptides of the A- and L-type on membrane domain organization. In zwitterionic binary systems composed of mixtures of phosphatidylcholine and phosphatidylethanolamine, both types of peptides associated with the fluid phase. While binding with high affinity to fluid membranes, peptides were unable to penetrate into the lipid membrane in the gel state. If trapped kinetically by cooling from the fluid phase, peptides dissociated from the gel membrane on the time scale of several hours. While the geometrical shape of the alpha-helical peptides determines their interactions with membranes with non-bilayer phase propensity, the shape complementarity mechanism by itself is unable to induce lateral phase separation in a fluid membrane. Charge-charge interactions are capable of inducing lateral domain formation in fluid membranes. Both peptides had affinity for anionic lipids which resulted in about 30% enrichment of acidic lipids within several nanometers of the peptide's tryptophan, but there was no long-range order in peptide-induced lipid demixing. Peptide insertion in fluid acidic membranes was accompanied by only a small increase in bilayer surface and a decrease in polarity in the membrane core. Peptide-lipid charge-charge interactions were also capable of modulating existing domain composition in the course of the main phase transition in mixtures of anionic phosphatidylglycerol with zwitterionic phosphatidylcholine.

Thin layer chromatography-densitometric determination of some non-sedating antihistamines in combination with pseudoephedrine or acetaminophen in synthetic mixtures and in pharmaceutical formulations.

PubMed

El-Kommos, Michael E; El-Gizawy, Samia M; Atia, Noha N; Hosny, Noha M

2014-03-01

The combination of certain non-sedating antihistamines (NSA) such as fexofenadine (FXD), ketotifen (KET) and loratadine (LOR) with pseudoephedrine (PSE) or acetaminophen (ACE) is widely used in the treatment of allergic rhinitis, conjunctivitis and chronic urticaria. A rapid, simple, selective and precise densitometric method was developed and validated for simultaneous estimation of six synthetic binary mixtures and their pharmaceutical dosage forms. The method employed thin layer chromatography aluminum plates precoated with silica gel G 60 F254 as the stationary phase. The mobile phases chosen for development gave compact bands for the mixtures FXD-PSE (I), KET-PSE (II), LOR-PSE (III), FXD-ACE (IV), KET-ACE (V) and LOR-ACE (VI) [Retardation factor (Rf ) values were (0.20, 0.32), (0.69, 0.34), (0.79, 0.13), (0.36, 0.70), (0.51, 0.30) and (0.76, 0.26), respectively]. Spectrodensitometric scanning integration was performed at 217, 218, 218, 233, 272 and 251 nm for the mixtures I-VI, respectively. The linear regression data for the calibration plots showed an excellent linear relationship. The method was validated for precision, accuracy, robustness and recovery. Limits of detection and quantitation were calculated. Statistical analysis proved that the method is reproducible and selective for the simultaneous estimation of these binary mixtures. Copyright © 2013 John Wiley & Sons, Ltd.

High resolution mass spectrometric brain proteomics by MALDI-FTICR-MS combined with determination of P, S, Cu, Zn and Fe by LA-ICP-MS

NASA Astrophysics Data System (ADS)

Becker, J. Susanne; Zoriy, Miroslav; Przybylski, Michael; Becker, J. Sabine

2007-03-01

The combination of atomic and molecular mass spectrometric methods was applied for characterization and identification of several human proteins from Alzheimer's diseased brain. A brain protein mixture was separated by two-dimensional (2D) gel electrophoresis and the protein spots were fast screened by microlocal analysis using LA-ICP-MS (laser ablation inductively coupled plasma mass spectrometry) in respect to phosphorus, sulfur, copper, zinc and iron content. Five selected protein spots in 2D gel containing these elements were investigated after tryptic digestion by matrix assisted laser desorption ionization Fourier transform ion cyclotron resonance mass spectrometry (MALDI-FTICR-MS). Than element concentrations (P, Cu, Zn and Fe) were determined in three identified human brain proteins by LA-ICP-MS in the 2D gel. Results of structure analysis of human brain proteins by MALDI-FTICR-MS were combined with those of the direct determination of phosphorus, copper, zinc and iron concentrations in protein spots with LA-ICP-MS. From the results of atomic and molecular mass spectrometric techniques the human brain proteins were characterized in respect to their structure, sequence, phosphorylation state and metal content as well.

Development of a fiber coating based on molecular sol-gel imprinting technology for selective solid-phase micro extraction of caffeine from human serum and determination by gas chromatography/mass spectrometry.

PubMed

Rajabi Khorrami, Afshin; Rashidpur, Amene

2012-05-21

In this work, a molecular sol-gel imprinting approach has been introduced to produce a fiber coating for selective direct immersion solid-phase microextraction (SPME) of caffeine. The polymerization mixture was composed of vinyl trimethoxysilane and methacrylic acid as vinyl sol-gel precursor and functional monomer, respectively. Caffeine was used as template molecule during polymerization process. The prepared fibers could be coupled directly to gas chromatography/mass spectrometry (GC/MS) and used for trace analysis of caffeine in a complex sample such as human serum. The parameters influencing SPME such as time, temperature and stirring speed were optimized. The prepared coating showed good selectivity towards caffeine in the presence of some structurally related compounds. Also, it offered high imprinting capability in comparison to bare fiber and non-imprinted coating. Linear range for caffeine detection was 1-80 μg mL(-1) and the limit of detection was 0.1 μg mL(-1). The intra-day and inter-day precisions of the peak areas for five replicates were 10 and 16%, respectively. Copyright © 2012 Elsevier B.V. All rights reserved.

Phenomenological model and phase behavior of saturated and unsaturated lipids and cholesterol.

PubMed

Putzel, G Garbès; Schick, M

2008-11-15

We present a phenomenological theory for the phase behavior of ternary mixtures of cholesterol and saturated and unsaturated lipids, one that describes both liquid and gel phases. It leads to the following description of the mechanism of the phase behavior: In a binary system of the lipids, phase separation occurs when the saturated chains are well ordered, as in the gel phase, simply due to packing effects. In the liquid phase, the saturated ones are not sufficiently well ordered for separation to occur. The addition of cholesterol, however, increases the saturated lipid order to the point that phase separation is once again favorable. Our theory addresses this last mechanism-the means by which cholesterol-mediated ordering of membrane lipids leads to liquid-liquid immiscibility. It produces, for the system above the main chain transition of the saturated lipid, phase diagrams in which there can be liquid-liquid phase separation in the ternary system but not in any of the binary ones, while below that temperature it yields the more common phase diagram in which a gel phase, rich in saturated lipid, appears in addition to the two liquid phases.

Quantification of iprodione in dry basil using silica gel supported titanium dioxide.

PubMed

Maeda, Osamu; Oikawa, Chie; Noguchi, Kentaro; Shiomi, Nobuo; Toriba, Akira; Hayakawa, Kazuichi

2010-02-10

Iprodione is an agricultural fungicide that is difficult to detect in foods by HPLC because it coelutes with natural compounds in the food. We previously showed that food matrix could be degraded with titanium dioxide powder (TP). Here we describe an improved method for detection of iprodione using silica gel supported titanium dioxide (SGT). To synthesize SGT, titania-sol was mixed with diethanolamine, 2-propanol, and titanium tetraisopropoxide. After titania-sol was infiltrated into the silica gel (particle diameter 4 mm), the mixture was dried and then heated. Crude basil extract containing iprodione was mixed with SGT in a quartz vial, and the vial was irradiated with a UV light to selectively decompose the matrix interfering with the iprodione determination. In HPLC chromatograms of the treated solution, the interference peak decreased 35 times faster with SGT than with TP. When SGT (11 g) was added to the extract (20 mL) of dry basil (2 g), black light irradiation for 30 min was enough to quantify iprodione. The recovery rate of iprodione was 99.1%. Thus, the photocatalytic cleanup method using SGT is effective for analyzing residual iprodione in dry basil.

Proton dynamics and surface heterogeneity of silica gel with adsorbed benzene below one monolayer coverage

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

Peterson, E.M.; O'Reilly, D.E.; Tsangb), T.

1979-04-01

Proton and deuteron NMR relaxation times of C/sub 6/H/sub 6/, C/sub 6/D/sub 6/, and mixtures of these molecules have been measured on a superpure silica gel (SPSG) and a sample of a Matheson silica gel (MSG) both dehydrated at 600/sup 0/ C and rotational (intramolecular) and translational (intermolecular) correlation times have been computed from the relaxation time data at a statistical coverage theta=0.6. Three kinds of adsorption sites have been observed: (1) A sites, which are probably oxygen vacancies on the surface, (2) B sites which are assigned to paired hydroxyl groups on the surface, and finally (3) C sitesmore » which comprise 80% of the occupied surface and are primarily isolated hydroxyl groups. Rotational and translational motions are highly correlated for the A and B site molecules. The mean number of molecules clustered at the A and B sites are inferred from the intermolecular second moments associated with each of these sites. The surface density of the A sites is 1.1 x 10/sup 12/ cm/sup -2/ for SPSG and 3.1 x 10/sup 12/ cm/sup -2/ for MSG.« less

Hydrophilic Dogwood Extracts as Materials for Reducing the Skin Irritation Potential of Body Wash Cosmetics.

PubMed

Nizioł-Łukaszewska, Zofia; Osika, Paweł; Wasilewski, Tomasz; Bujak, Tomasz

2017-02-19

A significant problem related to the use of surfactants in body wash cosmetics is their propensity to trigger skin irritations. Only scarce literature exists on the effect of plant extracts on the skin irritation potential. The present study is an attempt to determine the effect of hydrophilic dogwood extracts on the irritant potential of body wash gels. Extractants used in the study were water and mixtures of water with glycerine, water with trimethylglycine (betaine), and water with plant-derived glycol (propanediol). The basic biochemical properties, i.e., the ability to neutralize free radicals, and the content of polyphenols, anthocyanins and flavonoids, were determined. An attempt was undertaken to analyze the impact of the extract added to natural body wash gel formulations on product properties. The skin irritation potential was assessed by determining the zein number and the increase in the pH level of the bovine serum albumin (BSA) solution. The viscosity and foaming ability of the resulting products were evaluated. The studies revealed that an addition of dogwood extract contributes to an improvement in the properties of body wash gels and significantly increases the safety of product use through reducing the skin irritation effect.

The Properties of HPMC:PEO Extended Release Hydrophilic Matrices and their Response to Ionic Environments.

PubMed

Hu, Anran; Chen, Chen; Mantle, Michael D; Wolf, Bettina; Gladden, Lynn F; Rajabi-Siahboomi, Ali; Missaghi, Shahrzad; Mason, Laura; Melia, Colin D

2017-05-01

Investigate the extended release behaviour of compacts containing mixtures of hydrophilic HPMC and PEO in hydrating media of differing ionic strengths. The extended release behaviour of various HPMC:PEO compacts was investigated using dissolution testing, confocal microscopy and magnetic resonance imaging, with respect to polymer ratio and ionic strength of the hydrating media. Increasing HPMC content gave longer extended release times, but a greater sensitivity to high ionic dissolution environments. Increasing PEO content reduced this sensitivity. The addition of PEO to a predominantly HPMC matrix reduced release rate sensitivity to high ionic environments. Confocal microscopy of early gel layer development showed the two polymers appeared to contribute independently to gel layer structure whilst together forming a coherent and effective diffusion barrier. There was some evidence that poorly swollen HPMC particles added a tortuosity barrier to the gel layer in high ionic strength environments, resulting in prolonged extended release. MRI provides unique, non-invasive spatially resolved information from within the HPMC:PEO compacts that furthers our understanding of USP 1 and USP 4 dissolution data. Confocal microscopy and MRI data show that combinations of HPMC and PEO have advantageous extended release properties, in comparison with matrices containing a single polymer.

Formation of gold and silver nanostructures within polyvinylpyrollidone (PVP) gel

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

Kan Caixia, E-mail: cxkan@nuaa.edu.c; Wang Changshun; Zhu Jiejun

2010-04-15

Study on reduction of Au(III) and Ag(I) and the formation of Au and Ag nanostructures was performed on the gels of metal precursor and PVP polymer mixture. Some comparing samples were prepared for better understanding the role of reactants on the reduction of metal ions and further growth of nanocrystals. The results suggest that, in addition to its function of generating stable colloids, PVP not only has a reducing effect on metal ions, but also acts as a crystal growth modifier. At low temperatures, the reducing effect of PVP is strong on Ag(I) ions in AgNO{sub 3}, while the reductionmore » of complex Au(III) ions in HAuCl{sub 4} is slow, involving two steps of Au(III)->Au(I)->Au. In the study of temperature disturbance on crystal growth, Au nanoplates of new and well-defined star shape were observed. The differences in the size and shape of nanoparticles are discussed from the colloid chemistry. - Graphical abstract: If a temperature difference was introduced to the gel of Au{sup 3+}(H{sub 2}O)-PVP, large sized Au nanoplates with new and well-defined star shape were observed.« less

Multilocus sequence typing and pulsed-field gel electrophoresis analysis of Oenococcus oeni from different wine-producing regions of China.

PubMed

Wang, Tao; Li, Hua; Wang, Hua; Su, Jing

2015-04-16

The present study established a typing method with NotI-based pulsed-field gel electrophoresis (PFGE) and stress response gene schemed multilocus sequence typing (MLST) for 55 Oenococcus oeni strains isolated from six individual regions in China and two model strains PSU-1 (CP000411) and ATCC BAA-1163 (AAUV00000000). Seven stress response genes, cfa, clpL, clpP, ctsR, mleA, mleP and omrA, were selected for MLST testing, and positive selective pressure was detected for these genes. Furthermore, both methods separated the strains into two clusters. The PFGE clusters are correlated with the region, whereas the sequence types (STs) formed by the MLST confirm the two clusters identified by PFGE. In addition, the population structure was a mixture of evolutionary pathways, and the strains exhibited both clonal and panmictic characteristics. Copyright © 2015 Elsevier B.V. All rights reserved.

Evaluation of several two-dimensional gel electrophoresis techniques in cardiac proteomics.

PubMed

Li, Zhao Bo; Flint, Paul W; Boluyt, Marvin O

2005-09-01

Two-dimensional gel electrophoresis (2-DE) is currently the best method for separating complex mixtures of proteins, and its use is gradually becoming more common in cardiac proteome analysis. A number of variations in basic 2-DE have emerged, but their usefulness in analyzing cardiac tissue has not been evaluated. The purpose of the present study was to systematically evaluate the capabilities and limitations of several 2-DE techniques for separating proteins from rat heart tissue. Immobilized pH gradient strips of various pH ranges, parameters of protein loading and staining, subcellular fractionation, and detection of phosphorylated proteins were studied. The results provide guidance for proteome analysis of cardiac and other tissues in terms of selection of the isoelectric point separating window for cardiac proteins, accurate quantitation of cardiac protein abundance, stabilization of technical variation, reduction of sample complexity, enrichment of low-abundant proteins, and detection of phosphorylated proteins.

Flavourzyme, an Enzyme Preparation with Industrial Relevance: Automated Nine-Step Purification and Partial Characterization of Eight Enzymes.

PubMed

Merz, Michael; Eisele, Thomas; Berends, Pieter; Appel, Daniel; Rabe, Swen; Blank, Imre; Stressler, Timo; Fischer, Lutz

2015-06-17

Flavourzyme is sold as a peptidase preparation from Aspergillus oryzae. The enzyme preparation is widely and diversely used for protein hydrolysis in industrial and research applications. However, detailed information about the composition of this mixture is still missing due to the complexity. The present study identified eight key enzymes by mass spectrometry and partially by activity staining on native polyacrylamide gels or gel zymography. The eight enzymes identified were two aminopeptidases, two dipeptidyl peptidases, three endopeptidases, and one α-amylase from the A. oryzae strain ATCC 42149/RIB 40 (yellow koji mold). Various specific marker substrates for these Flavourzyme enzymes were ascertained. An automated, time-saving nine-step protocol for the purification of all eight enzymes within 7 h was designed. Finally, the purified Flavourzyme enzymes were biochemically characterized with regard to pH and temperature profiles and molecular sizes.

Development of a conductivity-based photothermal absorbance detection microchip using polyelectrolytic gel electrodes.

PubMed

Chun, Honggu; Dennis, Patty J; Ferguson Welch, Erin R; Alarie, Jean Pierre; Jorgenson, James W; Ramsey, J Michael

2017-11-10

The development and application of polyelectrolytic gel electrodes (PGEs) for a microfluidic photothermal absorbance detection system is described. The PGEs are used to measure changes in conductivity based on heat generation by analytes absorbing light and changing the solution viscosity. The PGEs are suitable for direct contact conductivity measurements since they do not degrade with exposure to high electric fields. Both a 2-electrode system with DC voltages and a 3-electrode system with AC voltages were investigated. Experimental factors including excitation voltage, excitation frequency, laser modulation frequency, laser power, and path length were tested. The limits of detection for the 3-electrode and 2-electrode systems are 500nM and 0.55nM for DABSYL-tagged glucosamine, respectively. In addition, an electrokinetic separation of a potassium, DABSYL-tagged glucosamine, Rhodamine 6G, and Rhodamine B mixture was demonstrated. Copyright © 2017 Elsevier B.V. All rights reserved.

Synthesis of nano-titanium dioxide by sol-gel route

NASA Astrophysics Data System (ADS)

Kaler, Vandana; Duchaniya, R. K.; Pandel, U.

2016-04-01

Nanosized titanium dioxide powder was synthesised via sol-gel route by hydrolysis of titanium tetraisopropoxide with ethanol and water mixture in high acidic medium. The synthesized nanopowder was further characterized by X-ray Diffraction, Scanning Electron Microscopy, Fourier Transform Infrared Spectroscopy, and Ultraviolet Visible Spectroscopy in order to determine size, morphology and crystalline structure of the material. The synthesis of nano-TiO2 powder in anatase phase was realized by XRD. The optical studies of nano-TiO2 powder was carried out by UV-Vis spectroscopy and band gap was calculated as 3.5eV, The SEM results with EDAX confirmed that prepared nano-TiO2 particles were in nanometer range with irregular morphology. The FTIR analysis showed that only desired functional groups were present in sample. These nano-TiO2 particles have applications in solar cells, chemical sensors and paints, which are thrust areas these days.

Electrophoretic Mobility Shift Assay (EMSA) for Detecting Protein-Nucleic Acid Interactions

PubMed Central

Hellman, Lance M.; Fried, Michael G.

2009-01-01

The gel electrophoresis mobility shift assay (EMSA) is used to detect protein complexes with nucleic acids. It is the core technology underlying a wide range of qualitative and quantitative analyses for the characterization of interacting systems. In the classical assay, solutions of protein and nucleic acid are combined and the resulting mixtures are subjected to electrophoresis under native conditions through polyacrylamide or agarose gel. After electrophoresis, the distribution of species containing nucleic acid is determined, usually by autoradiography of 32P-labeled nucleic acid. In general, protein-nucleic acid complexes migrate more slowly than the corresponding free nucleic acid. In this article, we identify the most important factors that determine the stabilities and electrophoretic mobilities of complexes under assay conditions. A representative protocol is provided and commonly used variants are discussed. Expected outcomes are briefly described. References to extensions of the method and a troubleshooting guide are provided. PMID:17703195

Investigation of Dissolution Behavior HPMC/Eudragit®/Magnesium Aluminometasilicate Oral Matrices Based on NMR Solid-State Spectroscopy and Dynamic Characteristics of Gel Layer.

PubMed

Naiserová, M; Kubová, K; Vysloužil, J; Pavloková, S; Vetchý, D; Urbanová, M; Brus, J; Vysloužil, J; Kulich, P

2018-02-01

Burst drug release is often considered a negative phenomenon resulting in unexpected toxicity or tissue irritation. Optimal release of a highly soluble active pharmaceutical ingredient (API) from hypromellose (HPMC) matrices is technologically impossible; therefore, a combination of polymers is required for burst effect reduction. Promising variant could be seen in combination of HPMC and insoluble Eudragits ® as water dispersions. These can be applied only on API/insoluble filler mixture as over-wetting prevention. The main hurdle is a limited water absorption capacity (WAC) of filler. Therefore, the object of this study was to investigate the dissolution behavior of levetiracetam from HPMC/Eudragit ® NE matrices using magnesium aluminometasilicate (Neusilin ® US2) as filler with excellent WAC. Part of this study was also to assess influence of thermal treatment on quality parameters of matrices. The use of Neusilin ® allowed the application of Eudragit ® dispersion to API/Neusilin ® mixture in one step during high-shear wet granulation. HPMC was added extragranularly. Obtained matrices were investigated for qualitative characteristics, NMR solid-state spectroscopy (ssNMR), gel layer dynamic parameters, SEM, and principal component analysis (PCA). Decrease in burst effect (max. of 33.6%) and dissolution rate, increase in fitting to zero-order kinetics, and paradoxical reduction in gel layer thickness were observed with rising Eudragit ® NE concentration. The explanation was done by ssNMR, which clearly showed a significant reduction of the API particle size (150-500 nm) in granules as effect of surfactant present in dispersion in dependence on Eudragit ® NE amount. This change in API particle size resulted in a significantly larger interface between these two entities. Based on ANOVA and PCA, thermal treatment was not revealed as a useful procedure for this system.

Molten carbonate fuel cell cathode with mixed oxide coating

DOEpatents

Hilmi, Abdelkader; Yuh, Chao-Yi

2013-05-07

A molten carbonate fuel cell cathode having a cathode body and a coating of a mixed oxygen ion conductor materials. The mixed oxygen ion conductor materials are formed from ceria or doped ceria, such as gadolinium doped ceria or yttrium doped ceria. The coating is deposited on the cathode body using a sol-gel process, which utilizes as precursors organometallic compounds, organic and inorganic salts, hydroxides or alkoxides and which uses as the solvent water, organic solvent or a mixture of same.

A Review of the Literature on the Applications of CW Agents with Recommendations of Further Research on Thickened GD

DTIC Science & Technology

1975-12-01

be effective not only in GD but also in VX, although as much as 30% is needed to form a gel. Wills cites the polymethacrylates : the methyl and ethyl...percutaneous toxicity of additives. Horton et al showed that a 50/50 mixture of GB with hexafluoroglutaric acid , phosgene oxime, or xylene is signifi- cantly...amounts of certain products of the decomposition of the agent, viz pinacolyl hydrogen methylphosphonate and methylphosphonic acid , as much as 40 weeks

Durable zinc oxide-containing sorbents for coal gas desulfurization

DOEpatents

Siriwardane, Ranjani V.

1996-01-01

Durable zinc-oxide containing sorbent pellets for removing hydrogen sulfide from a gas stream at an elevated temperature are made up to contain titania as a diluent, high-surface-area silica gel, and a binder. These materials are mixed, moistened, and formed into pellets, which are then dried and calcined. The resulting pellets undergo repeated cycles of sulfidation and regeneration without loss of reactivity and without mechanical degradation. Regeneration of the pellets is carried out by contacting the bed with an oxidizing gas mixture.

Elasticity dominated surface segregation of small molecules in polymer mixtures

NASA Astrophysics Data System (ADS)

Croce, Salvatore; Krawczyk, Jaroslaw; McLeish, Tom; Chakrabarti, Buddhapriya

When a binary polymer mixture with mobile components is left to equilibrate, the low molecular weight component migrates to the free surface. A balance between loss of translational entropy and gain in surface energy dictates the equilibrium partitioning ratio and the migrant fraction. Despite its ubiquity and several theoretical and experimental investigations, the phenomenon is not fully understood. Further, methods by which migration can be controlled are in its nascent stage of development. We propose a new phenomenological free energy functional that incorporates the elasticity of bulk polymer mixtures (reticulated networks and gels) and show (using mean field and self-consistent field theories) that the migrant fraction decreases with increasing the bulk modulus of the system. Further, a wetting transition observed otherwise for large values of miscibility parameter and polymerization index can be avoided by increasing the elastic modulus of the system. Estimated values of moduli (for the effect to be observable) are akin to those of rubbery polymers. Our work paves the way for controlling surface migration in complex industrial formulations with polymeric ingredients where this effect leads to decreased product stability and performance.

Investigation of Shear-Thinning Behavior on Film Thickness and Friction Coefficient of Polyalphaolefin Base Fluids With Varying Olefin Copolymer Content

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

Zolper, Thomas J.; He, Yifeng; Delferro, Massimiliano

2016-08-11

This study investigates the rheological properties, elastohydrodynamic (EHD) film-forming capability, and friction coefficients of low molecular mass poly-alpha-olefin (PAO) base stocks with varying contents of high molecular mass olefin copolymers (OCPs) to assess their shear stability and their potential for energy-efficient lubrication. Several PAO-OCP mixtures were blended in order to examine the relationship between their additive content and tribological performance. Gel permeation chromatography (GPC) and nuclear magnetic resonance (NMR) spectroscopy were used to characterize the molecular masses and structures, respectively. Density, viscosity, EHD film thickness, and friction were measured at 303 K, 348 K, and 398 K. Film thickness andmore » friction were studied at entrainment speeds relevant to the boundary, mixed, and full-film lubrication regimes. The PAO-OCP mixtures underwent temporary shear-thinning resulting in decreases in film thickness and hydrodynamic friction. These results demonstrate that the shear characteristics of PAO-OCP mixtures can be tuned with the OCP content and provide insight into the effects of additives on EHD characteristics.« less

Magnetic susceptibility and magnetic resonance measurements of the moisture content and hydration condition of a magnetic mixture material

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

Tsukada, K., E-mail: tsukada@cc.okayama-u.ac.jp; Kusaka, T.; Saari, M. M.

2014-05-07

We developed a magnetic measurement method to measure the moisture content and hydration condition of mortar as a magnetic mixture material. Mortar is a mixture of Portland cement, sand, and water, and these materials exhibit different magnetic properties. The magnetization–magnetic field curves of these components and of mortars with different moisture contents were measured, using a specially developed high-temperature-superconductor superconducting quantum interference device. Using the differences in magnetic characteristics, the moisture content of mortar was measured at the ferromagnetic saturation region over 250 mT. A correlation between magnetic susceptibility and moisture content was successfully established. After Portland cement and water aremore » mixed, hydration begins. At the early stage of the hydration/gel, magnetization strength increased over time. To investigate the magnetization change, we measured the distribution between bound and free water in the mortar in the early stage by magnetic resonance imaging (MRI). The MRI results suggest that the amount of free water in mortar correlates with the change in magnetic susceptibility.« less

Two schemes for production of biosurfactant from Pseudomonas aeruginosa MR01: Applying residues from soybean oil industry and silica sol-gel immobilized cells.

PubMed

Bagheri Lotfabad, Tayebe; Ebadipour, Negisa; Roostaazad, Reza; Partovi, Maryam; Bahmaei, Manochehr

2017-04-01

Rhamnolipids are the most common biosurfactants and P. aeruginosa strains are the most frequently studied microorganisms for the production of rhamnolipids. Eco-friendly advantages and promising applications of rhamnolipids in various industries are the major reasons for pursuing the economic production of these biosurfactants. This study shows that cultivation of P. aeruginosa MR01 in medium contained inexpensive soybean oil refinery wastes which exhibited similar levels and homologues of rhamnolipids. Mass spectrometry indicated that the Rha-C10-C10 and Rha-Rha-C10-C10 constitute the main rhamnolipids in different cultures of MR01 including one of oil carbon source analogues. Moreover, rhamnolipid mixtures extracted from different cultures showed critical micelle concentrations (CMC) in the range of ≃24 to ≃36mg/l with capability to reduce the surface tension of aqueous solution from 72 to ≃27-32mN/m. However, the sol-gel technique using tetraethyl orthosilicate (TEOS) was used as a gentler method in order to entrap the P. aeruginosa MR01 cells in mold silica gels. Immobilized cells can be utilized several times in consecutive fermentation batches as well as in flow fermentation processes. In this way, reusability of the cells may lead to a more economical fermentation process. Approximately 90% of cell viability was retained during the silica sol-gel immobilization and ≃84% of viability of immobilized cells was preserved for 365days of immobilization and storage of the cells in phosphate buffer at 4°C and 25°C. Moreover, mold gels showed good mechanical stability during the seven successive fermentation batches and the entrapped cells were able to efficiently preserve their biosurfactant-producing potential. Copyright © 2017 Elsevier B.V. All rights reserved.

Elastic Characterization of Transversely Isotropic Soft Materials by Dynamic Shear and Asymmetric Indentation

PubMed Central

Namani, R.; Feng, Y.; Okamoto, R. J.; Jesuraj, N.; Sakiyama-Elbert, S. E.; Genin, G. M.; Bayly, P. V.

2012-01-01

The mechanical characterization of soft anisotropic materials is a fundamental challenge because of difficulties in applying mechanical loads to soft matter and the need to combine information from multiple tests. A method to characterize the linear elastic properties of transversely isotropic soft materials is proposed, based on the combination of dynamic shear testing (DST) and asymmetric indentation. The procedure was demonstrated by characterizing a nearly incompressible transversely isotropic soft material. A soft gel with controlled anisotropy was obtained by polymerizing a mixture of fibrinogen and thrombin solutions in a high field magnet (B = 11.7 T); fibrils in the resulting gel were predominantly aligned parallel to the magnetic field. Aligned fibrin gels were subject to dynamic (20–40 Hz) shear deformation in two orthogonal directions. The shear storage modulus was 1.08 ± 0. 42 kPa (mean ± std. dev.) for shear in a plane parallel to the dominant fiber direction, and 0.58 ± 0.21 kPa for shear in the plane of isotropy. Gels were indented by a rectangular tip of a large aspect ratio, aligned either parallel or perpendicular to the normal to the plane of transverse isotropy. Aligned fibrin gels appeared stiffer when indented with the long axis of a rectangular tip perpendicular to the dominant fiber direction. Three-dimensional numerical simulations of asymmetric indentation were used to determine the relationship between direction-dependent differences in indentation stiffness and material parameters. This approach enables the estimation of a complete set of parameters for an incompressible, transversely isotropic, linear elastic material. PMID:22757501

Fibroblasts regulate the migration of MCF7 mammary carcinoma cells in hydrated collagen gel.

PubMed

Rossi, L; Reverberi, D; Capurro, C; Aiello, C; Cipolla, M; Bonanno, M; Podestà, G

1994-01-01

We have defined a tissue culture method suitable to study cell-cell interactions in an environmental set close to in vivo conditions. It consists of heterotypic cell populations mixed together inside a collagen gel in a chamber slide for a period of up to 14 days. When the three-dimensional system is saturated, cells will start to move on the plastic surface as monolayers surrounding the gel, with a characteristic speed depending on cell type. Usually fibroblasts move fast, while epithelial cells demonstrate a much lower pace of migration. At any given time gel contraction can be measured, and thus the rate of cell expansion, by knowing the distance from the edge of the gel to the leading edge of cell migration. By using this approach it was found that MCF7 mammary carcinoma cells display a great variety of morphologies following their mixture with different fibroblastic cell lines. In particular, when MCF7 cells were mixed with fibroblasts from human fetus, dog thymus and rat kidney, they migrated up to the leading edge of the fibroblastic front as isolated single cells or as cellular aggregates, many of which became necrotic in time, or took on an elongated morphology. Selective necrosis of MCF7 cells was also induced with serum concentration of 15% and 20% FCS, but only when they were mixed with fibroblasts. No necrosis was induced in MCF7 cells cultured alone. From these observations it is suggested that necrosis may sometimes favor the detachment and infiltration of resistant epithelial tumor cells by increasing their autonomous behaviour. Fibroblasts seem to be instrumental in regulating this process.

Influence of the intrinsic membrane protein bacteriorhodopsin on gel-phase domain topology in two-component phase-separated bilayers.

PubMed Central

Schram, V; Thompson, T E

1997-01-01

We have investigated the effect of the intrinsic membrane protein bacteriorhodopsin of Halobacterium halobium on the lateral organization of the lipid phase structure in the coexistence region of an equimolar mixture of dimyristoylphos-phatidylcholine and distearoylphosphatidylcholine. The fluorescence recovery after photobleaching (FRAP) technique was used to monitor the diffusion of both a lipid analog (N-(7-nitrobenzoxa-2,3-diazol-4-yl)-dimyristoylphosphatidyle thanolamine, NBD-DMPE) and fluorescein-labeled bacteriorhodopsin (Fl-BR). In the presence of bacteriorhodopsin, the mobile fractions of the two fluorescent probes display a shift of the percolation threshold toward lower temperatures (larger gel-phase fractions), independent of the protein concentration, from 43 degrees C (without bacteriorhodopsin) to 39 degrees C and 41 degrees C for NBD-DMPE and Fl-BR, respectively. Moreover, in the presence of bacteriorhodopsin, the gel-phase domains are much less efficient in restricting the diffusion of both probes than they are in the absence of the protein in the two-phase coexistence region. Bacteriorhodopsin itself, however, obstructs diffusion of NBD-DMPE and Fl-BR to about the same extent in the fluid phase of the two-phase region as it does in the homogeneous fluid phase. These observations suggest that 1) the protein induces the formation of much larger and/or more centrosymmetrical gel-phase domains than those formed in its absence, and 2) bacteriorhodopsin partitions almost equally between the coexisting fluid and gel phases. Although the molecular mechanisms involved are not clear, this phenomenon is fully consistent with the effect of the transmembrane peptide pOmpA of Escherichia coli investigated by electron spin resonance in the same lipid system. PMID:9129824

An ion-imprinted silica-supported organic-inorganic hybrid sorbent prepared by a surface imprinting technique combined with a polysaccharide incorporated sol-gel process for selective separation of cadmium(II) from aqueous solution.

PubMed

Li, Feng; Jiang, Hongquan; Zhang, Shusheng

2007-03-15

Ion-imprinting concept and polysaccharide incorporated sol-gel process were applied to the preparation of a new silica-supported organic-inorganic hybrid sorbent for selective separation of Cd(II) from aqueous solution. In the prepared shell/core composite sorbent, covalently surface coating on the supporting silica gel was achieved by using a Cd(II)-imprinting sol-gel process starting from an inorganic precursor, gamma-glycidoxypropyltrimethoxysiloxane (GPTMS), and a functional biopolymer, chitosan (CS). The sorbent was prepared through self-hydrolysis of GPTMS, self-condensation and co-condensation of silanol groups (Si-OH) from siloxane and silica gel surface, in combination with in situ covalent cross-linking of CS with partial amine shielded by Cd(II) complexation. Extraction of the imprinting molecules left a predetermined arrangement of ligands and tailored binding pockets for Cd(II). The prepared sorbent was characterized by using X-ray energy dispersion spectroscopy (EDX), X-ray diffraction (XRD), and scanning electron microscopy (SEM). Batch experiments were conducted to study the sorption performance by removal of Cd(II) when present singly or in binary system, an aqueous Cd(II) and Zn(II) mixture. The ion-imprinted composite sorbent offered a fast kinetics for the sorption of Cd(II) and the maximum capacity was 1.14mmolg(-1). The uptake capacity of the imprinted sorbent and the selectivity coefficient were much higher than that of the non-imprinted sorbent. The imprinted sorbent exhibited high reusability. The prepared functional sorbent was shown to be promising for the preconcentration of cadmium in environmental and biological samples.

Identification of Fur, Aconitase, and Other Proteins Expressed by Mycobacterium tuberculosis under Conditions of Low and High Concentrations of Iron by Combined Two-Dimensional Gel Electrophoresis and Mass Spectrometry

PubMed Central

Wong, Diane K.; Lee, Bai-Yu; Horwitz, Marcus A.; Gibson, Bradford W.

1999-01-01

Iron plays a critical role in the pathophysiology of Mycobacterium tuberculosis. To gain a better understanding of iron regulation by this organism, we have used two-dimensional (2-D) gel electrophoresis, mass spectrometry, and database searching to study protein expression in M. tuberculosis under conditions of high and low iron concentration. Proteins in cellular extracts from M. tuberculosis Erdman strain grown under low-iron (1 μM) and high-iron (70 μM) conditions were separated by 2-D polyacrylamide gel electrophoresis, which allowed high-resolution separation of several hundred proteins, as visualized by Coomassie staining. The expression of at least 15 proteins was induced, and the expression of at least 12 proteins was decreased under low-iron conditions. In-gel trypsin digestion was performed on these differentially expressed proteins, and the digestion mixtures were analyzed by matrix-assisted laser desorption ionization time-of-flight mass spectrometry to determine the molecular masses of the resulting tryptic peptides. Partial sequence data on some of the peptides were obtained by using after source decay and/or collision-induced dissociation. The fragmentation data were used to search computerized peptide mass and protein sequence databases for known proteins. Ten iron-regulated proteins were identified, including Fur and aconitase proteins, both of which are known to be regulated by iron in other bacterial systems. Our study shows that, where large protein sequence databases are available from genomic studies, the combined use of 2-D gel electrophoresis, mass spectrometry, and database searching to analyze proteins expressed under defined environmental conditions is a powerful tool for identifying expressed proteins and their physiologic relevance. PMID:9864233

Evaluation of human exposure to metals from some commonly used bathing soaps and shower gels in Nigeria.

PubMed

Iwegbue, Chukwujindu M A; Emakunu, Omotekoro S; Nwajei, Godwin E; Bassey, Francisca I; Martincigh, Bice S

2017-02-01

The concentrations of nine metals (Cd, Pb, Ni, Cr, Co, Cu, Fe, Mn and Zn) were measured in selected brands of medicated, moisturizing and skin-lightening soaps and shower gels with the aim of evaluating the human health risk associated with metal exposure from the use of these products. The concentrations of metals in these products were determined by means of atomic absorption spectrophotometry after sample digestion with a mixture of acids. The concentration ranges of the metals in the bathing soaps and shower gels were found to be: <0.06-3.4 μg g -1 for Cd, <0.09-26.5 μg g -1 for Pb, <0.12-43.0 μg g -1 for Cr, <0.06-32.5 μg g -1 for Ni, <0.06-40.5 μg g -1 for Cu, <0.12-8.0 μg g -1 for Co, 61.8-4000 μg g -1 for Fe, <0.09-29.5 μg g -1 for Mn, and 25.5-1000 μg g -1 for Zn. The systemic exposure dosage values for these metals obtained from the application of these brands of bathing soaps and shower gels were below their respective provisional tolerable daily intake/or recommended daily intake values. The margin of safety values obtained for the metals were greater than 100 which indicated that there was no significant risk to the users of these brands of bathing soaps and shower gels, except in the case of Co. Copyright © 2016 Elsevier Inc. All rights reserved.

Stability of model membranes in extreme environments.

PubMed

Namani, Trishool; Deamer, David W

2008-08-01

The first forms of cellular life required a source of amphiphilic compounds capable of assembling into stable boundary structures. Membranes composed of fatty acids have been proposed as model systems of primitive membranes, but their bilayer structure is stable only within a narrow pH range and low ionic strength. They are particularly sensitive to aggregating effects of divalent cations (Mg+2, Ca+2, Fe+2) that would be present in Archaean sea water. Here we report that mixtures of alkyl amines and fatty acids form vesicles at strongly basic and acidic pH ranges which are resistant to the effects of divalent cations up to 0.1 M. Vesicles formed by mixtures of decylamine and decanoic acid (1:1 mole ratio) are relatively permeable to pyranine, a fluorescent anionic dye, but permeability could be reduced by adding 2 mol% of a polycyclic aromatic hydrocarbon such as pyrene. Permeability to the dye was also reduced by increasing the chain length of the amphiphiles. For instance, 1:1 mole ratio mixtures of dodecylamine and dodecanoic acid were able to retain pyranine dye during and following gel filtration. We conclude that primitive cell membranes were likely to be composed of mixtures of amphiphilic and hydrophobic molecules that manifested increased stability over pure fatty acid membranes.

Impact of gastric pH profiles on the proteolytic digestion of mixed βlg-Xanthan biopolymer gels.

PubMed

Dekkers, B L; Kolodziejczyk, E; Acquistapace, S; Engmann, J; Wooster, T J

2016-01-01

The understanding of how foods are digested and metabolised is essential to enable the design/selection of foods as part of a balanced diet. Essential to this endeavour is the development of appropriate biorelevant in vitro digestion tools. In this work, the influence of gastric pH profile on the in vitro digestion of mixtures of β-lactoglobulin (βlg) and xanthan gum prior to and after heat induced gelation was investigated. A conventional highly acidic (pH 1.9) gastric pH profile was compared to two dynamic gastric pH profiles (initial pH of 6.0 vs. 5.2 and H(+) secretion rates of 60 vs. 36 mmol h(-1)) designed to mimic the changes in gastric pH observed during clinical trials with high protein meals. In moving away from the pH 1.9 model, to a pH profile reflecting in vivo conditions, the initial rate and degree of protein digestion halved during the first 45 minutes. After 90 minutes of gastric digestion, all three pH profiles caused similar extents of protein digestion. Given that 50% gastric emptying times of (test) meals are in range of 30-90 min, it would seem highly relevant to use a dynamic pH gastric model rather than a pH 1.9 (USP) or pH 3 model (INFOGEST) in assessing the impact of food structuring approaches on protein digestion. The impact that heat induced gelation had on the degree of gel digestion by pepsin was also investigated. Surprisingly, it was found that heat induced gelation of βlg-xanthan mixtures at 70-90 °C for 20 minutes lead to a considerable decrease in the rate of proteolysis, which contrasts many studies of dispersed aggregates and gels of βlg alone whose heating accelerates pepsin activity due to unfolding. In the present case, the formation of a dense protein network created a fine pore structure which restricted pepsin access into the gel thereby slowing proteolysis. This work not only has implications for the in vitro assessment of protein digestion, but also highlights how protein digestion might be slowed, learnings that might have an influence on the design of foods as part of a satisfying balanced diet.

The effect of different composition of ternary mixtures of emulsifying salts on the consistency of processed cheese spreads manufactured from Swiss-type cheese with different degrees of maturity.

PubMed

Salek, R N; Černíková, M; Maděrová, S; Lapčík, L; Buňka, F

2016-05-01

The scope of this work was to investigate the dependence of selected textural (texture profile analysis, TPA) and viscoelastic properties of processed cheese on the composition of ternary mixtures of emulsifying salts [disodium hydrogenphosphate, DSP; tetrasodium diphosphate, TSPP; sodium salt of polyphosphate (with mean length n ≈ 20), P20; and trisodium citrate, TSC] during a 60-d storage period (6±2°C). The processed cheese samples [40% wt/wt dry matter (DM) content, 50% wt/wt fat in DM content] were manufactured using Swiss-type cheese (as the main raw material) with 4 different maturity degrees (4, 8, 12, and 16 wk of ripening). Moreover, the pH of the samples was adjusted (the target values within the range of 5.60-5.80), corresponding to the standard pH values of spreadable processed cheese. With respect to the individual application of emulsifying salts (regardless of the maturity degree of the Swiss-type cheese applied), the samples prepared with P20 were the hardest, followed by those prepared with TSPP, TSC, and DSP. Furthermore, a specific ratio of DSP:TSPP (1:1) led to a significant increase in the hardness of the samples. On the whole, the hardness of all processed cheese samples increased with the prolonging storage period, whereas their hardness significantly dropped with the rising ripening stage of the raw material utilized. In all of the cases, the trends of hardness development remained analogous, and only the absolute values differed significantly. Moreover, the findings of TPA were in accordance with those of the rheological analysis. In particular, the specific ratio of DSP:TSPP (1:1) resulted in the highest gel strength and interaction factor values, followed by P20, TSPP, TSC, and DSP (used individually), reporting the same trend which was demonstrated by TPA. The monitored values of the gel strength and interaction factor decreased with the increasing maturity degree of the Swiss-type cheese used. The intensity of the rigidity of the samples showed an analogous relationship to the intensity of the gel strength; the higher the gel strength of the sample, the more inflexible the product is expected to be. Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Mineral Precipitation in Porous Media: Laboratory Diffusion Experiments as Analogues for Concretion Formation in Utah and on Mars

NASA Astrophysics Data System (ADS)

Barge, L. M.; Petruska, J.; Potter, S.; Cho, J.; Chan, M.; Nealson, K.

2007-12-01

We present results of laboratory gel diffusion experiments designed to simulate the precipitation of iron minerals in natural systems. Liesegang bands and crystals of various iron minerals were formed in aqueous gels, "mini- concretions" of mineral precipitate were formed in both sand and a sand/agarose mixture, and the formation of hollow mineral spheres was observed in gel precipitation experiments where organics were introduced. These mineral structures are analogous to concretion forms observed in the Navajo Sandstone region of Utah, which have been suggested as terrestrial analogs for the "blueberry" hematite concretions on Mars. Iron mineral precipitates (perhaps with a gel precursor) occur in many forms in the Navajo Sandstone, including "mini- concretions" (solid concretions 1-2 mm in diameter), "rind-like" concretions (hollow spheres of hematite several cm in diameter, surrounding a region of sandstone), and Liesegang banding (banded patterns that form at reaction fronts through diffusion of ions from one reservoir to another). On Mars only small (4-5mm) and mini-concretions (~ 1mm) have been observed; Liesegang bands or large rind-like concretions have not yet been discovered. The varying conditions that give rise to each of these mineral structures in the laboratory indicate that the small, spheroidal types of iron precipitates found in the Utah and Martian environments may be diagnostic of the diffusion medium, presence of organics, and characteristics of fluid in that region.

Volumetric muscle loss injury repair using in situ fibrin gel cast seeded with muscle-derived stem cells (MDSCs)

PubMed Central

Matthias, Nadine; Hunt, Samuel D.; Wu, Jianbo; Lo, Jonathan; Smith Callahan, Laura A.; Li, Yong; Huard, Johnny; Darabi, Radbod

2018-01-01

Volumetric muscle defect, caused by trauma or combat injuries, is a major health concern leading to severe morbidity. It is characterized by partial or full thickness loss of muscle and its bio-scaffold, resulting in extensive fibrosis and scar formation. Therefore, the ideal therapeutic option is to use stem cells combined with bio-scaffolds to restore muscle. For this purpose, muscle-derived stem cells (MDSCs) are a great candidate due to their unique multi-lineage differentiation potential. In this study, we evaluated the regeneration potential of MDSCs for muscle loss repair using a novel in situ fibrin gel casting. Muscle defect was created by a partial thickness wedge resection in the tibialis anterior (TA)muscles of NSG mice which created an average of 25% mass loss. If untreated, this defect leads to severe muscle fibrosis. Next, MDSCs were delivered using a novel in situ fibrin gel casting method. Our results demonstrated MDSCs are able to engraft and form new myofibers in the defect when casted along with fibrin gel. LacZ labeled MDSCs were able to differentiate efficiently into new myofibers and significantly increase muscle mass. This was also accompanied by significant reduction of fibrotic tissue in the engrafted muscles. Furthermore, transplanted cells also contributed to new vessel formation and satellite cell seeding. These results confirmed the therapeutic potential of MDSCs and feasibility of direct in situ casting of fibrin/MDSC mixture to repair muscle mass defects. PMID:29331939

Separation and identification of mouse liver membrane proteins using a gel-based approach in combination with 2DnanoLC-Q-TOF-MS/MS

NASA Astrophysics Data System (ADS)

Thanh Tran, The; Phan, Van Chi

2010-03-01

In this work, we present results of membrane proteome profiling from mouse liver tissues using a gel-based approach in combination with 2DnanoLC-Q-TOF-MS/MS. Following purification of the membrane fraction, SDS-PAGE was carried out as a useful separation step. After staining, gels with protein bands were cut, reduced, alkylated and trypsin-digested. The peptide mixtures extracted from each gel slice were fractionated by two-dimensional nano liquid chromatography (2DnanoLC) coupled online with tandem mass spectrometry analysis (NanoESI-Q-TOF-MS/MS). The proteins were identified by MASCOT search against a mouse protein database using a peptide and fragment mass tolerance of ±0.5 Da. Protein identification was carried out using a Mowse scoring algorithm with a confidence level of 95% and processed by MSQuant v1.5 software for further validation. In total, 318 verified membrane proteins from mouse liver tissues were identified; 66.67% of them (212 proteins) contained at least one or more transmembrane domains predicted by the SOSUI program and 43 were found to be unique microsome membranes. Furthermore, GRAVY values of membrane proteins varied in the range -1.1276 to 0.9016 and only 31 (9.76%) membrane proteins had positive values. The functions and subcellular locations of the identified proteins were categorized as well, according to universal GO annotations.

Improved scar appearance with combined use of silicone gel and vitamin C for Asian patients: a comparative case series.

PubMed

Yun, In Sik; Yoo, Han-Su; Kim, Yong Oock; Rah, Dong Kyun

2013-12-01

In Asians, facial scars, even fine surgical scars, often can be conspicuous and uncomfortable. The authors used a topical silicone gel containing vitamin C on facial scars for the purpose of making the scar less distinct. The study enrolled 80 patients. For the experimental group, the topical silicone gel mixture containing vitamin C was applied from the time of stitch removal to 6 months after the operation. The control group did not undergo any adjunctive treatment. Each participant was evaluated using the modified Vancouver Scar Scale (VSS) as well as erythema and melanin indices by spectrophotometer. With the modified VSS, the experimental group showed a significant decrease in scar elevation (p = 0.026) and erythema (p = 0.025). The hypo- or hyperpigmentation of the scars was more normalized in the experimental group. In the measured results via spectrophotometer, the experimental group showed a significant decrease in the melanin index (p = 0.045). The erythema index showed a statistically significant difference between the time of stitch removal and 6 months after the operation in the experiment group only. Topical use of silicone gel containing vitamin C has the effect of improving the appearance of fine surgical scars in Asian facial skin. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Dermal bioaccessibility of flame retardants from indoor dust and the influence of topically applied cosmetics.

PubMed

Pawar, Gopal; Abdallah, Mohamed Abou-Elwafa; de Sáa, Eugenia Villaverde; Harrad, Stuart

2017-01-01

Despite extensive literature on their potential adverse health effects, there is a lack of information on human dermal exposure to organic flame retardant chemicals (FRs). This study applies an in vitro physiologically based extraction test to provide new insights into the dermal bioaccessibility of various FRs from indoor dust to synthetic sweat/sebum mixture (SSSM). The bioaccessible fractions of α-, β- and γ-hexabromocyclododecane (HBCD) and tetrabromobisphenol A (TBBPA) to 1:1 (sweat/sebum) mixture were 41%, 47%, 50% and 40%, respectively. For Tris-2-chloroethyl phosphate (TCEP), tris (1-chloro-2-propyl) phosphate (TCIPP) and tris-1,3-dichloropropyl phosphate (TDCIPP), bioaccessible fractions were 10%, 17% and 19%. Composition of the SSSM and compound-specific physicochemical properties were the major factors influencing the bioaccessibility of target FRs. Except for TBBPA, the presence of cosmetics (moisturising cream, sunscreen lotion, body spray and shower gel) had a significant effect (P<0.05) on the bioaccessibility of the studied FRs. The presence of cosmetics decreased the bioaccessibility of HBCDs from indoor dust, whereas shower gel and sunscreen lotion enhanced the bioaccessibility of target PFRs. Our bioaccessibility data were applied to estimate the internal exposure of UK adults and toddlers to the target FRs via dermal contact with dust. Our worst-case scenario exposure estimates fell far below available health-based limit values for TCEP, TCIPP and TDCIPP. However, future research may erode the margin of safety for these chemicals.

Effects of Nickel, Chlorpyrifos and Their Mixture on the Dictyostelium discoideum Proteome

PubMed Central

Boatti, Lara; Robotti, Elisa; Marengo, Emilio; Viarengo, Aldo; Marsano, Francesco

2012-01-01

Mixtures of chemicals can have additive, synergistic or antagonistic interactions. We investigated the effects of the exposure to nickel, the organophosphate insecticide chlorpyrifos at effect concentrations (EC) of 25% and 50% and their binary mixture (Ec25 + EC25) on Dictyostelium discoideum amoebae based on lysosomal membrane stability (LMS). We treated D. discoideum with these compounds under controlled laboratory conditions and evaluated the changes in protein levels using a two-dimensional gel electrophoresis (2DE) proteomic approach. Nickel treatment at EC25 induced changes in 14 protein spots, 12 of which were down-regulated. Treatment with nickel at EC50 resulted in changes in 15 spots, 10 of which were down-regulated. Treatment with chlorpyrifos at EC25 induced changes in six spots, all of which were down-regulated; treatment with chlorpyrifos at EC50 induced changes in 13 spots, five of which were down-regulated. The mixture corresponding to EC25 of each compound induced changes in 19 spots, 13 of which were down-regulated. The data together reveal that a different protein expression signature exists for each treatment, and that only a few proteins are modulated in multiple different treatments. For a simple binary mixture, the proteomic response does not allow for the identification of each toxicant. The protein spots that showed significant differences were identified by mass spectrometry, which revealed modulations of proteins involved in metal detoxification, stress adaptation, the oxidative stress response and other cellular processes. PMID:23443088

Miscibility and Phase Behavior of N-Acylethanolamine/Diacylphosphatidylethanolamine Binary Mixtures of Matched Acyl Chainlengths (n = 14, 16)

PubMed Central

Kamlekar, Ravi Kanth; Satyanarayana, S.; Marsh, Derek; Swamy, Musti J.

2007-01-01

The miscibility and phase behavior of hydrated binary mixtures of two N-acylethanolamines (NAEs), N-myristoylethanolamine (NMEA), and N-palmitoylethanolamine (NPEA), with the corresponding diacyl phosphatidylethanolamines (PEs), dimyristoylphosphatidylethanolamine (DMPE), and dipalmitoylphosphatidylethanolamine (DPPE), respectively, have been investigated by differential scanning calorimetry (DSC), spin-label electron spin resonance (ESR), and 31P-NMR spectroscopy. Temperature-composition phase diagrams for both NMEA/DMPE and NPEA/DPPE binary systems were established from high sensitivity DSC. The structures of the phases involved were determined by 31P-NMR spectroscopy. For both systems, complete miscibility in the fluid and gel phases is indicated by DSC and ESR, up to 35 mol % of NMEA in DMPE and 40 mol % of NPEA in DPPE. At higher contents of the NAEs, extensive solid-fluid phase separation and solid-solid immiscibility occur depending on the temperature. Characterization of the structures of the mixtures formed with 31P-NMR spectroscopy shows that up to 75 mol % of NAE, both DMPE and DPPE form lamellar structures in the gel phase as well as up to at least 65°C in the fluid phase. ESR spectra of phosphatidylcholine spin labeled at the C-5 position in the sn-2 acyl chain present at a probe concentration of 1 mol % exhibit strong spin-spin broadening in the low-temperature region for both systems, suggesting that the acyl chains pack very tightly and exclude the spin label. However, spectra recorded in the fluid phase do not exhibit any spin-spin broadening and indicate complete miscibility of the two components. The miscibility of NAE and diacyl PE of matched chainlengths is significantly less than that found earlier for NPEA and dipalmitoylphosphatidylcholine, an observation that is consistent with the notion that the NAEs are most likely stored as their precursor lipids (N-acyl PEs) and are generated only when the system is subjected to membrane stress. PMID:17369415

Investigations of the small-scale thermal behavior of sol-gel thermites.

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

Warren, Mial E.; Farrow, Matthew; Tappan, Alexander Smith

2009-02-01

Sol-gel thermites, formulated from nanoporous oxides and dispersed fuel particles, may provide materials useful for small-scale, intense thermal sources, but understanding the factors affecting performance is critical prior to use. Work was conducted on understanding the synthesis conditions, thermal treatments, and additives that lead to different performance characteristics in iron oxide sol-gel thermites. Additionally, the safety properties of sol-gel thermites were investigated, especially those related to air sensitivity. Sol-gel thermites were synthesized using a variety of different techniques and there appear to be many viable routes to relatively equivalent thermites. These thermites were subjected to several different thermal treatments undermore » argon in a differential scanning calorimeter, and it was shown that a 65 C hold for up to 200 minutes was effective for the removal of residual solvent, thus preventing boiling during the final thermal activation step. Vacuum-drying prior to this heating was shown to be even more effective at removing residual solvent. The addition of aluminum and molybdenum trioxide (MoO{sub 3}) reduced the total heat release per unit mass upon exposure to air, probably due to a decrease in the amount of reduced iron oxide species in the thermite. For the thermal activation step of heat treatment, three different temperatures were investigated. Thermal activation at 200 C resulted in increased ignition sensitivity over thermal activation at 232 C, and thermal activation at 300 C resulted in non-ignitable material. Non-sol-gel iron oxide did not exhibit any of the air-sensitivity observed in sol-gel iron oxide. In the DSC experiments, no bulk ignition of sol-gel thermites was observed upon exposure to air after thermal activation in argon; however ignition did occur when the material was heated in air after thermal treatment. In larger-scale experiments, up to a few hundred milligrams, no ignition was observed upon exposure to air after thermal activation in vacuum; however ignition by resistively-heated tungsten wire was possible. Thin films of thermite were fabricated using a dispersed mixture of aluminum and iron oxide particles, but ignition and propagation of these films was difficult. The only ignition and propagation observed was in a preheated sample.« less

Colloidal chemical synthesis and formation kinetics of uniformly sized nanocrystals of metals, oxides, and chalcogenides.

PubMed

Kwon, Soon Gu; Hyeon, Taeghwan

2008-12-01

Nanocrystals exhibit interesting electrical, optical, magnetic, and chemical properties not achieved by their bulk counterparts. Consequently, to fully exploit the potential of nanocrystals, the synthesis of nanocrystals must focus on producing materials with uniform size and shape. Top-down physical processes can produce large quantities of nanocrystals, but controlling the size is difficult with these methods. On the other hand, colloidal chemical synthetic methods can produce uniform nanocrystals with a controlled particle size. In this Account, we present our synthesis of uniform nanocrystals of various shapes and materials, and we discuss the kinetics of nanocrystal formation. We employed four different synthetic approaches including thermal decomposition, nonhydrolytic sol-gel reactions, thermal reduction, and use of reactive chalcogen reagents. We synthesized uniform oxide nanocrystals via heat-up methods. This method involved slowly heat-up reaction mixtures composed of metal precursors, surfactants, and solvents from room temperature to high temperature. We then held reaction mixtures at an aging temperature for a few minutes to a few hours. Kinetics studies revealed a three-step mechanism for the synthesis of nanocrystals through the heat-up method with size distribution control. First, as metal precursors thermally decompose, monomers accumulate. At the aging temperature, burst nucleation occurs rapidly; at the end of this second phase, nucleation stops, but continued diffusion-controlled growth leads to size focusing to produce uniform nanocrystals. We used nonhydrolytic sol-gel reactions to synthesize various transition metal oxide nanocrystals. We employed ester elimination reactions for the synthesis of ZnO and TiO(2) nanocrystals. Uniform Pd nanoparticles were synthesized via a thermal reduction reaction induced by heating up a mixture of Pd(acac)(2), tri-n-octylphosphine, and oleylamine to the aging temperature. Similarly, we synthesized nanoparticles of copper and nickel using metal(II) acetylacetonates. Ni/Pd core/shell nanoparticles were synthesized by simply heating the reaction mixture composed of acetylacetonates of nickel and palladium. Using alternative chalcogen reagents, we synthesized uniform nanocrystals of various metal chalcogenides. Uniform nanocrystals of PbS, ZnS, CdS, and MnS were obtained by heating reaction mixtures composed of metal chlorides and sulfur dissolved in oleylamine. In the future, a detailed understanding of nanocrystal formation kinetics and synthetic chemistry will lead to the synthesis of uniform nanocrystals with controlled size, shape, and composition. In particular, the synthesis of uniform nanocrystals of doped materials, core/shell materials, and multicomponent materials is still a challenge. We expect that these uniformly sized nanocrystals will find important applications in areas including information technology, biomedicine, and energy/environmental technology.

Recent advances in topical anesthesia

PubMed Central

2016-01-01

Topical anesthetics act on the peripheral nerves and reduce the sensation of pain at the site of application. In dentistry, they are used to control local pain caused by needling, placement of orthodontic bands, the vomiting reflex, oral mucositis, and rubber-dam clamp placement. Traditional topical anesthetics contain lidocaine or benzocaine as active ingredients and are used in the form of solutions, creams, gels, and sprays. Eutectic mixtures of local anesthesia cream, a mixture of various topical anesthetics, has been reported to be more potent than other anesthetics. Recently, new products with modified ingredients and application methods have been introduced into the market. These products may be used for mild pain during periodontal treatment, such as scaling. Dentists should be aware that topical anesthetics, although rare, might induce allergic reactions or side effects as a result of an overdose. Topical anesthetics are useful aids during dental treatment, as they reduce dental phobia, especially in children, by mitigating discomfort and pain. PMID:28879311

Superparamagnetic iron oxide nanoparticles incorporated into silica nanoparticles by inelastic collision via ultrasonic field: Role of colloidal stability

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

Sodipo, Bashiru Kayode; Azlan, Abdul Aziz; Innovation

2015-04-24

Superparamagnetic iron oxide nanoparticles (SPION)/Silica composite nanoparticles were prepared by ultrasonically irradiating colloidal suspension of silica and SPION mixture. Both silica and SPION were synthesized independently via co-precipitation and sol-gel method, respectively. Their mixtures were sonicated at different pH between 3 and 5. Electrophoresis measurement and other physicochemical analyses of the products demonstrate that at lower pH SPION was found incorporated into the silica. However, at pH greater than 4, SPION was unstable and unable to withstand the turbulence flow and shock wave from the ultrasonic field. Results suggest that the formation of the SPION/silica composite nanoparticles is strongly relatedmore » to the inelastic collision induced by ultrasonic irradiation. More so, the formation the composite nanoparticles via the ultrasonic field are dependent on the zeta potential and colloidal stability of the particles.« less

Thread-like supercapacitors based on one-step spun nanocomposite yarns.

PubMed

Meng, Qinghai; Wang, Kai; Guo, Wei; Fang, Jin; Wei, Zhixiang; She, Xilin

2014-08-13

Thread-like electronic devices have attracted great interest because of their potential applications in wearable electronics. To produce high-performance, thread-like supercapacitors, a mixture of stable dispersions of single-walled carbon nanotubes and conducting polyaniline nanowires are prepared. Then, the mixture is spun into flexible yarns with a polyvinyl alcohol outer sheath by a one-step spinning process. The composite yarns show excellent mechanical properties and high electrical conductivities after sufficient washing to remove surfactants. After applying a further coating layer of gel electrolyte, two flexible yarns are twisted together to form a thread-like supercapacitor. The supercapacitor based on these two yarns (SWCNTs and PAniNWs) possesses a much higher specific capacitance than that based only on pure SWCNTs yarns, making it an ideal energy-storage device for wearable electronics. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Experimental and computational fluid dynamics studies of mixing of complex oral health products

NASA Astrophysics Data System (ADS)

Cortada-Garcia, Marti; Migliozzi, Simona; Weheliye, Weheliye Hashi; Dore, Valentina; Mazzei, Luca; Angeli, Panagiota; ThAMes Multiphase Team

2017-11-01

Highly viscous non-Newtonian fluids are largely used in the manufacturing of specialized oral care products. Mixing often takes place in mechanically stirred vessels where the flow fields and mixing times depend on the geometric configuration and the fluid physical properties. In this research, we study the mixing performance of complex non-Newtonian fluids using Computational Fluid Dynamics models and validate them against experimental laser-based optical techniques. To this aim, we developed a scaled-down version of an industrial mixer. As test fluids, we used mixtures of glycerol and a Carbomer gel. The viscosities of the mixtures against shear rate at different temperatures and phase ratios were measured and found to be well described by the Carreau model. The numerical results were compared against experimental measurements of velocity fields from Particle Image Velocimetry (PIV) and concentration profiles from Planar Laser Induced Fluorescence (PLIF).

Latent curing systems stabilized by reaction equilibrium in homogeneous mixtures of benzoxazine and amine

PubMed Central

Wang, Jun; Xu, Ya Zhen; Fu, Ya Fei; Liu, Xiang Dong

2016-01-01

Latent curing systems are widely used in industrial thermosets in applications such as adhesion, coating, and composites. Despite many attempts to improve the practicality of this dormant reaction system, the majority of commercially available latent products still use particulate hardeners or liquid compounds with blocked active groups. These formulations generally lack fluidity or rapid reaction characteristics and thus are problematic in some industry applications. Here we describe a novel concept that stabilizes highly reactive benzoxazine/amine mixtures by reaction equilibrium. These new latent benzoxazine curing systems have a long storable lifetime but very short gel time at 150 °C. The reversible reaction between benzoxazine and amine is further demonstrated by FT-IR spectral measurements and rheological experiments, and it is shown that the overall characteristics of the latent system are promising for many industrial applications. PMID:27917932

Analysis of free and bound chlorophenoxy acids in cereals.

PubMed

Lokke, H

1975-06-01

Extraction of the chlorophenoxy acids 2,4-D and dichlorprop in cereals has been examined by analyzing barley from spraying experiments. A procedure has been set up by combination of acid hydrolysis and enzymatic degradation followed by extraction and clean up on either silica gel or basic aluminum oxide. The final determination is based on reaction with diazomethane and subsequently GLC with ECD. This procedure was compared with two different extraction procedures previously described in the literature. The one comparative procedure uses a mixture of 50% diethyl ether/hexane in presence of sulphuric acid and resulted in residues up to ten times lower than found after the combined acid hydrolysis/enzymatic degradation procedure. In the second comparison a direct extraction was made with a mixture of 65% (v/v) acetonitrile in water. No differences were found between this and the combined acid hydrolysis/enzymatic degradation procedure.

Laser engineering of microbial systems

NASA Astrophysics Data System (ADS)

Yusupov, V. I.; Gorlenko, M. V.; Cheptsov, V. S.; Minaev, N. V.; Churbanova, E. S.; Zhigarkov, V. S.; Chutko, E. A.; Evlashin, S. A.; Chichkov, B. N.; Bagratashvili, V. N.

2018-06-01

A technology of laser engineering of microbial systems (LEMS) based on the method of laser-induced transfer of heterogeneous mixtures containing microorganisms (laser bioprinting) is described. This technology involves laser printing of soil microparticles by focusing near-infrared laser pulses on a specially prepared gel/soil mixture spread onto a gold-coated glass plate. The optimal range of laser energies from the point of view of the formation of stable jets and droplets with minimal negative impact on living systems of giant accelerations, laser pulse irradiation, and Au nanoparticles was found. Microsamples of soil were printed on glucose-peptone-yeast agar plates to estimate the LEMS process influence on structural and morphological microbial diversity. The obtained results were compared with traditionally treated soil samples. It was shown that LEMS technology allows significantly increasing the biodiversity of printed organisms and is effective for isolating rare or unculturable microorganisms.

White Light Emission from Vegetable Extracts

NASA Astrophysics Data System (ADS)

Singh, Vikram; Mishra, Ashok K.

2015-06-01

A mixture of extracts from two common vegetables, red pomegranate and turmeric, when photoexcited at 380 nm, produced almost pure white light emission (WLE) with Commission Internationale d’Eclairage (CIE) chromaticity index (0.35, 0.33) in acidic ethanol. It was also possible to obtain WLE in polyvinyl alcohol film (0.32, 0.25), and in gelatin gel (0.26, 0.33) using the same extract mixture. The colour temperature of the WLE was conveniently tunable by simply adjusting the concentrations of the component emitters. The primary emitting pigments responsible for contributing to WLE were polyphenols and anthocyanins from pomegranate, and curcumin from turmeric. It was observed that a cascade of Forster resonance energy transfer involving polyphenolics, curcumin and anthocyanins played a crucial role in obtaining a CIE index close to pure white light. The optimized methods of extraction of the two primary emitting pigments from their corresponding plant sources are simple, cheap and fairly green.

Encapsulating Cytochrome c in Silica Aerogel Nanoarchitectures without Metal Nanoparticles while Retaining Gas-phase Bioactivity

PubMed Central

Harper-Leatherman, Amanda S.; Pacer, Elizabeth R.; Kosciuszek, Nina D.

2016-01-01

Applications such as sensors, batteries, and fuel cells have been improved through the use of highly porous aerogels when functional compounds are encapsulated within the aerogels. However, few reports on encapsulating proteins within sol–gels that are processed to form aerogels exist. A procedure for encapsulating cytochrome c (cyt. c) in silica (SiO2) sol-gels that are supercritically processed to form bioaerogels with gas-phase activity for nitric oxide (NO) is presented. Cyt. c is added to a mixed silica sol under controlled protein concentration and buffer strength conditions. The sol mixture is then gelled and the liquid filling the gel pores is replaced through a series of solvent exchanges with liquid carbon dioxide. The carbon dioxide is brought to its critical point and vented off to form dry aerogels with cyt. c encapsulated inside. These bioaerogels are characterized with UV-visible spectroscopy and circular dichroism spectroscopy and can be used to detect the presence of gas-phase nitric oxide. The success of this procedure depends on regulating the cyt. c concentration and the buffer concentration and does not require other components such as metal nanoparticles. It may be possible to encapsulate other proteins using a similar approach making this procedure important for potential future bioanalytical device development. PMID:26967257

Controlled Thermoresponsive Hydrogels by Stereocomplexed PLA-PEG-PLA Prepared via Hybrid Micelles of Pre-Mixed Copolymers with Different PEG Lengths

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

Abebe, Daniel G.; Fujiwara, Tomoko

2012-09-05

The stereocomplexed hydrogels derived from the micelle mixture of two enantiomeric triblock copolymers, PLLA-PEG-PLLA and PDLA-PEG-PDLA, reported in 2001 exhibited sol-to-gel transition at approximately body temperature upon heating. However, the showed poor storage modulus (ca. 1000 Pa) determined their insufficiency as injectable implant biomaterials for many applications. In this study, the mechanical property of these hydrogels was significantly improved by the modifications of molecular weights and micelle structure. Co-micelles composed of block copolymers with two sizes of PEG block length were shown to possess unique and dissimilar properties from the micelles composed of single-sized block copolymers. The stereomixture of PLA-PEG-PLAmore » comicelles showed a controllable sol-to-gel transition at a wide temperature range of 4 and 80 C. The sol-gel phase diagram displays a linear relationship of temperature versus copolymer composition; hence, a transition at body temperature can be readily achieved by adjusting the mixed copolymer ratio. The resulting thermoresponsive hydrogels exhibit a storage modulus notably higher (ca. 6000 Pa) than that of previously reported hydrogels. As a physical network solely governed by self-reorganization of micelles, followed by stereocomplexation, this unique system offers practical, safe, and simple implantable biomaterials.« less

Biocompatible Nb2O5 thin films prepared by means of the sol-gel process.

PubMed

Velten, D; Eisenbarth, E; Schanne, N; Breme, J

2004-04-01

Thin biocompatible oxide films with an optimised composition and structure on the surface of titanium and its alloys can improve the implant integration. The preparation of these thin oxide layers with the intended improvement of the surface properties can be realised by means of the sol-gel process. Nb2O5 is a promising coating material for this application because of its extremely high corrosion resistance and thermodynamic stability. In this study, thin Nb2O5 layers ( < 200 nm) were prepared by spin coating of polished discs of cp-titanium with a sol consisting of a mixture of niobium ethoxide, butanol and acetylacetone. The thickness, phase composition, corrosion resistance and the wettability of the oxide layers were determined after an optimisation of the processing parameters for deposition of oxide without any organic impurities. The purity of the oxide layer is an important aspect in order to avoid a negative response to the cell adhesion. The biocompatibility of the oxide layers which was investigated by in vitro tests (morphology, proliferation rate, WST-1, cell spreading) is improved as compared to uncoated and TiO2 sol-gel coated cp-titanium concerning the spreading of cells, collagen I synthesis and wettability.

A Robust Two-Dimensional Separation for Top-Down Tandem Mass Spectrometry of the Low-Mass Proteome

PubMed Central

Lee, Ji Eun; Kellie, John F.; Tran, John C.; Tipton, Jeremiah D.; Catherman, Adam D.; Thomas, Haylee M.; Ahlf, Dorothy R.; Durbin, Kenneth R.; Vellaichamy, Adaikkalam; Ntai, Ioanna; Marshall, Alan G.; Kelleher, Neil L.

2010-01-01

For fractionation of intact proteins by molecular weight (MW), a sharply improved two-dimensional (2D) separation is presented to drive reproducible and robust fractionation before top-down mass spectrometry of complex mixtures. The “GELFrEE” (i.e., gel-eluted liquid fraction entrapment electrophoresis) approach is implemented by use of Tris-glycine and Tris-tricine gel systems applied to human cytosolic and nuclear extracts from HeLa S3 cells, to achieve a MW-based fractionation of proteins from 5 to >100 kDa in 1 h. For top-down tandem mass spectroscopy (MS/MS) of the low-mass proteome (5–25 kDa), between 5 and 8 gel-elution (GE) fractions are sampled by nanocapillary-LC-MS/MS with 12 or 14.5 tesla Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometers. Single injections give about 40 detectable proteins, about half of which yield automated ProSight identifications. Reproducibility metrics of the system are presented, along with comparative analysis of protein targets in mitotic versus asynchronous cells. We forward this basic 2D approach to facilitate wider implementation of top-down mass spectrometry and a variety of other protein separation and/or characterization approaches. PMID:19747844

Magnetic nanoparticles and thermally responsive polymer for targeted hyperthermia and sustained anti-cancer drug delivery.

PubMed

Wang, Sarah Y; Liu, Michelle C; Kang, Kyung A

2013-01-01

A novel cancer treatment method is being designed using a combination of iron oxide (Fe(3)O(4)) nanoparticles (IONPs) and Pluronic F-127 (PF127). IONPs have been used for heating tumors via an alternating electromagnetic (AEM) field. PF127 is a polymer possessing thermo-reversible and concentration-dependent gelation properties in aqueous solutions. PF127, as a gel, is an attractive drug delivery vehicle due to its zero-order drug release property. The combination of IONPs and PF127 would allow both short-term, tumor-specific, hyperthermic treatment, and long-term sustained drug delivery. As a preliminary study, the gelling and heating properties of IONPs/PF127 mixtures were investigated: 18% (w/w) PF127 was found to be ideal for our purpose because it gels at 28.0°C, i.e., it would be injectable at room temperature (20-25°C) and forms gel upon injection into the body (37°C). IONPs in PF127 showed little effect on gelation temperatures. The heating performance of IONPs in PF127 slightly, but linearly decreased with PF127. In the IONP concentration range of 0.01-0.05% (w/v) mixed with PF127 at 18% (w/w), the heating performance increased linearly with the increase in IONP concentration.

Hybrid Protein–Glycosaminoglycan Hydrogels Promote Chondrogenic Stem Cell Differentiation

PubMed Central

2017-01-01

Gelatin–hyaluronic acid (Gel–HA) hybrid hydrogels have been proposed as matrices for tissue engineering because of their ability to mimic the architecture of the extracellular matrix. Our aim was to explore whether tyramine conjugates of Gel and HA, producing injectable hydrogels, are able to induce a particular phenotype of encapsulated human mesenchymal stem cells without the need for growth factors. While pure Gel allowed good cell adhesion without remarkable differentiation and pure HA triggered chondrogenic differentiation without cell spreading, the hybrids, especially those rich in HA, promoted chondrogenic differentiation as well as cell proliferation and adhesion. Secretion of chondrogenic markers such as aggrecan, SOX-9, collagen type II, and glycosaminoglycans was observed, whereas osteogenic, myogenic, and adipogenic markers (RUNX2, sarcomeric myosin, and lipoproteinlipase, respectively) were not present after 2 weeks in the growth medium. The most promising matrix for chondrogenesis seems to be a mixture containing 70% HA and 30% Gel as it is the material with the best mechanical properties from all compositions tested here, and at the same time, it provides an environment suitable for balanced cell adhesion and chondrogenic differentiation. Thus, it represents a system that has a high potential to be used as the injectable material for cartilage regeneration therapies. PMID:29214232

Sol gel synthesis and characterization studies of Cupromanganite CaCu3Mn4O12

NASA Astrophysics Data System (ADS)

Nurulhuda, A.; Warikh, A. R. M.; Hafizzal, Y.

2017-08-01

A single-phase CaCu3Mn4O12 electroceramic had been prepared via sol gel method and fairly well densified at relative low temperature under atmospheric condition where the crystallization of CaCu3Mn4O12 occurred due to amorphous polymeric mixture. The precursor was prepared by mixing the solutions with 0.6 M citric acid (C6H8O7) as a chelating reagent with the mol ratio 1:2. The precursor gel formed was calcined and sintered at range 400 °C to 800°C by varying dwell time. Material formations under the reported conditions have been confirmed by X-ray diffraction (XRD). The results show that the formation of CaCu3Mn4O12 started at 500 ° C and was formed completely at 700 ° C for 18 hours. The microstructure of all CaCu3Mn4O12 was analysed using field emission scanning electron microscopy (FESEM). A smaller particle size with higher grain boundary was obtained at sintering 700°C to 800°C. FESEM results show the significant influence of calcinations and sintering parameter on the microstructure behaviour of CaCu2Mn4O12.

Evaluation of mineral oil as an acoustic coupling medium in clinical MRgFUS.

PubMed

Gorny, K R; Hangiandreou, N J; Hesley, G K; Felmlee, J P

2007-01-07

We empirically evaluate mineral oil as an alternative to the mixture of de-gassed water and ultrasound gel, which is currently used as an acoustic coupling medium in clinical magnetic resonance guided focused ultrasound (MRgFUS) treatments. The tests were performed on an ExAblate 2000 MRgFUS system (InSightec Inc., Haifa, Israel) using a clinical patient set-up. Acoustic reflections, treatment temperatures, sonication spot dimensions and position with respect to target location were measured, using both coupling media, in repeated sonications in a tissue mimicking gel phantom. In comparison with the water-gel mix, strengths of acoustic reflections from coupling layers prepared with mineral oil were on average 39% lower and the difference was found to be statistically significant (p = 3.3 x 10(-8)). The treatment temperatures were found to be statistically equivalent for both coupling media, although temperatures corresponding to mineral oil tended to be somewhat higher (on average 1.9 degrees C) and their standard deviations were reduced by about 1 degrees C. Measurements of sonication spot dimensions and positions with respect to target location did not reveal systematic differences. We conclude that mineral oil may be used as an effective non-evaporating acoustic coupling medium for clinical MRgFUS treatments.

Development of an on-line mixed-mode gel liquid chromatography×reversed phase liquid chromatography method for separation of water extract from Flos Carthami.

PubMed

Wang, Yu-Qing; Tang, Xu; Li, Jia-Fu; Wu, Yun-Long; Sun, Yu-Ying; Fang, Mei-Juan; Wu, Zhen; Wang, Xiu-Min; Qiu, Ying-Kun

2017-10-13

A novel on-line comprehensive two-dimensional liquid chromatography (2D-LC) method by coupling mixed-mode gel liquid chromatography (MMG-LC) with reversed phase liquid chromatography (RPLC) was developed. A mixture of 17 reference compounds was used to study the separation mechanism. A crude water extract of Flos Carthami was applied to evaluate the performance of the novel 2D-LC system. In the first dimension, the extract was eluted with a gradient of water/methanol over a cross-linked dextran gel Sephadex LH-20 column. Meanwhile, the advantages of size exclusion, reversed phase partition and adsorption separation mechanism were exploited before further on-line reversed phase purification on the second dimension. This novel on-line mixed-mode Sephadex LH-20×RPLC method provided higher peak resolution, sample processing ability (2.5mg) and better orthogonality (72.9%) versus RPLC×RPLC and hydrophilic interaction liquid chromatography (HILIC)×RPLC. To the best of our knowledge, this is the first report of a mixed-mode Sephadex LH-20×RPLC separation method with successful applications in on-line mode, which might be beneficial for harvesting targets from complicated medicinal plants. Copyright © 2017 Elsevier B.V. All rights reserved.

Encapsulating Cytochrome c in Silica Aerogel Nanoarchitectures without Metal Nanoparticles while Retaining Gas-phase Bioactivity.

PubMed

Harper-Leatherman, Amanda S; Pacer, Elizabeth R; Kosciuszek, Nina D

2016-03-01

Applications such as sensors, batteries, and fuel cells have been improved through the use of highly porous aerogels when functional compounds are encapsulated within the aerogels. However, few reports on encapsulating proteins within sol-gels that are processed to form aerogels exist. A procedure for encapsulating cytochrome c (cyt. c) in silica (SiO2) sol-gels that are supercritically processed to form bioaerogels with gas-phase activity for nitric oxide (NO) is presented. Cyt. c is added to a mixed silica sol under controlled protein concentration and buffer strength conditions. The sol mixture is then gelled and the liquid filling the gel pores is replaced through a series of solvent exchanges with liquid carbon dioxide. The carbon dioxide is brought to its critical point and vented off to form dry aerogels with cyt. c encapsulated inside. These bioaerogels are characterized with UV-visible spectroscopy and circular dichroism spectroscopy and can be used to detect the presence of gas-phase nitric oxide. The success of this procedure depends on regulating the cyt. c concentration and the buffer concentration and does not require other components such as metal nanoparticles. It may be possible to encapsulate other proteins using a similar approach making this procedure important for potential future bioanalytical device development.

Evaluation of agarose gel electrophoresis for characterization of silver nanoparticles in industrial products.

PubMed

Jimenez, Maria S; Luque-Alled, Jose M; Gomez, Teresa; Castillo, Juan R

2016-05-01

Agarose gel electrophoresis (AGE) has been used extensively for characterization of pure nanomaterials or mixtures of pure nanomaterials. We have evaluated the use of AGE for characterization of Ag nanoparticles (NPs) in an industrial product (described as strong antiseptic). Influence of different stabilizing agents (PEG, SDS, and sodium dodecylbenzenesulfonate), buffers (TBE and Tris Glycine), and functionalizing agents (mercaptosuccinic acid (TMA) and proteins) has been investigated for the characterization of AgNPs in the industrial product using different sizes-AgNPs standards. The use of 1% SDS, 0.1% TMA, and Tris Glycine in gel, electrophoresis buffer and loading buffer led to the different sizes-AgNPs standards moved according to their size/charge ratio (obtaining a linear relationship between apparent mobility and mean diameter). After using SDS and TMA, the behavior of the AgNPs in the industrial product (containing a casein matrix) was completely different, being not possible their size characterization. However we demonstrated that AGE with LA-ICP-MS detection is an alternative method to confirm the protein corona formation between the industrial product and two proteins (BSA and transferrin) maintaining NPs-protein binding (what is not possible using SDS-PAGE). © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Features of the phase composition and morphology of the particles of sialon synthesized from silicon and aluminum nitrides

NASA Astrophysics Data System (ADS)

Ivicheva, S. N.; Lysenkov, A. S.; Ovsyannikov, N. A.; Titov, D. D.; Kargin, Yu F.

2018-04-01

The phase composition and morphological features of sialons were studied under the same conditions of firing (duration, temperature) using different initial components, silicon nitride, aluminum nitride, and a mixture of silicon nitrides and aluminum with the application of nitrides of the corresponding oxide (aluminum or silicon) sol-gel method. The effect of the initial reagents composition on the phase composition of the final product and the morphological features of the sialon powders obtained in a single firing step in a nitrogen atmosphere is shown.

Metal-Free Oxidation of Primary Amines to Nitriles through Coupled Catalytic Cycles.

PubMed

Lambert, Kyle M; Bobbitt, James M; Eldirany, Sherif A; Kissane, Liam E; Sheridan, Rose K; Stempel, Zachary D; Sternberg, Francis H; Bailey, William F

2016-04-04

Synergism among several intertwined catalytic cycles allows for selective, room temperature oxidation of primary amines to the corresponding nitriles in 85-98% isolated yield. This metal-free, scalable, operationally simple method employs a catalytic quantity of 4-acetamido-TEMPO (ACT; TEMPO=2,2,6,6-tetramethylpiperidine N-oxide) radical and the inexpensive, environmentally benign triple salt oxone as the terminal oxidant under mild conditions. Simple filtration of the reaction mixture through silica gel affords pure nitrile products. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Genetic and Physiological Studies of Bacillus anthracis Related to Development of An Improved Vaccine

DTIC Science & Technology

1989-07-01

enzyme in a 1.5 ml Eppendorf tube. Appropriate amounts of distilled water and 1OX buffer were added to give a total volume of 100 pl. Reaction...mixtures were incubated in a 370 C water bath for 2 to 15 h. Digests were heated at 650C for 10 minutes to stop reactions and then resolved on agarose gels...430 C water bath with shaking (160 rpm) for 4 hours. The culture was transferred in a similar manner three additional times. Following the fourth

[Isolation and preliminary characterization of carotenoids from pink-pigmented methylotrophs].

PubMed

Konovalova, A M; Shylin, S O; Rokytko, P V

2006-01-01

An effective method was developed for complete removal of pigments from the cells and solvent mixture for further separation of pigments using thin layer chromatography on silica gel. Carotenoid samples that have been obtained in this way are of good purity for further investigations. Carotenoid pigments of pink-pigmented facultative methylotrophic bacteria Methylobacterium have been characterized. These carotenoids are represented mainly by xanthophylls, particularly hydroxycarotenoids. Strains M. fujisawaense B-3365 and M. mesophilicum B-3352 also have nonpolar carotenes in a small amount. Physico-chemical properties of carotenoids have been studied.

A Preliminary Study of the Preparation of Slurry Fuels from Vaporized Magnesium

NASA Technical Reports Server (NTRS)

Witzke, Walter R; Prok, George M; Walsh, Thomas J

1954-01-01

Slurry fuels containing extremely small particles of magnesium were prepared by concentrating the dilute slurry product resulting from the shock-cooling of magnesium metal vapors with a liquid hydrocarbon spray. A complete description of the equipment and procedure used in preparing the fuel is given. Ninety-five percent by weight of the solid particles formed by this process passed through a 100-mesh screen. The particle-size distribution of the screened fraction of one run, as determined by sedimentation analysis, indicated that 73 percent by weight of the metal particles were finer than 2 microns in equivalent spherical diameter. The purity of the solid particles ranged as high as 98.9 percent by weight of free magnesium. The screened product was concentrated by means of a bowl-type centrifuge from 0.5 to more than 50 percent by weight solids content to form an extremely viscous, clay-like mass. By addition of a surface active agent, this viscous material was converted into a pumpable slurry fuel.

Viscometric and misting properties of polymer-modified fuel

NASA Technical Reports Server (NTRS)

Grens, E. A., II; Williams, M. C.

1982-01-01

Solutions of polyisobutylenes L160, L200, B200, and B230 in Jet-A were prepared at concentrations up to 3000 ppm. These polymers have molecular weights in the range 5 to 9 x 1,00,000 and have previously been shown to induce anti-misting properties in Jet-A. In connection with the pumpability of such solutions, especially at low temperatures, the shear viscosity, eta, of these solutions was measured at temperatures 25 C, 0 C, and -25 C. Concentration-dependence of eta was very similar for all four polymer solutes, the increase of eta(c) at 3000 ppm being roughly four-fold (relative to Jet-A) for the L-series and five-fold for the B-series. This behavior prevailed at all temperatures, and there was no evidence of phase separation or other chemical instability at -25 C at any concentration. In the more practical c-range for anti-misting applications, say within 1000 ppm, the increase of eta(c) was only twofold.

Co-micellized Pluronic mixture with thermo-sensitivity and residence stability as an injectable tissue adhesion barrier hydrogel.

PubMed

Oh, Se Heang; Kang, Jun Goo; Lee, Jin Ho

2018-01-01

Although the tissue adhesion which leads to various complications frequently occurs after surgery, the development of an ideal tissue adhesion barrier is still a challenge. In this study, a thermo-sensitive hydrogel, which can fulfill the essential requirements of tissue adhesion barrier (that is, ease of handling for surgeon, flowing down prevention after application, stable residence on the injury during wound healing, and no use of toxic additives), was developed using biocompatible polyethylene glycol-polypropylene glycol copolymers (Pluronic F127/F68/P123 mixture). From the in vitro cell culture and in vivo animal study, it was observed that the Pluronic mixtures showed sol-gel transition at approximately body temperature (for easy injection or coating on the injury site and flowing down prevention after application) and prolonged residence stability in aqueous environment (> ∼7 days for stable protection of injury tissues/organs during wound healing), and thus was highly effective for the prevention of tissue adhesion without adverse tissue responses. Based on these results, the Pluronic F127/F68/P123 mixture itself (without any additives) can be a good candidate as an injectable or coatable tissue adhesion barrier hydrogel applicable to various injury tissues in terms of ease of use, effectiveness, and safety. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 172-182, 2018. © 2016 Wiley Periodicals, Inc.

In vitro and in vivo ocular safety and eye surface permanence determination by direct and Magnetic Resonance Imaging of ion-sensitive hydrogels based on gellan gum and kappa-carrageenan.

PubMed

Fernández-Ferreiro, Anxo; González Barcia, Miguel; Gil-Martínez, María; Vieites-Prado, Alba; Lema, Isabel; Argibay, Barbara; Blanco Méndez, José; Lamas, Maria Jesus; Otero-Espinar, Francisco Javier

2015-08-01

Gellan gum, kappa-carrageenan and alginates are natural polysaccharides able to interact with different cations that can be used to elaborate ion-activated in situ gelling systems for different uses. The interaction between fluid solutions of these polysaccharides and cations presents into the tear made these biopolymers very interesting to elaborate ophthalmic drug delivery systems. The main purpose of this study is to evaluate the ability of mixtures of these polymers to obtain ion-activated ophthalmic in situ gelling systems with optimal properties for ocular use. To achieve this purpose different proportion of the biopolymers were analyzed using a mixture experimental design evaluating their transparency, mechanical properties and bioadhesion in the absence and presence of simulated tear fluid. Tear induces a rapid sol-to-gel phase transition in the mixtures forming a consistent hydrogel. The solution composed by 80% of gellan gum and 20% kappa-carrageenan showed the best mechanical and mucoadhesive properties. This mixture was evaluated for rheological behavior, microstructure, cytotoxicity, acute corneal irritancy, ex-vivo and in vivo ocular toxicity and in vivo corneal contact time using Magnetic Resonance Images (MRI) techniques. Result indicates that the system is safe at ophthalmic level and produces an extensive ocular permanence higher than 6h. Copyright © 2015 Elsevier B.V. All rights reserved.

Highly Luminescent Hybrid SiO2-Coated CdTe Quantum Dots Retained Initial Photoluminescence Efficiency in Sol-Gel SiO2 Film.

PubMed

Sun, Hongsheng; Xing, Yugui; Wu, Qinan; Yang, Ping

2015-02-01

A highly luminescent silica film was fabricated using tetraethyl orthosilicate (TEOS) and 3-aminopropyltrimethoxysilane (APS) through a controlled sol-gel reaction. The pre-hydrolysis of TEOS and APS which resulted in the mixture of TEOS and APS in a molecular level is a key for the formation of homogenous films. The aminopropyl groups in APS play an important role for obtaining homogeneous film with high photoluminescence (PL). Red-emitting hybrid SiO2-coated CdTe nano-crystals (NCs) were fabricated by a two-step synthesis including a thin SiO2 coating via a sol-gel process and a subsequent refluxing using green-emitting CdTe NCs. The hybrid SiO2-coated CdTe NCs were embedded in a functional SiO2 film via a two-step process including adding the NCs in SiO2 sol with a high viscosity and almost without ethanol and a subsequent spinning coating. The hybrid SiO2-coated CdTe NCs retained their initial PL efficiency (54%) in the film. Being encapsulated with the hybrid NCs in the film, no change on the absorption and PL spectra of red-emitting CdTe NCs (632 nm) was observed. This indicates the hybrid NCs is stable enough during preparation. This phenomenon is ascribed to the controlled sol-gel process and a hybrid SiO2 shell on CdTe NCs. Because these films exhibited high PL efficiency and stability, they will be utilizable for potential applications in many fields.

Vortex-homogenized matrix solid-phase dispersion for the extraction of short chain chlorinated paraffins from indoor dust samples.

PubMed

Chen, Yu-Hsuan; Chang, Chia-Yu; Ding, Wang-Hsien

2016-11-11

A simple and effective method for determining short chain chlorinated paraffins (SCCPs) in indoor dust is presented. The method employed a modified vortex-homogenized matrix solid-phase dispersion (VH-MSPD) prior to its detection by gas chromatography - electron-capture negative-ion mass spectrometry (GC-ECNI-MS) operating in the selected-ion-monitoring (SIM) mode. Under the best extraction conditions, 0.1-g of dust sample was dispersed with 0.1-g of silica gel by using vortex (2min) instead of using a mortar and pestle (3min). After that step, the blend was transferred to a glass column containing 3-g acidic silica gel, 2-g basic silica gel, and 2-g of deactivated silica gel, used as clean-up co-sorbents. Then, target analytes were eluted with 5mL of n-hexane/dichloromethane (2:1, v/v) mixture. The extract was evaporated to dryness under a gentle stream of nitrogen. The residue was then re-dissolved in n-hexane (10μL), and subjected to GC-ECNI-MS analysis. The limits of quantitation (LOQs) ranged from 0.06 to 0.25μg/g for each SCCP congener. Precision was less than 7% for both intra- and inter-day analysis. Trueness was above 89%, which was calculated by mean extraction recovery. The VH-MSPD combined with GC-ECNI-MS was successfully applied to quantitatively detect SCCPs from various indoor dust samples, and the concentrations ranged from 1.2 to 31.2μg/g. Copyright © 2016 Elsevier B.V. All rights reserved.

Sol–gel synthesis of MCM-41 silicas and selective vapor-phase modification of their surface

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

Roik, N.V., E-mail: roik_nadya@ukr.net; Belyakova, L.A.

2013-11-15

Silica particles with uniform hexagonal mesopore architecture were synthesized by template directed sol–gel condensation of tetraethoxysilane or mixture of tetraethoxysilane and (3-chloropropyl)triethoxysilane in a water–ethanol–ammonia solution. Selective functionalization of exterior surface of parent materials was carried out by postsynthetic treatment of template-filled MCM-41 and Cl-MCM-41 with vapors of (3-chloropropyl)triethoxysilane and 1,2-ethylenediamine in vacuum. The chemical composition of obtained mesoporous silicas was estimated by IR spectroscopy and chemical analysis of surface products of reactions. Characteristics of porous structure of resulting materials were determined from the data of X-ray, low-temperature nitrogen ad-desorption and transmission electron microscopy measurements. Obtained results confirm invariability ofmore » highly ordered mesoporous structure of MCM-41 and Cl-MCM-41 after their selective postsynthetic modification in vapor phase. It was proved that proposed method of vapor-phase functionalization of template-filled starting materials is not accompanied by dissolution of the template and chemical modification of pores surface. This provides preferential localization of grafted functional groups onto the exterior surface of mesoporous silicas. - Graphical abstract: Sol–gel synthesis and postsynthetic chemical modification of template-filled MCM-41 and Cl-MCM-41 with (3-chloropropyl)triethoxysilane and 1,2-ethylenediamine in vapor phase. Display Omitted - Highlights: • Synthesis of MCM-41 silica by template directed sol–gel condensation. • Selective vapor-phase functionalization of template-filled silica particles. • Preferential localization of grafted groups onto the exterior surface of mesoporous silicas.« less

Volumetric muscle loss injury repair using in situ fibrin gel cast seeded with muscle-derived stem cells (MDSCs).

PubMed

Matthias, Nadine; Hunt, Samuel D; Wu, Jianbo; Lo, Jonathan; Smith Callahan, Laura A; Li, Yong; Huard, Johnny; Darabi, Radbod

2018-03-01

Volumetric muscle defect, caused by trauma or combat injuries, is a major health concern leading to severe morbidity. It is characterized by partial or full thickness loss of muscle and its bio-scaffold, resulting in extensive fibrosis and scar formation. Therefore, the ideal therapeutic option is to use stem cells combined with bio-scaffolds to restore muscle. For this purpose, muscle-derived stem cells (MDSCs) are a great candidate due to their unique multi-lineage differentiation potential. In this study, we evaluated the regeneration potential of MDSCs for muscle loss repair using a novel in situ fibrin gel casting. Muscle defect was created by a partial thickness wedge resection in the tibialis anterior (TA) muscles of NSG mice which created an average of 25% mass loss. If untreated, this defect leads to severe muscle fibrosis. Next, MDSCs were delivered using a novel in situ fibrin gel casting method. Our results demonstrated MDSCs are able to engraft and form new myofibers in the defect when casted along with fibrin gel. LacZ labeled MDSCs were able to differentiate efficiently into new myofibers and significantly increase muscle mass. This was also accompanied by significant reduction of fibrotic tissue in the engrafted muscles. Furthermore, transplanted cells also contributed to new vessel formation and satellite cell seeding. These results confirmed the therapeutic potential of MDSCs and feasibility of direct in situ casting of fibrin/MDSC mixture to repair muscle mass defects. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

Purification, characterization and preliminary crystallographic studies of a cysteine protease from Pachyrrhizus erosus seeds.

PubMed

Chang, Shaojie; Song, Xiaomin; Yan, Ming; Zhou, Zhaocai; Wu, Fang; Gong, Weimin

2004-01-01

The proteins Spe31 and Spe32, named after their respective molecular weights of about 31 and 32 kDa, were purified simultaneously from the seeds of Pachyrrhizus erosus. They cannot be separated from each other by column chromatography. N-terminal sequence analysis indicated that they belonged to the papain family of cysteine proteases. An in-gel activity assay revealed that Spe31 possesses proteolytic activity while Spe32 only displays very weak activity for protein degradation. Both of them are glycoproteins as detected by the periodic acid and Schiff's reagent method. Crystals were obtained from the protein mixture by the hanging-drop vapour-diffusion method; they diffracted to a resolution of 2.61 A on an in-house X-ray source. The crystals belong to space group P4(1(3))2(1)2, with unit-cell parameters a = b = 61.96, c = 145.61 A. Gel electrophoresis under non-denaturing conditions showed that the protein crystallized was Spe31.

Optical sensing elements for nitrogen dioxide (NO.sub.2) gas detection, a sol-gel method for making the sensing elements and fiber optic sensors incorporating nitrogen dioxide gas optical sensing elements

DOEpatents

Mechery, Shelly John [Mississippi State, MS; Singh, Jagdish P [Starkville, MS

2007-07-03

A sensing element, a method of making a sensing element, and a fiber optic sensor incorporating the sensing element are described. The sensor can be used for the quantitative detection of NO.sub.2 in a mixture of gases. The sensing element can be made by incorporating a diazotizing reagent which reacts with nitrous ions to produce a diazo compound and a coupling reagent which couples with the diazo compound to produce an azo dye into a sol and allowing the sol to form an optically transparent gel. The sensing element changes color in the presence of NO.sub.2 gas. The temporal response of the absorption spectrum at various NO.sub.2 concentrations has also been recorded and analyzed. Sensors having different design configurations are described. The sensing element can detect NO.sub.2 gas at levels of parts per billion.

Sol-Gel Synthesis of Carbon Xerogel-ZnO Composite for Detection of Catechol

PubMed Central

Li, Dawei; Zang, Jun; Zhang, Jin; Ao, Kelong; Wang, Qingqing; Dong, Quanfeng; Wei, Qufu

2016-01-01

Carbon xerogel-zinc oxide (CXZnO) composites were synthesized by a simple method of sol-gel condensation polymerization of formaldehyde and resorcinol solution containing zinc salt followed by drying and thermal treatment. ZnO nanoparticles were observed to be evenly dispersed on the surfaces of the carbon xerogel microspheres. The as-prepared CXZnO composites were mixed with laccase (Lac) and Nafion to obtain a mixture solution, which was further modified on an electrode surface to construct a novel biosensing platform. Finally, the prepared electrochemical biosensor was employed to detect the environmental pollutant, catechol. The analysis result was satisfactory, the sensor showed excellent electrocatalysis towards catechol with high sensitivity (31.2 µA·mM−1), a low detection limit (2.17 µM), and a wide linear range (6.91–453 µM). Moreover, the biosensor also displayed favorable repeatability, reproducibility, selectivity, and stability besides being successfully used in the trace detection of catechol existing in lake water environments. PMID:28773407

Degradation of a Sodium Acrylate Oligomer by an Arthrobacter sp

PubMed Central

Hayashi, Takaya; Mukouyama, Masaharu; Sakano, Kouichi; Tani, Yoshiki

1993-01-01

Arthrobacter sp. strain NO-18 was first isolated from soil as a bacterium which could degrade the sodium acrylate oligomer and utilize it as the sole source of carbon. When 0.2% (wt/wt) oligomer was added to the culture medium, the acrylate oligomer was found to be degraded by 70 to 80% in 2 weeks, using gel permeation chromatography. To determine the maximum molecular weight for biodegradation, the degradation test was done with the hexamer, heptamer, and octamer, which were separated from the oligomer mixture by fractional gel permeation chromatography. The hexamer and heptamer were consumed to the extents of 58 and 36%, respectively, in 2 weeks, but the octamer was not degraded. Oligomers with three different terminal groups were synthesized to examine the effect of the different terminal groups on biodegradation, but few differences were found. Arthrobacter sp. NO-18 assimilated acrylic acid, propionic acid, glutaric acid, 2-methylglutaric acid, and 1,3,5-pentanetricarboxylic acid. Degradation of the acrylic unit structure by this strain is discussed. PMID:8517751

[Determination of phthalate plasticizers in foods by high performance liquid chromatography with gel permeation chromatographic clean-up].

PubMed

Zhang, Chunyu; Wang, Hui; Zhang, Xiaohui; Ma, Zhongqiang; Deng, Wanmei; Hu, Ke; Ding, Mingyu

2011-12-01

A method of gel permeation chromatography-high performance liquid chromatography (GPC-HPLC) was established for the simultaneous determination of 5 main phthalate plasticizers in foods (edible oil, instant noodles, fried pastries, Saqima, etc.). The samples were extracted with petroleum ether in an ultrasonator, purified by a GPC column, and analyzed by HPLC. The chromatographic separation was achieved on a Labtech-C18 column (250 mm x 4.6 mm, 5 microm) using acetonitrile and water mixture as the mobile phases in a gradient elution mode. The developed method exhibited a linear correlation coefficient of more than 0.997 and the detection limits of 3.25 - 13.4 microg/L. The spike recoveries were between 70.4% and 113.6% with the relative standard deviations (RSDs, n = 3) of 0.3% - 5.8% at the spiked level of 50 mg/L. This method is simple, rapid and practical, and can be used for the simultaneous determination of PAEs in grease food samples.

Bond rupture between colloidal particles with a depletion interaction

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

Whitaker, Kathryn A.; Furst, Eric M., E-mail: furst@udel.edu

The force required to break the bonds of a depletion gel is measured by dynamically loading pairs of colloidal particles suspended in a solution of a nonadsorbing polymer. Sterically stabilized poly(methyl methacrylate) colloids that are 2.7 μm diameter are brought into contact in a solvent mixture of cyclohexane-cyclohexyl bromide and polystyrene polymer depletant. The particle pairs are subject to a tensile load at a constant loading rate over many approach-retraction cycles. The stochastic nature of the thermal rupture events results in a distribution of bond rupture forces with an average magnitude and variance that increases with increasing depletant concentration. The measuredmore » force distribution is described by the flux of particle pairs sampling the energy barrier of the bond interaction potential based on the Asakura–Oosawa depletion model. A transition state model demonstrates the significance of lubrication hydrodynamic interactions and the effect of the applied loading rate on the rupture force of bonds in a depletion gel.« less

Physics of Colloids in Space-2 (PCS-2)

NASA Technical Reports Server (NTRS)

Sankaran, Subramanian; Gasser, Urs; Manley, Suliana; Valentine, Megan; Prasad, Vikram; Rudhardt, Daniel; Bailey, Arthur; Dinsmore, Anthony; Segre, Phil; Doherty, Michael P.

2001-01-01

The Physics of Colloids-2 (PCS-2) experiment is aimed at investigating the basic physical properties of several types of colloidal suspensions. The three broad classes of colloidal systems of interest are binary colloids, colloid-polymer mixtures, and fractal gels. The objective is to understand their phase behavior as well as the kinetics of the phase transitions in the absence of gravity. The nucleation, growth, and morphology characteristics of the crystals and gels that form would be studied using confocal microscopy. These will be observed directly with excellent time resolution, and therefore extensive information about the different phases and their growth mechanisms will be gained. With the laser tweezers, it will be possible to measure the strength of these structures and to modify them in a controlled way, and the spectrophotometer will provide the possibility to probe their optical properties. We believe that this experiment will provide the basis for future 'colloid engineering' in which complicated structures with novel properties (e.g., photonic crystals) will be grown by controlled self-assembly.

Composition and apparatus for detecting gamma radiation

DOEpatents

Hofstetter, Kenneth J.

1994-01-01

A gamma radiation detector and a radioluminiscent composition for use therein. The detector includes a radioluminscent composition that emits light in a characteristic wavelength region when exposed to gamma radiation, and means for detecting said radiation. The composition contains a scintillant such as anglesite (PbSO.sub.4) or cerussite (PbCO.sub.3) incorporated into an inert, porous glass matrix via a sol-gel process. Particles of radiation-sensitive scintillant are added to, a sol solution. The mixture is polymerized to form a gel, then dried under conditions that preserve the structural integrity and radiation sensitivity of the scintillant. The final product is a composition containing the uniformly-dispersed scintillant in an inert, optically transparent and highly porous matrix. The composition is chemically inert and substantially impervious to environmental conditions including changes in temperature, air pressure, and so forth. It can be fabricated in cylinders, blocks with holes therethrough for flow of fluid, sheets, surface coatings, pellets or other convenient shapes.

Composition and apparatus for detecting gamma radiation

DOEpatents

Hofstetter, K.J.

1994-08-09

A gamma radiation detector and a radioluminescent composition for use therein. The detector includes a radioluminescent composition that emits light in a characteristic wavelength region when exposed to gamma radiation, and means for detecting said radiation. The composition contains a scintillant such as anglesite (PbSO[sub 4]) or cerussite (PbCO[sub 3]) incorporated into an inert, porous glass matrix via a sol-gel process. Particles of radiation-sensitive scintillant are added to, a sol solution. The mixture is polymerized to form a gel, then dried under conditions that preserve the structural integrity and radiation sensitivity of the scintillant. The final product is a composition containing the uniformly-dispersed scintillant in an inert, optically transparent and highly porous matrix. The composition is chemically inert and substantially impervious to environmental conditions including changes in temperature, air pressure, and so forth. It can be fabricated in cylinders, blocks with holes therethrough for flow of fluid, sheets, surface coatings, pellets or other convenient shapes. 3 figs.

Conventional and two step sintering of PZT-PCN ceramics

NASA Astrophysics Data System (ADS)

Keshavarzi, Mostafa; Rahmani, Hooman; Nemati, Ali; Hashemi, Mahdieh

2018-02-01

In this study, PZT-PCN ceramic was made via sol-gel seeding method and effects of conventional sintering (CS) as well as two-step sintering (TSS) were investigated on microstructure, phase formation, density, dielectric and piezoelectric properties. First, high quality powder was achieved by seeding method in which the mixture of Co3O4 and Nb2O5 powder was added to the prepared PZT sol to form PZT-PCN gel. After drying and calcination, pyrochlore free PZT-PCN powder was synthesized. Second, CS and TSS were applied to achieve dense ceramic. The optimum temperature used for 2 h of conventional sintering was obtained at 1150 °C; finally, undesired ZrO2 phase formed in CS procedure was removed successfully with TSS procedure and dielectric and piezoelectric properties were improved compared to the CS procedure. The best electrical properties obtained for the sample sintered by TSS in the initial temperature of T 1 = 1200 °C and secondary temperature of T 2 = 1000 °C for 12 h.

Temporal Control of Gelation and Polymerization Fronts Driven by an Autocatalytic Enzyme Reaction.

PubMed

Jee, Elizabeth; Bánsági, Tamás; Taylor, Annette F; Pojman, John A

2016-02-05

Chemical systems that remain kinetically dormant until activated have numerous applications in materials science. Herein we present a method for the control of gelation that exploits an inbuilt switch: the increase in pH after an induction period in the urease-catalyzed hydrolysis of urea was used to trigger the base-catalyzed Michael addition of a water-soluble trithiol to a polyethylene glycol diacrylate. The time to gelation (minutes to hours) was either preset through the initial concentrations or the reaction was initiated locally by a base, thus resulting in polymerization fronts that converted the mixture from a liquid into a gel (ca. 0.1 mm min -1 ). The rate of hydrolytic degradation of the hydrogel depended on the initial concentrations, thus resulting in a gel lifetime of hours to months. In this way, temporal programming of gelation was possible under mild conditions by using the output of an autocatalytic enzyme reaction to drive both the polymerization and subsequent degradation of a hydrogel.

The impact of thermal treatment conditions on the formation of crystalline structure of Ce-Zr-oxide composite obtained by a modified sol-gel technique

NASA Astrophysics Data System (ADS)

Trusova, E. A.; Khrushcheva, A. A.; Shvorneva, L. I.

2012-02-01

We present the results of the modified sol-gel synthesis of ultrafine ceria-doped zirconia powder for medical ceramics (implants) and catalytic purposes (environmental catalysis and petrochemistry). Special attention has been paid to study the influence of thermal treatment on crystallite size and crystal lattice parameters of zirconia doped by ceria. Zirconyl chloride and cerium nitrate were used as metal sources, and tetraethylammonium hydroxide (TEAH) was used as a sol stabilizer at molar ratio TEAH/Σ (Ce + Zr) equal to 0.5. It was proved that zirconium and cerium practically completely were included in the obtained solid solutions, since their phase compositions fully correspond to initial quantities of cerium and zirconium in reaction mixture. It was shown that average crystallite size of the obtained powders did not exceed 75Å, and the powders were resistant to thermal treatment. It was established that stabilization of the crystal lattice of ZrO2 occurs through formation of a cubic ceria sublattice.

Synthesis of nano-titanium dioxide by sol-gel route

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

Kaler, Vandana, E-mail: vandana.kaler@gmail.com; Duchaniya, R. K.; Pandel, U.

Nanosized titanium dioxide powder was synthesised via sol-gel route by hydrolysis of titanium tetraisopropoxide with ethanol and water mixture in high acidic medium. The synthesized nanopowder was further characterized by X-ray Diffraction, Scanning Electron Microscopy, Fourier Transform Infrared Spectroscopy, and Ultraviolet Visible Spectroscopy in order to determine size, morphology and crystalline structure of the material. The synthesis of nano-TiO{sub 2} powder in anatase phase was realized by XRD. The optical studies of nano-TiO{sub 2} powder was carried out by UV-Vis spectroscopy and band gap was calculated as 3.5eV, The SEM results with EDAX confirmed that prepared nano-TiO{sub 2} particles weremore » in nanometer range with irregular morphology. The FTIR analysis showed that only desired functional groups were present in sample. These nano-TiO{sub 2} particles have applications in solar cells, chemical sensors and paints, which are thrust areas these days.« less

Fabrication and properties of aluminum silicate fibrous materials with in situ synthesized K2Ti6O13 whiskers

NASA Astrophysics Data System (ADS)

Liu, Hao; Wei, Nan; Wang, Zhou-fu; Wang, Xi-tang; Ma, Yan

2017-11-01

To improve their mechanical and thermal insulation properties, aluminum silicate fibrous materials with in situ synthesized K2Ti6O13 whiskers were prepared by firing a mixture of short aluminum silicate fibers and gel powders obtained from a sol-gel process. During the preparation process, the fiber surface was coated with K2Ti6O13 whiskers after the fibers were subjected to a heat treatment carried out at various temperatures. The effects of process parameters on the microstructure, compressive strength, and thermal conductivity were analyzed systematically. The results show that higher treatment temperatures and longer treatment durations promoted the development of K2Ti6O13 whiskers on the surface of aluminum silicate fibers; in addition, the intersection structure between whiskers modulated the morphology and volume of the multi-aperture structure among fibers, substantially increasing the fibers' compressive strength and reducing their heat conduction and convective heat transfer at high temperatures.

Molecular Dynamics Simulation Study of the Selectivity of a Silica Polymer for Ibuprofen

PubMed Central

Concu, Riccardo; Cordeiro, M. Natalia D. S.

2016-01-01

In the past few years, the sol-gel polycondensation technique has been increasingly employed with great success as an alternative approach to the preparation of molecularly imprinted materials (MIMs). The main aim of this study was to study, through a series of molecular dynamics (MD) simulations, the selectivity of an imprinted silica xerogel towards a new template—the (±)-2-(P-Isobutylphenyl) propionic acid (Ibuprofen, IBU). We have previously demonstrated the affinity of this silica xerogel toward a similar molecule. In the present study, we simulated the imprinting process occurring in a sol-gel mixture using the Optimized Potentials for Liquid Simulations-All Atom (OPLS-AA) force field, in order to evaluate the selectivity of this xerogel for a template molecule. In addition, for the first time, we have developed and verified a new parameterisation for the Ibuprofen® based on the OPLS-AA framework. To evaluate the selectivity of the polymer, we have employed both the radial distribution functions, interaction energies and cluster analyses. PMID:27399685

Molecular Dynamics Simulation Study of the Selectivity of a Silica Polymer for Ibuprofen.

PubMed

Concu, Riccardo; Cordeiro, M Natalia D S

2016-07-07

In the past few years, the sol-gel polycondensation technique has been increasingly employed with great success as an alternative approach to the preparation of molecularly imprinted materials (MIMs). The main aim of this study was to study, through a series of molecular dynamics (MD) simulations, the selectivity of an imprinted silica xerogel towards a new template-the (±)-2-(P-Isobutylphenyl) propionic acid (Ibuprofen, IBU). We have previously demonstrated the affinity of this silica xerogel toward a similar molecule. In the present study, we simulated the imprinting process occurring in a sol-gel mixture using the Optimized Potentials for Liquid Simulations-All Atom (OPLS-AA) force field, in order to evaluate the selectivity of this xerogel for a template molecule. In addition, for the first time, we have developed and verified a new parameterisation for the Ibuprofen(®) based on the OPLS-AA framework. To evaluate the selectivity of the polymer, we have employed both the radial distribution functions, interaction energies and cluster analyses.

Inactivation of bacteria using dc corona discharge: role of ions and humidity.

PubMed

Dobrynin, Danil; Friedman, Gary; Fridman, Alexander; Starikovskiy, Andrey

2011-10-01

Here we present the results of an experimental study of the effect of ions produced in a dc corona discharge on inactivation of bacteria on the surface of agarose gel. Both positive and negative corona discharges in various gases at different humidities were studied. The measurements in air, O(2), N(2), Ar and He mixtures show that there is no inactivation in pure N(2), pure O(2) and an N(2)-H(2)O mixture. The best results were achieved in the case of direct treatment, when discharge was ignited in oxygen and water-containing mixtures. We show that neither UV radiation, ozone or H(2)O(2) nor other neutral active species alone produced by corona have an effect on bacteria viability. It is shown that the main role of charged particles may be related to the faster transport of active peroxide species-cluster ions OH(-)(H(2)O)(n) and H(3)O(+)(H(2)O)(n). The efficiency of these radicals is much higher than that of the oxygen radicals and ions (including [Formula: see text] and O(3)) and that of nitrogen and argon ions.

Tuning of thermally induced sol-to-gel transitions of moderately concentrated aqueous solutions of doubly thermosensitive hydrophilic diblock copolymers poly(methoxytri(ethylene glycol) acrylate)-b-poly(ethoxydi(ethylene glycol) acrylate-co-acrylic acid).

PubMed

Jin, Naixiong; Zhang, Hao; Jin, Shi; Dadmun, Mark D; Zhao, Bin

2012-03-15

We report in this article a method to tune the sol-to-gel transitions of moderately concentrated aqueous solutions of doubly thermosensitive hydrophilic diblock copolymers that consist of two blocks exhibiting distinct lower critical solution temperatures (LCSTs) in water. A small amount of weak acid groups is statistically incorporated into the lower LCST block so that its LCST can be tuned by varying solution pH. Well-defined diblock copolymers, poly(methoxytri(ethylene glycol) acrylate)-b-poly(ethoxydi(ethylene glycol) acrylate-co-acrylic acid) (PTEGMA-b-P(DEGEA-co-AA)), were prepared by reversible addition-fragmentation chain transfer polymerization and postpolymerization modification. PTEGMA and PDEGEA are thermosensitive water-soluble polymers with LCSTs of 58 and 9 °C, respectively, in water. A 25 wt % aqueous solution of PTEGMA-b-P(DEGEA-co-AA) with a molar ratio of DEGEA to AA units of 100:5.2 at pH = 3.24 underwent multiple phase transitions upon heating, from a clear, free-flowing liquid (<15 °C) to a clear, free-standing gel (15-46 °C) to a clear, free-flowing hot liquid (47-56 °C), and a cloudy mixture (≥57 °C). With the increase of pH, the sol-to-gel transition temperature (T(sol-gel)) shifted to higher values, while the gel-to-sol transition (T(gel-sol)) and the clouding temperature (T(clouding)) of the sample remained essentially the same. These transitions and the tunability of T(sol-gel) originated from the thermosensitive properties of two blocks of the diblock copolymer and the pH dependence of the LCST of P(DEGEA-co-AA), which were confirmed by dynamic light scattering and differential scanning calorimetry studies. Using the vial inversion test method, we mapped out the C-shaped sol-gel phase diagrams of the diblock copolymer in aqueous buffers in the moderate concentration range at three different pH values (3.24, 5.58, and 5.82, all measured at ~0 °C). While the upper temperature boundaries overlapped, the lower temperature boundary shifted upward and the critical gelation concentration increased with the increase of pH. The AA content in PTEGMA-b-P(DEGEA-co-AA) was found to have a significant effect on the pH dependence of T(sol-gel). For PTEGMA-b-P(DEGEA-co-AA) with a molar ratio of DEGEA to AA units of 100:10, the T(sol-gel) of its 25 wt % aqueous solution increased faster with the increase of pH than that of PTEGMA-b-P(DEGEA-co-AA) with a DEGEA-to-AA molar ratio of 100:5.2. © 2012 American Chemical Society

High-Melting Lipid Mixtures and the Origin of Detergent-Resistant Membranes Studied with Temperature-Solubilization Diagrams

PubMed Central

Sot, Jesús; Manni, Marco M.; Viguera, Ana R.; Castañeda, Verónica; Cano, Ainara; Alonso, Cristina; Gil, David; Valle, Mikel; Alonso, Alicia; Goñi, Félix M.

2014-01-01

The origin of resistance to detergent solubilization in certain membranes, or membrane components, is not clearly understood. We have studied the solubilization by Triton X-100 of binary mixtures composed of egg sphingomyelin (SM) and either ceramide, diacylglycerol, or cholesterol. Solubilization has been assayed in the 4–50°C range, and the results are summarized in a novel, to our knowledge, form of plots, that we have called temperature-solubilization diagrams. Despite using a large detergent excess (lipid/detergent 1:20 mol ratio) and extended solubilization times (24–48 h) certain mixtures were not amenable to Triton X-100 solubilization at one or more temperatures. DSC of all the lipid mixtures, and of all the lipid + detergent mixtures revealed that detergent resistance was associated with the presence of gel domains at the assay temperature. Once the system melted down, solubilization could occur. In general adding high-melting lipids limited the solubilization, whereas the addition of low-melting lipids promoted it. Lipidomic analysis of Madin-Darby canine kidney cell membranes and of the corresponding detergent-resistant fraction indicated a large enrichment of the nonsolubilized components in saturated diacylglycerol and ceramide. SM-cholesterol mixtures were special in that detergent solubilization was accompanied, for certain temperatures and compositions, by an independent phenomenon of reassembly of the partially solubilized lipid bilayers. The temperature at which lysis and reassembly prevailed was ∼25°C, thus for some SM-cholesterol mixtures solubilization occurred both above and below 25°C, but not at that temperature. These observations can be at the origin of the detergent resistance effects observed with cell membranes, and they also mean that cholesterol-containing detergent-resistant membrane remnants cannot correspond to structures existing in the native membrane before detergent addition. PMID:25517149

Intragastric Gelation of Heated Soy Protein Isolate-Alginate Mixtures and Its Effect on Sucrose Release.

PubMed

Huang, Zhaozhi; Gruen, Ingolf; Vardhanabhuti, Bongkosh

2018-06-15

The goal of our study was to investigate the effect of alginate on in vitro gastric digestion and sucrose release of soy protein isolate (SPI) in model beverages. Model beverages containing 5% w/w SPI, 0% to 0.20% w/w alginate, and 10% w/w sucrose were prepared by heating the mixtures at 85 °C for 30 min at pH 6.0 or 7.0. Characterizations of beverages included determination of zeta potential, particle size and rheological properties. Digestion patterns and sucrose release profiles were determined during 2 hr in vitro gastric digestion using SDS-PAGE and HPLC analysis, respectively. Increasing alginate concentration led to increased negative surface charge, particle size, as well as viscosity and pseudoplastic behavior; however, no phase separation was observed. SPI beverages formed intragastric gel during in vitro gastric digestion when the formulations contained alginate or at pH 6.0 without alginate. Formation of the intragastric gel led to delayed protein digestion and release of sucrose. Higher resistance to digestion and a slower sucrose release rate were exhibited at increased alginate concentration, and to a lesser extent, at pH 6.0. This suggests that electrostatic interaction between SPI and alginate that occurred when the beverages were under gastric condition could be responsible for the intragastric gelation. These results could potentially lead to the formulation of SPI beverages with functionality to lower postprandial glycemic response. The results could be used to design beverages or semi solid food products with altered digestion properties and lowered or slower glucose release. © 2018 Institute of Food Technologists®.

Unusually large acrylamide induced effect on the droplet size in AOT/Brij30 water-in-oil microemulsions.

PubMed

Poulsen, Allan K; Arleth, Lise; Almdal, Kristoffer; Scharff-Poulsen, Anne Marie

2007-02-01

Droplet microemulsions are widely used as templates for controlled synthesis of nanometer sized polymer gel beads for use as, e.g., nanobiosensors. Here we examine water-in-oil microemulsions typically used for preparation of sensors. The cores of the microemulsion droplets are constituted by an aqueous component consisting of water, reagent monomer mixture, buffer salts, and the relevant dyes and/or enzymes. The cores are encapsulated by a mixture of the surfactants Brij30 and AOT and the resulting microemulsion droplets are suspended in a continuous hexane phase. The size of the final polymer particles may be of great importance for the applications of the sensors. Our initial working hypothesis was that the size of the droplet cores and therefore the size of the synthesized polymer gel beads could be controlled by the surfactant-to-water ratio of the template microemulsion. In the present work we have tested this hypothesis and investigated how the monomers and the ratio between the two surfactants affect the size of the microemulsion droplets and the microemulsion domain. We find that the monomers in water have a profound effect on the microemulsion domain as well as on the size of the microemulsion droplets. The relation between microemulsion composition and droplet size is in this case more complicated than assumed in standard descriptions of microemulsions [R. Strey, Colloid Polym. Sci. 272 (1994) 1005-1019; I. Danielsson, B. Lindman, Colloids Surf. 3 (1981) 391-392; Y. Chevalier, T. Zemb, Rep. Progr. Phys. 53 (1990) 279-371].

Photochemically deposited nano-Ag/sol-gel TiO2-In2O3 mixed oxide mesoporous-assembled nanocrystals for photocatalytic dye degradation.

PubMed

Sreethawong, Thammanoon; Ngamsinlapasathian, Supachai; Yoshikawa, Susumu

2014-05-01

This work focused on the improvement of the photocatalytic activity for Congo Red (CR) azo dye degradation of mesoporous-assembled 0.95 TiO2-0.05 In2O3 mixed oxide photocatalyst (with a TiO2-to-In2O3 molar ratio of 0.95:0.05) by loading with Ag nanoparticles. The mesoporous-assembled 0.95TiO2-0.05In2O3 mixed oxide photocatalyst was synthesized by a hydrolytic sol-gel method with the aid of a structure-directing surfactant, prior to loading with various Ag contents (0.5-2 wt.%) by a photochemical deposition method. The optimum Ag loading content was found to be 1.5 wt.%, exhibiting a great increase in photocatalytic CR dye degradation activity. The 1.5 wt.% Ag-loaded 0.95TiO2-0.05In2O3 mixed oxide photocatalyst was further applied for the CR dye degradation in the presence of water hardness. Different types (Ca2+ and Ca2+ -Mg2+ mixture) and concentrations (200 and 500 mg/l) of water hardness were investigated. The results showed that the water hardness reduced the photocatalytic CR dye degradation activity, particularly for the extremely hard water with 500 mg/l of Ca2+ -Mg2+ mixture. The adjustment of initial solution pH of the CR dye-containing hard water to an appropriate value was found to improve the photocatalytic CR dye degradation activity under the identical reaction conditions. Copyright © 2014 Elsevier Inc. All rights reserved.

Sequestration of dyes from artificially prepared textile effluent using RSM-CCD optimized hybrid backbone based adsorbent-kinetic and equilibrium studies.

PubMed

Sukriti; Sharma, Jitender; Chadha, Amritpal Singh; Pruthi, Vaishali; Anand, Prerna; Bhatia, Jaspreet; Kaith, B S

2017-04-01

Present work reports the synthesis of semi-Interpenetrating Network Polymer (semi-IPN) using Gelatin-Gum xanthan hybrid backbone and polyvinyl alcohol in presence of l-tartaric acid and ammonium persulphate as the crosslinker-initiator system. Reaction parameters were optimized with Response Surface Methodology (RSM) in order to maximize the percent gel fraction of the synthesized sample. Polyvinyl alcohol, l-Tartaric acid, ammonium persulphate, reaction temperature, time and pH of the reaction medium were found to make an impact on the percentage gel fraction obtained. Incorporation of polyvinyl alcohol chains onto hybrid backbone and crosslinking between the different polymer chains were confirmed through techniques like FTIR, SEM-EDX and XRD. Semi-IPN was found to be very efficient in the removal of cationic dyes rhodamine-B (70%) and auramine-O (63%) from a mixture with an adsorbent dose of 700 mg, initial concentration of rhodamine-B 6 mgL -1 and auramine-O 26 mgL -1 , at an time interval of 22-25 h and 30 °C temp. Further to determine the nature of adsorption Langmuir and Freundlich adsorption isotherm models were studied and it was found that Langmuir adsorption isotherm was the best fit model for the removal of mixture of dyes. Kinetic studies for the sorption of dyes favored the reaction mechanism to occur via a pseudo second order pathway with R 2 value about 0.99. Copyright © 2017 Elsevier Ltd. All rights reserved.

Selective filling for patterning in microfluidic channels and integration of chromatography in "lab-on-a-chip" devices using sol-gel technology

NASA Astrophysics Data System (ADS)

Jindal, Rohit

The last decade has seen tremendous advancement in the development of miniaturized chemical analysis system also known as "lab-on-a-chip". It is believed that the true potential of these devices will be achieved by integrating various functions such as separation, reaction, sensing, mixing, pumping, injection and detection onto a single chip. The ability to pattern different functionalities is indispensable for the development of highly integrated devices. In this work, a simple method based on the concept of selective filling is described for patterning in the microfluidic channels. It is based on the difference in the free energy of filling between an open and a covered part of the channel. This method was used for the integration of chromatography in the microfluidic devices. A chromatographic column was realized by utilizing sol-gel as an immobilization matrix for entrapping reversed phase chromatographic particles. Localization of the stationary phase was achieved using the selective filling technique. Channels were fabricated in quartz using photolithography and wet etching. Electroosmotic flow was used for manipulating fluid movement in the channels. Cross channel design was used for making a pulse injection of the solutes in the separation channel. An optical fiber setup was developed for carrying out on-chip UV absorbance detection. Stationary phase was created under different sol-gel synthesis conditions. It was established that the sol-gel synthesis carried out under acidic conditions provides the optimum synthesis conditions for creating separation column. Chromatographic performance of the stationary phase material was demonstrated by separating peptides present in a mixture. The sol-gel immobilization method was extended for the integration of micropump in the chip. The micropump enables pumping of the fluid in field free channels. Preliminary results, demonstrating the potential of carbon nanotubes as a support material in the microfluidic channels, were obtained using CVD (chemical vapor deposition) grown tubes in the channel. Results obtained in this work demonstrate the potential of selective filling technique along with sol-gel technology as a useful tool for the fabrication of multifunctional "lab-on-a-chip" devices.

An Improved 2-Dimensional Gel Electrophoresis Method for Resolving Human Erythrocyte Membrane Proteins

PubMed Central

Kumar, Manoj; Singh, Rajendra; Meena, Anil; Patidar, Bhagwan S; Prasad, Rajendra; Chhabra, Sunil K; Bansal, Surendra K

2017-01-01

The 2-dimensional gel electrophoresis (2-DE) technique is widely used for the analysis of complex protein mixtures extracted from biological samples. It is one of the most commonly used analytical techniques in proteomics to study qualitative and quantitative protein changes between different states of a cell or an organism (eg, healthy and diseased), conditionally expressed proteins, posttranslational modifications, and so on. The 2-DE technique is used for its unparalleled ability to separate thousands of proteins simultaneously. The resolution of the proteins by 2-DE largely depends on the quality of sample prepared during protein extraction which increases results in terms of reproducibility and minimizes protein modifications that may result in artifactual spots on 2-DE gels. The buffer used for the extraction and solubilization of proteins influences the quality and reproducibility of the resolution of proteins on 2-DE gel. The purification by cleanup kit is another powerful process to prevent horizontal streaking which occurs during isoelectric focusing due to the presence of contaminants such as salts, lipids, nucleic acids, and detergents. Erythrocyte membrane proteins serve as prototypes for multifunctional proteins in various erythroid and nonerythroid cells. In this study, we therefore optimized the selected major conditions of 2-DE for resolving various proteins of human erythrocyte membrane. The modification included the optimization of conditions for sample preparation, cleanup of protein sample, isoelectric focusing, equilibration, and storage of immobilized pH gradient strips, which were further carefully examined to achieve optimum conditions for improving the quality of protein spots on 2-DE gels. The present improved 2-DE analysis method enabled better detection of protein spots with higher quality and reproducibility. Therefore, the conditions established in this study may be used for the 2-DE analysis of erythrocyte membrane proteins for different diseases, which may help to identify the proteins that may serve as markers for diagnostics as well as targets for development of new therapeutic potential. PMID:28469466

Novel Approach for Enhanced Scandium and Titanium Leaching Efficiency from Bauxite Residue with Suppressed Silica Gel Formation.

PubMed

Alkan, Gözde; Yagmurlu, Bengi; Cakmakoglu, Seckin; Hertel, Tobias; Kaya, Şerif; Gronen, Lars; Stopic, Srecko; Friedrich, Bernd

2018-04-04

The need of light weight alloys for future transportation industry puts Sc and Ti under a sudden demand. While these metals can bring unique and desired properties to alloys, lack of reliable sources brought forth a supply problem which can be solved by valorization of the secondary resources. Bauxite residue (red mud), with considerable Ti and Sc content, is a promising resource for secure supply of these metals. Due to drawbacks of the direct leaching route from bauxite residue, such as silica gel formation and low selectivity towards these valuable metals, a novel leaching process based on oxidative leaching conditions, aiming more efficient and selective leaching but also considering environmental aspects via lower acid consumption, was investigated in this study. Combination of hydrogen peroxide (H 2 O 2 ) and sulfuric acid (H 2 SO 4 ) was utilized as the leaching solution, where various acid concentrations, solid-to-liquid ratios, leaching temperatures and times were examined in a comparative manner. Leaching with 2.5 M H 2 O 2 : 2.5 M H 2 SO 4 mixture at 90 °C for 30 min was observed to be the best leaching conditions with suppressed silica gel formation and the highest reported leaching efficiency with high S/L ratio for Sc and Ti; 68% and 91%; respectively.

Is a cross-β-sheet structure of low molecular weight peptides necessary for the formation of fibrils and peptide hydrogels?

PubMed

Ilawe, Niranjan V; Schweitzer-Stenner, Reinhard; DiGuiseppi, David; Wong, Bryan M

2018-04-26

Short peptides have emerged as versatile building blocks for supramolecular structures and hydrogels. In particular, the presence of aromatic amino acid residues and/or aromatic end groups is generally considered to be a prerequisite for initiating aggregation of short peptides into nanotubes or cross β-sheet type fibrils. However, the cationic GAG tripeptide surprisingly violates these rules. Specifically, in water/ethanol mixtures, GAG peptides aggregate into very long crystalline fibrils at temperatures below 35 °C where they eventually form a spanning network structure and, thus, a hydrogel. Two gel phases are formed in this network, and they differ substantially in chirality and thickness of the underlying fibrils, their rheological parameters, and the kinetics of oligomerization, fibrilization, and gel formation. The spectroscopic data strongly suggests that the observed fibrils do not exhibit canonical cross β-sheet structures and are indicative of a yet unknown secondary conformation. To complement our unusual experimental observations in this perspective article, we performed large-scale DFT calculations to probe the geometry and spectroscopic properties of these GAG oligomers. Most importantly, our experimental and computational results yield rather unconventional structures that are not reminiscent of classical cross-β-sheet structures, and we give two extremely likely candidates for oligomer structures that are consistent with experimental amide I' profiles in IR and vibrational circular dichroism (VCD) spectra of the two gel phases.

Synthesis of Copper–Silica Core–Shell Nanostructures with Sharp and Stable Localized Surface Plasmon Resonance

DOE PAGES

Crane, Cameron C.; Wang, Feng; Li, Jun; ...

2017-02-21

Copper nanoparticles exhibit intense and sharp localized surface plasmon resonance (LSPR) in the visible region; however, the LSPR peaks become weak and broad when exposed to air due to the oxidation of Cu. In this work, the Cu nanoparticles are successfully encapsulated in SiO 2 by employing trioctyl-n-phosphine (TOP)-capped Cu nanoparticles for the sol–gel reaction, yielding an aqueous Cu–SiO 2 core–shell suspension with stable and well-preserved LSPR properties of the Cu cores. With the TOP capping, the oxidation of the Cu cores in the microemulsion was significantly reduced, thus allowing the Cu cores to sustain the sol–gel process used formore » coating the SiO 2 protection layer. It was found that the self-assembled TOP-capped Cu nanoparticles were spontaneously disassembled during the sol–gel reaction, thus recovering the LSPR of individual particles. During the disassembling progress, the extinction spectrum of the nanocube agglomerates evolved from a broad extinction profile to a narrow and sharp peak. For a mixture of nanocubes and nanorods, the spectra evolved to two distinct peaks during the dissembling process. The observed spectra match well with the numerical simulations. In conclusion, these Cu–SiO 2 core–shell nanoparticles with sharp and stable LSPR may greatly expand the utilization of Cu nanoparticles in aqueous environments.« less

Differentiation of low-attenuation intracranial hemorrhage and calcification using dual-energy computed tomography in a phantom system

PubMed Central

Nute, Jessica L.; Roux, Lucia Le; Chandler, Adam G.; Baladandayuthapani, Veera; Schellingerhout, Dawid; Cody, Dianna D.

2015-01-01

Objectives Calcific and hemorrhagic intracranial lesions with attenuation levels of <100 Hounsfield Units (HU) cannot currently be reliably differentiated by single-energy computed tomography (SECT). The proper differentiation of these lesion types would have a multitude of clinical applications. A phantom model was used to test the ability of dual-energy CT (DECT) to differentiate such lesions. Materials and Methods Agar gel-bound ferric oxide and hydroxyapatite were used to model hemorrhage and calcification, respectively. Gel models were scanned using SECT and DECT and organized into SECT attenuation-matched pairs at 16 attenuation levels between 0 and 100 HU. DECT data were analyzed using 3D Gaussian mixture models (GMMs), as well as a simplified threshold plane metric derived from the 3D GMM, to assign voxels to hemorrhagic or calcific categories. Accuracy was calculated by comparing predicted voxel assignments with actual voxel identities. Results We measured 6,032 voxels from each gel model, for a total of 193,024 data points (16 matched model pairs). Both the 3D GMM and its more clinically implementable threshold plane derivative yielded similar results, with >90% accuracy at matched SECT attenuation levels ≥50 HU. Conclusions Hemorrhagic and calcific lesions with attenuation levels between 50 and 100 HU were differentiable using DECT in a clinically relevant phantom system with >90% accuracy. This method warrants further testing for potential clinical applications. PMID:25162534

Al{sub 2}O{sub 3} - TiO{sub 2}-A simple sol-gel strategy to the synthesis of low temperature sintered alumina-aluminium titanate composites through a core-shell approach

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

Jayasankar, M.; Ananthakumar, S.; Mukundan, P.

A simple sol-gel based core-shell approach for the synthesis of alumina-aluminium titanate composite is reported. Alumina is the core and titania is the shell. The coating of titania has been performed in aqueous medium on alumina particle by means of heterocoagulation of titanyl chloride. Further heat treatment results in low temperature formation of aluminium titanate as well as low temperature sintering of alumina-aluminium titanate composites. The lowering of the reaction temperature can be attributed to the maximisation of the contact surface between the reactants due to the core-shell approach involving nanoparticles. The mechanism of formation of aluminium titanate and themore » observations on densification features in the present process are compared with that of mixture of oxides under identical conditions. The sintered alumina-aluminium titanate composite has an average grain size of 2 {mu}m. - Graphical abstract: The article presents a simple sol-gel process through core-shell approach to the synthesis of low temperature sintered alumina-aluminium titanate. The lowering of the reaction temperature can be attributed to the maximisation of the contact surface between the reactant due to the core-shell approach. This material showed the better microstructure control compared to the standard solid-state mixing route.« less

Preparation and characterization of strontium-fluorapatite nanopowders by sol-gel method

NASA Astrophysics Data System (ADS)

Kamaei, Maryam; Fathi, Mohammad Hossein

2018-01-01

Biomaterials based on calcium orthophosphate are especially attractive for use in medicine, for bone and teeth implants due to their biological properties, such as biocompatibility and bioactivity. Among them, hydroxyapatite (HAP; Ca10(PO4)6(OH)2) is used particularly because of its similarities to the inorganic component of bone. Hydroxyapatite has been widely used for biomedical applications. Despite desirable properties such as bioactivity, biocompatibility, solubility and adsorption, synthetic HA is limited in application due to poor thermostability and poor mechanical properties. Properties of HA can be tailored over a wide range by incorporating different ions into HA lattice. Use of the sol-gel technique is technically simple, cost effective and beneficial for fabrication biomaterials. This research aimed to prepare and characterize Sr-doped FA nanopowders (Sr-FA). Sr-FA with different Sr contents was prepared by sol-gel method. The designated degree of substitution of Ca by Sr in the mixture was determined by the x value in the general formula of (Ca10-x Srx(PO4)6F2), where x=0,0.5,1. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) techniques were utilized to characterize the obtained nano powders. Results showed that Sr ions entered into the fluorapatite lattice and occupied Ca sites. The incorporation of Sr ions into the fluorapatite resulted in the increase of the lattice parameters.

Raman Spectroscopy of Isotopic Water Diffusion in Ultraviscous, Glassy, and Gel States in Aerosol by Use of Optical Tweezers.

PubMed

Davies, James F; Wilson, Kevin R

2016-02-16

The formation of ultraviscous, glassy, and amorphous gel states in aqueous aerosol following the loss of water results in nonequilibrium dynamics due to the extended time scales for diffusive mixing. Existing techniques for measuring water diffusion by isotopic exchange are limited by contact of samples with the substrate, and methods applied to infer diffusion coefficients from mass transport in levitated droplets requires analysis by complex coupled differential equations to derive diffusion coefficients. We present a new technique that combines contactless levitation with aerosol optical tweezers with isotopic exchange (D2O/H2O) to measure the water diffusion coefficient over a broad range (Dw ≈ 10(-12)-10(-17) m(2)·s(-1)) in viscous organic liquids (citric acid, sucrose, and shikimic acid) and inorganic gels (magnesium sulfate, MgSO4). For the organic liquids in binary and ternary mixtures, Dw depends on relative humidity and follows a simple compositional Vignes relationship. In MgSO4 droplets, water diffusivity decreases sharply with water activity and is consistent with predictions from percolation theory. These measurements show that, by combining micrometer-sized particle levitation (a contactless measurement with rapid mixing times) with an established probe of water diffusion, Dw can be simply and directly quantified for amorphous and glassy states that are inaccessible to existing methods.

Raman Spectroscopy of Isotopic Water Diffusion in Ultraviscous, Glassy, and Gel States in Aerosol by Use of Optical Tweezers

DOE PAGES

Davies, James F.; Wilson, Kevin R.

2016-01-11

The formation of ultraviscous, glassy, and amorphous gel states in aqueous aerosol following the loss of water results in nonequilibrium dynamics due to the extended time scales for diffusive mixing. Existing techniques for measuring water diffusion by isotopic exchange are limited by contact of samples with the substrate, and methods applied to infer diffusion coefficients from mass transport in levitated droplets requires analysis by complex coupled differential equations to derive diffusion coefficients. Here, we present a new technique that combines contactless levitation with aerosol optical tweezers with isotopic exchange (D 2O/H 2O) to measure the water diffusion coefficient over amore » broad range (D w ≈ 10 -12-10 -17 m 2s -1) in viscous organic liquids (citric acid, sucrose, and shikimic acid) and inorganic gels (magnesium sulfate, MgSO 4). For the organic liquids in binary and ternary mixtures, D w depends on relative humidity and follows a simple compositional Vignes relationship. In MgSO 4 droplets, water diffusivity decreases sharply with water activity and is consistent with predictions from percolation theory. These measurements show that, by combining micrometer-sized particle levitation (a contactless measurement with rapid mixing times) with an established probe of water diffusion, D w can be simply and directly quantified for amorphous and glassy states that are inaccessible to existing methods.« less

Synthesis of Copper–Silica Core–Shell Nanostructures with Sharp and Stable Localized Surface Plasmon Resonance

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

Crane, Cameron C.; Wang, Feng; Li, Jun

Copper nanoparticles exhibit intense and sharp localized surface plasmon resonance (LSPR) in the visible region; however, the LSPR peaks become weak and broad when exposed to air due to the oxidation of Cu. In this work, the Cu nanoparticles are successfully encapsulated in SiO 2 by employing trioctyl-n-phosphine (TOP)-capped Cu nanoparticles for the sol–gel reaction, yielding an aqueous Cu–SiO 2 core–shell suspension with stable and well-preserved LSPR properties of the Cu cores. With the TOP capping, the oxidation of the Cu cores in the microemulsion was significantly reduced, thus allowing the Cu cores to sustain the sol–gel process used formore » coating the SiO 2 protection layer. It was found that the self-assembled TOP-capped Cu nanoparticles were spontaneously disassembled during the sol–gel reaction, thus recovering the LSPR of individual particles. During the disassembling progress, the extinction spectrum of the nanocube agglomerates evolved from a broad extinction profile to a narrow and sharp peak. For a mixture of nanocubes and nanorods, the spectra evolved to two distinct peaks during the dissembling process. The observed spectra match well with the numerical simulations. In conclusion, these Cu–SiO 2 core–shell nanoparticles with sharp and stable LSPR may greatly expand the utilization of Cu nanoparticles in aqueous environments.« less

Effect of short range hydrodynamic on bimodal colloidal gel systems

NASA Astrophysics Data System (ADS)

Boromand, Arman; Jamali, Safa; Maia, Joao

2015-03-01

Colloidal Gels and disordered arrested systems has been studied extensively during the past decades. Although, they have found their place in multiple industries such as cosmetic, food and so on, their physical principals are still far beyond being understood. The interplay between different types of interactions from quantum scale, Van der Waals interaction, to short range interactions, depletion interaction, and long range interactions such as electrostatic double layer makes this systems challenging from simulation point of view. Many authors have implemented different simulation techniques such as molecular dynamics (MD) and Brownian dynamics (BD) to capture better picture during phase separation of colloidal system with short range attractive force. However, BD is not capable to include multi-body hydrodynamic interaction and MD is limited by the computational resources and is limited to short time and length scales. In this presentation we used Core-modified dissipative particle dynamics (CM-DPD) with modified depletion potential, as a coarse-grain model, to address the gel formation process in short ranged-attractive colloidal suspensions. Due to the possibility to include and separate short and long ranged-hydrodynamic forces in this method we studied the effect of each of those forces on the final morphology and report one of the controversial question in this field on the effect of hydrodynamics on the cluster formation process on bimodal, soft-hard colloidal mixtures.

Photo-induced free radicals on a simulated Martian surface

NASA Technical Reports Server (NTRS)

Tseng, S.-S.; Chang, S.

1974-01-01

Results of an electron spin resonance study of free radicals in the ultraviolet irradiation of a simulated Martian surface suggest that the ultraviolet photolysis of CO or CO2, or a mixture of both, adsorbed on silica gel at minus 170 C involves the formation of OH radicals and possibly of H atoms as the primary process, followed by the formation of CO2H radicals. It is concluded that the photochemical synthesis of organic compounds could occur on Mars if the siliceous surface dust contains enough silanol groups and/or adsorbed H2O in the form of bound water.

Reactive decontamination formulation

DOEpatents

Giletto, Anthony [College Station, TX; White, William [College Station, TX; Cisar, Alan J [Cypress, TX; Hitchens, G Duncan [Bryan, TX; Fyffe, James [Bryan, TX

2003-05-27

The present invention provides a universal decontamination formulation and method for detoxifying chemical warfare agents (CWA's) and biological warfare agents (BWA's) without producing any toxic by-products, as well as, decontaminating surfaces that have come into contact with these agents. The formulation includes a sorbent material or gel, a peroxide source, a peroxide activator, and a compound containing a mixture of KHSO.sub.5, KHSO.sub.4 and K.sub.2 SO.sub.4. The formulation is self-decontaminating and once dried can easily be wiped from the surface being decontaminated. A method for decontaminating a surface exposed to chemical or biological agents is also disclosed.

The Use of Sugar-Oximes and Other Glycosylated Drugs in Treatment against Organophosphate Poisoning

DTIC Science & Technology

1985-06-30

process on a column of silica gel (100g). The crude quarternized products were eluted from the column when the polarity of chloroform-methanol...mixture exceeded 25% of methanol. The iodide ion was exchanged with chloride by passing the crude product on a Dowex 1 anion exchange resin (30g). The... product turned out to be a very hygroscopic material). Cpd. E-357 ’H nmr: (D,0-DSS) 1.9-2.1 (12H, 4Ac); 2.6-4.0 (m, H. of the pyranose ring and CH of

Immobilized lipid-bilayer materials

DOEpatents

Sasaki, Darryl Y.; Loy, Douglas A.; Yamanaka, Stacey A.

2000-01-01

A method for preparing encapsulated lipid-bilayer materials in a silica matrix comprising preparing a silica sol, mixing a lipid-bilayer material in the silica sol and allowing the mixture to gel to form the encapsulated lipid-bilayer material. The mild processing conditions allow quantitative entrapment of pre-formed lipid-bilayer materials without modification to the material's spectral characteristics. The method allows for the immobilization of lipid membranes to surfaces. The encapsulated lipid-bilayer materials perform as sensitive optical sensors for the detection of analytes such as heavy metal ions and can be used as drug delivery systems and as separation devices.

Physicochemical properties of sorbents based on silica gel modified by 1-phenylazo-2-naphtholic complexes of transition metals

NASA Astrophysics Data System (ADS)

Makarycheva, A. I.; Slizhov, Yu. G.

2017-09-01

Gas chromatography sorbents based on Silokhrom C80 and modified by 1-phenylazo-2-naphtholic complexes of 3 d metals (Co(II), Ni(II), Cu(II)) are obtained. Their structural, chromatographic, and sorption characteristics are investigated. It is found that modifying them with 1-phenylazo-2-naphthols of transition metals has a considerable effect on the chromatographic polarity and selectivity of sorption materials. The prospects for the practical application of the obtained sorbents are demonstrated by experiments on the gas chromatographic separation of mixtures of different classes of organic compounds.

Preparation of xerogel SiO2 from roasted iron sand under various acidic solution

NASA Astrophysics Data System (ADS)

Ramelan, A. H.; Wahyuningsih, S.; Ismoyo, Y. A.; Pranata, H. P.; Munawaroh, H.

2016-11-01

Xerogel SiO2 had been prepared from roasted iron sand through variation of Na2CO3 addition and sol-gel process under various acidic solution. Roasting treatment was carried out on the compositional variation of iron sand:Na2CO3 = 1:2; 1:1 and 2:1 at 1100 °C. While the sol-gel process was conducted at room temperature and neutralized using HCl 0.1 M and 6 M. The color characteristics of roasted iron sand shown light brown, dark brown and dark gray of the compositional variation of iron sand:Na2CO3 = 1:2; 1:1 and 2:1, respectively. In addition, the levels of thoughness increased by increasing the ratio of sand in the composition of the mixture. The best composition of roasted treatment was at a variety of iron sand:Na2SiO3 = 1:2 with 57.72% had been dissolved in hot water. The addition of Na2CO3 will influence the Na2SiO3 formation, because of the increase of Na2CO3 capable produced the iron sand decomposition product. Na2SiO3 gel had been produced after it was neutralized with certain amount of HCl solution. The neutralization was more effective if using high concentration of HCl because of the formation of gel SiO2 will be easier occurred. The results of SiO2 had been identified by the FTIR spectra, which an absorption spectra of Si-O-Si asymmetric stretching at 1098.51 cm-1, symmetric stretching of Si-O-Si at 804.35 cm-1 and the bending O-Si-O at 469.69 cm'1. The result of SiO2 content by XRF analysis is about 85.15%.

Ultrastructure of hybrid chitosan-glycerol phosphate blood clots by environmental scanning electron microscopy.

PubMed

Iliescu, M; Hoemann, C D; Shive, M S; Chenite, A; Buschmann, M D

2008-03-01

Chitosan-based polymers have been extensively studied for biomedical applications. Recently, liquid solutions of chitosan in a glycerol phosphate buffer (chitosan-GP) with physiological pH and osmolality were mixed with autologous blood to form hybrid chitosan-GP/blood implants that improved the repair of articular cartilage lesions in a large animal model. The mixture of chitosan-GP and blood forms a viscous liquid, which solidifies in minutes via normal blood coagulation as well as chitosan-mediated mechanisms. Here we have examined the ultrastructure of these chitosan-GP/blood clots as well as regular blood clots and chitosan-GP gels, the latter produced by heating. Both unfixed and fixed samples of chitosan-GP/blood clots, regular blood clots, and chitosan-GP gels were investigated by environmental scanning electron microscopy (ESEM) in conjunction with energy dispersive X-ray spectrometry (EDS), the former permitting direct observation of the ultrastructure in hydrated conditions simulating the natural state. By examination of unfixed specimens using ESEM we found that chitosan formed a network structure in both chitosan-GP gels and chitosan-GP/blood clots; however this structure was altered by aldehyde fixation to produce artifactual aggregates of chitosan microparticles. We were also able to identify chitosan in chitosan-GP/blood clots by washing samples in low concentration NaCl solutions followed by local EDS analyses to identify excess chloride versus sodium, and thus presence of cationic chitosan in analyzed features. Additional results indicated that the majority of glycerol phosphate diffuses freely from chitosan-GP gels (by EDS of phosphorus) and that hyperosmotic paraformaldehyde-based fixatives (i.e. 4% w/v) significantly disturb erythrocyte morphology in fixed whole blood clots. (c) 2007 Wiley-Liss, Inc.

Evaluation of hybrid sol-gel incorporated with nanoparticles as nano paint

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

Jameel, Zainab N., E-mail: zeinb76-alrekbe@yahoo.com; Haider, Adawiya J., E-mail: adawiyahaider@yahoo.com; Taha, Samar Y., E-mail: samarjam2002@yahoo.com

A coating with self-cleaning characteristics has been developed using a TiO{sub 2}/SiO{sub 2} hybrid sol-gel, TiO{sub 2} nanoparticles and organosilicate nanoparticles (OSNP). A patented technology of the hybrid sol-gel and OSNP was combined with TiO{sub 2} nanoparticles to create the surface chemistry for self-cleaning. Two synthesis methods have been developed to prepare TiO{sub 2} nanoparticles (NPs), resulting in the enhancement of local paint by the addition of anatase and rutile TiO{sub 2} phases. The NPs size as determined by Dynamic Light Scattering (DLS) ranges within of (3-4) and (20-42) nm, which was also confirmed by Scanning Electron Microscopy (SEM). Themore » nanoparticles showed surface charge (zeta-potential, ζ) of +35 and +25.62 mV for the methods, respectively, and ζ values of +41.31 and 34.02 mV for anatase and rutile phases, respectively. The NPs were mixed with the coating solution (i.e., hybrid sol-gel and OSNP) in different concentrations and thin films were prepared by spin coating. Self-cleaning tests were performed using Rhodamine B (RhB) as a pollution indicator. The effect of UV-irradiation on the films was also studied. Anatase and rutile incorporated as a mixture with different ratios in local paint and washability as well as a contrast ratio tests were performed. It was found that the addition of TiO{sub 2} NPs in combination with irradiation show a great enhancement of RhB degradation (1%) wt. with a decrease in contact angle and improved washability.« less

Anti-adhesive effect of poloxamer-based thermo-sensitive sol-gel in rabbit laminectomy model.

PubMed

Shin, Sung Joon; Lee, Jae Hyup; So, Jungwon; Min, Kyungdan

2016-11-01

Poloxamer-based thermo-sensitive sol-gel has been developed to reduce the incidence of postoperative scar formation at the laminectomy site. The purpose of this study was to evaluate the anti-adhesive effect of poloxamer based thermo-sensitive sol-gel compared to hyaluronate based solution after laminectomy, using a rabbit model. A thermo-sensitive anti-adhesive with a property of sol-gel transition was manufactured by a physical mixture of Poloxamer188/407, Chitosan and Gelatin. The viscosity in different temperatures was assessed. 72 adult New Zealand rabbits underwent lumbar laminectomy and were randomly divided into experimental (treated with the newly developed agent), positive (treated with hyaluronate based solution), and negative control groups. Each group was subdivided into 1 and 4-week subgroups. Gross and histological evaluations were performed to assess the extent of epidural adhesion. The experimental group showed significantly higher viscosity compared to the positive control group and showed a significant increase of viscosity as the temperature increased. Gross evaluation showed no statistically significant differences between the 1- and 4-week subgroups. However, histologic evaluation showed significant differences both in 1- and 4-week subgroups. Although the 4-week histologic results of the experimental and the positive control subgroups showed no significant difference, both subgroups revealed higher value compared to the negative control subgroup with regard to the ratio of adhesion less than 50 %. The new poloxamer based thermo-sensitive agent showed superior efficacy over the hyaluronate based agent at 1 week postoperatively. At 4 weeks postoperatively, there were no statistically significant differences between the two agents, although both showed efficacy over the sham group.

Gelation-driven component selection in the generation of constitutional dynamic hydrogels based on guanine-quartet formation

PubMed Central

Sreenivasachary, Nampally; Lehn, Jean-Marie

2005-01-01

The guanosine hydrazide 1 yields a stable supramolecular hydrogel based on the formation of a guanine quartet (G-quartet) in presence of metal cations. The effect of various parameters (concentration, nature of metal ion, and temperature) on the properties of this gel has been studied. Proton NMR spectroscopy is shown to allow a molecular characterization of the gelation process. Hydrazide 1 and its assemblies can be reversibly decorated by acylhydrazone formation with various aldehydes, resulting in formation of highly viscous dynamic hydrogels. When a mixture of aldehydes is used, the dynamic system selects the aldehyde that leads to the most stable gel. Mixing hydrazides 1, 9 and aldehydes 6, 8 in 1:1:1:1 ratio generated a constitutional dynamic library containing the four acylhydrazone derivatives A, B, C, and D. The library constitution displayed preferential formation of the acylhydrazone B that yields the strongest gel. Thus, gelation redirects the acylhydrazone distribution in the dynamic library as guanosine hydrazide 1 scavenges preferentially aldehyde 8, under the pressure of gelation because of the collective interactions in the assemblies of G-quartets B, despite the strong preference of the competing hydrazide 9 for 8. Gel formation and component selection are thermoreversible. The process amounts to gelation-driven self-organization with component selection and amplification in constitutional dynamic hydrogels based on G-quartet formation and reversible covalent connections. The observed self-organization and component selection occur by means of a multilevel self-assembly involving three dynamic processes, two of supramolecular and one of reversible covalent nature. They extend constitutional dynamic chemistry to phase-organization and phase-transition events. PMID:15840720

Gelation-driven component selection in the generation of constitutional dynamic hydrogels based on guanine-quartet formation.

PubMed

Sreenivasachary, Nampally; Lehn, Jean-Marie

2005-04-26

The guanosine hydrazide 1 yields a stable supramolecular hydrogel based on the formation of a guanine quartet (G-quartet) in presence of metal cations. The effect of various parameters (concentration, nature of metal ion, and temperature) on the properties of this gel has been studied. Proton NMR spectroscopy is shown to allow a molecular characterization of the gelation process. Hydrazide 1 and its assemblies can be reversibly decorated by acylhydrazone formation with various aldehydes, resulting in formation of highly viscous dynamic hydrogels. When a mixture of aldehydes is used, the dynamic system selects the aldehyde that leads to the most stable gel. Mixing hydrazides 1, 9 and aldehydes 6, 8 in 1:1:1:1 ratio generated a constitutional dynamic library containing the four acylhydrazone derivatives A, B, C, and D. The library constitution displayed preferential formation of the acylhydrazone B that yields the strongest gel. Thus, gelation redirects the acylhydrazone distribution in the dynamic library as guanosine hydrazide 1 scavenges preferentially aldehyde 8, under the pressure of gelation because of the collective interactions in the assemblies of G-quartets B, despite the strong preference of the competing hydrazide 9 for 8. Gel formation and component selection are thermoreversible. The process amounts to gelation-driven self-organization with component selection and amplification in constitutional dynamic hydrogels based on G-quartet formation and reversible covalent connections. The observed self-organization and component selection occur by means of a multilevel self-assembly involving three dynamic processes, two of supramolecular and one of reversible covalent nature. They extend constitutional dynamic chemistry to phase-organization and phase-transition events.

Insecticidal components from field pea extracts: isolation and separation of peptide mixtures related to pea albumin 1b.

PubMed

Taylor, Wesley G; Fields, Paul G; Elder, James L

2004-12-15

Chromatographic fractionation of crude extracts (C8 extracts) from the protein-enriched flour of commercial field peas (Pisum sativum L.) has been shown here to yield peptide mixtures related to the pea albumin 1b (PA1b) family of cysteine-rich plant peptides. The mixtures were obtained initially by flash chromatography with silica gel. Following elution of soyasaponins and lysolecithins, the end fractions obtained with the use of two flash chromatographic solvent systems displayed activity in a flour disk antifeedant bioassay with the rice weevil [Sitophilus oryzae (L.)]. Chemical properties of these mixtures were compared by thin-layer chromatography, high-performance liquid chromatography (HPLC), IR, MS, and amino acid analyses. The major peptides of C8 extracts, with average masses of 3752, 3757, and 3805 Da, were isolated by anion exchange chromatography. Samples enriched in the peptide of mass 3752 were isolated by cation exchange chromatography. Reduction plus alkylation experiments in combination with electrospray ionization mass spectrometry showed that C8 extracts contained about 10 peptides and, like PA1b, each peptide possessed six cysteine residues (three disulfide bonds). Disulfide bond reduction with 2-mercaptoethanol destroyed the antifeedant activity. The native peptides of C8 extracts were found to be resolved into nine peaks with XTerra HPLC columns operating at alkaline pH. These columns were employed to assess the distribution of pea peptides in the isolated fractions, with photodiode array and electrospray detection.

Structural and viscoelastic characterization of ternary mixtures of sunflower oil, saturated monoglycerides and aqueous phases containing different bases.

PubMed

Valoppi, Fabio; Calligaris, Sonia; Barba, Luisa; Nicoli, Maria Cristina

2015-08-01

The structure at different length scales and the viscoelastic properties of ternary mixtures composed of saturated monoglycerides, sunflower oil and aqueous solutions of weak bases (KHCO 3 , NaHCO 3 , and NH 4 HCO 3 ) or strong bases (NaOH and KOH) were investigated. The characteristics of ternary mixtures were studied systematically by using polarized light microscopy, differential scanning calorimetry (DSC), synchrotron X-ray diffraction (XRD) and rheological analysis. Results showed that the base type and concentration greatly affected the structure of the mixtures. The use of strong bases allowed gelled systems to be obtained only at low concentrations (<10mM). On the contrary, the presence of weak bases induced gelling at all concentrations considered (from 1 to 1000mM). The increase of base concentration led to a reduction of the mean droplet diameter and melting temperature. At the same time, the viscoelastic characteristics as a function of base concentration followed a more complex behavior: G' and G″ progressively decreased as the salt concentration increased in a concentration range from 1 to 100mM, while the rheological parameters increased when salt concentration increased from 100 to 1000mM. The structural and viscoelastic behavior of systems prepared with different salts were commonly independent of the cation present in the medium. Results highlight that it is possible to tailor the structure of these gels by using specific bases. Copyright © 2015 Elsevier Ltd. All rights reserved.

Self assembly of oppositely charged latex particles at oil-water interface.

PubMed

Nallamilli, Trivikram; Ragothaman, Srikanth; Basavaraj, Madivala G

2017-01-15

In this study we explore the self assembly of oppositely charged latex particles at decane water interfaces. Two spreading protocols have been proposed in this context. In the first method oppositely charged particles are mixed prior to spreading at the interface, this is called "premixed-mixtures". In the second protocol negatively charged particles are first spread at the interface at known coverage followed by spreading positively charged particles at known coverage and this is called "sequential-mixtures". In premixed mixtures depending on particle mixing ratio (composition) and total surface coverage a number of 2d structures ranging from 2d crystals, aggregate-crystal coexistence and 2d-gels are observed. A detailed phase diagram of this system has been explored. In sequential-mixtures for the first time we observed a new phase in colloidal monolayers called 2d-bi crystalline domains. These structures consisted regions of two crystal phases of oppositely charged particles separated by a one dimensional chain of alternating positive and negative particles. Phase diagram of this system has also been explored at various combinations of first spread and second spread particles. A possible mechanism leading to formation of these 2d bi crystalline structures has been discussed. A direct visualization of breakage and reformation of particle barriers separating the crystal phases has been demonstrated through videos. Effect of salt in the water sub phase and particle hydrophobicity on domain formation is also investigated. Copyright © 2016 Elsevier Inc. All rights reserved.

Release profiles of phenytoin from new oral dosage form for the elderly.

PubMed

Watanabe, A; Hanawa, T; Sugihara, M; Yamamoto, K

1994-08-01

Utilization of the solid mass containing phenytoin, sodium caseinate and microcrystalline cellulose (MCC) as a new dosage form for the elderly was studied. The solid mass was prepared by treatment of the powder mixture with high pressure steam at 115 degrees C for 10 min. The stability of phenytoin in the solid mass was confirmed by infrared spectroscopy and high performance liquid chromatography. The extent of swelling of the solid mass containing phenytoin was investigated by water absorption test and gel strength test, and the swelling property was almost independent of the presence of phenytoin. The release profile of phenytoin from the solid mass was determined under various conditions, and was found to be influenced by the extent of swelling and the swollen state. It was observed that the protein adsorption to the phenytoin crystal surface and the addition of digestive enzyme also affected the release profile. In water, the solid mass prepared from a ground mixture of phenytoin and MCC showed remarkable improvement of release profile of phenytoin.

Fungicides degradation in an organic biomixture: impact on microbial diversity.

PubMed

Coppola, Laura; Comitini, Francesca; Casucci, Cristiano; Milanovic, Vesna; Monaci, Elga; Marinozzi, Maria; Taccari, Manuela; Ciani, Maurizio; Vischetti, Costantino

2011-12-15

Biological systems are being developed all over EU countries to protect water-bodies from pesticide contamination at farm level. A laboratory experiment was carried out to test the efficiency of a mixture of compost and straw in bio-degrading different mixtures of fungicides usually applied in vineyards. At the same time the effects of fungicide applications on microbial community of biomixture were also evaluated. Results showed that the biomixture had a good capability of degrading pesticides. Indeed, at the end of the experiment (112 days), the concentration of most of the pesticides was close to complete degradation. Denaturing gradient gel electrophoresis (DGGE) analysis showed an evident modification of microbial diversity after the addition of fungicides. However, at the end of degradation process, no significant changes in the composition of microbial community were seen. In this specific substrate used in the biomixture, yeast flora and ascomycete filamentous fungi seemed to be involved in the degradation activity. Copyright © 2011 Elsevier B.V. All rights reserved.

[Determination method of polysorbates in powdered soup by HPLC].

PubMed

Takeda, Y; Abe, Y; Ishiwata, H; Yamada, T

2001-04-01

A method for qualitative and quantitative analyses of polysorbates in powdered soup by HPLC was studied. Polysorbates in samples were extracted with acetonitrile after rinsing with n-hexane to remove fats and oils. The extract was cleaned up using a Bond Elut silica gel cartridge (500 mg). The cartridge was washed with ethyl acetate and polysorbates were eluted with a small amount of acetonitrile-methanol (1:2) mixture. The eluate was treated with cobalt thiocyanate solution to form a blue complex with polysorbate. In order to determine polysorbate, the complex was subjected to HPLC with a GPC column, using a mixture of acetonitrile-water (95:5) as a mobile phase, with a detection wavelength of 620 nm. The recoveries of polysorbate 80 added to powdered soups were more than 75% and the determination limit was 0.04 mg/g. When the proposed method was applied to the determination of polysorbates in 16 commercial samples of powdered soup for instant noodles and seasoning consomme, no polysorbates were detected in any sample.

Handedness inversion in preparing chiral 4, 4'-biphenylene-silica nanostructures

NASA Astrophysics Data System (ADS)

Li, Yi; Wang, Hairui; Wang, Liwen; Zhou, Feng; Chen, Yuanli; Li, Baozong; Yang, Yonggang

2011-04-01

An anionic gelator, D-C12ValC10COONa, derived from D-valine can cause physical gels in water and organic solvents. Helical 4, 4'-biphenylene-silica nanotubes and nanoribbons were prepared using it with 3-aminopropyltrimethoxysilane as a co-structure-directing agent and 4, 4'-bis(triethoxysilyl)-1, 1'-biphenyl (BTESB) as precursor. It was found that the handedness of the hybrid silica nanotubes/nanoribbons is sensitive to the pH value and the concentration of the reaction mixtures. However, handedness inversion was not found by changing the reaction temperature. Circular dichroism spectra of the 4, 4'-biphenylene-silica nanotubes indicated that the chirality of the organic self-assemblies were successfully transferred to the twist of the biphenylene rings through the co-structure-directing agent. The handedness of the 4, 4'-biphenylene rings was also tunable by changing the pH value and the concentration of the reaction mixtures. The FESEM images and CD spectra taken after different reaction times indicated that the handedness inversion occurred after adding BTESB.

Non-noble metal based electro-catalyst compositions for proton exchange membrane based water electrolysis and methods of making

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

Kumta, Prashant N.; Kadakia, Karan Sandeep; Datta, Moni Kanchan

The invention provides electro-catalyst compositions for an anode electrode of a proton exchange membrane-based water electrolysis system. The compositions include a noble metal component selected from the group consisting of iridium oxide, ruthenium oxide, rhenium oxide and mixtures thereof, and a non-noble metal component selected from the group consisting of tantalum oxide, tin oxide, niobium oxide, titanium oxide, tungsten oxide, molybdenum oxide, yttrium oxide, scandium oxide, cooper oxide, zirconium oxide, nickel oxide and mixtures thereof. Further, the non-noble metal component can include a dopant. The dopant can be at least one element selected from Groups III, V, VI and VIImore » of the Periodic Table. The compositions can be prepared using a surfactant approach or a sol gel approach. Further, the compositions are prepared using noble metal and non-noble metal precursors. Furthermore, a thin film containing the compositions can be deposited onto a substrate to form the anode electrode.« less

(ZnO){sub 3}In{sub 2}O{sub 3} fine powder prepared by combustion reaction of nitrates-glycine mixture

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

Kikkawa, S.; Sasaki, H.; Tamura, H.

2004-10-04

Conducting fine powder was obtained in the Zn-In-O system by combustion of the gel prepared from an aqueous solution of mixed zinc and indium nitrates in the presence of glycine. Glycine worked as a fuel as well as a gelling agent in the combustion under the strong oxidizing power of the nitrates. In spite of the low furnace temperature of 350 deg. C, the product was (ZnO){sub 3}In{sub 2}O{sub 3} which has been obtained above 1260 deg. C in a solid state reaction of a mixture of ZnO and In{sub 2}O{sub 3}. The combustion synthesis led to an aggregated finemore » powder of hexagonal platelets of about 40 nm in diameter. Its compacted mass showed an electrical resistivity of about 700 {omega} cm. The agglomeration was improved by dispersing the fine powder in an acetic acid aqueous solution.« less

Determination of fluorine and chlorine in geological materials by induction furnace pyrohydrolysis and standard-addition ion-selective electrode measurement.

PubMed

Rice, T D

1988-03-01

Fluorine and chlorine in geological materials are volatilized by pyrohydrolysis at about 1150 degrees in a stream of oxygen (1000 ml/min) plus steam in an induction furnace. The catalyst is a 7:2:1 mixture of silica gel, tungstic oxide and potassium dihydrogen phosphate. The sample/catalyst mixture is pyrohydrolysed in a re-usable alumina crucible (already containing four drops of 1 + 3 phosphoric acid) inserted in a silica-enclosed graphite crucible. The absorption solution is buffered at pH 6.5 and spiked with 1.6 mug of fluoride and 16 mug of chloride per g of solution, to ensure rapid and linear electrode response during subsequent standard-addition measurement. The simple plastic absorption vessel has 99.5% efficiency. The 3s limits of detection are 5-10 mug/g and 40-100 mug/g for fluorine and chlorine respectively. The procedure is unsuitable for determining chlorine in coal.

Modeling water partition in composite gels of BSA with gelatin following high pressure treatment.

PubMed

Semasaka, Carine; Mhaske, Pranita; Buckow, Roman; Kasapis, Stefan

2018-11-01

Changes in the structural properties of hydrogels made with gelatin and bovine serum albumin mixtures were recorded following exposure to high pressure at 300 MPa for 15 min at 10 and 80 °C. Dynamic oscillation, SEM, FTIR and blending law modelling were utilised to rationalise results. Pressurization at the low temperature end yielded continuous gelatin networks supporting discontinuous BSA inclusions, whereas an inverted dispersion was formed at the high temperature end with the continuous BSA network suspending the discontinuous gelatin inclusions. Lewis and Nielsen equations followed the mechanical properties of the composites thus arguing that solvent partition between the two phases was always in favour of the polymer forming the continuous network. As far as we are aware, this is the first attempt to elucidate the solvent partition in pressurised hydrogel composites using blending law theory. Outcomes were contrasted with earlier work where binary mixtures were subjected only to thermal treatment. Copyright © 2018. Published by Elsevier Ltd.

Characterization of Therapeutic Coatings on Medical Devices

NASA Astrophysics Data System (ADS)

Wormuth, Klaus

Therapeutic coatings on medical devices such as catheters, guide wires, and stents improve biocompatibility by favorably altering the chemical nature of the device/tissue or device/blood interface. Such coatings often minimize tissue damage (reduce friction), decrease chances for blood clot formation (prevent platelet adsorption), and improve the healing response (deliver drugs). Confocal Raman microscopy provides valuable information about biomedical coatings by, for example, facilitating the measurement of the thickness and swelling of frictionreducing hydrogel coatings on catheters and by determining the distribution of drug within a polymer-based drug-eluting coatings on stents. This chapter explores the application of Raman microscopy to the imaging of thin coatings of cross-linked poly(vinyl pyrrolidone) gels, parylene films, mixtures of dexamethasone with various polymethacrylates, and mixtures of rapamycin with hydrolysable (biodegradable) poly(lactide-co-glycolide) polymers. Raman microscopy measures the thickness and swelling of coatings, reveals the degree of mixing of drug and polymer, senses the hydrolysis of biodegradable polymers, and determines the polymorphic forms of drug present within thin therapeutic coatings on medical devices.

Synthesis and characterization of carbon cryogel microspheres from lignin-furfural mixtures for biodiesel production.

PubMed

Zainol, Muzakkir Mohammad; Amin, Nor Aishah Saidina; Asmadi, Mohd

2015-08-01

The aim of this work was to study the potential of biofuel and biomass processing industry side-products as acid catalyst. The synthesis of carbon cryogel from lignin-furfural mixture, prepared via sol-gel polycondensation at 90°C for 0.5h, has been investigated for biodiesel production. The effect of lignin to furfural (L/F) ratios, lignin to water (L/W) ratios and acid concentration on carbon cryogel synthesis was studied. The carbon cryogels were characterized and tested for oleic acid conversion. The thermally stable amorphous spherical carbon cryogel has a large total surface area with high acidity. Experimental results revealed the optimum FAME yield and oleic acid conversion of 91.3wt.% and 98.1wt.%, respectively were attained at 65°C for 5h with 5wt.% catalyst loading and 20:1 methanol to oleic acid molar ratio. Therefore, carbon cryogel is highly potential for heterogeneous esterification of free fatty acid to biodiesel. Copyright © 2015 Elsevier Ltd. All rights reserved.

Comparison of Radicular Peroxide Leakage from four Commonly used Bleaching agents following Intracoronal Bleaching in Endodontically treated teeth - An In Vitro Study.

PubMed

Madhu, Ks; Hegde, Swaroop; Mathew, Sylvia; Lata, DA; Bhandi, Shilpa H; N, Shruthi

2013-08-01

Non vital bleaching is simple, conservative procedure for esthetic correction of discolored endodontically treated teeth. The aim of this study was to determine and compare the amount of peroxide leakage from four different bleaching agents i.e superoxol, sodium perborate, combination of superoxol & sodium perborate and carbamide peroxide during intracoronal bleaching, as the safe and effective bleaching is the need of the hour. 50 extracted maxillary centrals were selected for the study. Following standardized protocol access, cleaning and shaping by step back technique and obturation was done using guttapercha and AH plus sealer. Access was sealed with Cavit G and outer root surface was coated with wax and nail varnish. The teeth were separated into crown and root and the root portion was placed in plastic tube containing distilled water for 7days.After incubation, 3mm of gutta-percha was removed below CEJ and 2mm glass ionomer cement base was placed. Grouped into five categories based on the bleaching agent placed in pulp chamber as -group1 (control)-distilled water, group 2-sodium perborate with distilled water , group 3- 30% hydrogen peroxide ,group 4-mixture of sodium perborate and 30% hydrogen peroxide and group 5-10% carbamide peroxide gel. Peroxide leakage was measured after 24hrs using ferrothiocyanate method and optical density using spectrophotometer. Statistical analysis of the data was conducted using ANOVA and multiple comparisons within the groups was done using BONFERRONI method (Post-Hoc tests). The results showed highest peroxide penetration from 30% hydrogen peroxide followed by mixture of sodium perborate with 30% hydrogen peroxide, mixture of sodium perborate with distilled water and least penetration from 10% carbamide peroxide gel. The results were statistically significant. Radicular peroxide leakage in 10% carbamide peroxide was significantly lower than the other tested bleaching agents making it a very safe alternative for intracoronal bleaching. How to cite this article: Madhu KS, Hegde S, Mathew S, Lata DA, Bhandi SH, Shruthi N. Comparison of Radicular Peroxide Leakage from four Commonly used Bleaching agents following Intracoronal Bleaching in Endodontically treated teeth - An In Vitro Study. J Int Oral Health 2013; 5(4):49-55.

A rapid analytical method to quantify complex organohalogen contaminant mixtures in large samples of high lipid mammalian tissues.

PubMed

Desforges, Jean-Pierre; Eulaers, Igor; Periard, Luke; Sonne, Christian; Dietz, Rune; Letcher, Robert J

2017-06-01

In vitro investigations of the health impact of individual chemical compounds have traditionally been used in risk assessments. However, humans and wildlife are exposed to a plethora of potentially harmful chemicals, including organohalogen contaminants (OHCs). An alternative exposure approach to individual or simple mixtures of synthetic OHCs is to isolate the complex mixture present in free-ranging wildlife, often non-destructively sampled from lipid rich adipose. High concentration stock volumes required for in vitro investigations do, however, pose a great analytical challenge to extract sufficient amounts of complex OHC cocktails. Here we describe a novel method to easily, rapidly and efficiently extract an environmentally accumulated and therefore relevant contaminant cocktail from large (10-50 g) marine mammal blubber samples. We demonstrate that lipid freeze-filtration with acetonitrile removes up to 97% of blubber lipids, with minimal effect on the efficiency of OHC recovery. Sample extracts after freeze-filtration were further processed to remove residual trace lipids via high-pressure gel permeation chromatography and solid phase extraction. Average recoveries of OHCs from triplicate analysis of killer whale (Orcinus orca), polar bear (Ursus maritimus) and pilot whale (Globicephala spp.) blubber standard reference material (NIST SRM-1945) ranged from 68 to 80%, 54-92% and 58-145%, respectively, for 13 C-enriched internal standards of six polychlorinated biphenyl congeners, 16 organochlorine pesticides and four brominated flame retardants. This approach to rapidly generate OHC mixtures shows great potential for experimental exposures using complex contaminant mixtures, research or monitoring driven contaminant quantification in biological samples, as well as the untargeted identification of emerging contaminants. Copyright © 2017 Elsevier Ltd. All rights reserved.

Probable effects of the proposed Sulphur Gulch Reservoir on Colorado River quantity and quality near Grand Junction, Colorado

USGS Publications Warehouse

Friedel, M.J.

2004-01-01

A 16,000 acre-foot reservoir is proposed to be located about 25 miles east of Grand Junction, Colorado, on a tributary of the Colorado River that drains the Sulphur Gulch watershed between De Beque and Cameo, Colorado. The Sulphur Gulch Reservoir, which would be filled by pumping water from the Colorado River, is intended to provide the Colorado River with at least 5,412.5 acre-feet of water during low-flow conditions to meet the East Slopes portion of the 10,825 acre-feet of water required under the December 20, 1999, Final Programmatic Biological Opinion for the Upper Colorado River. The reservoir also may provide additional water in the low-flow period and as much as 10,000 acre-feet of water to supplement peak flows when flows in the Colorado River are between 12,900 and 26,600 cubic feet per second. For this study, an annual stochastic mixing model with a daily time step and 1,500 Monte Carlo trials were used to evaluate the probable effect that reservoir operations may have on water quality in the Colorado River at the Government Highline Canal and the Grand Valley Irrigation Canal. Simulations of the divertible flow (ambient background streamflow), after taking into account demands of downstream water rights, indicate that divertible flow will range from 621,860 acre-feet of water in the driest year to 4,822,732 acrefeet of water in the wettest year. Because of pumping limitations, pumpable flow (amount of streamflow available after considering divertible flow and subsequent pumping constraints) will be less than divertible flow. Assuming a pumping capacity of 150 cubic feet per second and year round pumping, except during reservoir release periods, the simulations indicate that there is sufficient streamflow to fill a 16,000 acre-feet reservoir 100 percent of the time. Simulated pumpable flows in the driest year are 91,669 acre-feet and 109,500 acre-feet in the wettest year. Simulations of carryover storage together with year-round pumping indicate that there is generally sufficient pumpable flow available to refill the reservoir to capacity each year following peak-flow releases of as much as 10,000 acrefeet and low-flow releases of 5,412.5 acre-feet of water. It is assumed that at least 5,412.5 acre-feet of stored water will be released during low-flow conditions irrespective of the hydrologic condition. Simulations indicate that peak-flow release conditions (flows between 12,900 and 26,600 cubic feet per second) to allow release of 10,000 acre-feet of stored water in the spring will occur only about 50 percent of the time. Under typical (5 of 10 years) to moderately dry (3 of 10 years) hydrologic conditions, the duration of the peak-flow conditions will not allow the full 10,000 acre-feet to be released from storage to supplement peak flows. During moderate to extremely dry (2 of 10 years) hydrologic conditions, the peak-flow release conditions will not occur, and there will be no opportunity to release water from storage to supplement peak flows. In general, the simulated daily background dissolved-solids concentrations (salinity) increase due to the reservoir releases as hydrologic conditions go from wet to dry at the Government Highline Canal. For example, the simulated median concentrations during the low-flow period range from 417 milligrams per liter (wet year) to 723 milligrams per liter (dry year), whereas the simulated median concentrations observed during the peak-flow period range from 114 milligrams per liter (wet year) to 698 milligrams per liter (dry year). Background concentration values at the Grand Valley Irrigation Canal are generally only a few percent less than those at the Government Highline Canal except during dry years. Low-flow reservoir releases of 5,412.5 acre-feet and 10,825 acre-feet were simulated for a 30-day period in September, and low-flow releases of 5,412.5 acre-feet were simulated for a 78-day period in the months of August through October. In general, these low-flo

Traditional Portland cement and MgO-based cement: a promising combination?

NASA Astrophysics Data System (ADS)

Tonelli, Monica; Martini, Francesca; Calucci, Lucia; Geppi, Marco; Borsacchi, Silvia; Ridi, Francesca

2017-06-01

MgO/SiO2 cements are materials potentially very useful for radioactive waste disposal, but knowledge about their physico-chemical properties is still lacking. In this paper we investigated the hydration kinetics of cementitious formulations prepared by mixing MgO/SiO2 and Portland cement in different proportions and the structural properties of the hydrated phases formed in the first month of hydration. In particular, the hydration kinetics was investigated by measuring the free water index on pastes by means of differential scanning calorimetry, while the structural characterization was carried out by combining thermal (DTA), diffractometric (XRD), and spectroscopic (FTIR, 29Si solid state NMR) techniques. It was found that calcium silicate hydrate (C-S-H) and magnesium silicate hydrate (M-S-H) gels mainly form as separate phases, their relative amount and structural characteristics depending on the composition of the hydrated mixture. Moreover, the composition of the mixtures strongly affects the kinetics of hydration and the pH of the aqueous phase in contact with the cementitious materials. The results here reported show that suitable mixtures of Portland cement and MgO/SiO2 could be used to modify the properties of hydrated phases with potential application in the storage of nuclear waste in clayey disposal.

Toluene diisocyanate based phase-selective supramolecular oil gelator for effective removal of oil spills from polluted water.

PubMed

Wang, Yongzhen; Wang, Youshan; Yan, Xingru; Wu, Songquan; Shao, Lu; Liu, Yuyan; Guo, Zhanhu

2016-06-01

Due to tremendous resource wastes and great harm to ecological environment caused by the accidental oil spills, an alkyl bicarbamate supramolecular oil gelator was synthesized and applied to selectively gelate oils from oil/water mixtures. Interestingly, the oil gelator could be self-assembled in a series of organic solvents, i.e., edible oils and fuel oils to form 3D networks and then turned into thermally reversible organogels, allowing easy separation and removal of oil spills from oil/water mixtures. The possible self-assembly mode for the formation of organogels was proposed. What's more, the optimal conditions for using the oil gelator to recover oils were experimentally determined. Inspiringly, taking gasoline as the co-congealed solvent, a complete gelation of oil phase was achieved within 15 min with high oil removal rate and oil retention rate after convenient salvage and cleanup of oil gels from oil/water mixtures. The oil gelator had some advantages in solidifying oil spills on water surface, exhibiting fast oil gelation, convenient and thorough oil removal and easy recovery. This work illustrates the significant role of oil gelators in the potential cleanup of spilled oils for water purification. Copyright © 2016 Elsevier Ltd. All rights reserved.