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Polyacrylamide
Terms modified by Polyacrylamide Selected AbstractsINFILTRATION OF WASTEWATER AND SIMULATED RAINWATER AS AFFECTED BY POLYACRYLAMIDE,JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 4 2002Duane T. Gardiner ABSTRACT: Irrigation reduces infiltration rates for subsequent irrigations or rains, thus decreasing the efficiency of water use and impacting watersheds in agricultural areas. Reduced infiltration causes greater runoff with its accompanying erosion, pollution, and sedimentation. Small rates of polyacrylamide (PAM) improve infiltration and reduce erosion on irrigated fields. The effects of PAM on infiltration of rainwater, the longevity of the effects of various rates of PAM, and the effects of repeated or intermittent PAM applications are not understood. This study measured the effects of four PAM application rates (0, 10, 25, and 40 ppm) on the subsequent infiltration of wastewater or simulated rainwater for seven weeks following the initial treatments. Also, effects of repeated and intermittent PAM applications on infiltration were determined. Hydraulic conductivity was determined for each soil column using the falling head method. Two soil types from the coastal plain of south Texas were tested , a soil high in clay (Victoria) and a sandy loam (Willacy). Effects of PAM rates were significant, but effects of water type were not (P > 0.05). Benefits from single PAM applications disappeared within two weeks. Water enriched with PAM is so viscous and infiltrates so slowly that applying PAM in every irrigation event may not be feasible. However, repeating PAM applications every two weeks maintained high infiltration rates on the alternate weeks. This intermittent application of PAM may be a practical approach for improving infiltration rates on irrigated lands. [source] A fluorescence study on swelling of hydrogels (PAAm) at various cross-linker contentsADVANCES IN POLYMER TECHNOLOGY, Issue 4 2009Demet Kaya Akta Abstract Disk-shaped acrylamide (AAm) gels were prepared from AAm with various N,N,-methylenebisacrylamide (Bis) contents as cross-linker in the presence of ammonium persulfate as an initiator by free-radical cross-linking copolymerization in water. Polyacrylamide (PAAm) gels were dried before using for swelling experiments. Steady-state fluorescence spectrometer was employed during the swelling of PAAm hydrogels in water. Pyranine was introduced as a fluorescence probe. Fluorescence intensity of pyranine from various Bis content gel samples was measured during in situ swelling process. It was observed that fluorescence intensity decreased as swelling has proceeded. Gravimetric and volumetric experiments were also performed. The Li,Tanaka equation was used to determine the swelling time constants, ,c, and cooperative diffusion coefficients, Dc, from intensity, weight, and volume variations during the swelling processes. It was observed that swelling time constants, ,c, increased and diffusion coefficients, Dc, decreased as the cross-linker content was increased. © 2010 Wiley Periodicals, Inc. Adv Polym Techn 28:215,223, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20163 [source] Surface modification of PHBV films with different functional groups: Thermal properties and in vitro degradationJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2010Yu Ke Abstract Polyacrylamide was photografted on solution-cast poly(3-hydroxybutyric acid- co -3-hydroxyvaleric acid) (PHBV) films (amide-PHBV), on which amide groups were transformed into amine groups through Hofmann degradation reaction (amine-PHBV), followed by collagen coupling reaction to prepare collagen-modified PHBV (collagen-PHBV). Amide-, amine-, and collagen-PHBV had higher water absorption and d -spacing values than PHBV, and melting temperatures and enthalpies decreased in the order of collagen-PHBV < amine-PHBV < amide-PHBV < PHBV. Thermal decomposition kinetics of PHBV component in the films has been investigated by means of nonisothermal thermogravimetric and derivative thermogravimetric studies. Applying the Avrami-Erofeev equation with index of 2/5 as the probable kinetic function, the suitable activation energy was calculated by the Friedman method through linear fitting (correlation coefficient > 0.98). The activation energy of PHBV was lower than that of amide-PHBV but higher than that of amine- and collagen-PHBV. Being incubated in phosphate-buffered saline at 37°C, the modified PHBV films showed more weight loss than PHBV during 360 days; however, pH of degradation fluids was nearly neutral as the initial pH was recorded at 7.2. The modified PHBV films with different functional groups may provide an improved biodegradation rate for various cytocompatible biomaterials constructs. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Asymmetric Polymer Bridging Between Starch-Coated Colloidal Particles and Pulp Fibres by Cationic PolyacrylamideTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 5 2007Agatha Poraj-Kozminski Abstract Internal sizing agents are commonly used as additives in papermaking to impart hydrophobicity to paper. They are commonly added in the form of colloidal particles, stabilized by cationic starch. As an example we studied the deposition of micron-sized Alkyl Ketene Dimer (AKD) particles on pulp fibres by cationic polyacrylamide (cPAM), a common flocculent. It was found that cPAM did not adsorb on AKD particles stabilized by cationic starch. Despite this inability to adsorb, cPAM was found to drastically improve the deposition of AKD particles on pulp fibres. This deposition was ascribed to asymmetric polymer bridging, a phenomenon observed by us before, while studying clay deposition on fibres by polyethylene oxide. In asymmetric polymer bridging between two types of particles, the bridging polymer first adsorbs on one type of particle, since it is unable to adsorb on the second type. Asymmetric polymer bridging occurs when the enthalpy gain on both surfaces exceeds the entropy loss. The kinetics of AKD deposition on fibres was found to agree with the predictions of the asymmetric bridging theory. In addition, an increase in bond strength with time was found, due to starch and cPAM reconfiguration. The increase in AKD retention by cPAM is also observed in experiments on a laboratory twin-wire sheet former. Asymmetric polymer bridging by cPAM between starch-coated AKD particles and fibres is compared with classical polymer bridging by cPAM between fibres and AKD particles coated by carboxymethylcellulose. Des agents d'encollage internes sont communément utilisés comme additifs dans la fabrication du papier pour transmettre l'hydrophobicité au papier. Ils sont communément ajoutés sous la forme de particules colloïdales, stabilisées par l'amidon cationique. À titre d'exemple, on a étudié la déposition de particules microniques de dimère de cétène d'alkyle (AKD) sur des fibres de pâte par le polyacrylamide cationique (cPAM), un floculant commun. On a trouvé que le cPAM ne s'adsorbait pas sur les particules d'AKD stabilisées par l'amidon cationique. Malgré cette incapacité à s'adsorber, on a trouvé que le cPAM améliorait considérablement la déposition des particules d'AKD sur les fibres de pâte. Cette déposition est imputée au pontage de polymères asymétriques, un phénomène que nous avons observé précédemment, lors de l'étude de la déposition d'argile sur les fibres par l'oxyde de polyéthylène. Dans le pontage de polymères asymétriques entre deux types de particules, le polymère de pontage s'adsorbe d'abord sur un type de particules, vu qu'il est incapable de s'adsorber sur le second type de particules. Le pontage de polymères asymétriques survient lorsque le gain d'enthalpie sur les deux surfaces excède la perte d'entropie. On a trouvé que la déposition d'AKD sur les fibres concordait avec les prédictions de la théorie de pontage asymétrique. En outre, on a observé une augmentation de la force de liaison dans le temps, en raison de la reconfiguration de l'amidon et du cPAM. L'augmentation de la rétention de l'AKD par le cPAM est également observée dans les expériences sur un appareil de formage de feuilles à double toile de laboratoire. Le pontage de polymères asymétriques par le cPAM entre les particules d'AKD enduites d'amidon et les fibres est comparé au pontage de polymères classique par le cPAM entre les fibres et les particules d'AKD enduites de carboxyméthylcellulose. [source] Polyacrylamide-Based Functional Polymer-Immobilized Perruthenate for Aerobic Alcohol Oxidation.CHEMINFORM, Issue 42 2007Hiromi Hamamoto Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] ChemInform Abstract: Synthesis of Azidohydrins from Epoxides Using Quaternized Amino Functionalized Cross-Linked Polyacrylamide as a New Polymeric Phase-Transfer Catalyst.CHEMINFORM, Issue 7 2002B. Tamami Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Complications from Injectable Polyacrylamide Gel, a New Nonbiodegradable Soft Tissue FillerDERMATOLOGIC SURGERY, Issue 12p2 2004Snehal P. Amin Background. Polyacrylamide gels, containing a hydrogel composed of polyacrylamide and water, are used for soft tissue augmentation and contour correction. There are no reports of significant complications after injection of this material into the face. Objective. We report an inflammatory reaction after injection of polyacrylamide gels for zygomatic facial augmentation. Methods. A retrospective chart review of single case is presented. Results. An inflammatory reaction at the sites of polyacrylamide gels injection was noted at 1 month after initial injection. Despite two ensuing courses of broad-spectrum antibiotics, the patient presented to us with persistent draining nodules. Intralesional steroid injections resulted in prompt resolution and no recurrence. Conclusion. Inflammatory reactions have been noted in patients receiving polyacrylamide gels for breast augmentation. Facial polyacrylamide gels injections may also be associated with an inflammatory reaction that responds to intralesional steroids. With increasing availability of a variety of soft tissue fillers, dermatologists should be aware of this delayed complication from polyacrylamide gels. [source] The autocorrelation matrix probing biochemical relationships after metabolic fingerprinting with CEELECTROPHORESIS, Issue 7 2009Santiago Angulo Abstract Fingerprinting together with statistical analysis is often employed to compare samples in metabonomic studies of a disease. Correlation algorithms can aid by extracting information based on the variation patterns of key metabolites. This information can be linked to metabolite identification or to specific up/down-regulated biochemical pathways. Matlab-based software employing the Pearson's correlation algorithm was applied to urine electropherograms from 20 mice infected with the schistosoma parasite. The fingerprints were the sum of electropherograms analysed with normal and reverse polarity, in two different modes MEKC and CZE and with two different capillaries (uncoated and polyacrylamide coated) to provide a broad picture of the samples. Hippurate, a metabolite that was depleted in the infected group and is present in both polarities, was chosen as a test variable; it correlated with itself to a p value of <0.000. Phenylacetylglycine, a metabolite shown as over expressed in the disease, was positively correlated to three metabolites in its same pathway with a correlation coefficient of 0.7 and p<0.000 to phenylalanine, 0.7 and p<0.000 to 2-hydroxyphenylacetic and 0.55 and p<0.003 to phenylacetate. The study shows that the autocorrelation matrix is able to provide extra information from data files acquired by CE analyses. It underlined an up-regulated metabolic path by association in the schistosoma infection model. [source] Effects of lactate and acetate on the determination of serum ethyl glucuronide by CZEELECTROPHORESIS, Issue 23 2006Michaela Mrázková Abstract The analysis of ethyl glucuronide,(EtG), a marker of recent alcohol consumption, in serum with an optimized CZE assay is reported. The method uses a 0.1-mm,id fused-silica capillary of 50,cm effective length that is coated with linear polyacrylamide, a pH,4.4 nicotinic acid/,-aminocaproic acid (EACA) BGE, reversed polarity and indirect analyte detection. The assay is based on a 1:1 dilution of serum with deionized water and has LODs for EtG, lactate and acetate of 3.8×10,7,M, 2.60×10,6,M and 2.18×10,6,M, respectively. Separation of EtG from endogenous macro- and microcomponents (anionic serum components of high and low concentration, respectively) and its quantification are shown to be possible for a wide range of lactate (stacker) and acetate (destacker) concentrations, macrocomponents that have an impact on the CZE behavior of EtG and that change after intake of ethanol. The assay has been successfully applied to the analysis of EtG, lactate and acetate in (i),sera of volunteers that ingested known amounts of alcohol and (ii),samples of patients that were classified (teetotalers and social drinkers vs. alcohol abusers) via analysis of carbohydrate-deficient transferrin. [source] Scale-up development of high-performance polymer matrix for DNA sequencing analysisELECTROPHORESIS, Issue 19 2006Fen Wan Abstract Linear polyacrylamide (LPA) has been widely used as a replaceable separation matrix in CE. An increase in the molecular weight of the separation medium favors the separation of larger DNA fragments. In order to obtain ultrahigh-molecular-weight (UHMW) LPA, a "frozen" method was developed to synthesize the LPA homopolymer. This approach has three major advantages when compared with other existing routes of LPA synthesis: (i),long LPA chains could be obtained easily, with their average molecular weight (MW) being in the high 10,MDa range; (ii),the desired MW could be adjusted over a broad range by controlling the temperature and the concentration of initiators during synthesis; (iii),the product solution contains only a tiny amount of impurity besides the solvent and LPA. Both static and dynamic laser light scattering measurements were carried out to characterize the synthesized LPA in the buffer solution. The DNA sequencing matrix prepared from LPA using this method was studied and the results were compared with the newly developed commercial product POP7 from Applied Biosystems. It should be noted that this approach can be applied to synthesize other water-soluble polymers, resulting in UHMW products because the chain transfer constant is smaller at lower temperatures. [source] A robust cross-linked polyacrylamide coating for microchip electrophoresis of dsDNA fragmentsELECTROPHORESIS, Issue 19 2006Joann J. Lu Abstract Surface derivatization plays an important role in microchip electrophoresis. It not only enhances the resolution, but also improves the reproducibility. So far, the most popularly used derivatization method for glass microchannels is to covalently attach a layer of linear polyacrylamide,(LPA) to the channel surfaces. However, LPA coating has two problems: incomplete coverage and limited lifetime. To address these issues, we have recently developed a cross-linked polyacrylamide,(CPA) derivatization protocol and demonstrated it for high-resolution protein separations by CIEF, CGE, and CZE. In this report, we used this protocol to coat microchip channels and exhibited the reliability and robustness of CPA coating for microchip electrophoresis of DNA molecules. dsDNA fragments were used as our test samples. High resolutions were obtained for fragments ranging from 100,bp to 10,kpb. After more than 800,runs, the CPA-coated microchannels still performed well and comparable resolutions were maintained throughout these runs. [source] An optimized microchip electrophoresis system for mutation detection by tandem SSCP and heteroduplex analysis for p53,gene exons,5,9ELECTROPHORESIS, Issue 19 2006Christa N. Hestekin Abstract With the complete sequencing of the human genome, there is a growing need for rapid, highly sensitive genetic mutation detection methods suitable for clinical implementation. DNA-based diagnostics such as single-strand conformational polymorphism (SSCP) and heteroduplex analysis (HA) are commonly used in research laboratories to screen for mutations, but the slab gel electrophoresis (SGE) format is ill-suited for routine clinical use. The translation of these assays from SGE to microfluidic chips offers significant speed, cost, and sensitivity advantages; however, numerous parameters must be optimized to provide highly sensitive mutation detection. Here we present a methodical study of system parameters including polymer matrix, wall coating, analysis temperature, and electric field strengths on the effectiveness of mutation detection by tandem SSCP/HA for DNA samples from exons,5,9 of the p53 gene. The effects of polymer matrix concentration and average molar mass were studied for linear polyacrylamide (LPA) solutions. We determined that a matrix of 8%,w/v 600,kDa LPA provides the most reliable SSCP/HA mutation detection on chips. The inclusion of a small amount of the dynamic wall-coating polymer poly- N -hydroxyethylacrylamide in the matrix substantially improves the resolution of SSCP conformers and extends the coating lifetime. We investigated electrophoresis temperatures between 17 and 35°C and found that the lowest temperature accessible on our chip electrophoresis system gives the best condition for high sensitivity of the tandem SSCP/HA method, especially for the SSCP conformers. Finally, the use of electrical fields between 350 and 450,V/cm provided rapid separations (<10,min) with well-resolved DNA peaks for both SSCP and HA. [source] SDS-CGE of proteins in microchannels made of SU-8 filmsELECTROPHORESIS, Issue 18 2006Maria Agirregabiria Abstract This work describes the SDS-CGE of proteins carried out in microchannels made of the negative photoresist EPON SU-8. Embedded electrophoretic microchannels have been fabricated with a multilayer technology based on bonding and releasing steps of stacked SU-8 films. This technology allows the monolithic integration of the electrodes in the device. A high wafer fabrication yield and mass production compatibility guarantees low costs and high reliability. A poly(methyl methacrylate) (PMMA) packaging allows an easy setup and replacement of the device for electrophoresis experiments. In addition, the wire-bonding step is avoided. The electrophoretic mobilities of four proteins have been measured in microchannels filled with polyacrylamide. Different pore sizes have been tested obtaining their Ferguson plots. Finally, a separation of two proteins (20 and 36,kDa) has been carried out confirming that this novel device is suitable for protein separation. A resolution of 2.75 is obtained. This is the first time that this SU-8 microfluidic technology has been validated for SDS-CGE of proteins. This technology offers better separation performance than glass channels, at lower costs and with an easy packaging procedure. [source] Proteomic mapping of the hyperthermophilic and acidophilic archaeon Sulfolobus solfataricus P2ELECTROPHORESIS, Issue 14 2006Richard C. Barry Abstract A proteomic map of Sulfolobus solfataricus,P2, an archaeon that grows optimally at 80°C and pH,3.2, was developed using high-resolution 2-DE and peptide mass fingerprinting. A total of 867,protein spots (659,aqueous Tris-soluble spots and 208,aqueous Tris-insoluble) were mapped over IPG,3,10, 4,7, and 6,11, with second-dimensional gels made of 8,18%,polyacrylamide. Three hundred and twenty-four different gene products were represented by the 867,spots, with 274,gene products being identified in the Tris-soluble fractions and 100,gene products in the Tris-insoluble portion. Fifty gene products were found on gels from both fractions. Additionally, an average of 1.50 ± 0.12 isoforms/protein was identified. This mapping study confirmed the expression of proteins involved in numerous metabolic, transport, energy production, nucleic acid replication, translation, and transcription pathways. Of particular interest, phosphoenolpyruvate carboxykinase,(SSO2537) was detected even though the pathway for gluconeogenesis is unknown for this archaeon. Tris-soluble fractions contained many cytosolic proteins while Tris-insoluble fractions contained many membrane-associated proteins, including ABC transporters and an ATP synthase. This study provides an optimized 2-DE approach for investigating the biochemical pathways and post-translational modifications employed by Sulfolobus to survive in its extreme environment. [source] High-buffering capacity, hydrolytically stable, low-pI isoelectric membranes for isoelectric trapping separationsELECTROPHORESIS, Issue 20 2004Sanjiv Lalwani Abstract Hydrolytically stable, low-pI isoelectric membranes have been synthesized from low-pI ampholytic components, poly(vinyl alcohol), and a bifunctional cross-linker, glycerol-1,3-diglycidyl ether. The low-pI ampholytic components used contain one amino group and at least two weakly acidic functional groups. The acidic functional groups are selected such that the pI value of the ampholytic component is determined by the pKa values of the acidic functional groups. When the concentration of the ampholytic component incorporated into the membrane is higher than a required minimum value, the pI of the membrane becomes independent of variations in the actual incorporation rate of the ampholytic compound. The new, low-pI isoelectric membranes have been successfully used as anodic membranes in isoelectric trapping separations with pH < 1.5 anolytes and replaced the hydrolytically less stable polyacrylamide-based isoelectric membranes. The new low-pI isoelectric membranes have excellent mechanical stability, low electric resistance, good buffering capacity, and long life time, even when used with as much as 50 W power and current densities as high as 33 mA/cm2 during the isoelectric trapping separations. [source] Vertical agarose gel electrophoresis and electroblotting of high-molecular-weight proteinsELECTROPHORESIS, Issue 11 2003Chad M. Warren Abstract The electrophoretic separation of high-molecular-weight proteins (>,500 kDa) using polyacrylamide is difficult because gels with a large enough pore size for adequate protein mobility are mechanically unstable. A 1% vertical sodium dodecyl sulfate (SDS)-agarose gel electrophoresis (VAGE) system has been developed that allows titin (a protein with the largest known SDS subunit size of 3000,4000 kDa) to migrate over 10 cm in a ,13 cm resolving gel. Such migration gives clear and reproducible separation of titin isoforms. Proteins ranging in size from myosin heavy chain (,,220 kDa) up to titin can be resolved on this gel system. Electroblotting of these very large proteins was nearly 100% efficient. This VAGE system has revealed two titin size variants in rabbit psoas muscle, two N2BA bands in rabbit cardiac muscle, and species differences between titins from rat and rabbit muscle. Agarose electrophoresis should be the method of choice for separation and blotting of proteins with very large subunit sizes. [source] Separation of proteins in a multicompartment electrolyzer with chambers defined by a bed of gel beadsELECTROPHORESIS, Issue 4 2003Marina Cretich Abstract Multicompartment electrolyzers (MEs) with isoelectric membranes were introduced in 1989 for purifying proteins in an electric field. At the basis of ME technology there are membranes consisting of cross-linked copolymers of acrylamide and acrylamido monomers bearing protolytic groups. The technology employed for casting the membranes is an extension of the isoelectric focusing in immobilized pH gradient technique for which specific acrylamido monomers, known with the trade name of Immobiline, have been developed. However, the use of continuous membranes presents several disadvantages. Due to the mechanical characteristics of polyacrylamide, the gel must physically adhere onto a rigid support, which prevents it from collapsing. The support must have a highly porous structure in order to be permeable to proteins. The mechanical fragility of the membranes is one of the main problems that hinders the industrial scale application of ME separators. In order to overcome this problem, we propose to substitute the continuous membranes with a bed of gel beads of identical comonomer composition, obtained by an inverse emulsion polymerization process. [source] Alkaline leaching of printed circuit board sludgeENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, Issue 3 2006S.H. Hu Abstract The purpose of this study was to develop a treatment procedure for processing aluminum-contaminated sludge produced from the coagulation/flocculation process of wastewater treatment in the manufacture of printed circuit boards (PCBs). In this study, the reagent sodium hydroxide (2 N) was used to leach the heavy metal sludge and the dissolution of sludge's aluminum content was roughly 70%. The weight loss of the heavy metal sludge was caused by the dissolution of aluminum content of nearly 20%. Although dissolution of a small amount of copper occurred simultaneously during this leaching process, the dissolution of copper content was restricted within 0.72% in the leaching operation and the copper content was concentrated in the residue to increase the copper level. The large amounts of sodium hydroxide and Al3+ remaining in the leachate were recycled as neutralization and coagulation agents in wastewater treatment. Synthetic heavy metal wastewater was neutralized with the preceding leachate to estimate the reuse feasibility of recovered coagulant. The heavy metal concentration of the effluent met regulation standards after neutralization and precipitation. The settling rate could be significantly enhanced by the addition of 100 ppm supplemental polyacrylamide (PAM). © 2006 American Institute of Chemical Engineers Environ Prog, 2006 [source] Wastewater treatment polymers identified as the toxic component of a diamond mine effluentENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 9 2004Simone J. C. de Rosemond Abstract The EkatiÔ Diamond Mine, located approximately 300 km northeast of Yellowknife in Canada's Northwest Territories, uses mechanical crushing and washing processes to extract diamonds from kimberlite ore. The processing plant's effluent contains kimberlite ore particles (,0.5 mm), wastewater, and two wastewater treatment polymers, a cationic polydiallydimethylammonium chloride (DADMAC) polymer and an anionic sodium acrylate polyacrylamide (PAM) polymer. A series of acute (48-h) and chronic (7-d) toxicity tests determined the processed kimberlite effluent (PKE) was chronically, but not acutely, toxic to Ceriodaphnia dubia. Reproduction of C. dubia was inhibited significantly at concentrations as low as 12.5% PKE. Toxicity identification evaluations (TIE) were initiated to identify the toxic component of PKE. Ethylenediaminetetraacetic acid (EDTA), sodium thiosulfate, aeration, and solid phase extraction with C-18 manipulations failed to reduce PKE toxicity. Toxicity was reduced significantly by pH adjustments to pH 3 or 11 followed by filtration. Toxicity testing with C. dubia determined that the cationic DADMAC polymer had a 48-h median lethal concentration (LC50) of 0.32 mg/L and 7-d median effective concentration (EC50) of 0.014 mg/L. The anionic PAM polymer had a 48-h LC50 of 218 mg/L. A weight-of-evidence approach, using the data obtained from the TIE, the polymer toxicity experiments, the estimated concentration of the cationic polymer in the kimberlite effluent, and the behavior of kimberlite minerals in pH-adjusted solutions provided sufficient evidence to identify the cationic DADMAC polymer as the toxic component of the diamond mine PKE. [source] Enhancing the P trapping of pasture filter strips: successes and pitfalls in the use of water supply residue and polyacrylamideEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 2 2008M. R. Redding Summary In intensive pastoral systems the landscape at ground level is clad in dense, filtering vegetation , yet phosphorus losses in overland flow do occur, and pollution of surface waters is a serious consequence. The use of pre-applied polyacrylamide (PAM) or chitosan to trap particulate phosphorus (PP) and P-sorbing potable water treatment alum residue (PWTR) to enhance vegetative filtering effects is examined here using field and laboratory overland flow simulation (flows from 0.43 to 0.34 litres s,1 (m width),1) and analysis. Fitted equations suggest that up to 40% of dissolved reactive P applied (0.75 mg P litre,1) in overland flow could be captured in a flow length of 2.1 m (1 kg PWTR m,2). Unfortunately, drying decreased PWTR effectiveness, though little of the P captured was readily desorbed. This effect did not appear to be the result of gibbsite formation. Compared with the other treatments, there was a strong treatment effect of pre-applied PAM on the change in PP losses (P < 0.001) over time, though evidence suggests the PAM effect declined during a 44 minute flow period. We showed that the investigated two-pronged approach to the enhancement of the effectiveness of P trapping by pasture had limitations. Laboratory sheet-flow simulations suggest that a field-stable P sorber with sorption characteristics similar to those of the un-dried PWTR could be an effective retention enhancer for dissolved P. Pre-applied PAM can have an effect on particulate-P trapping but was rapidly dissolved and removed by flow. [source] Directed evolution of formate dehydrogenase from Candida boidinii for improved stability during entrapment in polyacrylamideFEBS JOURNAL, Issue 17 2006Marion B. Ansorge-Schumacher In two cycles of an error-prone PCR process, variants of formate dehydrogenase from Candida boidinii were created which revealed an up to 4.4-fold (440%) higher residual activity after entrapment in polyacrylamide gels than the wild-type enzyme. These were identified in an assay using single precursor molecules of polyacrylamide instead of the complete gel for selection. The stabilization resulted from an exchange of distinct lysine, glutamic acid, and cysteine residues remote from the active site, which did not affect the kinetics of the catalyzed reaction. Thermal stability increased at the exchange of lysine and glutamic acid, but decreased due the exchange of cysteine. Overall, the variants reveal very suitable properties for application in a technical synthetic process, enabling use of entrapment in polyacrylamide as an economic and versatile immobilization method. [source] A Gene Therapy Technology-Based Biomaterial for the Trigger-Inducible Release of Biopharmaceuticals in MiceADVANCED FUNCTIONAL MATERIALS, Issue 15 2010Michael M. Kämpf Abstract Gene therapy scientists have developed expression systems for therapeutic transgenes within patients, which must be seamlessly integrated into the patient's physiology by developing sophisticated control mechanisms to titrate expression levels of the transgenes into the therapeutic window. However, despite these efforts, gene-based medicine still faces security concerns related to the administration of the therapeutic transgene vector. Here, molecular tools developed for therapeutic transgene expression can readily be transferred to materials science to design a humanized drug depot that can be implanted into mice and enables the trigger-inducible release of a therapeutic protein in response to a small-molecule inducer. The drug depot is constructed by embedding the vascular endothelial growth factor (VEGF121) as model therapeutic protein into a hydrogel consisting of linear polyacrylamide crosslinked with a homodimeric variant of the human FK-binding protein 12 (FM), originally developed for gene therapeutic applications, as well as with dimethylsuberimidate. Administrating increasing concentrations of the inducer molecule FK506 triggers the dissociation of FM thereby loosening the hydrogel structure and releasing the VEGF121 payload in a dose-adjustable manner. Subcutaneous implantation of the drug depot into mice and subsequent administration of the inducer by injection or by oral intake triggers the release of VEGF121 as monitored in the mouse serum. This study is the first demonstration of a stimuli-responsive hydrogel that can be used in mammals to release a therapeutic protein on demand by the application of a small-molecule stimulus. This trigger-inducible release is a starting point for the further development of externally controlled drug depots for patient-compliant administration of biopharmaceuticals. [source] Construction and Characterization of Porous SiO2/Hydrogel Hybrids as Optical Biosensors for Rapid Detection of BacteriaADVANCED FUNCTIONAL MATERIALS, Issue 14 2010Naama Massad-Ivanir Abstract The use of a new class of hybrid nanomaterials as label-free optical biosensors for bacteria detection (E. coli K12 as a model system) is demonstrated. The hybrids combine a porous SiO2 (PSiO2) optical nanostructure (a Fabry,Pérot thin film) used as the optical transducer element and a hydrogel. The hydrogel, polyacrylamide, is synthesized in situ within the nanostructure inorganic host and conjugated with specific monoclonal antibodies (IgGs) to provide the active component of the biosensor. The immobilization of the IgGs onto the hydrogel via a biotin-streptavidin system is confirmed by fluorescent labeling experiments and reflective interferometric Fourier transform spectroscopy (RIFTS). Additionally, the immobilized IgGs maintain their immunoactivity and specificity when attached to the sensor surface. Exposure of these modified-hybrids to the target bacteria results in "direct cell capture" onto the biosensor surface. These specific binding events induce predictable changes in the thin-film optical interference spectrum of the hybrid. Preliminary studies demonstrate the applicability of these biosensors for the detection of low bacterial concentrations in the range of 103,105 cell mL,1 within minutes. [source] Abstracts: In vitro/in vivo and analytical evaluation of sunless tanning formulations containing different rheology modifiersINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 5 2010O. V. Dueva-Koganov pp. 73,83 In vitro data suggest that different in vivo performances are expected for two dihydroxyacetone (DHA)-containing formulations with similar concentrations of DHA and excipients but different commercially available rheology modifiers: one with a cationic polymer-based rheology modifier (blend) [dimethylacrylamide/ethyltrimonium chloride methacrylate copolymer (and) propylene glycol dicaprylate/dicaprate (and) PPG-1 trideceth-6 (and) C10-11 isoparaffin]; and the other with a polyacrylamide-based rheology modifier (blend) [polyacrylamide (and) C13-14 isoparaffin (and) laureth-7]. Both rheology modifiers (blends) contained comparable levels of polymers and were used at 3% w/w (as supplied). Differences in color development were illustrated in vitro with respect to the yellow/red and lightness/chroma parameters, which were confirmed in the followup in vivo studies. The test article with the cationic polymer-based rheology modifier produced a more natural sunless tan, comparable to a desirable sun-induced tan, for all panelists, one that was more uniform and lasted longer compared with the sunless tan generated by the test article with the polyacrylamide-based rheology modifier. A method for HPLC analysis of DHA in sunless tanning formulations was established and utilized to confirm concentrations of DHA in test articles. [source] Synthesis and characterization of polyacrylamides containing meso -2,3-dimercaptosuccinic acid end groupsADVANCES IN POLYMER TECHNOLOGY, Issue 1 2010Cemal Özero Abstract By using meso -2,3-dimercaptosuccinic acid-cerium(IV) sulfate and meso -2,3-dimercaptosuccinic acid-potassium permanganate redox systems, the polymerization reaction of acrylamide (AAm) monomer was examined in aqueous acidic medium at low temperatures. Water-soluble polyacrylamides bearing meso -2,3-dimercaptosuccinic acid end groups were synthesized using meso -2,3-dimercaptosuccinic acid as a reducing agent. The effects of parameters such as the molar ratio of acrylamide to initiator, temperature, polymerization time, and sulfuric acid concentration on the yields and molecular weights of polymers were investigated. The augmentation in initiator concentration resulted in a decrease in molecular weight but an increase in the yield of polymers. The increase in reaction temperature from 20 to 60°C led to a decrease in the yield from 56.80% to 20.58%. Ce(IV) and Mn(VII) ions are reduced to Ce(III) and Mn(II) ions in the polymerization reaction and the synthesized acrylamide polymers containing meso -2,3-dimercaptosuccinic acid end groups can absorb these ions at the end of the polymerization reaction. Ultraviolet-visible and atomic absorption measurements of polymer solutions were performed to indicate complexation between polyacrylamide and Ce(III) ions or Mn(II) ions. © 2010 Wiley Periodicals, Inc. Adv Polym Techn 29:45,53, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20180 [source] Novel polymeric flocculants based on polyacrylamide grafted dextran in kaolin suspensionJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010S. Krishnamoorthi Abstract A study is done on ceric-ammonium-nitrate (CAN) initiated graft copolymerization of polyacrylamide (PAM) on to dextran (Dx) by solution polymerization technique. The average molecular weight of dextran is 7.0 × 10,6 g/mole. By changing the concentrations of the initiator in the reaction feed, a series of graft copolymer (Dx-g-PAM1 to Dx-g-PAM4) with variation in the number and length of the grafted PAM chains are obtained. The flocculation characteristics of various polymers are investigated by the use of settling tests in 2 wt % using kaolin suspensions. Among the series of graft copolymers, the one with highest molecular weight shows superior performance. The flocculation characteristics of the best-performing graft copolymer (Dx-g-PAM3) are compared with those of various commercially available flocculants and PAM in the kaolin suspension. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Poly(vinyl alcohol),polyacrylamide blends with cesium salts of heteropolyacid as a polymer electrolyte for direct methanol fuel cell applicationsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2010M. Helen Abstract A class of inorganic,organic hybrid membranes with low methanol permeability characteristics for possible direct methanol fuel cell (DMFC) applications was architected, formulated, and fabricated through the blending of poly(vinyl alcohol) (PVA) and polyacrylamide (PAM) followed by crosslinking with glutaraldehyde (Glu). Cesium salts of different heteropolyacids, including phosphomolybdic acid (PMA), phosphotungstic acid (PWA), and silicotungstic acid (SWA), were incorporated into the polymer network to form corresponding hybrid membrane materials, namely, PVA,PAM,CsPMA,Glu, PVA,PAM,CsPWA,Glu, and PVA,PAM,CsSWA,Glu, respectively (where "Cs" together with a heteropolyacid abbreviation indicates the cesium salt of that acid). All the three hybrid polymer membranes fabricated exhibited excellent swelling, thermal, oxidative, and additive stability properties with desired proton conductivities in the range 10,2 S/cm at 50% relative humidity. A dense network formation was achieved through the blending of PVA and PAM and by crosslinking with Glu, which led to an order of magnitude decrease in the methanol permeability compared to the state-of-the-art commercial Nafion 115 membrane. The hybrid membrane containing CsSWA exhibited a very low methanol permeability (1.4 × 10,8 cm2/s) compared to other membranes containing cesium salt of heteropolyacids such as PMA and PWA. The feasibility of these hybrid membranes as proton-conducting electrolytes in DMFC was investigated, and the preliminary results were compared with those of Nafion 115. The results illustrate the attractive features and suitability of the fabricated hybrid membranes as an electrolyte for DMFC applications. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Effect of polymerization method on structure and properties of cationic polyacrylamideJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2008Yinghua Shen Abstract Acrylamide and 2-(methacryloyloxy)ethyltrimethylammonium chloride (AM/MADQUAT) copolymers were synthesized by solution and inverse microemulsion polymerization using (NH4)2S2O8/NaHSO3 as redox initiator at the same feed mole ratio, and their microstructure, such as sequence distribution and composition distribution, was calculated from monomer reactivity ratios of different polymerization methods. The results show that charge distribution is more uniform for copolymer prepared in inverse microemulsion than that in solution, and copolymer composition distribution is close to unity, and maintains approximately at the feed ratio. Furthermore, the influence of the two structures of cationic polyacrylamides on kaolinite floc size and effective floc density, reduction of Zeta potential and floc compressive yield stress had been investigated at pH 7. The results show that the kaolinite floc size and effective floc density are strongly dependent upon copolymer microstructure, with greater floc size and lower effective floc density being observed for copolymer prepared in inverse microemulsion than for that in solution. Copolymer microstructure has a marked effect on the Zeta potential, whose reduction in the magnitude was much greater in the presence of copolymer prepared in inverse microemulsion than that in solution. Greater compressive yield stress was achieved for the strong flocs produced by copolymer prepared in inverse microemulsion than for the weak flocs produced by that in solution. The difference in flocs compressive yield stress may be attributed to flocs structure. Therefore, in this article, a correlation between the cationic polyacrylamide structure and flocculation property for kaolinite suspension was established. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Characterization and solution properties of a partially hydrolyzed graft copolymer of polyacrylamide and dextranJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2008S. Krishnamoorthi Abstract Graft copolymers of dextran (Dx) and polyacrylamide (PAM) were synthesized through the grafting of PAM chains onto a Dx backbone with a ceric-ion-induced solution polymerization technique. By the variation of the amount of the initiator (ceric ammonium nitrate), four different grades of graft copolymers were synthesized. The partial alkaline hydrolysis of Dx- g -PAM was carried out in an alkaline medium. Three grades of partially hydrolyzed products were synthesized through the variation of the amount of alkali. These hydrolyzed graft copolymers were characterized with elemental analysis, infrared spectroscopy, neutralization equivalent measurements, a rheological technique, scanning electron microscopy, thermal analysis, viscometry, and X-ray diffraction. The flocculation efficiency and viscosifying characteristics of the graft copolymers were enhanced upon their alkaline hydrolysis. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008. [source] Polymer-acid solutions: Their use for the enhancement of oil reservoir stimulationJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2008Mohammed M. Amro Abstract A reduction in permeability occurring around the wellbore resulting from drilling, completion and/or workover fluids increases the flow resistance to the petroleum reservoir fluids and is defined as formation damage. Acidizing process removes near-wellbore damage and enhances hydrocarbon production from producing wells. This study investigates the effect of adding polymer as a retarding agent to acid solutions to slow and control the reaction in matrix acidizing treatment of carbonate rocks. Two different polymers, polyacrylamide (PAA) and polysaccharide (xanthan) and two different acids, acetic acid and formic acid, were used through this study. The results revealed that the presence of PAA did not change the viscosity of the acid solution significantly, while the viscosity of xanthan-acid solutions was decreased with increasing the acid concentration. Additionally, the reaction of polymer-acid solutions with the rock material was monitored under microscope. Original rock samples obtained from Saudi reservoirs containing mainly carbonate were used in the reaction. The PAA-acid solution did not show any decrease in the reaction rate compared to that of acid solution. Thus, the PAA solution applied in this study is not recommended as a retarder. However, xanthan-acid solutions showed a significant decrease in the reaction time. Therefore, xanthan was selected to perform further investigations in Rotating Disk Reactor at different pressures. Scanning electronic microscopy (SEM) was conducted on pretreated and posttreated rock samples. This provides the opportunity to perform a detailed description of the rock surface and facilitates the identification of the changes occurring due to polymer-acid treatment. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] | ||||||||||||||||||||||