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Various pH (various + ph)
Terms modified by Various pH Selected AbstractsMechanistic study of electroosmotic transport across hydrated nail plates: Effects of pH and ionic strengthJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 12 2008Jinsong Hao Abstract The objective of this study was to investigate the effects of pH and ionic strength on electroosmotic transport in transungual iontophoresis. Transungual iontophoretic transport of model neutral permeants mannitol (MA) and urea (UR) across fully hydrated human nail plates in phosphate-buffered saline of different pH and ionic strengths were investigated in vitro. Two protocols were involved in the transport experiments with each protocol divided into stages including passive and iontophoresis transport at 0.1 and/or 0.3 mA. Nail plate electrical resistance and water uptake of nail clippings were measured at various pH and ionic strengths. In the pH study, electroosmosis enhanced the anodal transport of MA at pH 9 and cathodal transport at pH 3. The Peclet numbers of MA were more than two times higher than those of UR under these conditions. No significant electroosmosis enhancement was observed for MA and UR at pH 5. In the ionic strength study, a decrease in solution ionic strength from 0.7 to 0.04 M enhanced electroosmotic transport. Nail electrical resistance increased with decreasing the ionic strength of the equilibrating solution, but reached a plateau when the ionic strength was less than approximately 0.07 M. Solution pH and ionic strength had no significant effect on nail hydration. Under the studied pH and ionic strength conditions, the effects of electroosmosis were small compared to the direct-field effects in transungual iontophoretic transport of small to moderate size permeants. © 2008 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 97:5186,5197, 2008 [source] Capillary electrophoresis of intact basic proteins using noncovalently triple-layer coated capillariesJOURNAL OF SEPARATION SCIENCE, JSS, Issue 14 2009Rob Haselberg Abstract The usefulness of a noncovalent, positively charged capillary coating for the efficient analysis of intact basic proteins with CE was studied. Capillaries were coated by subsequent flushing with solutions of 10% w/v Polybrene (PB), 3% w/v dextran sulfate (DS), and again 10% w/v PB. Coating characterization studies showed that stable coatings could be produced which exhibited a pH-independent and highly reproducible EOF. The PB,DS,PB coating was evaluated with Tris phosphate BGEs of various pH using the four basic model proteins: ,-chymotrypsinogen A, ribonuclease A, cytochrome c, and lysozyme. Typical migration time RSDs for the proteins were less than 0.85%, and apparent plate numbers were above 125 000 using a capillary length of 40 cm. The high separation efficiency allowed detection of several minor impurities in the model proteins. Using a BGE of medium pH, the CE system with triple-layer coating appeared to be useful for the repeatable profiling of recombinant humanized mouse monoclonal immunoglobulin G1 showing a characteristic pattern of glycoforms. The CE system was also applied to the characterization of two llama antibodies, which were produced in Saccharomyces cerevisiae, revealing the presence of a side product in one of the antibodies. The high migration time stability allowed the reliable determination of antibody,antigen binding by monitoring migration time shifts. Finally, the feasibility of using the PB,DS,PB coated capillaries for CE with mass spectrometric detection was shown by the characterization of the impure llama antibody sample. [source] Kinetic modeling of lutein production by heterotrophic Chlorella at various pH and temperaturesMOLECULAR NUTRITION & FOOD RESEARCH (FORMERLY NAHRUNG/FOOD), Issue 8 2006Xianming Shi Abstract Kinetics of lutein production by heterotrophic Chlorella protothecoides was investigated with respect to pH and temperature. Flask cultures with initial pH 5.0,8.0 were carried out, and it was found that pH 6.0 was optimal for the algal growth. Further tests in fermentors showed that the highest biomass concentration, maximum cellular lutein content and lutein yield were achieved at pH 6. 6. In addition, it was shown that optimal biomass concentration and lutein yield were obtained at 28°C, while application of 35°C resulted in the highest cellular lutein content. A mathematical model was developed for the description of the processes under these cultivation conditions and the kinetic model fitted well to the experimental data. The obtained results may contribute to the commercial production of lutein by C. protothecoides. [source] Perturbations produced by electrospray ionization mass spectrometry in the speciation of aluminium(III)/1,6-dimethyl-4-hydroxy-3-pyridinecarboxylate aqueous solutionsRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 7 2010Valerio B. Di Marco Electrospray ionization mass spectrometry (ESI-MS) is very often employed to study metal/ligand equilibria in aqueous solution. However, the ionization process can introduce perturbations which affect the speciation results in an unpredictable way. It is necessary to identify these perturbations in order to correctly interpret the ESI-MS speciation results. Aluminium(III)/1,6-dimethyl-4-hydroxy-3-pyridinecarboxylate (DQ716) aqueous solutions at various pH were analysed by ESI-MS, and speciation results were compared with those obtained by equilibrium techniques. Differences observed were both qualitative and quantitative. The ESI-MS spectral changes due to different settings of the following instrumental parameters were analyzed: the solution flow rate (FS), the nebulizer gas flow rate (FG), the potential applied at the entrance capillary (EC), and the temperature of the drying gas (TG). The effects produced by FS and EC on the spectra strongly suggest the key role of surface activity in determining the relative fraction of the ions reaching the detector. The experimental effects of FS and TG were interpreted considering the presence of at least two reactions in the gas phase and a dimerization occurring in the droplets. These perturbations cannot be generalized because they appear to be chemical system-related and instrument-dependent. Therefore, the identification of perturbations is a required task for any metal-ligand equilibrium study performed by ESI-MS. Our results indicate that perturbations can be identified by evaluating the effects produced in the spectra by a change of instrumental parameters. Copyright © 2010 John Wiley & Sons, Ltd. [source] Decolorization of RR-120 Dye Using Ozone and Ozone/UV in a Semi-Batch ReactorTHE CANADIAN JOURNAL OF CHEMICAL ENGINEERING, Issue 6 2004Mohammad Kazemi Abstract Treatability of RR-120 aqueous dye solutions using O3 and O3/UV was studied in a bench scale set-up. Reduction in colour and chemical oxygen demand (COD) under various pH and initial dye concentrations were investigated. Pseudo first order reaction rate was satisfactorily used for kinetic interpretations in destruction of the dye. The results showed that decolorization with O3 was faster at neutral pH values. While use of UV had a small effect on ozonation at low pH values, UV radiation had a considerable effect at pH values of 7 and above. It was found that ozone utilization efficiency of higher than 95% could be attained in the experimental set up. On a étudié la possibilité de traitement de solutions aqueuses de colorant RR-120 à l'aide d'O3 et O3/UV dans un banc d'essai. La réduction de la demande chimique en oxygène (DCO) et en colorant a été étudiée pour différentes concentrations initiales de colorant. La vitesse de réaction du pseudo-premier ordre a été utilisée avec succès pour les interprétations cinétiques de la destruction du colorant. Les résultats montrent que la décoloration avec l'O3 est plus rapide à des valeurs de pH neutres. Alors que le recours aux UV a un faible effet sur l'ozonation à de faibles valeurs de pH, la radiation par UV a un effet considérable à des valeurs de pH de 7 et au-dessus. On a trouvé qu'une efficacité d'utilisation de l'ozone supérieure à 95% pouvait être atteinte dans l'installation expérimentale. [source] Pyruvate Preserves Neutrophilic Superoxide Production in Acidic, High Glucose-Enriched Peritoneal Dialysis SolutionsARTIFICIAL ORGANS, Issue 3 2003Yi Tai Wu Abstract: Aim: To investigate effects of pyruvate (Py)-based peritoneal dialysis solutions (P-PDS) on neutrophilic superoxide (O2,) production against high glucose (HG) concentrations at acidic or physiologic pH value, and explore potential mechanisms. Methods: Human neutrophils were incubated with both dl -lactate (La, 40 mM)-based PDS (L-PDS) and equimolar P-PDS at various pH and HG levels, respectively. Hanks' balanced salt solution (HBSS) served as controls. O2, generation was determined by the reduction of ferricytochrome c. Results: Acidic pH and high La induced acute and substantial inhibitions of O2, production. HG in both PDS and HBSS resulted in a suppression of O2, in a dose-dependent manner. P-PDS generated near twofold O2, formation of L-PDS counterparts at various pH and HG levels. P-PDS with HG produced significantly more O2, than Py-free HBSS counterparts. Conclusions: Py in PDS effectively protected neutrophils from HG-induced inhibition of O2, production, even at a physiological pH. The Py cytoprotection may be associated with the preservation of carbohydrate metabolic pathways in addition to its alkalization. [source] An exclusion mechanism in ion exchange chromatographyBIOTECHNOLOGY & BIOENGINEERING, Issue 5 2006C. Harinarayan Abstract Protein dynamic binding capacities on ion exchange resins are typically expected to decrease with increasing conductivity and decreasing protein charge. There are, however, conditions where capacity increases with increasing conductivity and decreasing protein charge. Capacity measurements on two different commercial ion exchange resins with three different monoclonal antibodies at various pH and conductivities exhibited two domains. In the first domain, the capacity unexpectedly increased with increasing conductivity and decreasing protein charge. The second domain exhibited traditional behavior. A mechanism to explain the first domain is postulated; proteins initially bind to the outer pore regions and electrostatically hinder subsequent protein transport. Such a mechanism is supported by protein capacity and confocal microscopy studies whose results suggest how knowledge of the two types of IEX behavior can be leveraged in optimizing resins and processes. © 2006 Wiley Periodicals, Inc. [source] HMGA1a Protein Unfolds or Refolds Synthetic DNA,Chromophore Hybrid Polymers: A Chaperone-Like BehaviorCHEMBIOCHEM, Issue 2 2008Wei Wan Abstract High group mobility protein, HMGA1a, was found to play a chaperone-like role in the folding or unfolding of hybrid polymers that contained well-defined synthetic chromophores and DNA sequences. The synthetic and biological hybrid polymers folded into hydrophobic chromophoric nanostructures in water, but existed as partially unfolded configurations in pH or salt buffers. The presence of HMGA1a induced unfolding of the hybrid DNA,chromophore polymer in pure water, whereas the protein promoted refolding of the same polymer in various pH or salt buffers. The origin of the chaperone-like properties probably comes from the ability of HMGA1a to reversibly bind both synthetic chromophores and single stranded DNA. The unfolding mechanisms and the binding stoichiometry of protein,hybrid polymers depended on the sequence of the synthetic polymers. [source] Antibody response to aggregated human interferon alpha2b in wild-type and transgenic immune tolerant mice depends on type and level of aggregationJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 5 2006Suzanne Hermeling Abstract The aim of this study was to determine the sensitivity of transgenic immune tolerant mice for the type and level of aggregation of recombinant human interferon alpha2b (rhIFN,2b). RhIFN,2b was aggregated by metal-catalyzed oxidation or by incubation at elevated temperature and various pHs. Native rhIFN,2b was mixed with oxidized rhIFN,2b at different ratios to obtain samples with different aggregation levels. The preparations were characterized by UV and fluorescence spectroscopy, gel permeation chromatography (GPC), dynamic light scattering (DLS), sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS,PAGE) and Western blotting, and ELISA. The immunogenicity was evaluated in wild-type mice and transgenic mice immune tolerant for hIFN,2. Sera were analyzed by ELISA for the presence of rhIFN,2b-specific antibodies. The oxidized and aged preparations widely differed regarding the level and nature of aggregates. All preparations containing aggregates increased the immune response in the wild-type mice as compared to native rhIFN,2b and were able to break the tolerance of the transgenic mice. The more native-like the conformation of the aggregated proteins, the more immunogenic the preparations were in the transgenic mice. The native-like aggregates prepared via metal catalysis induced a dose-dependent loss of tolerance in the transgenic mice. In conclusion, the transgenic mouse model can be used to screen rhIFN,2b formulations for low levels of immunogenic aggregates obtained under accelerated storage conditions. © 2006 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 95:1084,1096, 2006 [source] Kinetic study of electrochemically induced Michael reactions of o -benzoquinones with 2-acetylcyclohexanone and 2-acetylcyclopentanoneJOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 1 2007Davood Nematollahi Abstract The reaction of electrochemically generated o -benzoquinones (2a-f) as Michael acceptors with 2-acetylcyclohexanone (ACH) and 2-acetylcyclopentanone (ACP), as nucleophiles has been studied in various pHs using cyclic voltammetry. The results indicate that the participation of o -benzoquinones (2a-f) in the Michael reaction with acetylcyclohexanone (ACH) to form the corresponding catechol derivatives (4a-f). Based on an EC mechanism, the homogeneous rate constants were estimated by comparing the experimental cyclic voltammetric responses with the digital simulated results. Copyright © 2007 John Wiley & Sons, Ltd. [source] Effect of pH and generation of dendron on single-step synthesis of gold nanoparticles using PEGylated polyamidoamine dendron in aqueous mediumJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 6 2010Atsushi Harada Abstract Three types of PEGylated polyamidoamine (PAMAM) dendrons were synthesized through PEGylation of primary amines at the periphery of second, third, and fourth generation dendrons. Au(III) precursors and the synthesized PEGylated PAMAM dendrons were mixed at various pHs to evaluate the effect of pH on gold nanoparticle (Au NP) synthesis by monitoring the change in surface plasmon resonance. The Au NP synthesis reaction was controlled by pH through the balance between protonated and deprotonated tertiary amines and the reactivity of Au(III) precursors. By using PEGylated PAMAM dendrons with higher generation, the obtained Au NPs had narrow size distribution with small average size because of the limitation of intermolecular space among PEGylated PAMAM dendrons for the growth to Au NP. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1391,1398, 2010 [source] Carrageenan- g -poly(acrylamide)/poly(vinylsulfonic acid, sodium salt) as a novel semi-IPN hydrogel: Synthesis, characterization, and swelling behaviorPOLYMER ENGINEERING & SCIENCE, Issue 9 2007Ali Pourjavadi A semi-interpenetrating polymer network (semi-IPN) hydrogel based on kappa-carrageenan (,C) and poly (vinylsulfonic acid, sodium salt) (PVSA) was prepared by graft copolymerization of acrylamide (AAm) using methylenebisacrylamide (MBA) as a crosslinking agent and ammonium persulfate (APS) as an initiator. FTIR spectroscopy was used for confirming the structure of the final product. It was found that the chemical composition of the Semi-IPN hydrogel is equal to the initial homopolymers and monomer feed compositions. The swelling capacity of the hydrogel was shown to be affected by the MBA, APS, and AAm concentration as well as ,C/PVSA weight ratio. The swelling behavior of the hydrogel was also investigated in various pHs and salt solutions. Since the highly swelling biopolymer-based hydrogel exhibits low salt-sensitivity, it may be referred to as an anti-salt superabsorbent hydrogel. The swelling kinetics of the superabsorbent hydrogels was studied as well. POLYM. ENG. SCI., 47:1388,1395, 2007. © 2007 Society of Plastics Engineers [source] Actions of cathepsins on troponin T during postmortem aging of porcine muscleANIMAL SCIENCE JOURNAL, Issue 4 2010Shin-ichi KITAMURA ABSTRACT In this study, we examined the contribution of the cathepsins (cathepsin D and crude cathepsins containing cathepsins B and L) to troponin T degradation during postmortem aging. The action of cathepsin D on troponin T was examined at various pHs (pH 4.0,6.5). The degradation of intact troponin T was observed at pH 4.0, but not observed at pH 5.5 and 6.5. As a result of the degradation of troponin T, the 30 kDa fragment was not generated in any pH condition. The action of the crude cathepsins on troponin T was also examined at various pHs (pH 4.0,6.5). The intact troponin T was degraded at pH 4.0 and the 30 kDa fragments were observed. These 30 kDa fragments disappeared during further incubation. On the other hand, at pH 5.5 and 6.5, the intact troponin T was degraded and the 30 kDa fragment was accumulated. These results suggested that the cathepsin D scarcely contributed to the degradation of troponin T during postmortem aging, but crude cathepsins containing cathepsins B and L were partially involved in the degradation of troponin T and the generation of 30 kDa fragments. [source] | ||||||||||||||||