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Basic pH (basic + ph)
Terms modified by Basic pH Selected AbstractsHigh-efficiency peptide analysis on monolithic multimode capillary columns: Pressure-assisted capillary electrochromatography/capillary electrophoresis coupled to UV and electrospray ionization-mass spectrometryELECTROPHORESIS, Issue 21 2003Alexander R. Ivanov Abstract High-efficiency peptide analysis using multimode pressure-assisted capillary electrochromatography/capillary electrophoresis (pCEC/pCE) monolithic polymeric columns and the separation of model peptide mixtures and protein digests by isocratic and gradient elution under an applied electric field with UV and electrospray ionization-mass spectrometry (ESI-MS) detection is demonstrated. Capillary multipurpose columns were prepared in silanized fused-silica capillaries of 50, 75, and 100 ,m inner diameters by thermally induced in situ copolymerization of methacrylic monomers in the presence of n -propanol and formamide as porogens and azobisisobutyronitrile as initiator. N -Ethylbutylamine was used to modify the chromatographic surface of the monolith from neutral to cationic. Monolithic columns were termed as multipurpose or multimode columns because they showed mixed modes of separation mechanisms under different conditions. Anion-exchange separation ability in the liquid chromatography (LC) mode can be determined by the cationic chromatographic surface of the monolith. At acidic pH and high voltage across the column, the monolithic stationary phase provided conditions for predominantly capillary electrophoretic migration of peptides. At basic pH and electric field across the column, enhanced chromatographic retention of peptides on monolithic capillary column made CEC mechanisms of migration responsible for separation. The role of pressure, ionic strength, pH, and organic content of the mobile phase on chromatographic performance was investigated. High efficiencies (exceeding 300,000 plates/m) of the monolithic columns for peptide separations are shown using volatile and nonvolatile, acidic and basic buffers. Good reproducibility and robustness of isocratic and gradient elution pressure-assisted CEC/CE separations were achieved for both UV and ESI-MS detection. Manipulation of the electric field and gradient conditions allowed high-throughput analysis of complex peptide mixtures. A simple design of sheathless electrospray emitter provided effective and robust low dead volume interfacing of monolithic multimode columns with ESI-MS. Gradient elution pressure-assisted mixed-mode separation CE/CEC-ESI-MS mass fingerprinting and data-dependent pCE/pCEC-ESI-MS/MS analysis of a bovine serum albumin (BSA) tryptic digest in less than 5 min yielding high sequence coverage (73%) demonstrated the potential of the method. [source] Identification of different isoforms of eEF1A in the nuclear fraction of human T-lymphoblastic cancer cell line specifically binding to aptameric cytotoxic GT oligomersFEBS JOURNAL, Issue 15 2003Barbara Dapas GT oligomers, showing a dose-dependent cytotoxic effect on a variety of human cancer cell lines, but not on normal human lymphocytes, recognize and form complexes with nuclear proteins. By working with human T-lymphoblastic CCRF-CEM cells and by using MS and SouthWestern blotting, we identified eukaryotic elongation factor 1 alpha (eEF1A) as the main nuclear protein that specifically recognizes these oligonucleotides. Western blotting and supershift assays confirmed the nature of this protein and its involvement in forming a cytotoxicity-related complex (CRC). On the contrary, normal human lymphocytes did not show nuclear proteins able to produce CRC in a SouthWestern blot. Comparative bidimensional PAGE and Western-blotting analysis for eEF1A revealed the presence of a specific cluster of spots, focusing at more basic pH, in nuclear extracts of cancer cells but absent in those of normal lymphocytes. Moreover, a bidimensional PAGE SouthWestern blot demonstrated that cytotoxic GT oligomers selectively recognized the more basic eEF1A isoform expressed only in cancer cells. These results suggest the involvement of eEF1A, associated with the nuclear-enriched fraction, in the growth and maintenance of tumour cells, possibly modulated by post-translational processing of the polypeptide chain. [source] Controlled size chitosan nanoparticles as an efficient, biocompatible oligonucleotides delivery systemJOURNAL OF APPLIED POLYMER SCIENCE, Issue 4 2010Romila Manchanda Abstract Polymeric nanoparticles of chitosan crosslinked with glutaraldehyde have been prepared using reverse micellar system. An optically clear solution was obtained on redispersing these nanoparticles in aqueous buffer. The nanoparticles were characterized for their size and surface morphology employing dynamic laser scattering (DLS) and transmission electron microscopy (TEM). The TEM images showed spherical particles with smooth surface and narrow size distribution of about 90 nm, which was also supported by DLS data. Size and morphology of the particles remains the same on redispersing the lyophilized powder of these nanoparticles in aqueous buffer. Further, these nanoparticles were loaded with different synthetic oligonucleotides (ODNs). In vitro pH dependent release of the adsorbed oligonucleotides from these nanoparticles was also studied. At basic pH the release of oligonucleotides was found higher as compared with neutral and acidic medium. Cytotoxicity studies done on HEK 293 cells reveals that oligonucleotide loaded nanoparticles have high cell viability of nearly 76,88% whereas those of lipofectamine was about 35%. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Effect of changes of pH on the anaerobic/aerobic transformations of biological phosphorus removal in wastewater fed with a mixture of propionic and acetic acidsJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 6 2006Yinguang Chen Abstract Most studies on the transformation of enhanced biological phosphorus removal have used acetic acid as the carbon source and focused on the anaerobic phase. In this paper the anaerobic and aerobic transformations of phosphorus removal microorganisms at various pH values were investigated with wastewater containing 3.14 mM C propionic acid and 1.56 mM C acetic acid. It was observed that the influence of acidic pH on the concentrations of mixed-liquor suspended solids and biomass was stronger than that of basic pH, and the maximal cell growth appeared at pH 7.6. The observed uptake rate of propionic acid was much faster than that of acetic acid at all pH values investigated, and both were affected by pH. The anaerobic transformations of polyhydroxyalkanoates and glycogen linearly decreased with increasing pH from 6.6 to 8.6, and a greater glycogen transformation correlated to greater polyhydroxyalkanoate transformation in both anaerobic and aerobic stages. Further studies revealed that at pH 6.6 and 8.6 the overall phosphorus release and uptake was low and there was no net phosphorus removal, although the initial phosphorus release was high. However, when the pH was controlled at pH 7.1 and 7.6, a phosphorus removal efficiency of 97.03% and 96.43% was achieved, respectively, which was greater than that of 87.46% at uncontrolled pH. Copyright © 2006 Society of Chemical Industry [source] Advanced oxidation processes for destruction of cyanide from thermoelectric power station waste watersJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 2 2004José M Monteagudo Abstract Several advanced oxidation processes for the destruction of cyanide contained in waste waters from thermoelectric power stations of combined-cycle were studied. Thus, oxidation processes involving ozonation at basic pH, ozone/hydrogen peroxide, ozone/ultraviolet radiation and ozone/hydrogen peroxide/ultraviolet radiation have been carried out in a semi-batch reactor. All these methods showed that total cyanide can be successfully degraded but with different reaction rates, and the decrease in the total cyanide concentration can be described by pseudo-first order kinetics. The influence of pH and initial concentration of hydrogen peroxide was studied to find the optimal conditions of the oxidation process. Experimental results of the single ozone treatment indicated that total cyanide is destroyed more rapidly at higher pH (12), while ozonation combined with H2O2 and/or UV is faster at pH 9.5. The optimum concentration of H2O2 was 20.58 × 10,2M because an excess of peroxide decreases the reaction rate, acting as a radical scavenger. The total cyanide degradation rate in the O3/H2O2(20.58 × 10,2M) treatment was the highest among all the combinations studied. However, COD reduction, in the processes using UV radiation such as O3/UV or O3/H2O2/UV was about 75%, while in the processes with H2O2 and/or O3/H2O2 was lower than 57% and was insignificant, when using ozone alone. Copyright © 2003 Society of Chemical Industry [source] Amino Acid, Fatty Acid, and Mineral Profiles of Materials Recovered from Rainbow Trout (Oncorhynchus mykiss) Processing By-Products Using Isoelectric Solubilization/PrecipitationJOURNAL OF FOOD SCIENCE, Issue 9 2007Y.-C. Chen ABSTRACT:, Protein, lipid, and insolubles (bones, skin, scales, fins, insoluble protein, and more) were recovered from rainbow trout processing by-products by means of isoelectric solubilization/precipitation at basic pH and acidic pH. Isoelectric solubilization/precipitation of the trout processing by-products resulted in the recovery of protein that was higher (P < 0.05) in essential amino acids (EAAs), non-EAAs, and total EAA/total AA ratio when compared to the processing by-products. Basic pH treatments yielded a higher (P < 0.05) content of EAAs than the acidic pH treatments. Nutritional quality of the recovered protein was high based on EAAs meeting the FAO/WHO/UNU recommendations for adults. The presence of omega-3 and omega-6 fatty acids (,-3, ,-6 FAs) and the ,-3/,-6 ratio in the recovered lipids were similar to the trout processing by-products, indicating that the pH treatments had no effect on these FAs. Ca and P contents of the processing by-products exceeded the recommended dietary allowances (RDA), but Fe and Mg did not. Basic pH treatments yielded protein with the lowest (P < 0.05) amount of minerals and the highest (P < 0.05) amount of Ca, P, and Mg in the insolubles when compared to acidic pH. The isoelectric solubilization/precipitation of the processing by-products effectively removed minerals from the recovered protein without removal of the bones, skin, scales, fins, and so on, prior to processing. The results indicated that isoelectric solubilization/precipitation, particularly at basic pH, permitted recovery of high-quality protein and lipids from fish processing by-products for human food uses; also, the recovered insolubles may be used in animal feeds as a source of minerals. [source] Factors Influencing the Occurrence of Methanethiol in Aqueous Slurries of Soy Protein ConcentratesJOURNAL OF FOOD SCIENCE, Issue 5 2003Q. Lei ABSTRACT : Aqueous slurries of 6 commercial soy protein concentrate (SPC) contained from 9.8 to 21.7 ppb methanethiol, which corresponds to odor values (in water) of 49 to 108. Effects of temperature (5.5, 24, and 65°C), pH (4.8,6.6, and 9.0), transition metals (FeCl3, FeCl2, and CuCl2), lipoxygenase, and EDTA on methanethiol levels in SPC slurries were investigated. Higher temperature (65°C), basic pH (9.0), transition metals, lipoxygenase, and EDTA caused significant increases in methanethiol compared with the control. CuCl2 caused greater increases in methanethiol than FeCl3 and FeCl2. In contrast, treatments with lower temperature (5.5°C) or acidic pH (4.8) resulted in lower levels of methanethiol in all commercial SPC samples examined. [source] Effects of sand and process water pH on toluene diluted heavy oil in water emulsions in turbulent flowAICHE JOURNAL, Issue 1 2009Chandra W. Angle Abstract The presence of sand in heavy oil production is known to enhance oil recovery. Sand can also be detrimental depending on the properties of the sand,water interface. In this process, the water soluble material interacts with both sand and oil droplets and affects emulsion stability. The formation and stability of heavy oil-in-water emulsions during turbulent flow using batch process stirred-tank mixing of oil, sand, and water were investigated at three pH. Size distributions were measured by laser diffraction. High-speed video photomicrography was used to observe the process during mixing. Results showed that the presence of sand enhanced formation of stable, fine emulsion at basic pH 8.5. When the pH of the water was reduced below 6.5 both sand and droplets surface properties changed, the emulsions became less stable and coalescence was apparent. The sand grains acted as coalescers at low pH and enhanced breakage at high pH. © Her Majesty the Queen in Right of Canada, as represented by the Minister of Natural Resources, 2008 AIChE J, 2009 [source] Synthesis and chemical stability of a disulfide bond in a model cyclic pentapeptide: Cyclo(1,4)-Cys-Gly-Phe-Cys-Gly-OHJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 10 2006Henry T. He Abstract Many cyclic peptides are formed using a disulfide bond to increase their conformational rigidity; this provides receptor selectivity and increased potency. However, degradation of the disulfide bond in formulation can lead to a loss of structural stability and biological activity of the peptide. Therefore, the objective of this study was to study the stability of peptide 1 (cyclo(1,4)-Cys-Gly-Phe-Cys-Gly-OH). This cyclic peptide was synthesized using Boc strategy via solution-phase peptide synthesis and purified using semi-preparative HPLC. The accelerated stability studies of the cyclic peptide were conducted in buffer solutions at pH 1.0,11.0 with controlled ionic strengths at 70°C. The pH-rate profile shows that the peptide has an optimal stability around pH 3.0 with a V-shape between pH 1.0 and 5.0. Two small plateaus are observed at pH 5.0,7.0 and pH 8.0,10.0, indicating hydrolysis on different ionized forms of the cyclic peptide. One product was observed at acidic pH due to peptide bond hydrolysis at Gly2-Phe3. The number of degradation products increases as the pH increases from neutral to basic, and most of the degradation products at neutral and basic pH are derived from the degradation at the disulfide bond. © 2006 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 95:2222,2234, 2006 [source] Raman and pulse radiolysis studies of the antioxidant properties of quercetin: Cu(II) chelation and oxidizing radical scavengingJOURNAL OF RAMAN SPECTROSCOPY, Issue 5 2005Armida Torreggiani Abstract Quercetin (Querc), a pentahydroxyflavonol, is suggested to give protection to living organisms by both direct scavenging of free radicals and metal chelation. The scavenging ability of Querc towards oxidizing radicals, such as ,OH, N3, and NO2,, was evaluated by pulse radiolysis studies in aqueous solutions at different pH. Phenoxyl radicals are the final transient products and are formed either by water elimination from ,OH-adducts or by one-electron transfer from the deprotonated OH groups. Their formation rate is strongly affected by pH and reaches the maximum values in alkaline medium. The Raman and IR spectra were useful to assess the relevant interaction of Querc with Cu(II) ions, which play an important role in the metal-catalysed generation of reactive oxygen species. Depending on pH and the metal-to-ligand ratio, the different chelating sites of Querc change their ability to complex copper ions. Under neutral conditions, the 5-OH group of ring A and CO-4 of ring C have a chelating power superior to that of the catechol group (ring B), whereas the complexation in alkaline medium occurs in the reverse order. In addition, experiments with Querc and Zn(II) ions, carried out at basic pH in order to verify the possible Cu(II)-catalysed oxidation of the ligand, indicated the absence of the above process. Copyright © 2005 John Wiley & Sons, Ltd. [source] Correlation between antiradical activity and stability of betanine from Beta vulgaris L roots under different pH, temperature and light conditionsJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 7 2001A Pedreño Abstract When the antiradical activity and stability of betanine were studied at pH values of 3.5 and 8.5 and temperatures of 25, 50 and 75,°C, the results showed that the antiradical activity was greater at acidic pH and lower at higher temperatures. At basic pH the activity of betanine correlated well with its stability at the three temperatures assayed, suggesting that the degradation products, betalamic acid (BA) and cyclo DOPA 5- O -,- D -glucoside (CDG), did not contribute to this activity under the experimental conditions used. However, at acidic pH the degradation product, CDG, did seem to contribute to the antiradical activity. Furthermore, at pH 3.5, betanine stability was so great that light conditions had no effect on the antiradical activity. At basic pH, too, light had no effect on betanine activity owing to the high instability of the pigment. © 2001 Society of Chemical Industry [source] Structural Studies of Bleached Melanin by Synchrotron Small-angle X-ray Scattering,PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 2 2003Kenneth C. Littrell ABSTRACT Small-angle X-ray scattering was used to measure the effects of chemical bleaching on the size and morphology of tyrosine-derived synthetic melanin dispersed in aqueous media. The average size as measured by the radius of gyration of the melanin particles in solution, at neutral to mildly basic pH, decreases from 16.5 to 12.5 Å with increased bleaching. The melanin particles exhibit scattering characteristic of sheet-like structures with a thickness of approximately 11 Å at all but the highest levels of bleaching. The scattering data are well described by the form factor for scattering from a pancake-like circular cylinder. These data are consistent with the hypothesis that unbleached melanin, at neutral to mildly basic pH, is a planar aggregate of 6- to 10-nm-sized melanin protomolecules, hydrogen bonded through their quinone and phenolic perimeters. The observed decrease in melanin particle size with increased bleaching is interpreted as evidence for deaggregation, most probably the result of oxidative disruption of hydrogen bonds and an increase in the number of charged, carboxylic acid groups, whereby the melanin aggregates disassociate into units composed of decreasing numbers of protomolecules. [source] Modulation of gene expression by extracellular pH variations in human fibroblasts: A transcriptomic and proteomic studyPROTEINS: STRUCTURE, FUNCTION AND BIOINFORMATICS, Issue 5 2003Maja A. Bumke Abstract Homeostasis of the intracellular ionic concentration, in particular that of hydrogen ions, is pivotal to the maintenance of cell function and viability. Nonetheless, pH fluctuations in both the intracellular and the extracellular compartments can occurr during development, in physiological processes and in disease. The influence of pH variations on gene expression has been studied in different model systems, but only for a limited number of genes. We have performed a broad range analysis of the patterns of gene expression in normal human dermal fibroblasts at two different pH values (in the presence and in the absence of serum), with the aim of getting a deeper insight into the regulation of the transcriptional program as a response to a pH change. Using the Affymetrix gene chip system, we found that the expression of 2068 genes (out of 12,565) was modulated by more than two-fold at 24, 48 or 72 h after the shift of the culture medium pH to a more acidic value, stanniocalcin 1 being a remarkable example of a strongly up-regulated gene. Genes displaying a modulated pattern of expression included, among others, cell cycle regulators (consistent with the observation that acidic pH abolishes the growth of fibroblasts in culture) and relevant extracellular matrix (ECM) components. Extracellular matrix protein 2, a protein with a restricted pattern of expression in adult human tissues, was found to be remarkably overexpressed as a consequence of serum starvation. Since ECM components, whose expression is controlled by pH, have been used as targets for biomolecular intervention, we have complemented the Affymetrix analysis with a two-dimensional polyacrylamide gel electrophoresis analysis of proteins which are differentially secreted by fibroblasts at acidic or basic pH. Mass spectrometric analysis of more than 650 protein spots allowed the identification of 170 protein isoforms or fragments, belonging to 40 different proteins. Some proteins were only expressed at basic pH (including, for instance, tetranectin), while others (e.g., agrin) were only detectable at acidic pH. Some of the identified proteins may represent promising candidate targets for biomedical applications, e.g., for antibody-mediated vascular targeting strategies. [source] Limnological changes in a sub-tropical shallow hypertrophic lake during its restoration: two years of a whole-lake experimentAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 1 2001F. Scasso Abstract 1.,Lake Rodó is a turbid system, a condition attributed to algal biomass. The proximal source of the eutrophication was stormwater discharges from an ill-defined urban area. This paper describes an attempt to restore the water quality of Lake Rodó, the first time this has been done in Uruguay. In spring 1996 it was drained, sediments were removed and stream inputs were diverted. Groundwater was used to re-fill the lake. Due to its high nutrient concentration a re-circulation system was designed, pumping water from associated pools covered with free-floating plants. 2.,After the lake was refilled, the system was characterized by oxygen saturation or over-saturation, neutral to basic pH, and high phosphorus, nitrogen and silicate concentrations. Ratios of total nitrogen (TN):total phosphorus (TP) and chlorophyll a (Chl a):TP indicated that phosphorus was the primary limiting nutrient during the period of groundwater supply. Once groundwater pumping had ceased, there was a decrease in TN:TP and Chl a:TP ratios, suggesting N-limiting conditions prevailed in some periods. 3.,Before restoration, the phytoplankton community was dominated year-round by Planktothrix agardhii; since restoration the community has been more diverse. This change has favoured grazing by mesozooplankton, and the onset of clear-water phases in spring. 4.,Abundant populations of small omnivorous fish maintained a high predation pressure on zooplankton, restricting the abundance of large-bodied herbivores, which, in turn, allowed an increase in phytoplanton biomass and a decrease in water transparency. Based on this observation, together with the phosphorus concentration and the low abundance of filamentous cyanobacteria compared with previous studies, we suggest that top-down control has played a key role in increasing transparency in Lake Rodó. 5.,A nutrient reduction programme, by the mechanical harvest of floating plants, and a removal of small omnivorous fishes and stocking strictly with piscivores, could be key factors in the achievement of a stable clear-water phase. However, if blooms of Microcystis or other similar genera occur in summer, additional measures (e.g. reduction of the hydraulic residence time) will be needed to improve water transparency. Copyright © 2001 John Wiley & Sons, Ltd. [source] | ||||||||||||||||||||||