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Basic pH Values (basic + ph_value)
Selected AbstractsEffect of temperature on the chromatographic retention of ionizable compounds.JOURNAL OF SEPARATION SCIENCE, JSS, Issue 6-7 2008Abstract We propose a general simple equation for accurately predicting the retention factors of ionizable compounds upon simultaneous changes in mobile phase pH and column temperature at a given hydroorganic solvent composition. Only four independent experiments provide the input data: retention factors measured in two pH buffered mobile phases at extreme acidic and basic pH values (e. g., at least ± 2 pH units far from the analyte pKa) and at two column temperatures. The equations, derived from the basic thermodynamics of the acid,base equilibria, additionally require the knowledge of the solute pKa and enthalpies of acid,base dissociation of both the solute and the buffer components in the hydroorganic solvent mixture. The performance of the predictive model is corroborated with the comparison between theoretical and experimental retention factors of several weak acids and bases of important pharmacological activity, in mobile phases containing different buffer solutions prepared in 25% w/w ACN in water and at several temperatures. [source] Texture and colour properties of proteins recovered from whole gutted silver carp (Hypophthalmichthys molitrix) using isoelectric solubilisation/precipitationJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 2 2009Latif Taskaya Abstract BACKGROUND: According to an FAO report, carp are the cheapest and by far the most commonly consumed fish in the world. Carp have minimal growth requirements, yet rapid growth rates. Although carp are generally considered unsuitable for human consumption in the USA, they have rapidly started populating major bodies of fresh water in the USA to the extent that commercial processing becomes of interest. However, typical mechanical means of meat recovery from carp are impractical owing to the bony nature of the carp carcass. Therefore the aim of the present study was to devise processing strategies to recover fish meat from carp that could be used in the development of human food products. RESULTS: Isoelectric solubilisation/precipitation at acidic and basic pH values was applied to whole gutted silver carp. Depending on the solubilisation pH, protein and fat recovery yields were approximately 420,660 and 800,950 g kg,1 respectively. The process effectively removed impurities such as bones, scales, skin, fins, etc. from whole gutted carp. The proteins were concentrated to approximately 900 g kg,1, while the fat was reduced by 970,990 g kg,1. Functional additives (potato starch, beef plasma protein, transglutaminase and polyphosphate) improved (P < 0.05) the texture of carp protein-based gels such that it was generally comparable to the texture of Alaska pollock surimi gels. Although titanium dioxide improved (P < 0.05) the whiteness of carp gels, it was lower (P < 0.05) than the whiteness of Alaska pollock surimi gels. CONCLUSION: Isoelectric solublisation/precipitation allows protein and lipid recovery from whole gutted carp. However, if the proteins are used as a gelling ingredient in fish food products, functional additives are recommended. Copyright © 2008 Society of Chemical Industry [source] A Highly Charged Ag64+ Core in a DNA-Encapsulated Silver NanoclusterCHEMISTRY - A EUROPEAN JOURNAL, Issue 11 2010Konrad Koszinowski Dr. Highly charged: Electrospray-ionization mass spectrometry shows that single-stranded oligonucleotide dC12 -encapsulated silver nanoclusters contain Ag64+ cores at basic pH values (see section of spectrum). The high positive charge of the cluster cores is presumably essential for preventing the multiply deprotonated dC12 ligand from unfolding. [source] Fabrication of Luminescent CdS Nanoparticles on Short-Peptide-Based Hydrogel Nanofibers: Tuning of Optoelectronic PropertiesCHEMISTRY - A EUROPEAN JOURNAL, Issue 28 2009Goutam Palui Abstract The pH-induced self-assembly of three synthetic tripeptides in water medium is used to immobilize luminescent CdS nanoparticles. These peptides form a nanofibrillar network structure upon gelation in aqueous medium at basic pH values (pH,11.0,13.0), and the fabrication of CdS nanoparticles on the gel nanofiber confers the luminescent property to these gels. Atomic force microscopy, field-emission scanning electron microscopy, and high-resolution transmission electron microscopy clearly reveal the presence of CdS nanoparticles in a well-defined array on the gel nanofibers. This is a convenient way to make organic nanofiber,inorganic nanoparticle hybrid nanocomposite systems. The size of the CdS nanoparticles remains almost same before and after deposition on the gel nanofiber. Photoluminescence (PL) measurement of the CdS nanoparticles upon deposition on the gel nanofibers shows a significant blue shift in the emission spectrum of the nanoparticles, and there is a considerable change in the PL gap energy of the CdS nanoparticles after immobilization on different gel nanofibrils. This finding suggests that the optoelectronic properties of CdS nanoparticles can be tuned upon deposition on gel nanofibers without changing the size of the nanoparticles. [source] | ||||||||||