Search results for "alkaline"
showing 10 items of 283 documents
Novel acrylamido monomers with higher hydrophilicity and improved hydrolytic stability: II. Properties of N-acryloylaminopropanol
1996
The physico-chemical properties and the electrophoretic behavior of the novel set of monomers reported by (Simo-Alfonso et al., Electrophoresis 1996, 17, 723-731) have been evaluated. Of utmost importance was the combination of high hydrophilicity and extreme hydrolytic stability, most desired properties for, any electrophoretic matrix, especially for protein fractionation. One of these monomers (N-acryloylaminopropanol, AAP) was found indeed to be extremely hydrophilic (with a partition coefficient P of only 0.10, vs. P = 0.13 for N-acryloylaminoethoxyethanol and P = 0.20 for acrylamide) and to possess excellent stability to alkaline hydrolysis. Its hydrolysis constant (0.008 L mol-1 min-1…
Chemoenzymatic synthesis of a poly(hydroquinone)
1999
Chemoenzymatic synthesis of a poly(hydroquinone) was achieved by enzymatic oxidative polymerization of 4-hydroxyphenyl benzoate, followed by alkaline hydrolysis of the resulting polymer. The polymerization of 4-hydroxyphenyl benzoate was performed using a peroxidase and hydrogen peroxide as catalyst and oxidizing agent, respectively, in an aqueous organic solvent. Soybean peroxidase afforded the polymer in good yields. IR analysis of the polymer showed the formation of the polymer consisting of a mixture of phenylene and oxyphenylene units. By alkaline hydrolysis of the resulting polymer, benzoate moiety was completely removed to give poly(hydroquinone).
Kinetics of alkaline phosphatase from pig kidney. Influence of complexing agents on stability and activity
1976
Metal ion-complexing agents, like KCN, EDTA etc., inactivate alkaline phosphatase of pig kidney. This inactivation is reversible at low concentrations of the complexing agents and irreversible at high concentrations. The reversible inhibition is probably due to removal of Zn2+ ions from the active site, where they are necessary for catalytic action, whereas the irreversible inhibition results from the removal of Zn2+ ions necessary for preservation of the structure. The inactivation is pseudo-first order. It depends on the concentration, size and charge of the complexing agents. β-Glycerophosphate and Mg2+ ions protect the enzyme from inactivation by complexing agents. Quantitative examinat…
Organometallic complexes with biological molecules. XV. Effects of tributyltin(IV)chloride on enzyme activity, Ca2+, and biomolecule and synthesis in…
2001
Considerable attention has been given in recent years to the possibility that xenobiotics in the environment may affect reproduction in animals. In this study, the relative impact of tributyltin(IV) (TBT) chloride, one of the most toxic environmental pollutants, was investigated using Ciona intestinalis ovary as a model system. The pleiotropic effects of TBT exposure are concentration dependent and include a decrease of ATP levels, lipid content and nucleic acid content and synthesis. In contrast, a marked increase in calcium (Ca2+) and glucose content is observed. Furthermore, TBT alters enzymatic activity, inhibiting creatine kinase and stimulating alkaline phosphatase and cholinesterase …
Die herstellung molekulareinheitlicher leiteroligomerer und einer molekulareinheitlichen hexaacrylsäure. IV. Mitt.: Modelle für matrizenreaktionen
1968
Die phenolischen Hydroxylgruppen molekulareinheitlicher Mehrkernverbindungen mit vier und funf pKresolbausteinen je Molekul konnten vollstandig mit Acrylsaurechlorid in Gegenwart von Triathylamin verestert werden. Lies man auf die in siedendem Benzol stark verdunnten mehrafachen Acrylsaureester einen Uberschus an Radikalen aus α.α′-Azoisobutyrodinitril einwirken, so bildeten sich mit guter Ausbeute molekulareinheitliche, dunnschichtchromatographisch reine Leiteroligomere. Die alkalische Verseifung des Leiteroilgomeren mit vier p-Kresolbausteinen gab eine molekulareinheitliche Hexaacrylsaure, die als Hexamethylester durch Elementaranalyse und Molekulargewicht charakterisiert wurde; die gefun…
Bestimmung des vernetzungsgrades schwach vernetzter, noch löslicher copolymerer aus styrol und bisacrylsäurephenylestern durch hydrolytischen abbau
1970
Aus Styrol und Bisacrylsaurephenylester durch radikalische, vernetzende Polymerisation erhaltene und in Toluol sowie Dioxan noch losliche Copolymere wurden durch alkalische Hydrolyse gezielt in die linear strukturierten Bestandteile zerlegt. Diese enthielten neben sehr vielen Styrolbausteinen wenige aus dem Vernetzer stammende Acrylsaurebausteine. UV-Spektren zeigten, das die Vernetzerreste durch den hydrolytischen Abbau vollstandig abgespalten waren. Von den linearen Baustucken wurden viskosimetrisch, osmometrisch und z. T. colorimetrisch die Molekulargewichte bestimmt. Die Hydrolyseprodukte zeigten eine unerwartet bei 320 mμ auftretende Extinktion, deren Ursache nicht restlos aufgeklart w…
Die Kationische ɛ-Caprolactam-Polymerisation. V. Die quantitative Bestimmung der N-Acyllactam-Gruppen bei der Initiierung mit wasserfreien Säuren und…
1971
Als Beitrag zur Aufklarung des Mechanismus der kationischen Caprolactam-Polymerisation mit wasserfreien Sauren (z. B. HCl) als Initiatoren wurde der Gehalt der C-terminal entstehenden N-Acyllactam-Endgruppen und anderer funktioneller Gruppen der gebildeten Oligo- und Polyamide quantitative bestimmt. Dies erfolgte auf IR-spektroskopischem Wege und durch potentiometrische Titration der nach alkalischer Hydrolyse gebildeten Carboxylgruppen. Fur die Polymerisation wurde ein verbessertes Verfahren ausgearbeitet, das vollstandigen Sauerstoff- und Feuchtigkeitsausschlus ermoglicht und damit besser reproduzierbare Ergebnisse liefert. Die Abhangigkeit der Konzentration verschiedener funktioneller Gr…
Multiple origins of methane in fluids circulating in the Othrys ophiolite, central Greece
2018
The complex geology of Greece includes two important parallel running ophiolitic belts. The Othrys Massif in central Greece belongs to westernmost of them. In and around this wide ophiolite outcrop, some cold hyperalkaline and some hypothermal (T < 40°C) alkaline springs are present. Thirty water samples were collected at 17 different sites and both bubbling and dissolved gases were analysed for their chemical (He, Ne, H2, O2, N2, CH4, C2H6, CO2 and H2S) and isotope (He, δ13C-CO2, δ 13C-CH4, δ 2H-CH4) composition. All samples except one have H2S contents below detection limit (10 μmol/mol), whilst H2 (from <2 to 2500 μmol/mol), CO2 (up to 26,000 but generally below 1000 μmol/mol) and …
Precipitation of potassium as hazenite from washing water of spent alkaline batteries
2022
Hazenite (KNaMg2(PO4)2 × 14 H2O), a new type of struvite mineral, was precipitated from the potassium-rich washing water of spent alkaline battery black mass. Hazenite can be used as a fertilizer, which would be an additional benefit derived from the sustainable recovery of battery materials. Precipitation experiments were performed using different pH values (9.5–12), Mg:K:PO4 ratios ((1.0–1.5):1:(1.0–1.5)) and temperatures (10–40 °C). Based on the results, hazenite precipitated in a wide pH range under alkaline conditions. The precipitation kinetics were fast, and the purity of the hazenite was high. Overall, hazenite can be precipitated at room temperature without the addition of excess c…
Advanced biorefinery concepts related to non-wood feedstocks
2018
Agricultural residues, such as wheat straw (Triticum aestivum), okra stalk (Abelmoschus esculentus), and giant miscanthus (Miscanthus × giganteus, a hybrid of M. sinensis and M. sacchariflorus) were investigated to assess their possible consumption for integrated lignocellulosic biorefining. The efficient fractionation and recovery of all important chemical components (cellulose, hemicelluloses, and lignin) of such feedstocks are a prerequisite for realistic biorefinery concepts. Water is one of the most eco-friendly solvents with the highest potential for industrial use, and it is also suitable for full-scale biorefinery purposes. For example, under pressure at elevated temperatures over 1…