scholarly journals Swellable Copolymers of N-isopropylacrylamide and Alkyl Acrylic Acids for Optical pH Sensing

Molecules ◽  
2020 ◽  
Vol 25 (6) ◽  
pp. 1408
Author(s):  
Barry K. Lavine ◽  
Sandhya R. Pampati ◽  
Kaushalya S. Dahal ◽  
Mariya Kim ◽  
U. D. Nuwan T. Perera ◽  
...  
Keyword(s):  
Ionic Strength ◽  
Dispersion Polymerization ◽  
High Ionic Strength ◽  
Ph Sensing ◽  
Buffer Solution ◽  
Hydrogel Membrane ◽  
Enthalpy And Entropy ◽  
Ph Range ◽  
Acrylic Acids ◽  
Pva Hydrogel

Swellable polymers that respond to pH (including a portion of the physiological pH range) have been prepared from N-isopropylacrylamide (NIPA) copolymerized with acrylic acid, methacrylic acid, ethacrylic acid or propacrylic acid by dispersion polymerization. When the swellable polymer particles are dispersed in a polyvinyl alcohol (PVA) hydrogel membrane, large changes occur in the turbidity of the membrane (which is measured using an absorbance spectrometer) as the pH of the buffer solution in contact with the hydrogel membrane is varied. The swelling of the NIPA copolymer is nonionic, as the ionic strength of the buffer solution in contact with the PVA membrane was increased from 0.1 to 1.0 M without a decrease in the swelling. For many of these NIPA copolymers, swelling was also reversible in both low- and high ionic strength pH-buffered media and at ambient and physiological temperatures. The composition of the formulation used to prepare these copolymers of NIPA can be correlated to the enthalpy and entropy of the pH-induced swelling.

scholarly journals Evaluation of the LIVE/DEAD BacLight Kit for Detection of Extremophilic Archaea and Visualization of Microorganisms in Environmental Hypersaline Samples

2004 ◽  
Vol 70 (11) ◽  
pp. 6884-6886 ◽  
Author(s):  
Stefan Leuko ◽  
Andrea Legat ◽  
Sergiu Fendrihan ◽  
Helga Stan-Lotter
Keyword(s):  
Ionic Strength ◽  
Potential Application ◽  
Environmental Samples ◽  
High Ionic Strength ◽  
Ph Range

ABSTRACT Extremophilic archaea were stained with the LIVE/DEAD BacLight kit under conditions of high ionic strength and over a pH range of 2.0 to 9.3. The reliability of the kit was tested with haloarchaea following permeabilization of the cells. Microorganisms in hypersaline environmental samples were detectable with the kit, which suggests its potential application to future extraterrestrial halites.

scholarly journals Spectrophotometric investigation of famotidine-Pd(II) complex and its analytical application in drug analysis

2004 ◽  
Vol 69 (6) ◽  
pp. 485-492 ◽  
Author(s):  
Zagorka Koricanac ◽  
Tatijana Jovanovic ◽  
Jelena Petkovic ◽  
Dragica Minic-Popovic
Keyword(s):  
Ionic Strength ◽  
Stability Constant ◽  
Drug Analysis ◽  
Dosage Forms ◽  
Conditional Stability ◽  
Buffer Solution ◽  
Conditional Stability Constant ◽  
Spectrophotometric Methods ◽  
Optimum Ph ◽  
Ph Range

By using different spectrophotometric methods, it was found that famotidine and palladium(II) ions form a complex, Pd(II): famotidine = 1:1, which has an absorptionmaximum at 345 nm. The formation of the complex between famotidine and palladium(II) chloride in Britton?Robinson buffer solution in the pH range 2.23?8.50 was studied. The conditional stability constant of the complex at the optimum pH 2.62 and ionic strength 0.5M was found to be log K?= 3.742 ??0.025. The Beer?s law was verified over the famotidine concentration range from 5x10-5?6x10-4 M. The proposed method was found to be suitable for accurate and sensitive analysis of famotidine both as the substance (RSD = 1.02?1.80 %) and its dosage forms (RSD = 1.75?1.83 %).

Importance of Protease Inhibition in Studies on Purified Factor VIII (Antihaemophilic Factor)

1976 ◽  
Vol 35 (01) ◽  
pp. 186-190 ◽  
Author(s):  
Eugen A. Beck ◽  
Peter Bachmann ◽  
Peter Barbier ◽  
Miha Furlan
Keyword(s):  
Ionic Strength ◽  
Factor Viii ◽  
Gel Filtration ◽  
High Ionic Strength ◽  
Procoagulant Activity ◽  
Carrier Protein ◽  
Protease Inhibition ◽  
Functional Sites ◽  
Molecular Weight Peak ◽  
Von Willebrand

SummaryAccording to some authors factor VIII procoagulant activity may be dissociable from carrier protein (MW~ 2 × 106) by agarose gel filtration, e.g. at high ionic strength. We were able to reproduce this phenomenon. However, addition of protease inhibitor (Trasylol) prevented the appearance of low molecular weight peak of factor VIII procoagulant activity both at high ionic strength and elevated temperature (37°C). We conclude from our results that procoagulant activity and carrier protein (von Willebrand factor, factor VIII antigen) are closely associated functional sites of native factor VIII macro molecule. Consequently, proteolytic degradation should be avoided in functional and structural studies on factor VIII and especially in preparing factor VIII concentrate for therapeutic use.

THE RELATIVE DISTRIBUTION OF THYROXINE, TRIIODOTHYRONINE AND 3,3′,5′-(REVERSE)-TRIIODOTHYRONINE IN VARIOUS FRACTIONS OF THYROGLOBULIN

1978 ◽  
Vol 88 (2) ◽  
pp. 298-305 ◽  
Author(s):  
Peter Laurberg
Keyword(s):  
Ionic Strength ◽  
Guinea Pig ◽  
Sucrose Gradient ◽  
Deae Cellulose ◽  
High Ionic Strength ◽  
Relative Distribution ◽  
Thyroid Extract ◽  
Reverse Triiodothyronine ◽  
Thyroid Secretion ◽  
Stable Iodine

ABSTRACT Thyroglobulin fractions rich and poor in new thyroglobulin were separated by means of DEAE-cellulose chromatography of dog thyroid extracts and by zonal ultracentrifugation in a sucrose gradient of guinea pig thyroid extract incubated at low temperature. The distribution of thyroxine, triiodothyronine and 3,3′,5′-(reverse)-triiodothyronine in hydrolysates of the different fractions was estimated by radioimmunoassays. Following DEAE-cellulose chromatography there was a small but statistically significant increase in the T4/T3 ratio in thyroglobulin fractions eluted at high ionic strength - that is fractions relatively rich in stable iodine but poor in fresh thyroglobulin. There were no differences in the T4/rT3 ratios between the different fractions. The ratios between iodothyronines were almost identical in the various thyroglobulin fractions following zonal ultracentrifugation in a sucrose gradient of cold treated guinea pig thyroid extract. These findings lend no support to the possibility that a relatively high content of triiodothyronines in freshly synthesized thyroglobulin modulates the thyroid secretion towards a preferential secretion of triiodothyronine and 3,3′,5′-(reverse)-triiodothyronine at the expense of the secretion of thyroxine.

Grand-Reaction Method for Simulations of Ionization Equilibria and Ion Partitioning in a Broad Range of pH and Ionic Strength

2019 ◽  
Author(s):  
Jonas Landsgesell ◽  
Oleg Rud ◽  
Pascal Hebbeker ◽  
Raju Lunkad ◽  
Peter Košovan ◽  
...  
Keyword(s):  
Mean Field ◽  
Coarse Grained ◽  
Reactive System ◽  
Acid Base ◽  
Buffer Solution ◽  
Reaction Method ◽  
Ionization Equilibria ◽  
Coarse Grained Simulations ◽  
Ph Range ◽  
Weak Polyelectrolytes

We introduce the grand-reaction method for coarse-grained simulations of acid-base equilibria in a system coupled to a reservoir at a given pH and concentration of added salt. It can be viewed as an extension of the constant-pH method and the reaction ensemble, combining explicit simulations of reactions within the system, and grand-canonical exchange of particles with the reservoir. Unlike the previously introduced methods, the grand-reaction method is applicable to acid-base equilibria in the whole pH range because it avoids known artifacts. However, the method is more general, and can be used for simulations of any reactive system coupled to a reservoir of a known composition. To demonstrate the advantages of the grand-reaction method, we simulated a model system: A solution of weak polyelectrolytes in equilibrium with a buffer solution. By carefully accounting for the exchange of all constituents, the method ensures that all chemical potentials are equal in the system and in the multi-component reservoir. Thus, the grand-reaction method is able to predict non-monotonic swelling of weak polyelectrolytes as a function of pH, that has been known from mean-field predictions and from experiments but has never been observed in coarse-grained simulations. Finally, we outline possible extensions and further generalizations of the method, and provide a set of guidelines to enable safe usage of the method by a broad community of users.<br><br>

Endo-D-galacturonanase immobilized by adsorption on porous polyethyleneterephthalate

1982 ◽  
Vol 47 (10) ◽  
pp. 2716-2723 ◽  
Author(s):  
Lubomíra Rexová-Benková ◽  
Jiřina Omelková ◽  
Vladimír Kubánek
Keyword(s):  
Ionic Strength ◽  
High Stability ◽  
Relative Activity ◽  
Operational Stability ◽  
The Other ◽  
Fixation Strength ◽  
Action Pattern ◽  
Salt Solutions ◽  
Buffer Solution ◽  
Degradation Degree

Endo-D-galacturonanase of Aspergillus sp. was irreversibly adsorbed on polyethyleneterephthalate in an acetate 0.1 mol l-1 buffer solution of pH 4.2. Immobilization of the enzyme resulted in lowering of its activity, the measure of which depended on the amount of the enzyme fixed on the carrier. The highest relative activity (42.4%) had the preparation containing 5.25 mg of the enzyme per 1 g of the carrier. The velocity and intensity of the sorption of the enzyme depended on the ionic strength of the medium, whilst pH, on the other hand, was of no influence. Endo-D-galacturonanase immobilized in a 0.1 mol l-1 buffer was characteristic a) of its fixation strength in salt solutions of various ionic strength and pH, in a 3 mol l-1 guanidine solution, and also in sodium pectate and pectin solutions, b) of its high stability during a long-lasting storage at 4 °C, c) of its operational stability. The immobilization led to a partial change of the action pattern onto the high-molecular substrate, manifested in lowering the decrease of viscosity to degradation degree ratio.

scholarly journals Kaolin based protective barrier in municipal landfills against adverse chemo-mechanical loadings

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Partha Das ◽  
Tadikonda Venkata Bharat
Keyword(s):  
Ionic Strength ◽  
High Ionic Strength ◽  
The Self ◽  
Design Parameters ◽  
Layered System ◽  
Geosynthetic Clay Liners ◽  
Clay Liners ◽  
Landfill Liner ◽  
First Time ◽  
Applied Stresses

AbstractIn this work, we assess the self-sealing and swelling ability of the compacted granular bentonite (GB) under an inorganic salt environment and induced overburden stresses from the landfill waste. The laboratory permeation tests with high ionic strength salt solutions reveal that the GB fails to seal and exhibits a significant mechanical collapse under different applied stresses. The applicability of GB in the form of geosynthetic clay liners as the bottom liner facilities in landfills that produce high ionic strength salt leachates, therefore, remains a serious concern. We propose an additional barrier system based on kaolin, for the first time, to address this problem. The proposed kaolin-GB layered system performs satisfactorily in terms of its sealing and swelling ability even in adverse saline conditions and low overburden stresses. The kaolin improves the osmotic efficiency of the self and also helps the underlying GB layer to seal the inter-granular voids. The estimated design parameters by through-diffusion test suggest that the kaolin-GB layered system effectively attenuates the permeant flux and suitable as a landfill liner.

scholarly journals Comprehensive analysis of the isozyme composition of laccase derived from Japanese lacquer tree, Toxicodendron vernicifluum

2021 ◽  
Vol 67 (1) ◽  
Author(s):  
Mariko Takano ◽  
Masaya Nakamura ◽  
Masanobu Tabata
Keyword(s):  
Isoelectric Focusing ◽  
Laccase Activity ◽  
Maximum Activity ◽  
Acetone Powder ◽  
Blue Color ◽  
Buffer Solution ◽  
Activity Staining ◽  
Water Extracts ◽  
Ph Range ◽  
Toxicodendron Vernicifluum

AbstractWe performed an analysis using isoelectric focusing to comprehensively clarify the isozyme composition of laccase derived from Japanese lacquer tree, Toxicodendron vernicifluum. When water extracts of acetone powder obtained from lacquer were subjected to isoelectric focusing, five bands within pI 7.35–9.30 and nine bands within pI 3.50–5.25 were detected using Coomassie staining. Similarly, laccase activity staining using guaiacol showed five bands within pI 7.35–9.30 and three bands within pI 3.50–4.25. However, laccase activity staining using gallic acid showed remarkable staining within pI 3.50–5.85, whereas staining was very weak within pI 7.35–9.30. When the water extracts of acetone powder were fractionated into the fractions containing bands within pI 7.35–9.30 and pI 3.50–5.85 by SP-Sepharose column chromatography, the former had a blue color and the latter a yellow color. The laccase activity was measured for each of the fractions in buffer solution in the pH range of 2.5–8.0. When syringaldazine, guaiacol, and 2,6-dimethoxyphenol were used as substrates, the yellow fraction showed considerably higher activity than the blue fraction for pH 5.5–7.5. When 3-methylcatechol and 4-methylcatechol were used as substrates, the yellow fraction showed higher activity for pH 4.5–6.5, and the blue fraction showed higher activity for pH 7.0–8.0. When 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) was used as the substrate, both fractions showed maximum activity at optimum pH of 3.0–4.0. Conventionally, in research on blue laccase derived from lacquer, the non-blue fraction corresponding to the yellow fraction lower than pI 6 has been removed during the purification process and thus has not been analyzed. Our results indicated that yellow laccase was present in the non-blue components of lacquer and that it may play a role in urushiol polymerization with previously reported blue laccase.

scholarly journals High ionic strength dissociation assay (HISDA) for high drug tolerant immunogenicity testing

Bioanalysis ◽  
2020 ◽  
Author(s):  
Gregor Jordan ◽  
Alexander Pöhler ◽  
Florence Guilhot ◽  
Meike Zaspel ◽  
Roland F Staack
Keyword(s):  
Ionic Strength ◽  
Acid Treatment ◽  
Structural Integrity ◽  
Drug Tolerance ◽  
High Ionic Strength ◽  
Acid Dissociation ◽  
High Drug ◽  
Overnight Incubation ◽  
Antidrug Antibody ◽  
High Doses

Aim: Antidrug antibody (ADA) assessment may be challenged in studies that involve the administration of high doses of biotherapeutics and/or with long half-lives. In such cases, ADA assays with optimized drug tolerance are desired. Material & Methods: We evaluated the use of MgCl2 to develop high ionic strength dissociation assays in two investigational examples (bridging enzyme-linked immunosorbent ADA assays) to attain high drug tolerance while maintaining best possible structural integrity of ADAs. Results: Both ADA-bridging assays treated with MgCl2 showed improved drug tolerance and higher signal-to-blank values compared with overnight incubation or acid treatment. Conclusion: The use of MgCl2 treatment in ADA-bridging assays provides a sensitive, drug tolerant and easy-to-use alternative in cases where acid dissociation is not possible or unwanted.

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