Studies on the effect of non-electrolytes on the stability of copper ferrocyanide sol

Summary In general the addition of non-electrolyte to hydrophobic sols results into an irregular change in the stability of the latter, towards electrolyte coagulation. Precipitation concentration of potassium chloride for copper ferrocyanide sol changes in the presence of ethyl alcohol, glycol or glycerol. Ethyl alcohol sensitizes while others stabilise the sol to different extents. In presence of these alcohols, electrolytic coagulation of copper ferrocyanide sol is attended by a decrease in the conductance and hydrogen ion concentration as compared to a pure sol (sol without non-electrolyte).

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Zusammenfassung Im allgemeinen verursacht das Zufügen von Nicht-Elektrolyten zu hydrophoben Solen eine irregul?re ?nderung der Stabilit?t der letzteren hinsichtlich der Elektrolytkoagulation. Die F?llungskonzentration von Kaliumchlorid für Kupfer-Ferrocyanid-Sol ?ndert sich bei Gegenwart von ?thylalkohol, Glykol oder Glycerin. ?thylalkohol sensibilisiert, w?hrend die anderen das Sol in verschiedenem Ausma\ stabilisieren. In Gegenwart dieser Alkohole ist die Elektrolytkoagulation des Kupfer-Ferrocyanid-Sols von einer Abnahme der Leitf?higkeit und der Wasserstoffionenkonzentration, verglichen mit den reinen Solen ohne Nicht-Elektrolyt begleitet.

     

QbD-driven development and validation of an efficient bioanalytical UPLC method for estimation of olmesartan medoxomil

The present studies describe quality by design-based development of bioanalytical ultra performance liquid chromatography method of olmesartan medoxomil. Initially, method objectives were defined and critical analytical attributes (CAAs) earmarked. Method optimization was conducted using a central composite design for optimizing mobile phase ratio and injection volume as the critical method parameters (CMPs) identified from risk assessment and factor screening studies, and evaluated for their influence on peak area, theoretical plates, and asymmetry factor as CAAs. Chromatographic separation was achieved using acetonitrile:water solvent system containing 0.1% orthophosphoric acid (54:46, v/v) as the mobile phase with UV detection at 243 nm. Further optimization of bioanalytical extraction process was accomplished using a Box–Behnken design selecting extraction time, centrifugation speed, and centrifugation time as the CMPs identified from failure mode and effect analysis, and evaluated for percent recovery, peak asymmetry, and theoretical plate count as the CAAs. Establishment of calibration curve indicated linearity between concentration range of 100 and 800 ng mL^?1, excellent accuracy and precision with limit of detection and limit of quantification as 6.2 and 19.0 ng mL^?1, respectively. Drug stability studies indicated mean percent recovery ranging between 92.4 and 97.3% under various stress conditions.     

Random fixed points for random multivalued operators defined on unbounded sets in banach spaces

Random fixed points for nonexpansive and pseudocontractive random multivalued operators defined on unbounded subsets of a Banach space are obtained     

Dissecting the effect of anions on Hg2+ detection using a FRET based DNA probe

Many biosensors have been developed to detect Hg(2+) using thymine-rich DNA. While sensor response to various cations is often studied to demonstrate selectivity, the effect of anions has been largely overlooked. Anions may compete with DNA for metal binding and thus produce a false negative result. Anions cannot be added alone; the cation part of a salt may cause DNA compaction and other effects, obscuring the role of anions. We find that the sensitivity of a FRET-based Hg(2+) probe is independent of Na(+) concentration. Therefore, by using various sodium salts, any change in sensitivity can be attributed solely to the effect of anions. Halide salts, sulfides, and amines are strong inhibitors; anions containing oxo or hydroxyl groups (e.g. nitrate, sulfate, phosphate, carbonate, acetate, and citrate) do not interfere with Hg(2+) detection even at 100 mM concentration. Mercury hydrolysis and its diffusion into polypropylene containers can also strongly affect the detection results. We conclude that thymine-rich DNA should be useful for Hg(2+) detection in many environmental water samples.     

Synthesis, characterization, and electrical conductivity of new Aurivillius-type oxide-ion conductor

A new oxide-ion conductor of Aurivillius family with a general formula Bi₂Al _x V_{1 − x} O_{5.5 − x − δ}; 0 ≤ x ≤ 0.20 (BIALVOX) was synthesized by the sol-gel citrate route. Powder X-ray diffraction and simultaneous thermogravimetric and differential thermal analyses confirmed that the calcination of BIALVOX xerogels is fully completed at around 500°C after three hours of thermal treatment. It has been found that the β-orthorhombic phase is stabilized with compositions x ≤ 0.07, whereas the stabilization of the γ′-phase takes place for x ≥ 0.10. AC impedance spectroscopic investigation suggested that the charge accumulation at grain boundaries is thermally activated process. However, the maximum electrical conductivity (7.73 × 10⁻⁵ S cm⁻¹) noticed for BIALVOX.13 at 300°C was attributed to the maximum vacancy concentration in the equatorial planes, responsible for the ion diffusion through the structure. This has been further evidenced by the temperature dependence of dielectric permittivity.     

Microwave solid synthesis and electrical properties of Aurivillius-type oxide-ion conductor

A new oxide-ion conductor of Aurivillius-type structure, namely BISRVOX (Bi₂Sr_xV_1−xO_{5.5-(3x/2)-δ}, 0≤x≤0.20), was successively synthesized by the microwave-assisted solid state reaction. 25 min of microwave irradiation was found to be quite sufficient to ensure the completion of reaction. Powder X-ray diffraction and differential thermal analysis showed better structural properties for the microwave-prepared samples compared to those obtained from the conventional solid synthesis route. Interestingly, the highly conducting γ-phase was effectively stabilized for x≥0.10. AC impedance spectroscopy evidenced the superiority of the microwave heating over conventional solid synthesis routes in exhibiting high oxide-ion performance.     

Fuzzy Transitive Relations

A modified definition of fuzzy transitivity is given.Several properties of this new definition are obtained.Effect of these new properties of transitivity on equivalence relations is also studied.     

Synthesis of new benzothiazole derivatives bearing thiadiazole as monoamine oxidase inhibitors

Monoamine oxidases (MAO) are enzymes that catalyze the oxidative deamination of monoamines such as dopamine, noradrenaline, adrenaline, and serotonin. Recent studies have shown that numerous benzothiazole derivatives exhibit hMAO inhibitory activity in the micromolar concentration range. In this study, a novel series of benzothiazole-thiadiazole (5a-5l ) was synthesized and characterized their chemical structures by ¹H-NMR, ¹³C-NMR, and Mass spectroscopy. These compounds were evaluated as inhibitors for types A and B MAO enzymes. Compounds 5f and 5l were the most active derivatives in the series with an IC₅₀ values of 0.107 ± 0.003 and 0.128 ± 0.004, respectively. Furthermore, cytotoxicity of compounds 5f and 5l were investigated and found as non-cytotoxic.     

A New Stationary Phase for Hydrophilic Interaction Chromatography: Polyacrylate-Based Hydrophilic,Monosized-Porous Beads with Zwitterionic Molecular Brushes

Hydrophilic, polyacrylate-based, monosized-porous beads with zwitterionic molecular brushes were synthesized as a new stationary medium for hydrophilic interaction chromatography. Monosized-porous poly(glycerol-1,3-diglycerolate diacrylate-co-glycerol dimethacrylate), poly(GDGDA-co-GDMA), beads 5 μm in size were obtained by a staged-shape template polymerization. As an initiator for surface-initiated atom transfer radical polymerization (SI-ATRP), bromine functionality was obtained on the beads by reacting their hydroxyl groups with 3-(aminopropyl)triethoxysilane and α-bromoisobutyryl bromide, respectively. Zwitterionic molecular brushes on the hydrophilic poly(GDGDA-co-GDMA) beads were generated by SI-ATRP of a sulfobetaine monomer, [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl) ammonium hydroxide (MESH). Poly(MESH)-grafted poly(GDGDA-co-GDMA), poly(MESH)g-poly(GDGDAco-GDMA), beads were slurry packed into the microbore columns with 2 mm i.d. and evaluated as stationary medium for the separation of organic acids, nucleosides and peptides using microbore columns in hydrophilic interaction chromatography with the plate numbers up to 30,000 plates m^?1.     

Synthesis,phase stability and oxide ion conductivity of Ce(IV)–Cd(II) double substituted bismuth vanadate

Bi₄V₂O_11-δ has been doped with Ce and Cd to study double substitution. The system with various dopant concentrations (0.07 ≤ x ≤ 0.30) was prepared by the standard solid-state reaction method. The correlation between the polymorphism and oxide ion performance was well investigated as a function of temperature and composition with the help of thermal analysis, X-ray diffraction (XRD) and AC impedance spectroscopy. From XRD results it is seen that the high oxide ion conducting tetragonal γ-phase is stabilized for x = 0.17. For the compositions x ≤ 0.10, monoclinic α-phase is retained at room temperature with clear evidence for two successive phase transitions α ? β and β ? γ. For x = 0.13, β ? γ phase transition is seen. However, the existence of order–disorder, γ' ? γ transition was confirmed for x = 0.17. It is seen that the highest low-temperature ionic conductivity at 320 °C is 3.19 × 10^?4 S cm^?1 which was observed for x = 0.17.