A nanoporous palladium(II) bridged coordination polymer acting as a peroxidase mimic in a method for visual detection of glucose in tear and saliva

A nanoporous coordination polymer (NPCP) was prepared from palladium(II) chloride and 4-amino-3-hydrazino-5-mercapto-1,2,4-triazole and is shown to act as a peroxidase mimetic. It can catalyze the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) by H₂O₂ which is formed on enzymatic oxidation of glucose by glucose oxidase. Based on these findings, a sensitive glucose test was worked out at 652 nm where the intensity if the greenish-blue product is related to the actual concentration of glucose. Figures of merit include (a) rather low Km value (30 μM) which evidences the strong binding affinity of the NPCP toward glucose, (b) a high v_(max) (8.5 M·s^?1), (c) a 47 nM detection limit, (d) a lifetime of a month, (e) a wide working pH range (2–10), and (f) a 25–80 °C temperature range. The assay was applied to non-invasive determination of glucose assay in tear, saliva where the detection limits are found to be 61 and 91 nM, respectively.

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Graphical abstract DSchematic of the mechanism of the peroxidase like catalytic activity of AHMT-Pd NPCP that was applied in a selective colorimetric method for glucose detection based on TMB oxidation in the presence of enzymatically generated H₂O₂.

     

An expeditious access of 2,5′-dioxo-5′,6′,7′,8′-tetrahydro-1′H-spiro[indoline-3,4′-quinoline]-3′-carboxylate by reaction of isatin,ethyl cyanoacetate and enaminone in water

We have demonstrated three component reaction of isatin, enaminone and ethyl cyanoacetate leading to sprirooxindole scaffold without catalyst in water. The synthetic protocol has several advantages like wide substrate scope, atom-economy and operationally simple experimental procedures which provides rapid access to library of compounds. The mechanistic details of the reaction has been investigated during the course of study.     

Evaluation of Anthocyanin Content,Antioxidant Potential and Antimicrobial Activity of Black,Purple and Blue Colored Wheat Flour and Wheat-Grass Juice against Common Human Pathogens

The present study aimed to analyze the antioxidant and antimicrobial activity of anthocyanins extracted from colored wheat flour and wheat-grass juice against human pathogens. The total anthocyanin content and antioxidant potential in colored wheat flour and wheat-grass juice extracts were significantly higher than white flour and wheat-grass juice extracts. Ultra-performance liquid chromatography showed the maximum number of anthocyanin peaks in black wheat, with delphinidin-3-o-galactoside chloride, delphinidin-3-o-glucoside chloride, and cyanindin-3-o-glucoside chloride as the major contributors. Among flour extracts, maximum zones of inhibition against Staphylococcus aureus (MTCC 1934), Pseudomonas aeruginosa (MTCC 1434), Escherichia coli, and Candida albicans (MTCC 227) were produced by black flour extract, having the highest anthocyanin content. It exhibited a minimum microbicidal concentration (MMC) of 200 mg/mL against E. coli and C. albicans; and 100 and 150 mg/mL against S. aureus and P. aeruginosa, respectively. Black and purple flour extracts exhibited a minimum inhibitory concentration (MIC) of 50 mg/mL against S. aureus and P. aeruginosa. White flour extracts did not show MMC against E. coli and C. albicans. Among wheat-grass juice extracts, black wheat-grass was most effective and showed an MIC of 100–150 mg/mL against all pathogens. It exhibited an MMC of 200 mg/mL against S. aureus and P. aeruginosa. Hence, anthocyanin-rich colored wheat could be of nutraceutical importance.     

Visible light promoted formation of N─S bond by photocatalyst Eosin Y

A novel efficient protocol for the synthesis of 5-imino-1,2,4-thiadiazole motif in open air and visible light has been reported. The reaction involves Eosin Y as photocatalyst which is a cost-effective organic dye. The designed protocol represents a novel, mild, metal free, green strategy for the construction of 1,2,4-thiadiazole nucleus by intramolecular cyclization via N─S bond formation. The reaction has been carried out under visible light exposure in ethanol: water (4:1) mixture using 2-aminopyridine and isocyanate as reactants.     

Interaction between electrical double layers of soil colloids and Fe/Al oxides in suspensions

Phyllosilicates with net negative surface charge and Fe/Al oxides with net positive surface charge coexist in variable-charge soils, and the interaction between these oppositely charged particles affects the stability of mixed colloids, aggregation, and even the surface chemical properties of variable-charge soils. The interaction of the diffuse layers of electrical double layers between the negatively charged soil colloidal particles and the positively charged particles of goethite or gamma-Al(2)O(3) was investigated in this article through the comparison of zeta potentials between single-soil colloidal systems and binary systems containing soil colloids and Fe/Al oxides. The results showed that the presence of goethite and gamma-Al(2)O(3) increased the zeta potential of the binary system containing soil colloids and Fe/Al oxides, which clearly suggests the overlapping of the diffuse layers in soil colloids and Fe/Al oxides. The overlapping of the diffuse layers leads to a decrease in the effective negative charge density on soil colloid and thus causes a shift of pH-zeta potential curves toward the more positive-value side. The interaction of the electrical double layers is also related to the charge characteristics on the Fe/Al oxides: the higher the positive charge density on Fe/Al oxides, the stronger the interaction of the electrical double layers between the soil colloid particles and the Fe/Al oxides.     

On minimal realization of fuzzy behaviour and associated categories

This paper is towards the study of minimal deterministic automata with fuzzy output which realizes the given fuzzy behaviour. The construction of such automaton is based on Myhill-Nerode’s theory, and it is shown that this automaton is a canonical realization of given fuzzy behaviour. Meanwhile, we introduce the categories of deterministic automata with fuzzy output and fuzzy behaviour. The relationship between both the categories through functors is also studied.     

Ion transport properties of NaPF6- and NaCl-doped poly(N-phenylene N′imino pentyl)imminium propane sulfonate

New polymer-salt systems have been prepared by doping synthesized poly(N-phenylene N′imino pentyl) imminium propane sulfonate with NaPF₆ and NaCl. The higher conductivity of the NaPF₆-doped system in comparison to the NaCl-containing sample indicated that a larger-sized anion is facilitating ion conduction. FTIR spectra confirmed the complexation of salt with polymer. The conductivity power law exponent, studied in the frequency range from 42 Hz to 5 MHz, varies with frequency and has values >1, demonstrating dominance of caged ion movement. The dominance of caged motion is more pronounced in the NaCl-doped sample, signifying that a smaller anion has greater chances of being caged. Anion size signature is also visible in temperature and humidity dependence of exponent n.     

Strain and temperature discrimination technique by use of A FBG written in erbium doped fiber

We propose and demonstrate strain and temperature discrimination technique using a single fiber Bragg grating (FBG) written in the core of an erbium doped fiber. We observed that amplified spontaneous emission power varying linearly from the erbium doped fiber with temperature which determines temperature changes and strain is estimated by subtracting the wavelength shift due to temperature change, from the measured shift corresponding to the dip in the transmission spectrum of the FBG. A simple and compact FBG sensor is presented with improved rms errors of 21.2 μ? and 1 °C over ranges of 0–800 μ? and 40–95 °C, respectively. The sensor is shown to have strain and temperature sensitivity of 0.8 pm/μ? and 12 pm/°C.     

Synchrotron μ‐XRF study on compositional uniformity of uranium–thorium oxide pellets prepared by different processes

A μ‐XRF study to assess the distribution of uranium and thorium in (U,Th)O₂ pellets covering the composition of advanced heavy water reactor (AHWR) fuel pellets prepared by powder metallurgical compaction (PMC) and coated agglomerate pelletization (CAP) routes was made using micro‐focus beam line (BL‐16) of Indus‐2 synchrotron radiation facility. The methodology thus developed was successfully applied to these pellets. The study reveals that the uranium distribution in pellets prepared by PMC route is uniform, whereas the pellets prepared through CAP route have a wide range of compositional variation. In addition, the uniformity in CAP route‐prepared pellets improves with increase in the relative amount of uranium in the pellets. The sample preparation in present methodology is very simple compared with scanning electron microscopy. The study reveals the utility of synchrotron‐based μ‐XRF for fuel pellet characterization of AHWR reactors. Alhough CAP route of fuel pellet preparation requires less exposure of personnel to high radiation dose, the non‐uniformity in the fuel pellet must be considered when using these pellets in reactors. Copyright © 2014 John Wiley & Sons, Ltd.     

A quaternionic map for the steady states of the Heisenberg spin-chain

We show that the steady states of the classical Heisenberg XXX spin-chain in an external magnetic field can be found by iterations of a quaternionic map. A restricted model, e.g., the xy spin-chain is known to have spatially chaotic steady states and the phase space occupied by these chaotic states is known to go through discrete changes as the field strength is varied. The same phenomenon is studied for the xxx spin-chain. It is seen that in this model the phase space volume varies smoothly with the external field.