Microfabricated ISEs: critical comparison of inherently conducting polymer and hydrogel based inner contacts

A rigorous side by side comparison of miniature planar potassium-selective electrodes with hydrogel and potassium hexacyanoferrate(II)/(III) doped polypyrrole (PPy/FeCN) based inner contacts is presented. The planar electrodes were manufactured by screen printing as four- and five-site arrays on ceramic substrates. These electrode arrays were incorporated into a flow-through cell, which could accommodate nine electrode sites. Two identical flow cells were connected in series and the effect of the inner contacts on the analytical performance of the respective electrodes has been critically evaluated. The time necessary to reach steady state conditions has been determined and the effect of experimental parameters (temperature, ambient light intensity, CO₂, and O₂ concentration of the sample) on the potential stability of the electrodes was analyzed. At controlled temperature, the drift of the planar potassium electrodes with hydrogel and PPy/FeCN solid contact were 0.11±0.02 mV h⁻¹ and 0.03±0.007 mV h⁻¹, respectively. The experimental data proved that there is no aqueous film formation between the PPy/FeCN film and the potassium-selective solvent polymeric membrane.     

Microencapsulated Cu(acac)2: a recoverable and reusable polymer-supported copper catalyst for aziridination of olefins

Microencapsulated copper(II) acetylacetonate was prepared and used in the aziridination of alkenes employing [N-(p-tolylsulfonyl)imino]phenyliodinane (PhINTs) as the nitrogen source. Microencapsulated copper(II) acetylacetonate [MC-Cu(acac)₂] catalyst was reused for several cycles with consistent activity.     

Nitrite and Nitric Oxide Interconversion at Mononuclear Copper(II): Insight into the Role of the Red Copper Site in Denitrification

Nitrite (NO₂⁻) and nitric oxide (NO) interconversion is crucial for maintaining optimum NO flux in mammalian physiology. Herein we demonstrate that [ L ₂Cu^II(nitrite)]⁺ moieties (in 2 a and 2 b ; where, L = Me₂PzPy and Me₂PzQu ) with distorted octahedral geometry undergo facile reduction to provide tetrahedral [ L ₂Cu^I]⁺ (in 3 a and 3 b ) and NO in the presence of biologically relevant reductants, such as 4-methoxy-2,6-di-tert-butylphenol (4-MeO-2,6-DTBP, a tyrosine model) and N-benzyl-1,4-dihydronicotinamide (BNAH, a NAD(P)H model). Interestingly, the reaction of excess NO gas with [ L ₂Cu^II(MeCN)₂]²⁺ (in 1 a ) provides a putative {CuNO}¹⁰ species, which is effective in mediating the nitrosation of various nucleophiles, such as thiol and amine. Generation of the transient {CuNO}¹⁰ species in wet acetonitrile leads to NO₂⁻ as assessed by Griess assay and ¹⁴N/¹⁵N-FTIR analyses. A detailed study reveals that the bidirectional NO_x-reactivity, namely, nitrite reductase (NIR) and NO oxidase (NOO), at a common Cu^II site, is governed by the geometric-preference-driven facile Cu^II/Cu^I redox process. Of broader interest, this study not only highlights potential strategies for the design of copper-based catalysts for nitrite reduction, but also strengthens the previous postulates regarding the involvement of red copper proteins in denitrification.     

A review on the dynamics of natural radionuclides along the coastal environs of Kerala,south west coast of India

Journal of Radioanalytical and Nuclear Chemistry - Extensive and systematic investigations have been carried in almost all parts of the world in order to obtain a clear understanding of basic...     

Chemical profiling and anti-psoriatic activity of methanolic extract of Andrographis nallamalayana J.L.Ellis

Andrographis nallamalayana is being widely used as tribal medicine in the treatment of leucoderma and mouth ulcers. Chemical profiling of methanolic extract of the whole plant (PE), using GC–MS and LC–MS, revealed the presence of compounds viz. α-tocopherol, β-sitosterol, tetradecanoic acid, monostearin, flavones/flavanones and their glycosides, chromones, etc. Topical application of imiquimod on the dorsal portion of male BALB/C mice resulted in the development of psoriatic symptoms (erythema, scaling, thickening and folding) with a mean disease activity index (DAI) of >7.0. Topical treatment with 100-μL PE (~6.4%/12.8%) formulations, for 12-days, resulted in the alleviation of disease symptoms. Compared to water-based formulations, emu oil-based formulation, PE400EO was found more effective in reducing the mean DAI (>84%), keratinocyte count (>65%) (p < 0.01) and interleukin-22 (~70%) (p < 0.05). We report, for the first time, anti-psoriatic activity of A. nallamalayana having great potential in developing a potent phytomedicine against psoriasis.     

Preparation and characterization of Eu(3+) doped powder spinel phosphors (MgAl(1.8)Y(0.2-x)O(4))

The photoluminescence (PL) studies of powder phosphors are under rigorous study in view of the applications they have in the field of technology. Different methods are available for the preparation of rare earth ions doped in different host environment of powder phosphors. In the present work, a novel route known as sol-gel technique is employed to prepare spinel phosphor MgAl(1.8)Y(0.2-x)O(4):Eu(x) (x = 2-6 mol%). Then the studies have been carried out to optimize the dopant concentration in the host lattice with the help of photoluminescence spectra. These phosphors have displayed bright red color under UV source. The emission intensities were determined and the relative fluorescence intensities have been estimated. The richness of the red color has been verified by determining their chromaticity coordinates (X, Y) from the CIE standard charts. With the help of XRD, electron spin resonance (ESR), and photo-acoustic (PA) spectra of the samples prepared are also used for the confirmity of the host and analyzing of the data.     

Event-driven stochastic approximation

We consider a Robbins-Monro type iteration wherein noisy measurements are event-driven and therefore arrive asynchronously. We propose a modification of step-sizes that ensures desired asymptotic behaviour regardless of this aspect. This generalizes earlier results on asynchronous stochastic approximation wherein the asynchronous behaviour is across different components, but not along the same component of the vector iteration, as is the case considered here.     

Human Rad51 mediated DNA unwinding is facilitated by conditions that favour Rad51-dsDNA aggregation

Background  

Human Rad51 (RAD51), analogous to its bacterial homolog, RecA, binds and unwinds double stranded DNA (dsDNA) in the presence of certain nucleotide cofactors. ATP hydrolysis is not required for this process, because even ATP non hydrolysable analogs like AMP-PNP and ATPγS, support DNA unwinding. Even ADP, the product of ATP hydrolysis, feebly supports DNA unwinding.     

Synthesis,biological evaluation,and docking study of a series of 1,4-disubstituted 1,2,3-triazole derivatives with an indole-triazole-peptide conjugate

A series of new compounds containing an indole-triazole - peptide conjugate were designed as potential agents possessing the dual anti-bacterial and anticancer activities. Accordingly, 20 compounds were prepared via a multi-step synthesis involving the copper-catalyzed azide-alkyne cycloaddition (CuAAC) as a key step in moderate to high yield. All the synthesized compounds were purified by chromatographic techniques and characterized by IR, ¹H and ¹³C NMR and mass spectral data. The synthesized derivatives were screened for their antimicrobial activities against one gram-positive (Staphylococcus aureus) and three gram-negative (Escherichia coli, Klebsiella pneumonia, and Proteus vulgaris) bacteria using an agar-well diffusion method. Most of the compounds showed moderate to reasonable antibacterial activities especially the compound 9e that showed good activities against all the strains. The potential of DNA gyrase inhibitory activity of this compound was assessed by using molecular docking studies in silico carried out using Autodock Vina software. The low ΔG_bind value (−9.4 Kcal/mol) of compound 9e suggested its good interactions with the target protein in silico. The cytotoxic activities of some of the compounds synthesized were evaluated via a MTT assay using the human lung cancer cell line A549. Several compounds showed promising activities among which compound 9b , 9k, and 9e showed low IC₅₀ values.