Selective uranyl ion detection by polymeric ion-selective electrodes based on salphenH2 derivatives

The new ion-selective electrodes (ISEs) based on salphenH₂ derivatives such as N,N′-(propylenedioxy)benzenebis(salicylideneimine) L¹ and N,N′-4,5-(propylenedioxy)benzenebis(3,5-di-tert-butylsalicylideneimine) L² as cation carriers are developed for a uranyl ion. The combination of these new ionophores with tris(2-ethylhexyl)phosphate (TEHP) as a plasticizer particularly shows near Nernstian slope in the wide concentration range (1.0 × 10⁻⁶ to 1.0 × 10⁻² M) of UO₂²⁺ and is observed well in the pH range from 1.0 to 5.0 with a response time less than 20 s. Since the employed ionophores were confirmed to form well-defined stable 1:1 complexes with UO₂²⁺, the observed high selectivity for a uranyl ion over the other cations was attributed to the selective complexation as well as the lipophilic behavior of these ligands especially for L². The proposed electrodes offered practically low detection limit of 6.5 × 10⁻⁷ M and reasonably good end-points within experimental error were obtained when the sensor was used as an indicator electrode for the potentiometric titration.     

Patterning polymerized lipid vesicles with soft lithography

The applications of soft lithography in patterning polymerized lipid vesicles of 1,2-bis(tricosa-10,12-diynoyl)-sn-glycero-3-phosphocholine on glass substrates are reported. We demonstrate that the polymerized vesicles can be used as a high molecular weight ink to be transferred from a PDMS stamp onto a glass substrate to form two-dimensional stripes with a controlled separation. By combining channel flow with dewetting within microfluidic networks, we assemble the polymerized vesicle into three-dimensional stripes and one-dimension lines on glass substrates. Atomic force microscopy shows that these patterned vesicle structures are stable on glass substrates. The simple, stable, and precise immobilization of lipid vesicles on solid substrates will open up the possibility of integrating them in biosensors and microelectronic devices.     

Electron deficiency of aldehydes controls the pyrrolidine catalyzed direct cross-aldol reaction of aromatic/heterocyclic aldehydes and ketones in water

A synthetically useful pyrrolidine catalyzed direct cross-aldol reaction of aromatic/heterocyclic aldehydes with ketones in water affords the aldol addition product in up to 93% yield. Electrophilicity of the aldehydes controls the course of the reaction.     

Use of ion-exchange chromatography coupled with TLC-laser scanning densitometry for the quantitation of fumonisin B(1)

A simple TLC-Laser scanning densitometric (TLC-LSD) method was developed for the quantitation of fumonisin B(1) (FB(1)) isolated from solid media cultures (corn) and liquid media cultures of toxigenic Fusarium moniliforme strains (F. moniliforme MRC 826, F. moniliforme 4223 and F. moniliforme 2927)). FB(1) was isolated from the cultures by solvent extraction (methanol:water, 3:1) and purified in a single step by ion-exchange chromatography using Dowex-1. FB(1) in the purified extracts was detected by TLC analysis using p-anisaldehyde as a post-chromatographic derivatizing agent. The major toxin identified was FB(1) (R(f) 0.51) along with traces of FB(2) (R(f) 0.57) and FB(3) (R(f) 0.60) based on their comparison with the reference standard fumonisins. The sensitivity of the TLC-LSD method for the quantitation of FB(1) was found to be 500 ng g(-1). The linear regression analysis performed for the quantitation of FB(1) by the TLC-LSD method showed a correlation coefficient (r) value of 0.9. Spiking studies revealed the recovery of standard FB(1) (5 and 10 mug g(-1)) loaded on to Dowex-1 in the range of 87-96%. The purity of FB(1) purified from the cultures was determined by the two-dimensional TLC analysis. Two-dimensional TLC-analysis of the purified FB(1) revealed the purity to be greater than 85%. The method developed may find wide application in the environmental monitoring of the FB(1) contaminations in the various agricultural commodities and screening fumonisin producing toxigenic strains of F. moniliforme.     

High-resolution diffusion-ordered spectroscopy to probe the microenvironment of JandaJel and Merrifield resins

The success of organic reactions performed on a gel-phase resin is highly dependent on the accessibility of solvents, catalysts, and reagents to the interior of the resin. A variety of techniques including EPR, fluorescence, and Hildebrand solubility parameters (delta) have been used to probe reaction capabilities and in particular the microenvironment of a gel-phase resin. To provide a more detailed picture of the matrix in question, researchers have turned to NMR for the determination of the diffusion coefficients of solvents and small molecules in swollen beads to provide a means to compare the microenvironment of swollen beads. Since Merrifield and JandaJel resins display different swelling properties and have significantly different kinetic behavior, we undertook a comparative study of the diffusion coefficients of solvents and small molecules in both resins by high-resolution (1)H DOSY NMR. Our results show the following: (1) diffusion values for all studied solvents and small molecules are 20-30% higher in JandaJel compared to Merrifield resins, (2) in the absence of interactions between the resin and a given molecule, the diffusion values mirror the swelling properties of the resin, and (3) in the presence of strong intermolecular interactions between the gel and the considered molecule, the diffusion behavior in the gel is primarily influenced by the strength of the interactions and secondarily by the swelling properties of the resin. These results clearly show that the microenvironment of JandaJels is more "solution-like" than that of Merrifield resins, presumably due to the higher swelling capacity.     

Green synthesis of silver nanoparticles using green alga (Chlorella vulgaris) and its application for synthesis of quinolines derivatives

Nanoparticles have been used century ago but have regained their importance in recent years being simple, ecofriendly, pollutant free, nontoxic, low-cost approach, and due good atom economy. In this report, we have demonstrated the synthesis of silver nanoparticles using green algae (Chlorella vulgaris) which in turn was used for synthesis of biologically important quinolines. Algal extract was prepared and treated with silver nitrate solution for the synthesis of silver nanoparticles. Synthesized nanoparticles were characterized with the help of analytical tools like UV, FTIR, X-ray, and SEM and used as a catalyst for the synthesis of quinolines.     

Di(2-ethylhexyl)sulfoxide as an extractant for plutonium(IV) from nitric acid medium

The liquid-liquid extraction behavior of plutonium(IV) from aqueous nitric acid media into n-dodecane by di(2-ethylhexyl)sulfoxide (DEHSO) was investigated over a wide range of conditions. Optimum-parameters such as the aqueous phase acidity, reagent and metal concentrations, etc., were established for efficient extraction-separation of tracer as well as macro levels of plutonium. It was found that the extraction increased with increasing nitric acid concentration up to 6M HNO₃ and then decreased. Extraction also increased with increasing extractant concentration. After loading of the organic phase with 2 to 50 mg/ml of U(VI), extractability of Pu(IV) became considerably lower. Recovery of Pu(IV) from the organic phase was accomplished using dilute uranium(IV) nitrate as the strippant.     

Erratum: “Martini Coarse-Grained Model for Polyethylenimine” [J. Comput. Chem. 2019, 40, 607–618, DOI:10.1002/jcc.25747]

Correction of calculation errors in the original article led to the change of bead type for the unprotonated beads in the coarse-grained polyethylenimine model. The original model was still of good quality while the updated model showed better performance in describing the interaction between polyethylenimine and DNA.     

Quantitative TLC Analysis of Sterol (24β-Ethylcholesta-5,22E,25-triene-3β-ol) in Agnimantha (Clerodendrum phlomidis Linn)

A quantitative method using silica gel 60F₂₅₄ high performance thin layer chromatography plates, automated bandwise sample application, and automated visible mode densitometric method has been developed for the determination of 24β-ethylcholesta-5,22E,25-triene-3β-ol (ECTO) in the aerial part of Clerodendrum phlomidis. ECTO was used as a chemical marker for the standardization of C. phlomidis plant extracts. The separation was performed on silica gel 60F₂₅₄ TLC plates using chloroform-methanol (98.5: 1.5, v/v) as mobile phase. The quantitation of ECTO was carried out using the densitometric reflection/absorption mode at 650 nm after post chromatographic derivatization with anisaldehyde reagent. A precise and accurate quantification can be performed in the linear working concentration range of 150–400 ng band⁻¹ with good correlation (r ² = 0.996). The method was validated for peak purities, precision, robustness, limit of detection (LOD) and quantitation (LOQ), etc. as per ICH guidelines.