High pressure liquid chromatographic separation of two major toxic compounds from Gymnodinium breve davis

Cultured Gymnodinium breve cells were extracted in acidified ether and fractionated by a new, convenient procedure utilizing thin layer chromatography or elution dry column chromatography. The most toxic fraction was further separated either directly by analytical high pressure liquid chromatography (HPLC) or in subsequent work by preparative, followed by analytical HPLC. Two toxic compounds, designated T46 and T47, were isolated; purity of each was demonstrated by rechromatography in analytical HPLC with both adsorptive and reverse phase packings. Both the single pass and recycle modes of operation were used with two detector systems in each to demonstrate a single entity. UV, fluorescence, and stability data differentiated these compounds from previously described, less toxic components from G. breve.     

Development and Characterization of Highly Conducting Nonfluorinated Di and Triblock Copolymers for Polymer Electrolyte Membranes

To achieve stable polymer electrolyte membranes (PEMs) with efficient ionic nano-channels, novel fully aromatic AB or ABA copolymers composed of poly(fluorenyl ether sulfone biphenyl)s (PFESBs) and poly(arylene ether sulfone)s (PAESs) were synthesized via polymerization and post-sulfonation methods, and were explored as fuel cell membranes. The structural analysis of synthesized copolymers and the corresponding membranes were ascertained by gel permeation chromatography (GPC), Fourier transform infrared (FTIR), and ¹H nuclear magnetic resonance (NMR) techniques. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) analysis showed that the prepared membranes were thermally stable, so that elevated temperature fuel cell operation would be possible. High hydrophilic and hydrophobic nano-phase separation and obvious ionic aggregate block morphology was observed in both triblock and diblock copolymers in atomic force microscopy (AFM) phase images, which may be highly related to their proton transport ability. A sulfonated AB diblock copolymer membrane with an ion-exchange capacity (IEC) of 2.06 meq g^?1 has a maximum proton conductivity of 184 mS cm^?1, which is higher than that of a perfluorosulfonic acid membrane under the same measurement conditions.     

Expeditious novel routes to enantiopure 3-amino tetrahydrofuran hydrochloride

The synthesis of chemically and enantiomerically pure (S)-3-amino tetrahydrofuran hydrochloride starting from the natural amino acids, l-aspartic acid or l-methionine is described. The process involves no chromatography and can be easily carried out on a large scale. The enantiopurity of the final product was established by NMR and chiral HPLC methods.     

Separation of carrier-free 90Y from high level waste by supported liquid membrane using KSM-17

A generator system has been developed for the preparation of carrier-free ⁹⁰Y from ⁹⁰Sr present in the high level waste (HLW) of the Purex process by employing a supported liquid membrane (SLM) using 2-ethylhexyl-2-ethylhexyl phosphonic acid (KSM-17 equivalent to PC 88A) supported on a polytetrafluoro ethylene (PTFE) membrane. When uranium depleted Purex HLW at appropriate acidity is passed sequentially through octyl (phenyl)-N,N-diisobutylcarbamoylmethylphosphine oxide (CMPO) sorbed on chromosorb-102 (abbreviated as CAC) and Zeolite AR1 (synthetic mordenite) columns, all the trivalent, tetravalent and hexavalent metal ions and monovalent ¹³⁷Cs ions are sorbed. After adjusting to pH 2 with NaOH the resulting effluent is used as feed in a single stage membrane cell partitioned with a PTFE membrane impregnated with KSM-17 and having a feed and receiver compartment with 5.0 ml capacity each. The receiver compartment was filled with a 0.5M HNO₃ or 0.5M HCl stripping solution. ⁹⁰Y alone is preferentially transported across the membrane leaving behind all the impurities viz. ⁹⁰Sr, ¹²⁵Sb, ¹⁰⁶Ru, ¹⁰⁶Rh, etc. in the feed compartment. This technique can yield ⁹⁰Y in mCi levels in a pure and carrier-free form for medical applications. The feed can be reused repeatedly after allowing for ⁹⁰Y buildup.     

Evaluation of nucleic acid duplex formation on gold over layers in biosensor fabricated using Czochralski-grown single-crystal silicon substrate

With a view to developing an economical and elegant biosensor chip, we compared the efficiencies of biosensors that use gold-coated single-crystal silicon and amorphous glass substrates. The reflectivity of light over a wide range of wavelengths was higher from gold layer coated single-crystal silicon substrates than from glass substrates. Furthermore, the efficiency of reflection from gold layers of two different thicknesses was examined. The thicker gold layer (100 nm) on the single-crystal silicon showed a higher reflectivity than the thinner gold film (10 nm). The formation of a nucleic acid duplex and aptamer–ligand interactions were evaluated on these gold layers, and a crystalline silicon substrate coated with the 100-nm-thick gold layer is proposed as an alternative substrate for studies of interactions of biomolecules.     

PdNi-decorated manganite nanocatalyst for electrooxidation of ethylene glycol in alkaline media

PdNi bimetallic nanoparticles coated onto manganite (MN) nanocatalyst was used for ethylene glycol (EG) and glycerol (Gly) electrooxidation in alkaline media. The MN nanorods were prepared by hydrothermal method, and the PdNi was coated on the rods by an in situ reduction method. The prepared nanocomposite was characterized by scanning electron microscopy (SEM), Transmission Electron Microscopy (TEM), Energy dispersive X-ray spectroscopy (EDS), and electrochemical methods. The SEM and TEM images exhibit the formation of nanorods of 10?nm and also show the formation of nanocrystalline PdNi on the walls of the MN nanorods. This study shows that the MN nanorods can be excellent support material and they supply oxygen to the catalyst, by which the catalytic activity is enhanced. The electrooxidation reactions in strong alkaline condition containing various concentrations of EG have been studied. Among the different concentrations, 9?M KOH/6?M EG exhibits the highest activity. PdNi/MN nanocatalyst exhibits better activity even in higher electrolytic concentrations of EG and alkali.     

Recovery of actinides extracted by Truex solvent from high level waste using complexing agents

This work deals with the batch studies on stripping of actinides extracted by a mixture octyl(phenyl)-N,N-diisobutyl-carbamoylmethylphosphine oxide (CMPO) and tri-n-butyl phosphate (TBP) in n-dodecane (Truex solvent) from simulated high level waste (HLW) solution. The stripping of americium and plutonium from acid-bearing CMPO-TBP mixture is carried out using a mixture of weak acid, weak base and complexing agent as strippant. A mixture of formic acid, hydrazine hydrate and citric acid appeared to be best suited for efficient stripping of americium and plutonium. With appropriate modifications in the concentration of individual constitutents, this strippant can be used for the recovery of actinides from loaded Truex solvent with any acid content.     

Fitted mesh method for singularly perturbed reaction-convection-diffusion problems with boundary and interior layers

A robust numerical method for a singularly perturbed secondorder ordinary differential equation having two parameters with a discontinuous source term is presented in this article. Theoretical bounds are derived for the derivatives of the solution and its smooth and singular components. An appropriate piecewise uniform mesh is constructed, and classical upwind finite difference schemes are used on this mesh to obtain the discrete system of equations. Parameter-uniform error bounds for the numerical approximations are established. Numerical results are provided to illustrate the convergence of the numerical approximations.     

Initial-Value Technique for Singularly Perturbed Boundary-Value Problems for Second-Order Ordinary Differential Equations Arising in Chemical Reactor Theory

An initial-value technique is presented for solving singularly perturbed two-point boundary-value problems for linear and semilinear second-order ordinary differential equations arising in chemical reactor theory. In this technique, the required approximate solution is obtained by combining solutions of two terminal-value problems and one initial-value problem which are obtained from the original boundary-value problem through asymptotic expansion procedures. Error estimates for approximate solutions are obtained. Numerical examples are presented to illustrate the present technique.