Anion-exchange separation of thorium and protactinium from uranium matrix

Summary The distribution behaviour of Th⁴⁺, Pa⁵⁺, and UO₂ ²⁺ ions between the anion-exchanger Amberlite IRA-400 and acetic acid-hydrochloric acid mixtures, has been investigated. It was found that the general behaviour of Th⁴⁺ ions is similar to that of UO₂ ²⁺ ions though the latter are much more highly adsorbed by the resin than Th⁴⁺. Protactinium exhibited a different behaviour from both Th⁴⁺ and UO₂ ²⁺ ions. The separation factors were calculated, and a Chromatographic procedure for sequential isolation of each element was developed.

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Zusammenfassung Das Verteilungsverhalten von Th⁴⁺, Pa⁵⁺ und UO₂ ²⁺ zwischen dem Anionenaustauscher Amberlit IRA-400 und Gemischen aus Essigsäure und Salzsäure wurde untersucht. Das allgemeine Verhalten von Th⁴⁺ ist ähnlich dem von Uranylionen, wenngleich letztere von dem Harz viel stärker adsorbiert werden als Th⁴⁺. Protactinium zeigt ein abweichendes Verhalten im Vergleich zu Th⁴⁺ und UO₂ ²⁺. Die Trennfaktoren wurden berechnet und ein chromatographisches Verfahren zur Isolierung der angeführten Ionen entwickelt.

     

Isolation and characterization of a novel lepidopteran-selective toxin from the venom of South Indian red scorpion, Mesobuthus tamulus

Background

Scorpion venom contains insect and mammal selective toxins. We investigated the venom of the South Indian red scorpion, Mesobuthus tamulus for the purpose of identifying potent insecticidal peptide toxins.

Results

A lepidopteran-selective toxin (Buthus tamulus insect toxin; ButaIT) has been isolated from this venom. The primary structure analysis reveals that it is a single polypeptide composed of 37 amino acids cross-linked by four disulfide bridges with high sequence homology to other short toxins such as Peptide I, neurotoxin P2, Lqh-8/6, chlorotoxin, insectotoxin I5A, insect toxin 15 and insectotoxin I1. Three dimensional modeling using Swiss automated protein modeling server reveals that this toxin contains a short α-helix and three antiparallel β-strands, similar to other short scorpion toxins. This toxin is selectively active on Heliothis virescens causing flaccid paralysis but was non-toxic to blowfly larvae and mice.

Conclusion

This is the first report of a Heliothine selective peptide toxin. Identification of diverse insect selective toxins offer advantages in employing these peptides selectively for pest control.     

Electronic Structure of Copper Corroles

The ground state electronic structure of copper corroles has been a topic of debate and revision since the advent of corrole chemistry. Computational studies formulate neutral Cu corroles with an antiferromagnetically coupled Cu^II corrole radical cation ground state. X‐ray photoelectron spectroscopy, EPR, and magnetometry support this assignment. For comparison, Cu^II isocorrole and [TBA][Cu(CF₃)₄] were studied as authentic Cu^II and Cu^III samples, respectively. In addition, the one‐electron reduction and one‐electron oxidation processes are both ligand‐based, demonstrating that the Cu^II centre is retained in these derivatives. These observations underscore ligand non‐innocence in copper corrole complexes.     

Vibrational pumping in surface enhanced Raman scattering (SERS)

In this tutorial review, the underlying principles of vibrational pumping in surface enhanced Raman scattering (SERS) are summarized and explained within the framework of their historical development. Some state-of-the-art results in the field are also presented, with the aim of giving an overview on what has been established at this stage, as well as hinting at areas where future developments might take place.     

An in situ amperometric biosensor for the detection of vapours from explosive compounds

An amperometric biosensor based on genetically-modified enzymes was used for the in situ detection of trace vapours from a number of explosive compounds. The vapour samples that were generated from a purpose-built vapour generator were collected and pre-concentrated using a trap able to concentrate samples at a rate of 60-fold per minute of sampling. The amperometric biosensor achieved a remarkably low vapour detection limit of 6 parts per trillion from a room temperature sample. The specific activity of the reported enzyme toward a number of explosive compounds was also confirmed using absorbance measurements.     

Heteropolymetallic copper(II)-gold(III) dithiocarbamate [2]catenanes via magic ring synthesis

A rare class of mixed-metal [2]catenane has been assembled via magic ring synthesis of dinuclear copper(II) and gold(III) dithiocarbamate macrocycles.     

Molecular orbital treatment of phenylfurans and bifurans

The molecule-in-molecule method of computation has been applied in a SCF study of the electronic absorption spectra of 2- and 3-phenylfurans and 2,2′- and 3,3′-bifurans. The computed values for the transition energies and band intensities differ for the different isomers and help one to assign the preferred conformer of the studied molecules. Computations were performed on planar as well as nonplanar conformers. The calculated parameters as well as the interaction energy suggest all-planar configuration for the studied molecules. A model potential for the sigma framework for the ortho-hydrogens is considered. The calculated steric repulsion energy is negligible compared to the π delocalization. The height of the rotational barrier was larger for 2-phenylfuran than for 3-phenylfuran, and larger for 2,2′-bifuran than for 3,3′-bifuran. This result is in accord with predictions based on the extent of “π” conjugation in these molecules.     

Regioselective Diastereomeric Michael Adducts as Building Blocks in Heterocyclic Synthesis

The reaction of 4‐(4‐acetylamino/bromophenyl)‐4‐oxobut‐2‐enoic acids with carbon nucleophiles afforded Michael adducts depending on the type of nucleophilic reagents and medium (acidic or basic). The adducts 2 and 3 were used as key starting materials to synthesize some heterocyclic compounds, which include pyridazinone, furanone, 1,2‐oxazin‐5‐one, 1.2‐diazapine, pyrane, and hydroxyl pyridine derivatives. The Steric factor plays an important role in regioselectivity. The structure of newly synthesized compounds was elucidated by elemental analysis and spectroscopic data.