O2 reduction to H2O by the multicopper oxidases

In nature the four electron reduction of O2 to H2O is carried out by Cytochrome c oxidase (CcO) and the multicopper oxidases (MCOs). In the former, Cytochrome c provides electrons for pumping protons to produce a gradient for ATP synthesis, while in the MCOs the function is the oxidation of substrates, either organic or metal ions. In the MCOs the reduction of O2 is carried out at a trinuclear Cu cluster (TNC). Oxygen intermediates have been trapped which exhibit unique spectroscopic features that reflect novel geometric and electronic structures. These intermediates have both intact and cleaved O-O bonds, allowing the reductive cleavage of the O-O bond to be studied in detail both experimentally and computationally. These studies show that the topology of the TNC provides a unique geometric and electronic structure particularly suited to carry out this key reaction in nature.     

The first example of a recursive function which is not primitive recursive

The first example of a recursive function which is not primitive recursive is usually attributed to W. Ackermann. The authors of the present paper show that such an example can also be found in a paper by G. Sudan, published concomitantly with Ackermann's paper.     

Trianglimine-Mediated Selective Sieving of Cis Isomer from the Mixture of Dihaloethenes: A Combined Molecular Dynamics and DFT Investigation

The manufacture of alkenyl halides on a larger scale often results in the formation of a mixture of isomers, each having individual significant applications while their separation from each other is a strenuous task. Since most of the conventional distillation techniques are known to be intricate, energy consuming and expensive, the quest for an alternative separation strategies is still continuing. In this context, the recently reported trianglimine macrocycle - a new class of intrinsically porous material, is promising in discerning cis isomer from a mixture of cis and trans dichloroethene. Herein, an attempt has been made to apprehend the host-guest inclusion phenomenon accountable for the selectivity of cis over the trans isomers of 1,2-dihaloethene (F, Cl and Br) using molecular dynamics simulation and density functional calculations at ω-B97xd/6-311G+(d,p) level of theory. The average binding energy of selected snapshots has been calculated at different loadings, temperatures and pressures from molecular dynamics simulation. Our results show that trianglimine can stabilise the cis isomers of the dihaloethenes inside its cavity forming complexes with high interaction energies and the rationale behind the recyclability of the host molecule has been clarified. The outcomes of the calculations bring out the potential utility of this new host architecture to produce highly pure value added chemicals in industries.     

Heterologous Expression and Engineering of the Nitrogenase Cofactor Biosynthesis Scaffold NifEN

NifEN plays a crucial role in the biosynthesis of nitrogenase, catalyzing the final step of cofactor maturation prior to delivering the cofactor to NifDK, the catalytic component of nitrogenase. The difficulty in expressing NifEN, a complex, heteromultimeric metalloprotein sharing structural/functional homology with NifDK, is a major challenge in the heterologous expression of nitrogenase. Herein, we report the expression and engineering of Azotobacter vinelandii NifEN in Escherichia coli. Biochemical and spectroscopic analyses demonstrate the integrity of the heterologously expressed NifEN in composition and functionality and, additionally, the ability of an engineered NifEN variant to mimic NifDK in retaining the matured cofactor at an analogous cofactor‐binding site. This is an important step toward piecing together a viable pathway for the heterologous expression of nitrogenase and identifying variants for the mechanistic investigation of this enzyme.     

An inertial method for a solution of split equality of monotone inclusion and the f$$ f $$-fixed point problems in Banach spaces

In this paper, we propose an inertial algorithm for solving split equality of monotone inclusion and $f$-fixed point of Bregman relatively $f$-nonexpansive mapping problems in reflexive real Banach spaces. Using the Bregman distance function, we prove a strong convergence theorem for the algorithm produced by the method in real reflexive Banach spaces. In addition, we provide some applications of our method and give numerical results to demonstrate the applicability and efficiency of the proposed method.     

Studies on microgels, 3. Synthesis using living free radical polymerization

Microgels which are soluble crosslinked polymer networks have been prepared using the nitroxide living free radical polymerization methodology. When heated in the presence of tert-butylstyrene and 1,4-divinylbenzene, the alkoxyamine 1 derived from 2,2′-azoisobutyronitrile (AIBN) afforded a high molecular weight soluble polymer which was shown by size exclusion chromatography in conjunction with an on-line multi angle laser light scattering (MALLS) detector to have microgel properties.