A hybrid proximal point algorithm for finding minimizers and fixed points in CAT(0) spaces

We introduce a hybrid proximal point algorithm and establish its strong convergence to a common solution of a proximal point of a lower semi-continuous mapping and a fixed point of a demicontractive mapping in the framework of a CAT(0) space. As applications of our new result, we solve variational inequality problems for these mappings on a Hilbert space. Illustrative example is given to validate theoretical result obtained herein.     

Super crystal structures of octahedral c-In2O3 nanocrystals

The three-dimensional self-assembly of a nanocrystal superlattice, i.e., a super crystal, has attracted increasing attention. The small building blocks for assemblies are usually spherical nanocrystals. Recent progress indicates that it is possible to achieve a super crystal using cubic nanocrystals. We further analyze and describe two-dimensional and some three-dimensional assemblies of uniform cubic-phase In2O3 nanocrystals with an octahedral shape. In this article, we demonstrate our amazing observations on these kinds of super crystals (or superlattices) as a model system, report their scale in at least tens of microns, and show other interesting features such as steps, terraces, kinks, and vacancies which are similar to those from a single crystal. Based on electron microscopy observations, three types of well-defined octahedral nanocrystal packed structures in such super crystal systems are also identified. The investigation of octahedral super crystal systems provides an alternate direction in research that may extend the interest of superlattice study to a broad spectrum by enriching and varying the shape of elemental building blocks. This may potentially result in new concepts and more challenging applications such as soft X-ray photonics.     

Investigation of Parameters that Affect Resin Swelling in Green Solvents

The influence of various physical and chemical factors on the swelling of polystyrene and PEG based resins in greener organic solvents has been systematically investigated. In general, chemical factors: the nature of the functionality/linker and the degree of loading were found to have a far larger influence on the swelling of the resins than physical parameters such as bead size. The results are interpreted in terms of Hansen solubility parameters for the solvents and there is evidence that some solvents interact with the polymeric core of a resin whilst others interact with the functionality. The results are extended to a study of the changes in resin swelling observed during both deprotection and chain elongation reactions during solid phase peptide synthesis.     

Separation of oxidized variants of a monoclonal antibody by anion-exchange

Monoclonal antibodies are subject to a variety of degradation mechanisms, therefore orthogonal techniques are required to demonstrate product quality. In this study, the three individual antibodies comprising a multi-antibody drug product, XOMA 3AB were evaluated by both cation-exchange (CEX) and anion-exchange chromatography (AEX). In contrast to CEX analysis which showed only a single, broad peak for the force-oxidized antibodies, AEX analysis of Ab-A (pI=7.6) revealed two more basic peaks. Ab-B (pI=6.7) bound but exhibited only a single major peak while Ab-C (pI=8.6) flowed through. Peptide mapping LC/MS analysis of the isolated Ab-A fractions demonstrated that the basic peaks resulted from oxidation in a complementary determining region (CDR). Differential scanning calorimetry (DSC) analysis of the oxidized Ab-A species showed a decrease in the Fab melting point for the oxidized species consistent with unfolding of the molecule. Greater/lesser surface exposure of ionic residues resulting from a conformational change provides a likely explanation for the dramatic shift in retention behavior for the Ab-A oxidized variants. Peptide mapping analysis of the Ab-B antibody showed, in contrast to Ab-A, no detectable CDR oxidation. Hence, the lack of separation of oxidized variants in Ab-B can be explained by the absence of CDR oxidation and the associated changes in secondary/tertiary structure which were observed for oxidized Ab-A. In summary, anion-exchange HPLC shows potential as an orthogonal analytical technique for assessing product quality of monoclonal antibody therapeutics. In the case of the XOMA 3AB drug product, two of the antibodies bound and one, Ab-A, exhibited separation of CDR oxidized variants.